University of Groningen Optimization of Mandibular Fracture Treatment

University of Groningen

Optimization of mandibular fracture treatment Batbayar, Enkh-Orchlon

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Download date: 08-10-2021 Optimization of mandibular fracture treatment The research presented in this thesis was performed at the Department of Oral and Maxillofacial Surgery, University Medical Center Groningen, the Netherlands.

Printing of this thesis was kindly supported by:

University Medical Center Groningen (UMCG), University of Groningen (RUG) Graduate School Of Medical Sciences, University of Groningen (RUG) KLS Martin, www.klsmartin.com Centre for East Asian Studies Groningen (CEASG), www.rug.nl/ceasg Hureelen project/Хүрээлэн төсөл, [email protected] SomnoMed Goedegebuure, www.iucn.org Straumann group, www.straumann-group.com

Cover design: Otgongerel Nyamsambuu Lay-out: Rianne Jongman ([email protected]) Printed by: Ipskamp Printing - Enschede ISBN (printed): 978-94-034-1605-2 ISBN (digital): 978-94-034-1604-5 Optimization of mandibular fracture treatment

PhD thesis

to obtain the degree of PhD at the University of Groningen on the authority of the Rector Magnificus prof. E. Sterken and in accordance with the decision by the College of Deans.

This thesis will be defended in public on

Monday 27 May 2019 at 14.30 hours

Enkh-Orchlon Batbayar

born on 23 August 1985 in Ulaanbaatar, Mongolia Supervisors Prof. R.R.M. Bos Prof. P.U. Dijkstra

Co-supervisor Dr. B. van Minnen

Assessment Committee Prof. S.K. Bulstra Prof. T. Forouzanfar Prof. J. de Lange Paranimfen Dr. T.A.van der Meulen Drs. O.Byambasukh TABLE OF CONTENTS

CHAPTER 1 Introduction and aim of the thesis 9

CHAPTER 2 Non-IMF mandibular fracture reduction techniques: 21 a review of the literature

CHAPTER 3 Accuracy and outcome of manibular fracture reduction 37 without and with aid of repositioning forceps

CHAPTER 4 Development and feasibility of a new reduction forceps 53 for mandibular fractures: a technical innovation

CHAPTER 5 Complications of locking and non-locking plate 63 systems in mandibular fractures: a systematic review and meta-analysis

CHAPTER 6 A treatment protocol for fractures of the edentulous 95 mandible

CHAPTER 7 Quantitative 3-dimensional computed tomography 113 measurements provide a precise diagnosis of fractures of the mandibular condylar process.

CHAPTER 8 General discussion 135

CHAPTER 9 Summary 145

CHAPTER 10 Nederlandse samenvatting (Summary in Dutch) 151

Acknowledgements 157 Appendix 169 Curriculum Vitae 173 For my beloved grandmother

Хайрт эмээ болон гэр бүлийнхэндээ зориулав Gobi bear Mazaalai (Ursus Arctos Gobiensis), Credit: Hureelen/ Ganbayar Urtnasan CHAPTER 1

INTRODUCTION AND AIM OF THE THESIS Chapter 1

INTRODUCTION

Management of mandibular fractures has a long and extensive history. The first known description of mandibular fracture treatment is described 1600 BC in an ancient Egyptian medical text known as the “Edwin Smith Papyrus”1. From this time till the 19th century, mandibular fractures were mainly immobilized with head-to-jaw bandages after manual repositioning of the fractures. From the 19th century, the management of mandibular fractures focused on restoration of the occlusion. Simultaneously, management of the fractures shifted from general surgeons to the oral and maxillofacial surgeons. Many intra- and extra-oral splints and circum-mandibular wiring techniques were introduced and modified to immobilize the fractures. For instance, the Gunning splint (by Thomas Gunning), wire ligatures (by Gurnell Hommond), re-introduction of intermaxillary fixation (by Thomas L.Gilmer), Angle’s apparatus (Dr. Angle), and the Ivy loop (Robert H.Ivy) were introduced during the 19th century1. All these methods were closed treatments of the mandibular fractures. The definition of terms “closed” and “open” treatment of the mandibular fractures has been controversial around the world. According to the consensus article by Bos et al.2 closed treatment is defined as any treatment that does not involve an open surgical exposure of the fracture whereas open treatment means surgical exposure of the fractures, reduction and fixation2. Closed treatment is still applied in certain cases of mandibular fractures, particularly for the treatment of incomplete fractures, high condylar fractures, and a selection of nondisplaced, immobile fractures.

To achieve uncomplicated fracture healing with open treatment, the following three factors must be considered:

1. Vascularization. The cranio-maxillo-facial region is the most vascularized region of the body, but the mandible is less vascularized than the midface region. The major blood supply of the mandible is provided by the lingual, facial and inferior alveolar arteries.

2. Adequate anatomical reposition (reduction). Reduction of the fractured mandible is crucial to achieve uncomplicated fracture healing. Reduction is the action of reestablishing a fracture by returning the affected segments of the mandible to their normal anatomical position.

10 Introduction and aim of the thesis

Fig 1. Schematic drawing of bone healing. A, Primary bone healing with direct bridging of the fracture through Haversian canals. B, Secondary bone healing though callus formation.

3. Immobilization by means of internal fixation. Open reduction is performed with surgical intervention and it is always followed by immobilization of the fracture. Immobilization has been routinely managed by internal fixation.

Stable immobilization leads to primary bone healing without callus formation. Conversely, if immobilization is not rigid enough, the fracture may heal by secondary healing which means that callus formation will occur (Fig 1). Besides these factors, other factors such as the patient’s age, general health, and type of fracture will influence the healing.

Surgical instruments like clamps or forceps have played an important role in the history of traumatology from 1600BC to recent years3. The first known pivot joint forceps were introduced by Charriere (1845)3,4. Subsequently, this pivot joint design was modified as a fracture holding forceps, by Faraboeuf and Lambotte3. Since then, all kinds of modifications have been made, and reduction forceps are routinely used in the modern practice of trauma surgery. The main function of a fracture holding forceps is to secure a firm grasp on the fracture segments in order to get an anatomical reduction of the fracture

11 Chapter 1

without damaging soft tissues and bone allowing comfortable and precise fixation of the fracture. In this manner, fracture fragments can be optimally reduced to enable primary bone healing. The development and use of fracture reduction instruments has mainly been restricted to the field of general trauma surgery and orthopaedic surgery. The role of these instruments in mandibular fracture treatment has been modest. So far no attempt has been made to estimate the benefits and pitfalls of fracture reduction forceps in mandibular fracture treatment. The first goal of this thesis was to review currently available mandibular fracture reduction/alignment methods. This was done with the idea that optimal fixation of a fracture can only be achieved after optimal reposition.

Nowadays, fixation of a mandibular fracture is always achieved by applying one of the available plate and screw systems. In 1886, the German surgeon Hansmann was the first to invent the plate-screw-system for fixation of bone fragments. Much later Luhr5 (1968) introduced the vitallium compression plate osteosynthesis for mandibular fractures, which had eccentric holes and screws with a conical head while the plates were shaped like a half-pipe surrounding the lower body of the mandible. Since then, numerous plate and screw systems have been introduced and applied for fracture fixation6.

Principally, an osteosynthesis of the mandible can be categorized as ‘load bearing’ or ‘load sharing’. Load bearing plates (also called reconstruction

Fig. 2. A, Regular mini-plate and self-tapping screw. B, Mini-locking-system plate and self-tapping locking screw (Synthes, Umkirch, Germany), Sauerbier S et al. 20086.

12 Introduction and aim of the thesis

plates) are applied when the osteosynthesis system has to withstand all the functional forces at the fracture site. Load-bearing plates are applied in case of complex comminuted fractures, infected fractures, and fractures of a severely atrophic mandible. The dimension of these plates is usually rather coarse. In 1 contrast, the smaller load sharing plates distribute functional forces between plate and bone. Generally, these plates are known as a mini-plates (Fig 2A). As a result of their smaller size they are suitable in cases where, after reduction, interfragmentary stability of the repositioned fragments contributes to the stability of the fracture as a whole. This principle of load sharing fixation only works if the mini-plates are placed in the so-called tension zone. This was made clear during the first attempts to fixate a mandibular fracture with mini-plates. Brons and Boering7, applied small finger plates developed for hand surgery6. However, they inserted the plates at the lower border of the mandible which was biomechanically unfavorable. Subsequently, Michelet et al. and Champy et al.8,9 developed the mini-plates systems, and contributed enormously to the understanding of the biomechanical characteristics of the mandible. The Champy’s principle was invented based on the previously introduced surgical device, the mini-plate. It shows that after careful investigation, sometimes it is possible to develop the new surgical techniques by considering surgical instruments.

Another basic concept of osteosynthesis is the locking plate system (Fig 2B). The distinctive feature of the locking plate system is that the screw head itself is threaded and locks firmly into a thread in the plate hole, and so works like an external fixation10–12. The locking plate systems are available for both load bearing and load sharing plates. Hypothetically, the advantages

Fig 3. Fixation of an apple on a plate. (A) With a locking screw, the assembly is stable. (B) With an untightened conventional screw, the assembly is unstable. (C) Compression is necessary against the plate, Cronier et al. 201010.

13 Chapter 1

Fig. 4. An example of virtual preoperative planning of the atrophic mandibular fracture.

of a locking plate system over a conventional plate system are less screw loosening, greater stability, while less accuracy is required in plate adaption (Fig 3). Although there are many reports in the literature on the outcome of a locking plate system, most are restricted to biomechanical studies, particularly in mandibular fractures13–16. While some clinical studies also tend to favor the use of a locking plate system in mandibular fractures, other clinical studies did not find a difference with regard to postoperative complications17–21.

Open reduction is facilitated by all instruments and osteosynthesis materials that have been developed in the past century. In addition, the methods for surgical access to the fractures have been improved. A more recent development is the possibility of pre-operative planning of complicated fractures (Fig 4). This development also contributes to anatomical reduction and stable fixation of the fractures.

However, the ultimate goal of the treatment of a fractured mandible is not only to restore the anatomy, but also the function. Although techniques and materials for open reduction have been improved continuously there is still room for closed treatment, especially in cases of fractures of the condylar process. Should these be treated open or closed?

Moreover the management of fractures of the edentulous and severely atrophic mandible is still controversial. It is possible that ongoing discussions on closed versus open treatment a caused by a lack of consensus on the exact

14 Introduction and aim of the thesis

diagnosis. Recently, three-dimensional analysis of fractures of tibial plateau and acetabular and as well as radial head fractures has been developed for general trauma surgeons, which provide additional information about the fracture extent and quality of the postoperative reduction23–25. The same method 1 could be applied on mandibular fractures in order to reach an undisputable 3D fracture diagnosis that could help to evaluate treatment outcome. Ultimately this could lead to a better consensus about choices for open and closed treatment.

15 Chapter 1

AIMS OF THE THIS THESIS

Although the outcome of mandibular fracture management is generally satisfactorily there still is room for improvement. The general aim of this thesis was to evaluate fracture reduction/alignment methods including reduction forceps, plate and screw systems, treatment modalities for the edentulous and severely atrophic mandible fractures, and to analyze the condylar process fracture characteristics using three-dimensional methods.

To be more specific: • to review currently available mandibular fracture reduction/alignment methods (Chapter 2) • to evaluate fracture reduction/alignment methods and their influence on postoperative complications (Chapter 3) • to design and develop sophisticated fracture reduction forceps and to test their feasibility (Chapter 4) • to review the cons and pros of locking and non-locking plate systems (Chapter 5) • to assess the management of fractures of the edentulous and atrophic mandible (Chapter 6) • to analyze characteristics of condylar process fractures, based on a three- dimensional analysis (Chapter 7)

16 Introduction and aim of the thesis

REFERENCES

1. Mukerji R., Mukerji G., McGurk M. Mandibular fractures: Historical perspective. Br J Oral Maxillofac Surg 2006;44(3):222–8. Doi: 10.1016/j.bjoms.2005.06.023. 1 2. Bos RR., Ward Booth RP., de Bont LG. Mandibular condyle fractures: a consensus. Br J Oral Maxillofac Surg 1999;37:87–9. Doi: 10.1016/S0266-4356(98)90014-6. 3. Kirkup J. The history and evolution of surgical instruments. X Clamps, haemostats and related pivot-controlled forceps. Ann R Coll Surg Engl 1999;81(6):420–8. 4. Buraimoh MA., Liu JZ., Sundberg SB., Mott MP. Eponymous Instruments in Orthopaedic Surgery n.d.;37. 5. Luhr HG. [On the stable osteosynthesis in mandibular fractures]. Dtsch Zahnarztl Z 1968;23(7):754. 6. Sauerbier S., Schön R., Otten JE., Schmelzeisen R., Gutwald R. The development of plate osteosynthesis for the treatment of fractures of the mandibular body - A literature review. J Cranio-Maxillofacial Surg 2008;36(5):251–9. Doi: 10.1016/j. jcms.2007.08.011. 7. Brons R., Boering G. Fractures of the mandibular body treated by stable internal fixation: a preliminary report.J Oral Surg 1970;28(6):407–15. 8. Michelet FX., Deymes J., Dessus B. Osteosynthesis with miniaturized screwed plates in maxillo-facial surgery. J Maxillofac Surg 1973;1(2):79–84. 9. Champy M., Wilk A., Schnebelen JM. [Tretment of mandibular fractures by means of osteosynthesis without intermaxillary immobilization according to F.X. Michelet’s technic]. Zahn Mund Kieferheilkd Zentralbl 1975;63(4):339–41. 10. Cronier P., Pietu G., Dujardin C., Bigorre N., Ducellier F., Gerard R. The concept of locking plates. Orthop Traumatol Surg Res 2010;96(4 SUPPL.). Doi: 10.1016/j. otsr.2010.03.008. 11. Raveh J., Stich H., Sutter F., Greiner R. Use of the titanium-coated hollow screw and reconstruction plate system in bridging of lower jaw defects. J Oral Maxillofac Surg 1984;42(5):281–94. 12. Herford AS., Ellis E. Use of a locking reconstruction bone plate/screw system for mandibular surgery. J Oral Maxillofac Surg 1998;56(11):1261–5. 13. Haim D., Muller A., Leonhardt H., Nowak A., Richter G., Lauer G. Biomechanical study of the Delta plate and the TriLock Delta condyle trauma plate. J Oral Maxillofac Surg 2011;69(10):2619–25. Doi: 10.1016/j.joms.2011.01.002. 14. Haug RH., Street CC., Goltz M. Does plate adaptation affect stability? A biomechanical comparison of locking and nonlocking plates. J Oral Maxillofac Surg 2002;60(11):1319–26. 15. Ribeiro-Junior PDD., Magro-Filho O., Shastri KAA., Papageorge MBB. In vitro evaluation of conventional and locking miniplate/screw systems for the treatment of mandibular angle fractures. Int J Oral Maxillofac Surg 2010;39(11):1109–14. Doi: 10.1016/j.ijom.2010.06.019.

17 Chapter 1

16. Zimmermann C., Henningsen A., Henkel K-O., Klatt J., Jürgens C., Seide K., et al. Biomechanical comparison of a multidirectional locking plate and conventional plates for the osteosynthesis of mandibular angle fractures—A preliminary study. J Cranio-Maxillofacial Surg 2017;45(12):1913–20. Doi: 10.1016/j.jcms.2017.05.020. 17. Collins CP., Pirinjian-Leonard G., Tolas A., Alcalde R. A prospective randomized clinical trial comparing 2.0-mm locking plates to 2.0-mm standard plates in treatment of mandible fractures. J Oral Maxillofac Surg 2004;62(11):1392–5. Doi: 10.1016/j.joms.2004.04.020. 18. Seemann R., Frerich B., Muller S., Koenke R., Ploder O., Schicho K., et al. Comparison of locking and nonlocking plates in the treatment of mandibular condyle fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108(3):328–34. Doi: 10.1016/j.tripleo.2009.04.026. 19. Zhang J., Wang X., Wu R-HR-H., Zhuang Q-WQ-W., Gu QP., Meng J. Comparative evaluation of 2.3 mm locking plate system vs conventional 2.0 mm non locking plate system for mandibular condyle fracture fixation: a seven year retrospective study. Eur Rev Med Pharmacol Sci 2015;19(5):712–8. 20. Yang L., Patil PM. Comparative evaluation of 2.0 mm locking plate system vs 2.0 mm non-locking plate system for mandibular angle fracture fixation: a prospective randomized study. Eur Rev Med Pharmacol Sci 2015;19(4):552–6. 21. Chrcanovic BRR. Locking versus non-locking plate fixation in the management of mandibular fractures: a meta-analysis. Int J Oral Maxillofac Surg 2014;43(10):1243– 50. Doi: 10.1016/j.ijom.2014.07.014. 22. Merema BJ., Kraeima J., ten Duis K., Wendt KW., Warta R., Vos E., et al. The design, production and clinical application of 3D patient-specific implants with drilling guides for acetabular surgery. Injury 2017;48(11):2540–7. Doi: 10.1016/j. injury.2017.08.059. 23. Meesters A. Three-dimensional computed tomography measurements of acetabular fractures Anne Meesters. University of Twente, 2018. 24. Assink N. Quantitative 3-dimensional fracture analysis and patient reported outcomes in patients with intra-articular tibial plateau fractures. University Medical Center Groningen, University of Groningen, 2019. 25. Guitton TG., Werf HJ Van Der., Ring D. Quantitative three-dimensional computed tomography measurement of radial head fractures. J Shoulder Elb Surg 2010;19(7):973–7. Doi: 10.1016/j.jse.2010.03.013.

18 Introduction and aim of the thesis

19 Siberian musk deer (Moschus moschiferus), Credit: Hureelen/ Ganbayar Urtnasan CHAPTER 2

NON-IMF MANDIBULAR FRACTURE REDUCTION TECHNIQUES:

A REVIEW OF THE LITERATURE

Enkh-Orchlon Batbayar, Baucke van Minnen, Ruud R.M.Bos J Craniomaxillofac Surg. 2017Aug;45(8):1327-1332. https://doi.org/10.1016/j.jcms.2017.05.017 Chapter 2

ABSTRACT

Background. Intermaxillary fixation (IMF) techniques are commonly used in mandibular fracture treatment to reduce bone fragments and re- establish normal occlusion. However, non-IMF reduction techniques such as repositioning forceps may be preferable due to their quick yet adequate reduction. The purpose of this paper is to assess which non-IMF reduction techniques and reduction forceps are available for fracture reduction in the mandible.

Methods. A systematic search was performed in the databases of Pubmed and EMBASE. The search was updated until February 2016 and no initial date and language preference was set.

Results. 14 articles were selected for this review, among them ten articles related to reduction forceps and four articles describing other techniques. Thus, modification and design of reduction forceps and other reduction techniques are qualitatively described.

Conclusion. Few designs of repositioning forceps have been proposed in the literature. Quick and adequate reduction of fractures seems possible with non- IMF techniques resulting in anatomic repositioning and shorter operation time, especially in cases with good interfragmentary stability. Further development and clinical testing of reduction forceps is necessary to establish their future role in maxillofacial fracture treatment.

22 Mandibular fracture reduction techiniques

INTRODUCTION

Mandibular fractures are the most common injuries of the maxillo-facial area.1 Reduction of the fractured bone segments is an important phase of fracture treatment of any bone, as precise reduction facilitates the bone healing process and reduces infections.2,3 Direct bone contact between the fracture segments supports primary bone healing, which leads to earlier bone regrowth and 2 stability across the fracture site. However, reduction gaps of more than 1 mm across fractured bone segments result in secondary healing, which causes callus formation and increases the risk of a malunion.4

Reduction of mandibular fractures is achieved by using intermaxillary fixation (either with IMF screws or splints), reduction forceps, manual reduction, or a combination of these methods. The choice of method depends on the location and severity of the trauma, preference of the surgeon, and the dislocation or comminution. The application of IMF with arch bars is time-consuming, and has several disadvantages, such as patient discomfort, gingivitis and infection. Recently, IMF screws have become more popular in mandibular trauma surgery due to their easy and quick application. However, screw failure, gingival and mucosal tissue damage and root injury may occur.5 In order to overcome the possible disadvantages of IMF techniques, some surgeons prefer to use manual repositioning or reduction forceps. Several studies have shown that reduction forceps could significantly reduce operation time, and their use results in adequate bone fragment reduction and causes few postoperative complications such as infection and occlusal disturbance.3,6,7 However, surgeons must pay attention to lingual site gapping when using reduction forceps, because it could cause separation of lingual borders of the mandible.

According to the literature, only a few types of repositioning forceps are available for application in OMF surgery. Frequently, modified larger towel clamps are used,6,8 but some surgeons and biomedical engineers have reported on the development of more efficient ones.7,9,10 The aim of this paper is to review all studies related to reduction forceps and other non-IMF reduction techniques in order to assess which forceps are available and which developments are needed.

23 Chapter 2

MATERIALS AND METHODS

In order to identify studies on reduction forceps for mandibular fractures, a systematic search was performed in the database of PUBMED and EMBASE. The search was updated until February, 2016 and no initial date and language preferences were set. Furthermore, citations of the retrieved articles were screened to identify additional relevant articles. Case reports, studies on small populations, technical notes and laboratory studies were all included in this review.

Pubmed search: (“Mandibular Fractures”[Mesh] OR (mandibula* AND fracture*)) AND (“Fracture Fixation, Internal”[Mesh] OR “Jaw Fixation Techniques”[Mesh] OR fixation*) AND (reduction* OR clamp* OR “forceps”) Embase search: ‘mandible fracture’/exp AND ‘fracture reduction’/exp OR ‘reduction forceps’ OR ‘reduction clamps’

RESULTS

The systematic search strategy resulted in 1285 hits from the Pubmed and Embase, of which 295 duplicates were removed. The titles of the remaining 990 articles were screened, after which another 925 hits were ejected due to irrelevancy. The abstracts of the remaining 65 articles were screened, and another 52 publications were excluded as they were not relevant or animal studies. Screening of the references resulted in one additional publication. Finally, 14 articles were chosen for this review (Fig 1). The selected articles were categorized as either clinical or experimental studies.

1. Clinical studies

Accuracy of fracture reduction

Eight of the 14 articles mentioned that stable pre-compression and reduction were achieved with help of a reduction forceps. Four articles described other techniques which will be described below.

Reduction forceps. In one study6, two modified reduction forceps were used for the symphyseal and parasymphyseal fractures. One was applied at the

24 Mandibular fracture reduction techiniques

Fig 1. Algorithm of study selection procedure.

25 Chapter 2

inferior border and another one in the subapical zone of the anterior mandible, in order to reduce lingual cortical bone sufficiently. In the other clinical studies, the reduction was achieved by using one clamp or forceps in the anterior and posterior region of the mandible.

The success of the reduction is described in terms of postoperative clinical observation and complications in all eight articles. Two studies described additional post-reduction radiography to confirm healing. Mandibular angle fracture cases were followed up prospectively via orthopantomograms (OPG) and reverse Towne views or both.3,7 The study of Choi et al.3 included two treatment groups (reduction forceps and IMF group) and used a scale of 1 to 3 to assess the accuracy of anatomic reduction in the radiographic image. A score of 1 indicated a poorly reduced fracture which required a second operation, while a score of 2 indicated a slight displacement but an acceptable occlusion. A score of 3 indicated a precise reduction. The reduction forceps group had a higher number of accurate anatomic alignments of the fractures than the IMF group.

Three studies provided information about the distance between the drill holes in which the teeth of the forceps find their grip. One study11 describes two monocortical holes were drilled, each 10 mm from the fracture line. A second study12 describes monocortical holes at approximately 12 mm from the fracture line at midway down the vertical height of the mandible. The third study describes either monocortical or bicortical holes depending on difficulties. These difficulties are not described in detail. In this study8, the distance of 5-8 mm from the fracture was chosen at the inferior margin of the mandible (Table 1).

Other techniques. Scafati et al.13 used elastic rubber bands stretched between screws placed across both sides of the fractured parts in order to reduce mandibular and orbito-maxillary fractures. Orthodontic rubber bands and two self-tapping monocortical titanium screws with 2 mm diameter and 9-13 mm length were used. The heads of the screws protruded about 5 mm and the axis had to be perpendicular to the fracture line. Degala et al.14 used comparable techniques for symphyseal, parasymphyseal and body fractures. Titanium screws with 2 mm diameter and 8 mm length were tightened at a distance of 10-20 mm from the line of fracture, and around 2 mm screw length remained above the bone to engage a 24 G wire loop. However, before applying this technique, they used IMF.

26 Mandibular fracture reduction techiniques

Table.1 General description of the studies Study Study type No. of Fracture location Type of reduction Drill holes patients method distance (from the fracture line) Kallela et Clinical/ 23 Angle, Shortened peaks At apical al.17 retrospective Parasymphyseal forceps with IMF and level lag-screw Žerdoner Clinical 60 Angle Self-cutting screw with 10 mm et al.11 Symphyseal reposition forceps 2 Parasymphyseal catching the screws Rogers et Clinical/ 100 Angle Modified large towel 5-8 mm at al.8 Ideas and Symphyseal clamp inferior innovations Parasymphyseal margin of mandible Choi et Clinical/ Angle Specifically designed al.9 Technical forceps of the angle - note fractures Choi et Clinical/ 46 Angle Same with above - al.3 Retrospectiv Intraoral e Shinohar Clinical/ 2 Symphyseal Modified reduction - a et al.6 Case report Parasymphyseal forceps Intraoral Kluszyns Clinical/ 4 Body Right angled reduction 12 mm at ki et al.12 Case report Symphyseal forceps midway Parasymphyseal level Scolozzi Clinical/ 7 Transverse angle Specifically designed et al.7 Case report with 70 degree angle in - tips Scafati et Clinical/ 104 Symphyseal Elastic internal traction 5-20 mm al.13 Technical Parasymphyseal note Body, Angle, Ramus Orbito-maxillary complex fractures Degala et Clinical/ 80 Body Tension band wiring 10-20 mm al.14 Technical Symphyseal note Parasymphyseal El- Clinical/ 24 Body Computer guided - Gengehi Clinical study Angle fracture reduction with et al.16 custom-fabricated surgical stent Beech et Clinical/ 1 Bilateral Vacuum-formed splint - al.15 Technical (Right angle, left note parasymphyseal) Choi et Experimental 36* Body Stress patterns 10-16 mm al.18 Symphyseal generated by Synthes in the 3 Parasymphyseal reduction forceps model different 398.98 level Kontio10 Experimental - Only virtual reduction in - a computer model with computer aided designed forceps * Photoelastic mandibular models

27 Chapter 2

Two publications describe reduction methods that use custom made splints. A vacuum-formed splint was used by Beech et al.15 in the reduction of one bilateral mandibular fracture case. In this case, the patient underwent two operations. Final precise reduction and fixation was done seven days after immediate stabilization with miniplates and screws followed by alginate impressions for manufacturing the splint. El-Gengehi et al.16 virtually reduced mandibular fracture segments based on three-dimensional reconstruction of a CBCT scan. Based on the reconstruction, custom made surgical guides were fabricated. At the start of the surgical treatment, the mandibular fracture segments were aligned with help of the custom made a surgical guide, which was placed in the subapical zone using monocortical mini screws. Above and below this guide the osteosynthesis material was placed to fixate the fracture. Finally the guide was removed.

Postoperative complications

Several authors6,8,11 did not mention post-operative complications, whereas other authors7,12 did not experience any complications when they used reduction forceps. Kallela et al.17 described some cases with infection and non-stable fixation. However, in this study, they used a lag screw technique for fixation instead of plates and screws. Choi et al.3 noted one case of infection in the reduction forceps group versus four cases in the IMF group. The IMF group had two cases with occlusal disturbance, while no occlusal disturbance was observed in the reduction forceps group. Furthermore, one case of dental root perforation due to the IMF screw and two cases of infections with malunion were observed in the elastic internal traction technique group.13 In a study on the tension band wiring technique14 three cases developed an infection and eight cases had a minor occlusal discrepancy.

Duration of surgery

Two studies reported on the duration of the operation when using reduction forceps. Shinohara et al.6 mentioned that using reduction forceps without IMF for mandibular fractures reduced the time of surgery, but they did not provide exact information on operation times. Choi et al.3 described operation times as being significantly reduced in the reduction forceps group; the average operation time was 41 minutes in the forceps group compared to 87 minutes in IMF group. With respect to other techniques, operative time was shortened in several studies13,14 but the authors did not provide exact information either.

28 Mandibular fracture reduction techiniques

2. Design of the repositioning forceps

Eight articles described a new design for reposition forceps.3,6–9,11,12,17 These designs can be divided into two groups.

A. Modified towel clamps 2 A standard towel clamp was modified by Rogers et 8 al. bending two ends of a clamp approximately 10 degrees outward. This was done to prevent disengagement from the bone (Fig 2-A). Kellela et al.17 modified a standard AO reduction forceps through shortening the teeth and made notches at the ends to grasp tightly in the drill holes (Fig 2B). Shinohara et al.6 used two modified reduction forceps: one was positioned at the inferior border and the other in the neutral subapical zone. However, the authors did not describe the modification technique (Fig 2C).

Fig 2. Schematic drawing of existing reduction forceps. A, Modified towel-clamp (Rogers et al.) B, Modified AO forceps (Kellela et al.) C, Modified reduction forceps (Shinohora et al.) D, Reduction forceps for mandibular angle fracture (Choi et al.), E, Commercially available reduction forceps (Synthes).

29 Chapter 2

B. Specific or new design

New reduction forceps were developed by Choi et al.3,9 for mandibular angle fractures based on the unique anatomy of the oblique line and body; one end of the forceps was designed for positioning in the fragment medial to the oblique line and another end was positioned in the distal fragment below the oblique line. The prongs are asymmetrically designed, with the medial prong being longer than the distal one (Fig 2D).

The reduction-compression forceps of Scolozzi et al.7 was designed similar to standard orthopedic atraumatic grasping forceps (Fig 3A).

Kluszynski et al.12 designed a prototype of a right-angled reduction forceps to prevent bone chipping of the drill holes during the reduction (Fig 3B).

Fig 3. Schematic drawing of existing reduction forceps (continues) A, Specific ad hoc, the prongs of the forceps made a 90-degree angle sagittally and a 70-degree angle coronally relative to the midline of the forceps (Scolozzi et al.) B, Right-angle, prongs are designed an approximately 90-degree angle coronally (Kluszynski et al.) C, Combination of self-cutting screws and a repositioning forceps (Zerdoner et al.).

30 Mandibular fracture reduction techiniques

Žerdoner et al.11 used a combination of self-cutting screws and a repositioning forceps which has butterfly-like shaped prongs. First, two screws are fastened on each side of the fracture line and then the reposition forceps is placed over the heads of the screws (Fig 3C).

3. Experimental studies 2 Choi et al. 18 evaluated the stress pattern generated by reduction forceps (Fig 2E; Model 398.98 Synthes, Waldenberg, Switzerland) with a photoelastic mandibular model in order to determine the ideal position of the reduction forceps. They osteotomized 36 mandibular models into three groups of fractures: symphyseal, parasymphyseal and body fractures. According to this study, symphyseal and parasymphyseal fractures have similar stress distributions, and a distance between the two engagement holes of more than 12 mm is ideal in both lingual and labial areas. Furthermore, reduction forceps should be placed between the midway level of the mandible or 5 mm below the midway level. In the case of body fractures, optimum stress distribution was achieved when both tips of a reduction forceps were placed more than 16 mm away from the fracture line at midway level. Virtually designed reduction forceps were developed using a parametric computer aided design (CAD) and additive manufacturing (AM) for the prototype.10 In this study, the instruments consist of three separate units: handle, jaw and bar. The prongs of this forceps hold the bone fragments rigidly and the oval axial line of the handles was designed to retract the buccal soft tissues and muscles. However, due to several design-related complications they were unable to make a prototype.

DISCUSSION

The use of reduction forceps has been known for many years in general trauma surgery, orthopedic surgery and plastic surgery. In OMF surgery traditionally the dental occlusion was used to perform and check reduction of mandibular fractures. Notwithstanding this historical background, reduction forceps can be used in mandibular fractures as in any other fracture as long as there is sufficient space and as long as the fracture surface permits stable placement and withstands the forces created by such a forceps. Although there have been a number of publications presenting various designs of reduction forceps for use in OMF surgery, a review never has been published.

31 Chapter 2

This article describes the advantages and weak points of the various reduction forceps and their clinical use and designs.

Each author almost exclusively uses his own type of forceps, although there are similarities in the designs. Generally, the curvature in the design of the prongs of any kind of grasping instruments such as bone forceps or towel clamps were kept in all models described in this review, except for a right-angle forceps (Fig.3B). Most of the authors6,8,17 simply bent the prongs of the forceps into different angles in order to improve their grip and the pre-compression during the reduction. Mandibular symphyseal and parasymphyseal fractures were rather easy to reduce with reduction forceps due to their curved shape. However, mandibular angle fractures are more challenging to reduce due to the difficulty of positioning the forceps intraorally. Therefore, a specific reduction forceps was designed3,9 for fractures of this area. However, this forceps was not able to reduce oblique fractures of the mandible. The modified towel clamp by Rogers et al.8 could be used in angle fracture via an extraoral incision, but this clamp is less effective in oblique fractures as well. Therefore, it would be desirable to develop a universal forceps design for all types of mandibular angle fractures.

The positioning of the forceps and location of drill holes are important for adequate reduction and compression. Clinical studies have suggested that a distance of the holes of at least 8-12mm (average 10mm) from the fracture line allows better reduction and pre-compression. Therefore, new designs for the reduction forceps need a certain freedom of movement to allow them to function when holes are at 8-16 mm from the fracture line, and also it should be able to lock fully. Applying reduction forceps can make IMF unnecessary and so reduces operation time. Additionally, with respect to the patient, IMF-related complications such as gingivitis, pain, discomfort or difficulties in maintaining oral hygiene and root injury by IMF screws are diminished by avoiding IMF. Treating patients without IMF could reduce the risk of injury or infection of the surgeons and nursing staff and decreases the number of assistants as well.

Other fracture reduction methods such as traction wire or elastic tension on screws are simple to use in the area of anterior mandibular fractures, but not in the posterior part of the mandible. In addition, this method may cause a gap at the lingual side of the fracture as an effect of the resultant of the force exerted on the protruding screws. This lingual gap should be prevented with reduction forceps as they grab inside the bone and are positioned at a distance of the

32 Mandibular fracture reduction techiniques

fractures site of at least 8-10 mm this should prevented.8,11,12 Choi et al.18 even suggested that tips of repositioning forceps should place at least 12mm from each site of the fracture line in case of symphyseal and parasympheseal fractures. In the mandibular body fractures, adequate stress pattern at the lingual site was found at least 16 mm from fracture line.

CONCLUSION 2

Based on this review it can be concluded that only a few designs of repositioning forceps have been proposed in the literature. Quick and adequate reduction of fractures seems possible with this technique resulting in anatomic repositioning and shorter operation time, especially in cases with good interfragmentary stability. A satisfying solution for the posterior part of the mandible is not yet available. Further development and clinical testing of reduction forceps is necessary to establish their future role in maxillofacial fracture treatment. Better reduction and decreasing of operation time are incentives to explore the possibilities.

ACKNOWLEDGEMENTS

The authors would like to thank Otgongerel Nyamsambuu, for drawing the forceps.

33 Chapter 2

REFERENCES

1. Gassner R., Tuli T., Hächl O., Rudisch A., Ulmer H. Cranio-maxillofacial trauma: A 10 year review of 9543 cases with 21 067 injuries. J Cranio-Maxillofacial Surg 2003;31(1):51–61. Doi: 10.1016/S1010-5182(02)00168-3. 2. Perren SM., Huggler A., Russenberger M., Straumann F., M¨ller ME., Allgöwer M. A Method of Measuring the Change in Compression Applied to Living Cortical Bone. Acta Orthop Scand 1969;40(sup125):1–63. Doi: 10.3109/ort.1969.40.suppl-125.01. 3. Choi BH., Kim HJ., Kim MK., Han SG., Huh JY., Kim BY., et al. Management of mandibular angle fractures using the mandibular angle reduction forceps. Int J Oral Maxillofac Surg 2005;34(3):257–61. Doi: 10.1016/j.ijom.2004.05.009. 4. Schmoker R., Von Allmen G., Tschopp HM. Application of functionally stable fixation in maxillofacial surgery according to the ASIF principles. J Oral Maxillofac Surg 1982;40(7):457–61. 5. Van Den Bergh B., Blankestijn J., Van Der Ploeg T., Tuinzing DB., Forouzanfar T. Conservative treatment of a mandibular condyle fracture: Comparing intermaxillary fixation with screws or arch bar. A randomised clinical trial. J Cranio-Maxillofacial Surg 2015;43(5):671–6. Doi: 10.1016/j.jcms.2015.03.010. 6. Shinohara EH., Mitsuda ST., Miyagusko JM., Horikawa FK. Mandibular fracture reduction without intraoperative intermaxillary fixation: A technique using two modified reduction forceps.J Contemp Dent Pract 2006;7(1):150–6. 7. Scolozzi P., Jaques B. Intraoral open reduction and internal fixation of displaced mandibular angle fractures using a specific ad hoc reduction-compression forceps: a preliminary study. Oral Surgery, Oral Med Oral Pathol Oral Radiol Endodontology 2008;106(4):497–501. Doi: 10.1016/j.tripleo.2008.01.018. 8. Rogers GF., Sargent L a. Modified towel-clamp technique to effect reduction of displaced mandible fractures. Plast Reconstr Surg 2000;105(2):695–7. Doi: 10.1097/00006534-200002000-00033. 9. Choi BH., Suh CH., Par JH., Yoo JH., Kim HJ. An effective technique for open reduction of mandibular angle fractures using new reduction forceps: technical innovations. Int J Oral Maxillofac Surg 2001;30(6):555–7. Doi: 10.1054/ ijom.2001.0158. 10. Kontio R. Designing and Additive Manufacturing A Prototype for A Novel Instrument for Mandible Fracture Reduction. Surg Curr Res 2013;03(01):2–4. Doi: 10.4172/2161-1076.S1-002. 11. Žerdoner D., Žajdela Z. Reposition forceps for osteosynthesis by means of miniplates. Br J Oral Maxillofac Surg 1998;36(5):392–3. Doi: 10.1016/S0266- 4356(98)90654-4. 12. Kluszynski BA., Wineland AM., Kokoska MS. Mechanical and clinical rationale of prototype bone reduction forceps. Arch Facial Plast Surg 2007;9(2):106–9. Doi: 10.1001/archfaci.9.2.106. 13. Taglialatela Scafati C., Facciuto E., Aliberti F. The Elastic Internal Traction (EIT): An

34 Mandibular fracture reduction techiniques

effective method to reduce the displaced facial fractures.Int J Oral Maxillofac Surg 2004;33(7):709–12. Doi: 10.1016/j.ijom.2004.02.008. 14. Degala S., Gupta N. “Tension Band Wiring” A Simplified Approach for Fracture Reduction and Intermittent Stabilization. J Maxillofac Oral Surg 2010;9(4):382–4. Doi: 10.1007/s12663-010-0111-y. 15. Beech AN., Farrier JN. Technical note Operative use of a vacuum-formed splint in the reduction of displaced mandibular fractures. Br J Oral Maxillofac Surg 2016;54(2):224–5. Doi: 10.1016/j.bjoms.2015.12.018. 2 16. el-Gengehi M., Seif S a. Evaluation of the Accuracy of Computer-Guided Mandibular Fracture Reduction. J Craniofac Surg 2015;26(5):1587–91. Doi: 10.1097/SCS.0000000000001773. 17. Kallela I., Ilzuka T., Laine P., Lindqvist C. Lag-screw fixation of mandibular parasymphyseal and angle fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82(5):510–6. 18. Choi BH., Park JH., Yoo TM., Huh JY., Suh CH. Evaluation of stress patterns generated by reduction forceps within a photoelastic mandibular model. J Cranio- Maxillofacial Surg 2003;31(2):120–5. Doi: 10.1016/S1010-5182(02)00185-3.

35 Pallas’s cat (Otocolobus manul), Credit: Otgonbayar Baatargal CHAPTER 3

ACCURACY AND OUTCOME OF MANDIBULAR FRACTURE REDUCTION WITHOUT AND WITH AID OF A REPOSITIONING FORCEPS

Enkh-Orchlon Batbayar, Somaia Malwand, Pieter U. Dijkstra, Ruud R.M. Bos, Baucke van Minnen Accepted version of: Oral Maxillofac Surg. (2019) DOI: 10.1007/s10006-019-00759-0 Chapter 3

ABSTRACT

Purpose. It is presumed that adequate reduction of a fracture of the mandible favors bone healing and diminishes the risk of complications. In this retrospective study, we compared the accuracy of fracture alignment and complication rate of mandibular fractures reduced without or with aid of a repositioning forceps.

Methods. Retrospective analysis of consecutive 252 patients with mandibular fractures treated between January 2010 and December 2016. Eligible for this study were patients with isolated mandibular fractures needing open reduction and internal fixation in whom pre- and postoperative radiographs and patient records were available. In total 131 (252 fractures) patients fulfilled the inclusion criteria.

Results. Seventy-one (54%) patients were men. Mean age of the patients was 33±16.5 years and the median and interquartile range of age was 25 (20;41). In 54 patients’ mandibular fractures were reduced without the aid of repositioning forceps, in the remaining 77 patients the fractures were reduced with the aid of the repositioning forceps. Anatomical alignment of the fractures was poor in the non-forceps aided group (48%) compared to the forceps-aided group (58%) (P=.067). Overall complication rate was higher in the group of fractures reduced without the aid of forceps (17%) than in the forceps-aided group (7%) ( P=.045; OR, 2.7; 95% CI, 1.0-7.4).

Conclusions. Mandibular fractures reduced with the aid of repositioning forceps are accompanied by a lower complication rate and better alignment. This is an important observation as better alignment of the fracture fragments favors bone healing and reduces complications.

38 Added value of using repositioning forceps in the mandibular fracture treatment

INTRODUCTION

Mandibular fracture treatment aims to achieve adequate reduction of the fracture fragments, to immobilize these fragments firmly in order to restore premorbid occlusion, and to promote direct bone healing. Common methods for reduction of mandibular fractures include intermaxillary fixation (IMF), manual reduction and the use of a repositioning forceps. After adequate reduction, the aligned fragments are fixated with osteosynthesis materials.

IMF is used primarily to restore occlusion and secondarily to reduce the fracture1,2. Commonly, IMF is applied by wiring the upper and lower jaws 3 with the arch bars, but there is a variety of alternative techniques including IMF screws. Although shown to be successful, the various IMF techniques have drawbacks including an increased risk of root injury, IMF screw failure, accidental needle stick injury and discomfort to the patient3–5. The use of IMF is not a prerequisite to reduce and fixate mandibular fractures6,7, manual reduction and use of repositioning forceps are reliable alternatives2,8–13. When performing manual reduction, extra hands to reduce the fracture fragments are needed, preferably with aid of a skilled assistant3. Moreover, there is not always sufficient room to insert osteosynthesis materials via intraoral approach due to the limited access to the fracture when manually aligning fracture fragments. With a repositioning forceps, a more accurate anatomical reduction and higher pre-compression can be achieved compared to IMF or manual reduction2. This better alignment of the fragments is presumed to favor bone healing and diminish risks of complications.

All above-mentioned mandibular fracture reduction techniques are viable options for treatment of mandibular fractures. In clinical practice, these techniques are often used in combination with each other. The objective of the current study was to analyze the added value of using repositioning forceps in the mandibular fracture treatment. We hypothesize that mandibular fracture treatment, when a repositioning forceps is used, will result in a more accurate fracture alignment and less postoperative complications.

39 Chapter 3

MATERIALS AND METHODS

Study population

The medical records of all patients who received surgical treatment for mandibular fractures between January 2010 and December 2016 at the Department of Oral and Maxillofacial Surgery, University Medical Centre Groningen, the Netherlands were assessed for eligibility. Inclusion criteria were isolated mandibular fractures that required treatment with open reduction and internal fixation (ORIF) and availability of pre- and postoperative radiographs and records. Both unilateral single/double fracture(s) and bilateral fractures of the mandible were included. Exclusion criteria were closed treatment of a mandibular fracture, bi-maxillary fractures, inadequate radiographs, and fractures older than 3 weeks at the time of treatment.

Fracture reduction techniques and surgery

Reduction of mandibular fractures was achieved by either manual reduction, IMF, the use of repositioning forceps or a combination of these techniques (Fig 1). The reduction techniques were grouped as follows: (1) fractures reduced without the aid of repositioning forceps, and (2) fracture reduced with the aid of repositioning forceps. All operations were performed under general anesthesia by an oral and maxillofacial surgeon assisted by residents. The choice of the reduction methods applied was based on the case complexity and the surgeon’s preference.

Study variables and outcome measurements

Age, gender, cause of trauma, comorbidity, occlusal state, oral hygiene, smoking habits, dental status, fracture type, fracture location and type, the order in which IMF, manual reduction and/or the use of a reduction forceps were used, fracture fixation method, postoperative fracture alignment and complications were extracted from the patient records. Postoperative fracture alignment was evaluated by two observers based on postoperative radiographs along with the clinical appraisal of occlusion according to the following score: (1) poor reduction of the fracture needing reoperation, (2) fracture was reduced with slight dislocation, but clinically with a satisfying occlusion, and (3) reduction of the fracture with anatomic alignment. The reported complications were

40 Added value of using repositioning forceps in the mandibular fracture treatment

Fig 1. Illustrative explanation of the fracture reduction techniques: A-Manual reduction, B-Repositioning forceps, C-IMF with arch bar and wire, and D-IMF screw and wire. The repositioning forceps aided group includes “B” alone; or “B” combination with (and/or) “A”, “C”, and ”D”. The non-forceps aided group includes “A”, “C”, and ”D” alone; or combination of those.

41 Chapter 3

divided into complications needing reoperation (major) and complications not needing surgical intervention (minor). The immediate postoperative occlusion was assessed by oral and maxillofacial surgeons of the department by clinical examnation and assessing the patients’s experience of occlusal disturbance.

Statistical analysis

We performed two groups of statistical analyses, one with the patient as unit of analysis, and one with the fracture as unit of analysis. Age, gender, cause of trauma, comorbidity, occlusal state, oral hygiene, smoking habits, dental status, fracture type and complications were analyzed per patient. Fracture location and type, fracture fixation method, postoperative fracture alignment, and complications were analyzed per fracture. When unit of analysis was fracture, possible concomitant condylar or ramus fractures were excluded from the comparison of reduction methods regarding complications, if the concomitant fractures were treated closed. In another words, the comparison was made only with fractures that underwent open reduction and internal fixation (ORIF).

Chi-square (Exact test when actual or expected cell filling was not too low), t-test, Mann-Whitney U and logistic regression analysis were applied to analyze differences between reduction techniques regarding reduction accuracy (alignment), patient and fracture characteristic, and postoperative complications.

To identify possible confounding factors, we explored associations between complications (no, yes) and the following variables: age, gender (male, female), co-morbidity (no, yes), smoking (no, yes), oral hygiene (good, poor), velocity of trauma (high, low), mandible fracture(s) concomitant with condyle (no, yes), fracture reduction techniques (with the aid of forceps, without the aid of forceps), fracture location, and fracture fixation methods (load sharing, load bearing or combination). Statistical significance was set at p≤ .05 and consistently evaluated using 2-sided tests. Data were analyzed with IBM SPSS version 23.0.03 software.

42 Added value of using repositioning forceps in the mandibular fracture treatment

RESULTS

General characteristics of patients

Of the 203 patients with mandibular fractures that were treated between January 2010 and December 2016, 131 patients with 252 fractures met the inclusion criteria (Fig 2). The mean age of the patients was 33±16.5, the median (interquartile range (IQR)) of age was 25 (20;41), and 103 patients (79%) were male. The median (IQR) number of fractures per patients was 2 (1; 2). Three patients had cardiovascular disease, three patients had diabetes (type II), two patients had alcohol abuse and one patient had a psychological problem. 3

Eighty-two (63%) out of the 131 eligible patients were fully dentate, 38 (29%) were partially dentate and 11 (8%) patients were edentulous. Eighteen (14%) patients were smokers. Oral hygiene status was not recorded in 11 (8%)

Fig 2. Flowchart of the patient selection process.

43 Chapter 3

edentulous patients. In 110 (92%) patients’ oral hygiene was good, and 10 (8%) patients had poor oral hygiene. The cause of the mandibular fractures was assault (n=45, 34%), fall (n=27, 21%), motor vehicle accident (n=25, 19%), bicycle accident (n=25, 19%), sports injury (n=7, 5%), and accident at home (n=2, 2%).

The fractures occurred in the mandibular (para)symphyseal region (n=67, 27%), body (n=54, 21%), angle (n=47, 19%), ramus (n=23, 9%) and condyle (n=61, 24%). Among the 252 fractures, 206 (82%) fractures were simple, 37 (14%) comminuted and 9 (4%) incomplete. The simple fractures were more frequently observed in the (para)symphyseal (n=53, 26%), angle (n=42, 21%), and condyle or ramus (n=75, 36%) region of the mandible, and less in the body region (n=36, 17%). The comminuted fractures were mainly observed in the

Table 1. Patients characteristics and reduction techniques (unit of analysis: patients, n=131) Reduction not Reduction P valuec aided by the aided by forceps the (n=54) a forceps (n=77) a Age (mean ± SD) 33.0±16.4 32.9±16.7 .687* Number of fractures (mean ± SD) 1.9±.7 1.8±.7 .186* Gender (n=131) Male 43 (80) 60 (78) .496 Female 11 (20) 17 (22) Smoking (n=131) No 49 (91) 64 (83) .161 Yes 5 (9) 13 (17) Oral hygiene Good 44 (92) 66 (92) .638 (n=120) Poor 4 (8) 6 (8) Co-morbidity No 45 (83) 73 (95) .039 (n=131) Yes 9 (17) 4 (5) Dental status Complete 37 (69) 45 (58) .156 (n=131) Partially 11 (20) 27 (35) Edentulous 6 (11) 5 (7) Fracture type Single fracture 19 (35 ) 17 (22) .432 (n=131) Single fracture 14 (26) 24 (31) concomitant condyle (unilateral or bilateral) Bilateral or unilateral 19 (35) 32 (42) double fracture Bilateral fracture 2 (4) 4 (5) concomitant condyle (unilateral or bilateral)) Complication No 39 (72) 71 (92) .005 Minor 10 (19) 3 (4) Major 5 (9) 3 (4) a Column percentage b Number of valid data (Fractures treated with closed treatment excluded, no reduction was needed) c Chi square test * Mann-Whitney U test

44 Added value of using repositioning forceps in the mandibular fracture treatment

(para)symphyseal (n=14, 38%) and body (n=18, 48%) region followed by angle (n=4, 11%) and condyle (n=1, 3%) region.

Patient characteristics and reduction techniques

In 54 patients the fractures were reduced without the aid of a repositioning forceps, and in 77 (66%) patients the fractures were reduced with the aid of the forceps. The two groups were similar with regard to age of the patients and number of mandibular fractures per patients (Table 1). Co-morbidity was observed more often in the non-forceps aided group (P=.04; OR=3.6, 95% CI, 1-12). 3

Of the minor complications observed (Table 1) in the non-forceps aid group, soft tissue infection was found in 6 patients (11%), periapical radiolucency due to IMF screw in 1 patient (2%), asymptomatic plate fracture in 1 patient (2%), and poor occlusal need elastic traction in 2 patients (4%). In the forceps-aided group, soft tissue infection was found in 1 patient (1%), and asymptomatic plate fracture in 2 patients (3%).

Table 2. Fracture characteristics and reduction techniques (unit of analysis: fracture, n=252) Open treatment and internal Closed P valuec fixation (n=179) (n=73) Reduction Reduction No Variables not aided by aided by reduction the forceps forceps (n=73) a (n=90) a (n=89) a Fracture (Para)Symphysesal 16 (18) 51 (57) 0 .001 locations Body 26 (29) 28 (32) 0 (n=252) Angle 37 (41) 10 (11) 0 Ramus 2 (2) 0 21(29) Condyle 9 (10) 0 52 (71) Fracture type Simple 74 (82) 69 (78) 64 (87) .001 (n=252) Comminuted 16 (18) 20 (22) 1 (2) Incomplete 0 0 8 (11) Fracture Load sharing 82 (91) 76 (85) .466 fixation Load bearing 2 (2) 4 (5) (n=178)b Both 6 (7) 9 (10) Complications No 75 (83) 83 (93) 73 (100) .001 (n=252) Yes 15 (17) 6 (7) 0 a Column percentage b Number of valid data (Fractures treated with closed treatment excluded due to no reduction was done) c Chi square test

45 Chapter 3

Of the major complications observed (Table 1) in the non-forceps aided group, insufficient reduction occurred in 4 patients (7%), and lingual flaring in1 patient (2%). In the forceps-aided group, non-union in 1 patient (1%), and lingual flaring in 2 patients (3%). The overall complication rate was significantly higher in the non-forceps aided group (P=.004; OR=4.5, 95% CI, 1.6-12.6).

Fracture characteristics and reduction techniques

Of the 252 fractures, a total of 179 (71%) primary fractures was treated by ORIF, and 73 (29%) concomitant fractures were treated closed (no reduction was needed). The forceps-aided fracture reduction was applied less often in the angle region than in the (para)symphysesal and the body region of the mandible (Table 2). Both simple and comminuted mandibular fractures were as often reduced with and without the aid of forceps. Internal fixation of the fractures was achieved with similar osteosynthesis methods in both groups. Fracture alignment tended to be better for the fractures reduced with the aid of repositioning forceps (Fig 3).

In the non-forceps aided group, 15 (17%) fractures had complications (minor n=10, 11%; major n=5, 6%), and in the forceps-aided group, 6 (7%) fractures had complications (minor n=3, 3.5%; major n=3, 3.5%). Detailed complications

Fig 3. Bar chart comparing the postoperative fracture alignment score by reduction techniques. A score 1- poorly reduced fracture needing reoperation, a score 2- reduced with slight dislocation, but clinically satisficing occlusion, a score 3- reduced with anatomic alignment (*Result of Mann- Whitney U).

46 Added value of using repositioning forceps in the mandibular fracture treatment

0 0 0 0 0 0

Condyle

reduction reduction 0 0 0 0 0 0 (n=7 3 ) 1* No Closed (n=73) Closed Ramus

0 0 0 0 0 0 0

Condyle

0 0 0 0 0 0 0 Ramus

0 0 0 0 3 6 (60) 1 (10) 2 (20) 1 (10) Angle

0 0 0 0 0 0 1 (4) Body 27(96)

0 0 0 0 0 0

Reduction aided by forceps (n=89) forceps by aided Reduction 1 (2) 50 (98) (Para) symphyseal

0 0 0 0 0 0 0

9 (100) Condyle

2 0 0 0 0 0 0 0 (100) Ramus

0 0 0 Open treatment and internal fixation (n=179) fixation internal and treatment Open 31 (83) 3 (8) 1 (3) 1 (3) 1 (3) Angle

0 0 0 0 20 (77) 1 (4) 2 (8) Body 3 (11)

0 0 0 0

1 (6) 1 (6) 1 (6) Reduction not aided by the forceps (n=90) forceps the by aided not Reduction 13 (82) (Para) symphyseal

occlusion needs elastic elastic needs occlusion union - union Complications fractures) (n=252 group each of location fracture with associated Complications Infections Poor traction fracture plate Asymptomatic to due radiolucency Periapical IMF screw reduction Insufficient flaring Lingual Non

Table 3. Table No Minor Major fractures ramus) and (condylar concomitant for correction foreseen a with result treatment closed *Expected

47 Chapter 3

are shown in Table 3. The overall complications rate was higher in the non- forceps aided group compared to the forceps-aided group (P=.045 ;OR=2.7, 95% CI, 1.0-7.4).

Confounders

The possible confounding factors for complications are summarized in Table 4. Medical comorbidities were more frequently observed in the fractures reduced by the non-forceps aided group. However, there was no association between comorbidities and postoperative complications in logistic regression analysis. The fractures of the angle region had a higher complication rate compare to the (para)symphyseal region of the mandible.

Table 4. Binary logistic regression analysis: Calculation of odds of having postoperative complications OR (CI 95%) P value Unit of analysis number of patients Age 1.0 (0.9-1.0) .927 Gender (male, female) 2.1 (0.7-5.9) .151 Comorbidity (no, yes) 0.9 (0.1-4.6) .947 Smoking (no, yes) 0.6 (0.1-2.9) .544 Oral hygiene (good, poor) 1.2 (0.2-6.5) .768 Dental status Complete Reference Partially 1.5 (0.5-4.1) .382 Edentulous 0.5 (0.6-4.9) .622 Velocity of fracture a (high, low) 1.6 (0.5-4.4) .364 Condyle fracture (with, without) 0.5 (0.1-1.6) .305 Fracture Single Reference Single condyle 0.4 (0.1-1.5) .412 Bilateral 0.6 (0.2-1.9) .440 Bilateral condyle 0.7 (0.0-6.8) .760 Reduction techniques Forceps aided Reference Non-forceps aided 4.5 (1.6-12.6) .004 Unit of analysis number of fracturesb Location (Para)symphyseal Reference Body 2.3 (0.6-8.4) .194 Angle 4.2 (1.2-14.5) .021 Fracture type Simple Reference Comminuted 0.9 (0.2-3.3) .900 Incomplete 0.0 .999 Fixation Load sharing Reference Load bearing 0.0 .999 Both 0.4 (0.6-3.9) .505 Reduction techniques Forceps aided Reference Non-forceps aided 2.7 (1.0-7.4) .045 a Low velocity (fall, assault, sport and home accident), High velocity (motor vehicle and bicycle accident) b Fracture of the condyle and ramus (concomitant) were excluded (treated closed)

48 Added value of using repositioning forceps in the mandibular fracture treatment

DISCUSSION

Internal fixation of fractures is always preceded by reduction of the fractured fragments. In case of mandibular fractures this reduction can be achieved by either IMF, manual reduction and/or using a repositioning forceps 3–5. In daily practice reduction starts at the moment IMF is applied or when dislocation is neutralized by hand. Additionally, in more complex or less stable cases, reduction can be facilitated and improved by using reduction forceps.

In this study, we analyzed the fracture alignment and postoperative complications of mandibular fractures reduced with or without the aid of 3 repositioning forceps. The results of this study show that the additional use of a repositioning forceps in the treatment of mandibular fractures, even when they are more complex, result in a better alignment of the fragments and less complications compared to manual repositioning and/or IMF only. These results are in accordance with those of previous studies 2,10 indicating that using repositioning forceps for the mandibular fracture decreases the postoperative complication rate and provides adequate reduction.

In this study, forceps aided reduction was mostly applied in the (para) symphyseal and body region, and less in the angle. The available forceps are less easy to apply in the posterior region. As this study has shown that a forceps is of additional value in mandibular fracture treatment, there is a need for development of a reduction forceps designed for application in posterior mandibular fractures.

One might expect that repositioning forceps would be used mainly to reduce simple, non-comminuted fractures. In our study, nearly half of the comminuted fractures were also reduced with the aid of repositioning forceps. In these cases, prior to fixation, the larger parts of comminuted fractures were first reduced with repositioning forceps, and then the smaller parts were fitted in. Independently of the reduction technique, complications were more often observed in the angle region compared to (para)symphyseal region of the mandible. This generally known from literature. Only a small number of fractures in the posterior region was treated with additional use of a forceps (Table 3). Therefore, we are not able to make a clear statement on the additional value of the use of forceps in this specific region.

49 Chapter 3

It has to be mentioned that, in this retrospective study, the method of fracture reduction was selected by the surgeons, which could lead to incorporation of bias. However, the group of mandibular fractures studied was a representative sample of the mandibular fractures treated during the inclusion period. As these fractures are treated by several surgeons in out of office hours the surgeons could not select the patients or fractures. Therefore, results of this study can be generalized to other surgeons as well. The results show that, irrespective of the use of forceps in simple or comminuted fractures, the application of a reduction forceps favors a positive outcome of mandibular fracture treatment. Mandibular fractures reduced by the aid of repositioning forceps are accompanied by lower complication rates and better alignment.

ACKNOWLEDGMENTS

Authors would like to thank Otgongerel Nyamsambuu, for the drawing the figure.

50 Added value of using repositioning forceps in the mandibular fracture treatment

REFERENCES

1. Mukerji R., Mukerji G., McGurk M. Mandibular fractures: Historical perspective. Br J Oral Maxillofac Surg 2006;44(3):222–8. Doi: 10.1016/j.bjoms.2005.06.023. 2. Choi BH., Kim HJ., Kim MK., Han SG., Huh JY., Kim BY., et al. Management of mandibular angle fractures using the mandibular angle reduction forceps. Int J Oral Maxillofac Surg 2005;34(3):257–61. Doi: 10.1016/j.ijom.2004.05.009. 3. Dimitroulis G. Management of fractured mandibles without the use of intermaxillary wire fixation. J Oral Maxillofac Surg 2002;60(12):1435–8. Doi: 10.1053/ joms.2002.36100. 4. Bali R., Sharma P., Garg A. Incidence and patterns of needlestick injuries during 3 intermaxillary fixation. Br J Oral Maxillofac Surg 2011;49(3):221–4. Doi: 10.1016/j. bjoms.2010.04.010. 5. Hashemi HM., Parhiz A. Complications using intermaxillary fixation screws. J Oral Maxillofac Surg 2011;69(5):1411–4. Doi: 10.1016/j.joms.2010.05.070. 6. Fordyce a M., Lalani Z., Songra AK., Hildreth AJ., Carton a TM., Hawkesford JE. Intermaxillary fixation is not usually necessary to reduce mandibular fractures.Br J Oral Maxillofac Surg 1999;37(1):52–7. Doi: 10.1016/S0278-2391(00)80039-7. 7. Bell RB., Wilson DM. Is the Use of Arch Bars or Interdental Wire Fixation Necessary for Successful Outcomes in the Open Reduction and Internal Fixation of Mandibular Angle Fractures? J Oral Maxillofac Surg 2008;66(10):2116–22. Doi: 10.1016/j. joms.2008.05.370. 8. Laurentjoye M., Majoufre-Lefebvre C., Caix P., Siberchicot F., Ricard AS. Treatment of Mandibular Fractures With Michelet Technique: Manual Fracture Reduction Without Arch Bars. J Oral Maxillofac Surg 2009;67(11):2374–9. Doi: 10.1016/j. joms.2009.04.100. 9. Hsu E., Crombie A., To P., Marquart L., Batstone MD. Manual reduction of mandibular fractures before internal fixation leads to shorter operative duration and equivalent outcomes when compared with reduction with intermaxillary fixation. J Oral Maxillofac Surg 2012;70(7):1622–6. Doi: 10.1016/j.joms.2012.03.012. 10. Kluszynski BA., Wineland AM., Kokoska MS. Mechanical and clinical rationale of prototype bone reduction forceps. Arch Facial Plast Surg 2007;9(2):106–9. Doi: 10.1001/archfaci.9.2.106. 11. Saman M., Kadakia S., Ducic Y. Postoperative maxillomandibular fixation after open reduction of mandible fractures. JAMA Facial Plast Surg 2014;16(6):410–3. Doi: 10.1001/jamafacial.2014.543. 12. Davison SP., Clifton MS., Davison MN., Hedrick M., Sotereanos G. Pediatric mandibular fractures: a free hand technique. Arch Facial Plast Surg 2001;3(3):185– 89; discussion 190. 13. Batbayar E-O., van Minnen B., Bos RRM. Non-IMF mandibular fracture reduction techniques: A review of the literature. J Cranio-Maxillofacial Surg 2017;45(8). Doi: 10.1016/j.jcms.2017.05.017.

51 Snow leopard (Panthera unicia schreber), Credit: Otgonbayar Baatargal CHAPTER 4

DEVELOPMENT AND FEASIBILITY OF A NEW REDUCTION FORCEPS FOR MANDIBULAR FRACTURES: A TECHNICAL INNOVATION

Enkh-Orchlon Batbayar, Joost de Beij, Ruud R.M Bos, Baucke van Minnen Submitted Chapter 4

ABSTRACT

This note reports a simple and effective method to reduce mandibular fractures with a newly designed fracture reduction forceps. Medical engineers and oral and maxillofacial surgeons discussed the problems related to existing reduction forceps and developed three forceps, specifically designed to use in fractures of the anterior and posterior mandible. Both forceps proved to be applicable for use in mandibular fractures when tested in clinical practice.

54 Mandibular fracture reduction forceps

INTRODUCTION

Mandibular fractures are routinely treated with open reduction and internal fixation with plate osteosynthesis. Prior to fixation, anatomical reduction of the fragments must be achieved. Intermaxillary fixation (IMF), manual reduction and reduction forceps are used to reduce the fragments of fractured mandibles. The use of reduction forceps has not been extensively investigated and is not widespread, but can be very effective1.

Fig 1. Morphological analysis

55 Chapter 4

In the literature, some modified and newly designed reduction forceps have been recommended for the reduction of mandibular fractures1–3. These forceps had a scissor-like profile, but the prongs differ from each other4. Most of these forceps were proposed to be used in the (para)symphyseal region of the mandible and only a few for the posterior region. (Para)symphyseal region fractures are easier to reduce with a forceps compared to posterior fractures, when used via an intraoral approach. However, in the frontal region a complication such as lingual flaring still can occur.

In our department, there is a tendency to use reduction forceps more often. We routinely used a standard, commercially available forceps. However, as also mentioned in other studies, we experienced difficulties to apply reduction forceps to the mandibular fractures. The study presented in this report aimed to design and develop a new reduction forceps for any region of the mandible via intra-oral approach and to test their feasibility.

Fig 2. Results of Kesselring method

56 Mandibular fracture reduction forceps

THE FORCEPS AND TECHNIQUE

The authors designed and developed the first prototype of the forceps, and tested these in a cadaver. To do so, at first technicians and clinicians (authors) started with a problem analysis by demonstrating the anatomical situation on a fresh cadaver. Based on the findings a morphological overview was made (Fig 1) in which all possible options included. Thereafter a requirements package was defined which included user requirements, manufacturing, and environmental requirements. The best option was then calculated using the Kesselring method (Fig 2).

Fig 3. Proposed fracture reduction forceps. Anterior region forceps (A), and posterior region forceps (B).

57 Chapter 4

Subsequently, the forceps were manufactured by a professional company (KLS Martin, Tutlingen, Germany ) (Fig 3). We developed three forceps; one for the (para)symphyseal and a right and a left one for the posterior area. The (para) symphyseal region reduction forceps (Fig 3A) has sharp-curved long prongs, and these prongs can be positioned at various distances in order to prevent lingual flaring. The posterior region reduction forceps (Fig 3B) has a sliding mechanism which allows to minimize the size of the forceps. Both forceps have a long cremaillère (rack-and-pinion) to make locking of the forceps at various distances possible, and are made of stainless steel. Both forceps can be operated with one hand.

Fig 4. The anterior region forceps applied to reduce a symphyseal fracture of the mandible (A), and with the osteosynthesis applied (B).

58 Mandibular fracture reduction forceps

The feasibility was tested in patients with mandibular fractures. The patient demonstrated here (Fig 4) had a symphyseal fracture due to a bike accident. The fracture was reduced using the anterior region forceps without intermaxillary fixation (IMF). After an intra-oral incision the fracture was exposed and two monocortical holes were made at 15 mm distance from the fracture line with 1.8 mm round bur taken into account that they should not interfere with the osteosynthesis plates and screws to be applied. Thereafter, the anterior region forceps was applied in the drill holes and the fracture anatomically reduced under compression of the forceps. Then the fracture was fixed with two four- hole mini-plates with the forceps still in situ (Fig 4). The forceps was removed after fixation of the fracture. The same procedure was applied in the angle forceps. The angle forceps not only serves to reduce the fracture but also to retract the soft tissues and provides enough room to apply the osteosynthesis. 4 DISCUSSION

We systematically developed a set of new fracture reduction forceps for fractures of the anterior as well as the posterior region of the mandible. The (para)symphyseal region forceps is easy to handle with a single hand, which could reduce the number of operation assistants. The design of the posterior region forceps is optimal for as the angel region, but also applicable in the posterior body regiondue to its sliding function and slim design. This provides good sight for the surgeon and enough room for application of osteosynthesis materials via an intraoral approach.

In our previous study, we reviewed the commercially available reduction forceps for mandibular fractures. According to this study, most of the proposed reduction forceps in the literature were only applicable in the (para)symphyseal region of the mandible due to their design3,5. Compared with these forceps, our design is almost generally applicable because of its smaller dimensions and long cremaillère Besides, a study by Choi et al. concluded that, in order to prevent flaring, the optimum stress distribution over the fracture site is achieved when placing the prongs of the forceps at least 12 mm away from the fracture line6. Different angulations of the forceps’ prongs were proposed by some authors2,5. However, in our experience, a sharp angulation of the prongs is better to achieve sufficient reduction under compression.

59 Chapter 4

Our design of the posterior region reduction forceps has advantages over previous forceps that have been proposed by others 2,7,8. Besides that its sliding mechanism minimizes the dimensions of the forceps our design is ideal for the posterior region compared to the design of the scissor-like forceps, because the prongs of our forceps can be positioned at the oblique ridge or at the lateral surface of the mandible through the mouth. However, in cases of very oblique, flat fractures without sufficient interfragmentary stability reduction with any kind of forceps may be impossible due to sliding of the fracture parts.

This project was undertaken to design, develop and evaluate new reduction forceps for mandibular fractures. We conclude that our proposed designs are applicable for the reduction of fractures of the anterior as well as the posterior region of the mandible.

60 Mandibular fracture reduction forceps

REFERENCE

1. Choi BH., Kim HJ., Kim MK., Han SG., Huh JY., Kim BY., et al. Management of mandibular angle fractures using the mandibular angle reduction forceps. Int J Oral Maxillofac Surg 2005;34(3):257–61. Doi: 10.1016/j.ijom.2004.05.009. 2. Scolozzi P., Jaques B. Intraoral open reduction and internal fixation of displaced mandibular angle fractures using a specific ad hoc reduction-compression forceps: a preliminary study. Oral Surgery, Oral Med Oral Pathol Oral Radiol Endodontology 2008;106(4):497–501. Doi: 10.1016/j.tripleo.2008.01.018. 3. Rogers GF., Sargent L a. Modified towel-clamp technique to effect reduction of displaced mandible fractures. Plast Reconstr Surg 2000;105(2):695–7. Doi: 10.1097/00006534-200002000-00033. 4. Batbayar E-O., van Minnen B., Bos RRM. Non-IMF mandibular fracture reduction techniques: A review of the literature. J Cranio-Maxillofacial Surg 2017;45(8):1327– 32. Doi: 10.1016/j.jcms.2017.05.017. 5. Kluszynski BA., Wineland AM., Kokoska MS. Mechanical and clinical rationale of 4 prototype bone reduction forceps. Arch Facial Plast Surg 2007;9(2):106–9. Doi: 10.1001/archfaci.9.2.106. 6. Choi BH., Park JH., Yoo TM., Huh JY., Suh CH. Evaluation of stress patterns generated by reduction forceps within a photoelastic mandibular model. J Cranio- Maxillofacial Surg 2003;31(2):120–5. Doi: 10.1016/S1010-5182(02)00185-3. 7. Choi BH., Suh CH., Par JH., Yoo JH., Kim HJ. An effective technique for open reduction of mandibular angle fractures using new reduction forceps: technical innovations. Int J Oral Maxillofac Surg 2001;30(6):555–7. Doi: 10.1054/ ijom.2001.0158. 8. Kallela I., Ilzuka T., Laine P., Lindqvist C. Lag-screw fixation of mandibular parasymphyseal and angle fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1996;82(5):510–6.

61 Takhi or Przewalski’s horse (equus przewalski ploiakov), Credit: Hureelen/ Ganbayar Urtnasan CHAPTER 5

COMPLICATIONS OF LOCKING AND NON- LOCKING PLATE SYSTEMS IN MANDIBULAR FRACTURES: A SYSTEMATIC REVIEW AND META-ANALYSIS

Accepted version of: Enkh-Orchlon Batbayar, Pieter U.Dijkstra, Ruud R.M.Bos, Baucke van Minnen Int J Oral Maxillofac Surg (2019) https://doi.org/10.10161010.1016/j.ijom.2019.02 Chapter 5

ABSTRACT

This systematic review and meta-analysis was performed to critically assess the methodological quality of the existing systematic reviews, and to evaluate the postoperative complications of the mandibular fractures treated with locking and non-locking plate systems. An electronic search was conducted in PubMed, Embase, Web of Science, Cochrane library’s electronic databases and grey literate using a combination of Medical Subject Heading terms and keywords, until September 2018. No restrictions were applied to the search strategy. In total, 3 relevant systematic reviews were included, and the quality of these studies was low. A total of 33 studies (20 randomized studies and 13 non-randomized studies) were included in this systematic review, and 16 of them included in meta-analysis. Most of the included randomized studies had an unclear risk of bias (Cochrane Collaboration); the quality of non-randomized studies ranged between 6-17 (MINORS). Based on the results of our meta- analysis, we conclude that locking plates are superior only with respect to the need for MMF in the early postoperative period.

64 Plate systems in mandibular fractures

INTRODUCTION

Postoperative complications after surgical treatment of the mandibular fractures occur in 20-26% of patients1–3. A wide variety of complications may occur after surgical treatment of mandibular fractures. Yet, infection is one of the most common complications resulting in abscesses, non-union, osteomyelitis and wound dehiscence4. Hardware failures such as screw loosening and plate fractures, is another commonly occurring complication2. These complications are associated with patient’s general health condition, and fracture type and location3,5,6. Particularly, comminuted and angle region fractures and a poor oral hygiene are associated with complications3,5,7.

To reduce the postoperative complications after surgical treatment of mandibular fractures, locking plate systems have been introduced8. Theoretically, the locking plate system has the advantages of less screw loosening and greater stability while less accuracy is required in plate adaption compared to non- locking plates9. Clinical studies have shown that locking plates give a more rigid fixation than non-locking plates10,11. But other clinical studies did not 5 show differences between locking and non-locking plate systems regarding postoperative complication rates12,13.

Systematic reviews and meta-analyses are powerful tools for clinical decision making and management of the hospital, and are used to develop clinical guidelines or for making policy decisions. Therefore, these reviews should be unbiased and the most recent studies should have been included. Currently, three systematic reviews and meta-analysis have been published comparing postoperative complications in locking and non-locking plate systems for mandibular fracture treatment14–16. However these reviews, all have several methodological weaknesses such as unreported inter-rater reliability and absence of a flow chart, but so far no critical appraisal of these reviews has been published.

The aim of this systematic review is to critically assess the methodological quality of the existing systematic reviews, and to synthesize the primary studies available in the literature comparing locking plate and non-locking plate systems in the treatment of patients with mandibular fractures regarding postoperative complications, including infection, occlusal disturbance, and hardware failure.

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MATERIALS AND METHODS

This systematic review was reported according to the PRISMA statement17.

Search strategy and selection criteria

A systematic literature search was conducted to identify studies comparing postoperative complications in locking and non-locking plate systems in the treatment of mandibular fractures. The search strategy was developed with help of biomedical information specialist (Sjoukje Van der Werf). We searched in PubMed, Embase, Web of Science, Cochrane library’s electronic databases and grey literate with a combination of Medical Subject Heading (MeSH) terms and keywords (Appendix 1) until September 2018. No restrictions were applied to the search strategy. References of the included studies were screened to identify additional relevant studies missed in the database search.

Included were systematic reviews and primary studies comparing locking and non-locking plates for treatment of mandibular fractures in humans regarding complications including infection, occlusal disturbance, and hardware failure. Excluded were animal studies, in vitro or biomechanical studies, expert opinions and case series that included less than 10 patients in each group. Two observers (E.O.B and P.U.D) independently assessed titles and abstracts using a pre-developed screening form (Appendix 2). After title and abstract assessment, the same form was used to assess full-text of the selected studies by two observers (E.O.B and B.v.M) independently. Inter-observer agreement was calculated (Cohen’s Kappa and absolute agreement), and disagreement between observers was resolved by discussion.

Quality assessment and data extraction

The methodological quality was assessed by two observers (E.O.B and P.U.D). Systematic reviews were assessed using the AMSTAR-2 (A MeaSurement Tool to Assess systematic Reviews) tool18 Quality of included randomized control trials was assessed using the Risk of Bias tool of the Cochrane Collaboration 19, and non-randomized (observational) studies were assessed using the MINORS (Methodological Index for Non-Randomized Studies) tool20 Data was extracted by two observers (E.O.B and R.R.M.B) independently using a pre- developed form (appendix 2), and inter-observer reliability was calculated.

66 Plate systems in mandibular fractures

The postoperative complications described in the studies were categorized because studies reported complications in different ways. Occlusal related complications included occlusal disturbances, mobility of fractures, step deformity, and loss of reduction and need of mandibulomaxillary fixation (MMF) which was used to solve a problem like mobility of a fracture and occlusal disturbances. Infection related complications included soft tissue infection, plate infection, hardware removal due to infection, and plate removal due to infection, wound dehiscence due to infection. The category hardware failure not related to infection included plate and screw loosening or plate fracture. If any other complications occurred, we categorized in other complications. Additionally the following information was extracted from the included studies: conflict of interest, informed consent, plate design and dimensions, and fracture fixation principles.

Statistical analysis

The observed complications were analyzed in the following postoperative timeframes: 1st-4th week (early), 1-3 months or 5th-12th week (intermediate), more 5 than 3 months or 13th week and further (late). If more than one complication occurred in the same patient and the cause was the same, they were counted as one complication (for instance, in case a patient had infection and hardware removal due to infection, this was counted as one complication). Inter-observer agreement was calculated with IBM SPSS Statistics for Windows, Version 22.0 (IBM Copr., Armonk, NY). Meta-analysis was performed if studies compared differences in complication rates in locking and non-locking plates and they compared the same types of plates regarding diameter, design and number of plates. Meta-analysis was performed using Comprehensive Meta-Analysis software (CMA, Biostat, Englewood, NJ, USA) with random effects model. Separate meta-analyses were conducted for randomized and non-randomized studies. Clinical heterogeneity was assessed by studying study methodology and patient characteristics. Statistical heterogeneity was assessed using I2 and Tau 2. As a result of all these assessment a random effects model was applied. Contrary to a fixed effect analyses, in which it is assumed that there is one true effect and that differences between studies are based on sampling variation, in a random effects model it is assumed that there are several effects which may vary based on for instance study population and study methodology.

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RESULTS

Study identification and selection

The database searches resulted in 503 records (Fig 1), and after duplicate removal 182 titles and abstracts were assessed. Fifty-six studies were included for full-text assessment. Cohen’s kappa and agreement (%) for the title and abstract assessment was 0.71 [95% CI 0.60-0.82] (88%). After full- text reading 3 systematic reviews (Table 1) and 33 studies (Table 2 and 3) were selected, and Cohen’s kappa and agreement (%) was 0.61 [95% CI 0.40-0.82] (77%) for this selection. Consensus was reached for all studies by discussion among the observers.

Characteristics and quality of existing systematic reviews

Three relevant systematic reviews were included (Table 1). These systematic reviews were published between 2014 and 2017, and the authors conducted meta-analyses. The reviews included randomized studies as well as non- randomized (observational) studies. The methodological qualities of the included studies in the systematic reviews were assessed using, the Jadad tool21 and Cochrane risk of bias tool19. Two of these reviews compared 2.0 mm locking and 2.0 mm non-locking plates15,16, and one compared various types of locking and non-locking plates14. All three reviews did not report a list of excluded studies and did not calculate kappa values as measure for inter- observer agreement for study selection. Moreover, the review by Wusiman et al.16 did not report a flowchart of the study selection process, and that review is almost identical to the review by Zhan et al15. The quality of published systematic reviews was low (Appendix 3). Cohen’s kappa and agreement was 0.51 [95% CI 0.33-0.69] (68%) for AMSTER-2 criteria. Consensus was reached by discussion.

Characteristics and quality of included primary studies

There were 2 identical studies22,23 and 2 studies13,24 seemed to include the same patient data. Therefore, we included the earliest studies in this review13,22 Of the 33 included studies, 20 were randomized studies (Table 2), 13 were non- randomized studies (Table 3). Thirteen of those 33 studies had been included in one or more of the previously published systematic reviews (Fig 2).

68 Plate systems in mandibular fractures

Records identified through database searching (n = 503)

PubMed (n=145), EMBASE (n=130), Web of Science (n=43), Cochrane library (n=9), and Google scholar (n=176)

Identification

Records after duplicates removed (n = 182)

Records screened Records excluded Screening (n = 182) (n = 126)

Full-text studies excluded, with reasons (n=24) Full-text studies assessed for eligibility - Plates compared in reconstruction surgeries -1 5 (n = 56) - Case report less than ten patients-1 - Technical note-2 - Two non-locking plates Eligibility compared-5 - Non comparative studies -15

Studies included in qualitative synthesis (n = 33) Search update Randomized=20 (n=1) Non randomized=13 Excluded from meta-analysis, with reasons (n=17)

- Comparison of different diameter plates -5 - Comparison of different plate Studies included in designs -8 Included - Comparison of single and quantitative synthesis double plates -2 (meta-analysis) - Identical study-2 (n = 16) Randomized=11 Non randomized=5

Fig 1. Flowchart of study selection.

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Table 1. General description of existing meta-analyses Author (year) Journal Date of last Number of Total Plate types Quality search included number of compared (AMSTAR-2) studies and patients study type reviewed Chrcanovic Int. J. Oral December 10 471 Various types Low quality (2014)14 Maxillofac. 2013 (8 RCT, Surg. 2 Non- RCT)

Zhan et al., J Craniofac ? 4 220 Only 2.0 mm Low quality (2014)15 Surg (3 RCT, vs. 2.0 mm 1 Non- RCT) Wusiman et J Craniofac ? 9 380 Only 2.0 mm Low quality al., (2017)16 Surg (7 RCT, vs. 2.0 mm 1CCT, 1 Non-RCT ) RCT-randomized controlled trials CCT-Controlled clinical trials

In 16 studies10–13,22,24–34 2.0 mm locking plates were compared with a 2.0 mm non-locking plate system. In 2 studies, a 2.0 mm locking plate, and 3D locking plate were compared with double 2.0 mm non-locking plates35,36. Other studies35,37–48 compared various types of locking and non-locking plates (Table 2 and 3). In 2 studies, locking plates, non-locking plates, lag screws and biodegradable plates were compared28,45.

Whereas, Champy principle was used in 14 studies11–13,24,26–28,30,32,34–36,41,42 in both locking and non-locking groups, AO/ASIF (Arbeitsgemeinschaft fuer Osteosynthesefragen/Association for the Study of Internal Fixation) principle was used in 1 study45 in the both groups. Four studies10,22,31,48 did not report which fixation principle was used, but reported that the surgical technique was standardized, or was the same for the two groups except the drilling. In 4 studies, the mandibular fractures were fixated according to Champy principle, and in the non-locking group according to AO/ASIF principles38,43,47,49 In 2 studies37,44, only condylar fractures were treated and fixated with double plates in each. In the remaining 7 studies23,29,33,39,40,46, the fixation principle was not reported.

Mandibular fractures concomitant with condylar fractures were included in 8 studies, and in 243,45 of them the condylar fractures were treated closed. In 2 studies33,39, the condylar fractures were treated with open reduction and internal fixation (ORIF), and 4 studies13,23,28,41 did not report whether the condylar fractures were treated with ORIF or closed. In 10 studies10–12,22,26,30,32,34,38,46

70 Plate systems in mandibular fractures

Fig 2. A Venn diagram of the included studies in the existing systematic reviews and the current one. *This study was not included in this review because a comparison was made between locking and non-locking plate system in reconstruction surgery of the mandible.

condylar fractures were excluded and 10 studies25,27,29,35,36,40,42,47–49 did not report whether these fractures were included or not. In the studies that included mandibular fractures concomitant with another mandibular fracture (bilateral or double unilateral), the concomitant fracture was fixated with non-locking 2.0 mm plates.

Conflict of interest was not reported in 12 12,25–27,32,33,37,39,41,42,46 studies . In 18 studies informed consent was reported11,13,22,23,27,29,31,35–38,43–45,48–51.

71 Chapter 5

- force Funding Funding

Evaluation/

Complications - Complication + Complications + Complications - Complications - Complications + force Bite + force Bite - Bite - Complications -

6 Follow (weeks) 24 8 2 8 13 26 13 6 6 12

- foraminal - foraminal Fracture Fracture Location Symphysis Parasymphysis Body Angle Ramus Symphysis Parasymphysis Body Angle Parasymphysis, Body, Angle Inter Symphysis Parasymhysis Body Angle Condyle Symphysis Parasymphysis Body Inter Any Any Symphysis, Parasymphysis, Body, Angle

Plate(s), material (company) mm, 2.0 - ( - ) mm 1.8 Titanium ( - ) mm 2.0 mm 2.4 and Titanium (Synthesis) mm 2x2.0 Titanium ( - ) mm 2.0 Titanium ( - ) mm 2.0 Titanium ( - ) mm 2.0 Titanium ( - ) mm 2.0 - ( - ) mm 2.0 - ( - ) mm 2.0 Titanium ( - )

(n) Fractures ------locking plate

Non

(n) Patients 15 20 42 20 10 15 10 10 10 10

Age± s.d. ( range) 27.7±8.3 ( - ) - ( - ) 25.6 ( - ) 37.0 ±10.4 ( - ) - ( - ) - ( - ) - ( 21 - 41 ) - ( - ) - ( - ) - ( - )

Plate(s), material (company) mm 2.0 - ( - ) 3D Titanium ( - ) mm 2.0 Titanium (Synthesis) mm 2.0 Titanium ( - ) along mm 1.8 mm 2.3 with mm 2.0 Titanium ( - ) 3D Titanium ( - ) mm 2.0 - ( - ) mm 2.0 - ( - ) mm 2.0 Titanium ( - ) Titanium ( - )

Fractures Fractures (n) ------

Locking plate

(n) Patients 15 20 45 20 10 15 10 10 10 10

- 45) Age± s.d. ( range) 29.1±9.1 ( - ) - ( - ) 35.4 ( - ) 36.8 ±9.5 ( - ) - ( - ) - ( - ) - (22 - ( - ) - ( - ) - ( - )

Total

patients

number of of number (fractures) ( - ) ( - ) 30 ( - ) 40 87 (112) 40 20 (30) 30 ( - ) 20 ( - ) 20 (31) 20 (31) 20 ( - )

s.d., - 53) - 54) ( range)

Mean age± age± Mean - ( - ) - ( - ) - ( - ) - ( - ) 30.6±10.2 (18 - (12 - ( - ) - ( 11 - 40 ) - ( 11 - 40 ) 29±7.5 ( 17 - 45 )

Patient consent

Country/ Country/

India / - / India + Brazil / + / India + / India - India + India + India + India - India -

Characteristics of the included primary studies (Randomized studies) (Randomized studies primary included the of Characteristics 30 50 38 36 48 23 25

. *

29 22 Authors Table 2 et Wakeel 2018 al., et Aggarwal 2017 al., et Jr Camino 2017 al., Vashistha et 2017 al., NK Kumar 2017 al., et Ali et al., 2016 et George 2016 al., Rastogi et 2016 al., Giri et al., 2015 et BP Kumar 2015 al.,

72 Plate systems in mandibular fractures

Complications - Complications - Bite force + Complications Bite force - Complications - Complications + Complications + Complications - Complications - +

6 3 9 6 2 6 1 13 - 26 12 6 21 - 30 6

Symphysis Symphysis Parasymphysis Parasymphysis, Parasymphysis, Body, Angle Angle Parasymphysis Angle Any Symphysis Parasymphysis Body Angle Parasymphysis Body Angle Condyle Any Condyle Any

) - 2x2.0 mm mm 2x2.0 Titanium ( - ) 2.0 mm mm 2.0 - ( - ) mm 2.0 - (Orthomax) mm 2.0 Stainlessstill (SK Surgicals) mm 2.0 Titanium (Synthes) mm 2.0 Titanium ( - ) mm 2.0 Titanium (Synthes) mm 2.0 - ( - ) condyle Modus plate Titanium - ( mm 2.0 Titanium (Synthes)

10 12 30 - 14 - 40 - 74 58

10 10 30 10 10 15 25 20 - - 5

- ( - ) - ( - ) 37.3 ( - ) - ( - ) - ( - ) - ( - ) - ( - ) - ( - ) - ( - ) - ( - )

2.0 mm 2.0 - ( - ) mm 2.0 - (Orthomax) mm 2.0 Stainlessstill (SK Surgicals) mm 2.0 Titanium (Synthes) 3D Titanium ( - ) mm 2.0 Titanium (Synthes) mm 2.0 - ( - ) Trilock condyleplate Titanium ( - ) mm 2.0 Titanium (Synthes) 3D 2.0 mm mm 2.0 3D Titanium ( - )

14 30 - 18 - 36 - 72 64 10

10 30 10 10 15 25 20 - - 10

- ( - ) 35.4 ( - ) - ( - ) - ( - ) - ( - ) - ( - ) - ( - ) - ( - ) - ( - ) - ( - )

( - ) (32) 20 ( - ) 60 ( - ) 20 20 30 (45) 50 (76) 40 (59) 129 (146) 90 (122) 20 (20)

- 30)

26 ( 12 - 43 ) - ( 18 - 60 ) 27.2 ( 14 - 56 ) - ( 46 - 60 ) - ( 16 - 60 ) 30.0±8.5 ( 16 - 52 ) - 37.2±17.5 ( - ) 25.9±6.7 ( 14 - 58 ) - (16

India India + China + India - India + India - India + India - Germany, Austria - USA - India India +

34 31 13 10 37 12

27 35 42 Not reported

Saha et al., al., et Saha 2015 and Yang Patil,2015 S et Kumar 2014 al., et Agarwal 2011 al., al., et Goyal 2011 et V Singh 2011 al., Saikrishna et 2009 al., et Seemann 2009 al., Collins et 2004 al., identical. (almost) are outcomes and interventions populations *Study - + Reported Jain et al., 2012

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Funding

Evaluation/

Complications + Complications + Complication - Complications - Complications + Complications + Complications + Complications - Complications + Complications -

ups

6 Follow (weeks) 13 26 13 26 2 26 26 13 13 6

- - Locations Inter foraminal Inter foraminal Any Angle Angle Angle Condyle Symphysis Parasymphysis Body Angle Angle Parasymphysis Body Angle

)

Plate(s),material (company) mm 2.0 Stainless still (S.K Surgical) 3D Titanium ( - ) 3D Titanium ( - ) and mm 2.00 mm 2x2.0 Titanium (Synthesis, KLSMartin, Medartis mm 2.0 Titanium (Synthes) mm 2.3 - (Leibinger) mm 2.0 shaped L - (Orthomax) mm 2.0 Stainless still ( - ) 3D - ( - ) mm 2.0 Titanium ( - )

(n) Fractures - - 15 - - - 50 30 - 44 - locking plate

Non

(n) Patients 15 20 10 70/ 35 20 10 50 30 25 30

- 90 )

Age± s.d. (range) - ( - ) - ( - ) 27.2± 11.35 ( - ) 31.0± 15.5, (16 26.4±10.1 26.3±2.4 ( - ) 37.3 ( 19 - 60 ) - ( - ) - ( - ) 27.6 ( - )

angle, angle,

(Synthes) Plate(s), material (company) 3D Stainless still (S.K Surgical) mm 2x2.0 Titanium ( - ) 3D Titanium ( - ) Modus Trillock mm 2.0 Titanium ( Synthes) mm 2.0 - 2.3 shaped L mm - (Orthomax) mm 2.0 Stainless still ( - ) mm 2.0 - ( - ) mm 2.0 Titanium ( - ) Titanium (Medartis)

Fractures Fractures (n) - - 12 - - - 51 34 - 44

Locking plate

(n) Patients 15 20 10 88 16 10 51 30 25 30

- 72) randomized studies) - randomized

Age± s.d (range) - - 25.5± 7.79 ( - ) 26.4 ±12.6, (16 29.5±10.9 26.1±2.3 ( - ) 35.8 ( 18 - 56 ) - ( - ) - ( - ) 28.4 ( - )

(n)

Total

patients

number of of number (fractures) ( - ) 30 ( - ) 40 ( - ) 20 (27) 193 ( - ) 36 ( - ) 20 101 (101) 60 (64) 50 ( - ) 60 (88)

)

s.d., - 50) - 56) ( range

Mean age± age± Mean (18 32.5 ( 15 - 50 ) - ( - ) - ( - ) 27.4±9.7 (15 - ( - ) - ( - ) - ( 15 - 60 ) - ( - ) - ( - )

consent

Country/ Informed India India + India - India - Austria - India - Egypt + China + India - India + India -

Characteristics of the included primary studies (Non studies primary included the of Characteristics 43

3 *

51 40 46 47 28 45 44 26 24 Authors Table al., et Budhraja 2018 al., et Passi 2017 and A Singh Arunkumar, 2016 al., et Strasz 2016 Bhatt et al., 2015 al., et Elsayed 2015 Zhang et al., 2015 Shaiket al., 2014 et RK Singh 2013 al., et I al., Kumar 2013

74 Plate systems in mandibular fractures

Complications - Complications - Complications -

6 13 12

- Body Body Angle Body Angle Condylar Inter foraminal Symphysis Parasymphysis Ramus Symphysis Parasymphysis

2.5 mm 2.5 Stainless still ( - ) mm 2.0 - ( - ) mm 2.0 - ( - )

- 13 22

10 10 22 5 - ( - ) - ( - ) - ( - )

2.0 mm 2.0 Stainless still ( - ) mm 2.0 - ( - ) mm 2.0 - ( - )

- 14 21

10 10 21 - ( - ) - ( - ) - ( - )

20 ( - ) 20 (27) 43 (43)

- ( 20 - 40 ) 35±11 ( 20 - 55 ) 20 - 65 ( - )

India India - India - India -

41 32 33 Not reported Baig et al., 2011 al., et Ramesh 2011 al., et Verma 2011 2011 al., et Singh of study with patients overlapped included to possible was might *Study - + Reported

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Table 4. Quality assessment of the randomized studies (Risk of Bias Tool) Studies Items 1 2 3 4 5 6 Wakeel et al., (2018)30 ? ? - ? ? + Budhraja et al., (2018)51 + ? - + ? - Camino Jr et al., (2017)38 + ? - ? - + Aggarwal et al., (2017)50 ? ? - ? ? + Vashistha et al., (2017)36 ? ? - ? ? + Kumar et al., (2017)39 ? ? - ? ? + George et al., (2016)48 ? ? - ? ? + Ali et al., (2016)29 ? ? - ? ? ? Rastogi et al., (2016)23 + ? ? ? ? + Giri et al., (2015)22 + + - ? ? + Kumar et al.,(2015)25 ? ? - ? ? + Saha et al., (2015)27 ? ? - ? ? + Yang and Patil (2015)11 ? ? - - ? + Kumar et al., (2014)34 ? ? - ? ? + Jain et al., (2012)35 ? ? - + ? + Agarwal et al., (2011)31 ? ? - ? ? + Goyal et al., (2011)42 ? ? - ? ? + Singh et al., (2011)13 + ? - ? ? + Saikrishna et al.,(2009)10 ? ? - ? ? + Seemann et al., (2009)37 + ? - ? ? + Collins et al., (2004)12 + ? - ? + + + Low risk, - High risk, ? Unclear 1-Random sequence generation 2-Allocation concealment 3-Blinding of participants and personnel 4-Blinding of outcome assessment 5-Incomplete outcome data (attrition bias) 6-Selective reporting

From most of the included randomized studies risk of bias could not be assessed because of unclear reporting (Table 2 and 3), and Cohen’s kappa and agreement (%) was 0.66 [95% CI 0.54-0.77] (79.4%). The quality of the non- randomized studies ranged between 6-17 (Median (interquartile range) 10.0 (8.2; 15.0) (Table 4). (Cohen’s kappa (% agreement) was 0.58 [95% CI 0.47- 0.68] (73.6%). Table 5 shows the quality of the non-randomized observational studies (MINORS tool).

Meta-analysis

In total, 16 studies were selected for the meta-analysis. Reasons for not being included in the meta-analysis were: comparison of different diameter plates n=538,39,41,44,45 (e.g. 2.0 mm locking vs. 2.3 mm non-locking), comparison of different plate designs n=835,37,40,42,43,48,50,51 (i.e. 3D vs. 2.0 mm), comparison of single and double plates n=236,47 identical study n=123 and duplicated study

76 Plate systems in mandibular fractures

Table 5. Quality assessment of the non-randomized (observational studies MINORS tool) Studies Items 1 2 3 4 5 6 7 8 9 10 11 12 Total Passi et al., (2017)40 1 0 0 1 0 2 0 0 2 0 0 0 6 Singh A and Arunkumar (2016)46 1 0 0 0 0 2 0 0 2 0 1 0 6 Strasz et al., (2016)47 2 2 1 2 0 2 1 0 2 2 1 1 16 Bhatt et al., (2015)28 2 2 1 2 0 2 0 0 2 2 1 1 15 Elsayed et al., (2015)45 2 0 1 2 1 2 0 0 2 2 2 1 15 Zhang et al., (2015)44 2 2 1 2 1 2 0 0 2 2 2 1 17 Shaik et al., (2014)26 1 2 0 2 0 2 0 0 2 0 1 0 10 Kumar et al., (2013 )24 1 0 1 2 0 2 0 0 2 2 1 1 12 Singh et al., (2013)43 1 1 0 2 0 2 0 0 2 0 0 0 8 Baig et al., (2011)41 2 0 0 2 0 1 0 0 2 2 1 0 10 Verma et al., (2011)33 1 0 0 2 0 2 0 0 2 2 0 0 9 Ramesh et al., (2011)32 1 0 0 2 0 2 0 0 2 2 0 0 9 -The items are scored 0 (not reported), 1 (reported but inadequate) or 2 (reported and adequate) -Highest possible score for a study is 24 1-A clearly stated aim 2-Inclusion of consecutive patients 3-Prospective collection of data 4-Endpoint appropriate to the study aim 5-Unbiased evaluation of endpoints 6-Follow-up period appropriate to the major endpoint 7-Loss to follow up not exceeding 5% 8-A control group having the gold standard intervention 9-Contemporary groups 5 10-Baseline equivalence of groups 11-Prospective calculation of the sample size 12-Statistical analyses adapted to the study design

n=124. Cohen’s kappa for ( % agreement) data extraction was kappa 0.72 [95% CI 0.62-0.81] (89%), and consensus was reached.

The study of Bhatt et al.28 compared more than 2 plate systems. We pooled only the data of locking and non-locking plates. In postoperative early results (1-4 weeks) (Fig 3), the need for MMF was significantly lower in the locking plate group compared to non-locking group in randomized studies (OR=0.2, p=0.001). In the intermediate results (1-3 months) (Fig 4) this difference remained and the need of MMF was significantly lower in locking group in both randomized (OR=0.3) and non-randomized (OR=0.1) studies. The last results (after 3 months or more) (Fig 5) showed no difference between locking and non-locking groups regarding the need of MMF in both randomized and non- randomized studies.

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Fig 3. Meta-analysis of Need of MMF (Early results) Random effects model Randomized studies: I2= 0.0%, Tau2=0.0% Non-randomized study: I2= 0.0%, Tau2 =0.0%

We were unable to perform a meta-analysis regarding infection that occurred in the first 4 weeks postoperatively due to an insufficient number of reported data. The infection-related complications did not differ significantly between the groups postoperative after 1-3 months and more than 3 months but with a tendency towards less infection related complications in the locking group in the randomized studies for the intermediate results (OR=0.5, p=0.089)

Fig 4. Meta-analysis of Need of MMF (Intermediate results) Random effects model Randomized studies: I2= 2.7%, Tau2=0.3% Non-randomized studies: I2= 0.0%, Tau2=0.0%

78 Plate systems in mandibular fractures

Fig 5. Meta-analysis of Need of MMF (Late results) Random effects model Randomized studies: I2= 0.0%, Tau2=0.0% Non-randomized study: I2= 0.0%, Tau2=0.0%

(Fig 6-7). A meta-analysis of hardware failure (not related to infection) was only applicable for the intermediate follow-up in one study and there was no difference between the groups found (OR=0.1, p=0.286). We were unable to 5 perform a meta-analysis regarding other complications because the author did not report the complication in details (reported as minor complications)27.

Fig 6. Meta-analysis of infection (Intermediate results) Random effects model Randomized studies: I2= 0.0%, Tau2=0.0% Non-randomized study: I2= 0.0%, Tau2=0.0%

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Fig 7. Meta-analysis of infection (Late results) Random effects model Randomized studies: I2= 0.0%, Tau2=0.0% Non-randomized study: I2= 0.0%, Tau2=0.0%

DISCUSSION

Based on the results of this review, mandibular fractures fixated with locking plate systems have less need for postoperative MMF in short and intermediate term. No difference between the two plate systems was found regarding the postoperative infection-related complications. These outcomes are based on 33 included studies evaluating locking and non-locking plates for mandibular fracture fixation. Despite this number of studies, this review provides low quality of evidence, due to the overall poor quality of the included studies.

Prior to this systematic review three systematic reviews and meta-analyses have been published comparing postoperative complications in locking and non-locking plate systems for mandibular fracture treatment. According to AMSTER-2 criteria, all three had a low quality. None of the reviews reported inter-rater reliability for the title and abstract selection, the full text selection and quality assessment. All three reviews included both randomized control trials and observational studies but did not perform separate meta-analyses for each study design. For quality assessment two reviews used the Risk of bias tools (Cochrane),and one used a Jadad score. However, these quality assessment tools are intended for randomized controlled trials19,21. Observational studies which were included in the reviews should have been assessed using an assessment tool for observational studies52.

80 Plate systems in mandibular fractures

The systematic review by Chranovic14 was conducted and written by one author. Logically no kappa value could be reported. In that review, several types of locking and non-locking plates were compared. The review by Zhan et al.15 compared only 2.0 mm locking and non-locking plates. However, their electronic search was completed using two online databases, and it is preferable to search from at least three sources18. Lastly, in the systematic review by Wusiman et al. (2017)16 the sentences to report the conclusions of the abstract, inclusion and exclusion criteria, statistical analysis in the methods section, some paragraphs of the results and discussion section, and the conclusions of the full text paper, are identical to sentences in the review of Zhan et al. (2014)15. Moreover, a flowchart of the study selection process is missing in the study of Wusiman et al.16.

The quality of included primary studies was moderate to low in both randomized and non-randomized studies. Furthermore, half of the included studies could not be included in the quantitative synthesis because they compared several types of locking and non-locking plates. Some of these studies compared a 2.0 mm locking plate with a 2.3 mm or a 2.4 mm non- 5 locking plate, and a single locking plate with double non-locking plates. Also, other studies compared a 3D locking plate with 2.0 mm plates or vice versa. When studying the effects of the locking and non-locking plates, the following confounding variables should be taken in to account: size or dimensions of the plates and screws, fracture fixation principles, number of plates and plate design. Furthermore, factors like dental status (periodontitis, number of teeth/occlusal units), smoking habits, concomitant fractures, and medical comorbities should be taken into account as well. First, it has been shown that a load bearing plate (2.3 mm or bigger diameter) is stronger and can bear more mechanical load than a load sharing plate (2.0 mm diameter)53. Secondly, fracture fixation principles differ according the biomechanics of the mandible. When Champy’s principle is followed, plates are fixated in the tensile zone of the mandible (upper border), and when AO principle is followed, plates are fixated in the compression zone of the mandible (lower border)53. Thirdly, the number of plates that has been applied in mandibular fractures can influence the postoperative complications54,55. Lastly, the plate designs (i.e. 3D) must be comparable regarding their biomechanics. Therefore, besides the locking or non-locking characteristics, the aforementioned other characteristics of the plates must be similar when comparing the outcome of the locking plate systems with non-locking plate systems in mandibular fractures.

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This meta-analysis was conducted only for those studies that compared plates that have the same dimensions, fixation principles, and design. A significant difference was found regarding the need of MMF in postoperative early and intermediate results in the locking plate group compared to the non-locking plate group. Early and intermediate postoperative evaluations showed that mandibular fractures fixated with locking plates are more stable than non- locking plates. These findings indicate that less occlusal deformities, fracture mobility, or loss of reduction occurred in the locking plate group. However, after 3 months follow-up, the difference was no longer observed probably because most cases had already been treated with MMF. In this review, we considered the need of MMF as a complication only if MMF was used to treat a complication like occlusal disturbance and fracture mobility. In most of the included studies, however, MMF was not considered as a complication in the final comparison between the groups, maybe because MMF is considered as a standard procedure in the treatment of mandibular fractures by many surgeons and authors.

Furthermore, studies that included mandibular fractures concomitant with condylar fractures or other mandibular fractures did not report how they treated these concomitant fractures. It is not clear whether the concomitant condylar fractures were treated with ORIF or closed treatment, and there is substantial chance that the types of fractures affect the occlusal disturbances or need for MMF postoperatively. The incidence of postoperative infections was not different between locking and non-locking groups in the period of postoperative months.

The results of the previous meta-analyses were similar regarding the postoperative infection rate and need of MMF. However, their results were based on few studies15,16, and on comparison of several types of plates beside the locking and non-locking characteristic. Additionally, those reviews did not perform separate analysis for studies with different methodology (randomized versus observational studies).

The strength of our current meta-analysis is the extensive literature search without language restriction which included also grey literature. Moreover, all the review stages were assessed by two reviewers and inter-observer agreement was reported. However, inter-observer agreement was moderate in the quality assessment stage, probably because included studies failed to report how they randomized participants, whether concealment of allocations

82 Plate systems in mandibular fractures

was performed and whether participants and outcome assessors were blinded. Also, we used the relevant tools of the quality assessment based on the study types. A meta-analysis was conducted separately for the randomized and non-randomized studies. This study was limited by the quality of the included studies and the moderate inter-observer agreement in some stages of the review. Moreover, we did not register the review on PROSPERO before starting the systematic review.

We suggest that future studies should carefully consider the inclusion criteria for their studies, try to compare locking or non-locking plates with otherwise (i) similar fracture locations and fixation principles between the groups, (ii) identical dimensions of the plates to be compared, (iii) identical number of plates and design of the plates to be compared. Furthermore, the treatment modalities of the concomitant fractures should be stated, and the timeframe in which complications occurred should be stated as well.

Based on the results of our meta-analysis, we conclude that locking plates are superior only with respect to the need for MMF in the early postoperative 5 period. However, due to the low quality of the included studies, properly designed studies are compulsory to evaluate the accurate effect on postoperative complications when treating mandibular fractures with locking plates respectively with non-locking plates.

ACKNOWLEDGMENT

The author would like to greatly acknowledge Sjoukje van der Werf for her support in the development of the search strategy. Also, we appreciate that Dr. Arpit Vashistha36 for providing missing information.

83 Chapter 5

Appendix1. Search strategy

Pubmed: ("Mandibular Fractures"[Mesh] OR ((lower jaw[tiab] OR mandib*[tiab]) AND fracture*[tiab])) AND ("locking"[tiab] OR "non locking"[tiab] OR conventional plat*[tiab] OR standard plat*[tiab]) EMBASE: mandible fracture'/exp OR ('lower jaw':ab,ti OR mandib*:ab,ti AND fracture*:ab,ti) AND (locking:ab,ti OR 'non locking*':ab,ti OR 'conventional plat*':ab,ti OR 'standard plat*':ab,ti) Web of science: TS=mandibular fracture AND (TI=locking plate OR TI=non locking plate OR

TI=conventional plate OR TI=standard plate)

Cochrane library [Mandibular Fractures] and locking plate:ti,ab,kw

Grey literature Mandibular fracture locking plate non-locking conventional plate comparative (Google Scholar)

84 Plate systems in mandibular fractures

Appendix 2. Pre-developed screening form for study selection

Aim: To compare postoperative complications in locking and non-locking plates used in mandibular fracture treatment.

1. The following inclusion and exclusion criteria will be used for the abstract and title screening. 2. If the study compared the locking and non-locking plates, however, postoperative complications were not clearly mentioned in the abstract – > Full text reading 3. If the study compared more than two osteosynthesis materials including the locking and non- locking systems and met the inclusion criteria –> Full text reading

Note: Please mark the relevant information on the abstract

Reviewer name:

Inclusion criteria Yes No Not Clear 1 Are mandibular fractures treated with osteosynthesis material? 2 Are locking plate and non-locking (Conventional or Standard miniplate) plates compared? 3 The study discussed postoperative complications? Infection ( nonunion, 5 osteomyelitis, wound dehiscence, soft tissue infection), hardware failure (plate fracture, screw loosing, dislocation of hardware), occlusal disturbance and need of IMF, paresthesia, hypoesthesia Exclusion criteria 4 Are alive humans studied? 5 Are mid-facial fractures excluded? 6 Are study is a review or expert opinion?

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Appendix 3. Outcomes of assessment of the meta-analyses according to AMSTAR-2 criteria

Items Chrcanovic (2014) Zhan et al. Wusiman et al. (2017) (2014) 1. YES NO NO 2. NO NO NO 3. YES YES NO 4. Partial YES NO NO 5. NO NO NO 6. NO YES NO 7. NO NO NO 8. Partial YES Partial YES Partial YES 9a. Partial YES NO NO 9b. NO NO NO 10. NO NO NO 11a NO NO NO 11b NO NO NO 12. NO NO YES 13. NO YES NO 14. YES YES YES 15. YES NO YES 16. YES YES YES 1. Did the research questions and inclusion criteria for the review include the components of PICO? 2. Did the report of the review contain an explicit statement that the review methods were established prior to the conduct of the review and did the report justify any significant deviations from the protocol? 3. Did the review authors explain their selection of the study designs for inclusion in the review? 4. Did the review authors use a comprehensive literature search strategy? 5. Did the review authors perform study selection in duplicate? 6. Did the review authors perform data extraction in duplicate? 7. Did the review authors provide a list of excluded studies and justify the exclusions? 8. Did the review authors describe the included studies in adequate detail? 9. Did the review authors use a satisfactory technique for assessing the risk of bias (RoB) in individual studies that were included in the review? 10. Did the review authors report on the sources of funding for the studies included in the review? 11. If meta-analysis was performed did the review authors use appropriate methods for statistical combination of results? 12. If meta-analysis was performed, did the review authors assess the potential impact of RoB in individual studies on the results of the meta-analysis or other evidence synthesis? 13. Did the review authors account for RoB in individual studies when interpreting/ discussing the results of the review? 14. Did the review authors provide a satisfactory explanation for, and discussion of, any heterogeneity observed in the results of the review? 15. If they performed quantitative synthesis did the review authors carry out an adequate investigation of publication bias (small study bias) and discuss its likely impact on the results of the review? 16. Did the review authors report any potential sources of conflict of interest, including any funding they received for conducting the review?

86 Plate systems in mandibular fractures

Appendix 4. Excluded studies after full-text reading

Number Reference Reason 1 Orion Luiz Haas Jr, Neimar Scolari, Lucas da Silva Meirelles, Ot_avio Emmel Technical note Becker, Marcelo Fernandes Santos Melo, Vin_ıcius Nery Viegas, Rog_erio Belle de Oliveira. Intraoral fixation not only prevents nerve damage and facial scarring but also minimizes the plate's risk of extraoral exposure and reduces surgical morbidity. Head Neck 38: 1436–1439, 2016 2 Harjani B, Singh RK, Pal US, Singh G. Locking v/s non-locking reconstruction Plates were plates in mandibular reconstruction. Natl J Maxillofac Surg 2012;3:159-65. compared in reconstruction surgery 3 Mohit Agarwal , Balram Meena, D. K. Gupta, Anjali Dave Tiwari, Sunil Kumar Two non-locking Jakhar. A Prospective Randomized Clinical Trial Comparing 3D and Standard plates compared Miniplates in Treatment of Mandibular Symphysis and Parasymphysis Fractures.. J Maxillofac Oral Surg. 2014;Jun;13(2):79-83 4 Kinra PK, Jayakumar K, Soumithran CS, Michael MJ, Passi D, Singh M. Two non-locking Comparative evaluation of bite force analytical study following mandibular plates compared osteosysthesis using three-dimensional and conventional locking miniplates. Natl J Maxillofac Surg 2017;8:34-40. 5 Ellis E. Treatment of mandibular fractures using a locking bone plate/screw system. J Non comparative Dent Res 76 (IADR Abstract) 1997 6 S. Rocton, A. Chaine, D. Ernenwein, C. Bertolus, A. Rigolet, J.-C. Bertrand, B. Non comparative Ruhin. Mandibular fractures: epidemiology, therapeutic management, and complications in a series of 563 cases. Rev Stomatol Chir Maxillofac 2007;108:3-12 7 Neal D. Futran . Management of comminuted mandible fractures. Operative Non comparative Techniques in Otolaryngology (2008) 19, 113-116 8 A.R.M. Cobb, S. Walsh, N.J. Lee, M. Kumar, B.M.W. Bailey. The addition of a Technical note locking plate to a modified transbuccal retractor confers increased stability and easier soft tissue control in the application of miniplates in the management of 5 mandibular angle fractures. British Journal of Oral and Maxillofacial Surgery 46 (2008) 247–248 9 Ayman Chritah, Stewart K. Lazow, Julius R. Berger. Transoral 2.0-mm Locking Non comparative Miniplate Fixation of Mandibular Fractures Plus 1 Week of Maxillomandibular Fixation:A Prospective Study. J Oral Maxillofac Surg 63:1737-1741, 2005 10 J. Bouguila,, I. Zairi, R.H. Khonsari, C. Lankriet, M. Mokhtar, A. Adouani. Non comparative Mandibular fracture: A 10-year review of 685 cases treated in Charles-Nicolle hospital (Tunis-Tunisia). Rev Stomatol Chir Maxillofac 2009;110:81-85 11 Kai-Hendrik Bormann, Sarah Wild, Nils-Claudius Gellrich, Horst Kokemüller, Non comparative Constantin Stühme, Rainer Schmelzeisen, Ralf Schön. Five-Year Retrospective Study of Mandibular Fractures in Freiburg, Germany: Incidence, Etiology, Treatment, and Complications. J Oral Maxillofac Surg 67:1251-1255, 2009 12 P. Amailuk, A. Cheng, A. Goss, P. Sambrook. Post operative infections in Non comparative mandibular fractures in Adelaide, Australia: incidence and patient factors during introduction period of locking plates 2010–2013. International Journal of Oral and Maxillofacial Surgery Volume 44, Supplement 1, October 2015, Pages e184-e185 13 Suraj Arjun Ahuja, Jyotsna Galinde, Usha Asnani, Yusuf A. Mistry. Comparative Two non-locking Evaluation of Clinical Outcomes Using Delta Plates and Conventional Miniplates for plates compared Internal Fixation of Mandibular Condylar Fractures in Adults. J Oral Maxillofac Surg 76:1255-1266, 2018 14 Chih-Wen Cheng, Rong-Wu Yong, Che-Yi Lin, Min-Te Chang, Chun-Jung Chen, Non comparative Wei-Fan Chiang. Two-Year Treatment Outcomes of Mandibular Fractures in a Suburban Hospital of Taiwan. Taiwan J Oral Maxillofac Surg 22: 175-188, September 2011 15 Giorgio Novelli, Cristiano Sconza, Emanuela Ardito, Alberto Bozzetti. Surgical Non comparative Treatment of the Atrophic Mandibular Fractures by Locked Plates Systems: Our and review Experience and a Literature Review. Craniomaxillofac Trauma Reconstruction 2012;5:65–74 16 Gokkulakrishnan S, Singh S, Sharma A, Shahi AK. An analysis of postoperative Non comparative complications and efficacy of 3-D miniplates in fixation of mandibular fractures. Dent Res J 2012;9:414-21. 17 Thomas Lee, Raja Sawhney, Yadranko Ducic. Miniplate Fixation of Fractures of the Non comparative Symphyseal and Parasymphyseal Regions of the Mandible. JAMA Facial Plast Surg. 2013;15(2):121-125. 18 Guruprasad Yadavalli, P Hema Mythily, Jayaprasad N Shetty. Clinical evaluation of Non comparative mandibular angle fractures with teeth in fracture line, treated with stable internal fixation. Indian J Stomatol 2011;2(4):216-21 87 19 R. Balasundaram, Kavitha Nanjundan. Locking plates and locking screws for Non comparative management of mandibular fractures. IOSR Journal of Dental and Medical Sciences 2018;17(2):38-42 20 Mahmoud E. Khalifa, Emad F. Essa and Rafic R. Pedar. Different Treatment Non comparative modalities for anterior mandibular fractures (A retrospective study). J Am Sci 2017;13(6):22-29

21 Singh RK, Agrawal A, Pal US, Singh G, Agrawal A, Singh G. Single miniplate Non comparative osteosynthesis in angle fracture. Natl J Maxillofac Surg [Internet]. 2011a Jan [cited 2018 Aug 27];2(1):47–50. Available from: http://www.njms.in/text.asp?2011/2/1/47/85853 22 Holaiel WN, Elprince N, Fahmy MN. Matrix Miniplate versus Locking Miniplate in Less than 10 the Management of Displaced Mandibular Angle Fractures. International Journal of cases in each Science and Research 2017;6(3):261-269 group 23 Sadhwani BS, Anchlia S. Conventional 2.0 mm miniplates versus 3-D plates in Two non-locking mandibular fractures. Ann Maxillofac Surg 2013;3:154-9. plates compared 24 Singh, V., Puri, P., Arya, S., Malik, S., & Bhagol, A. (2012). Conventional versus 3- Two non-locking Dimensional Miniplate in Management of Mandibular Fracture: A Prospective plates compared Randomized Study. Otolaryngology–Head and Neck Surgery, 147(3), 450–455. https://doi.org/10.1177/0194599812449437

Treatment of the Atrophic Mandibular Fractures by Locked Plates Systems: Our and review Experience and a Literature Review. Craniomaxillofac Trauma Reconstruction 2012;5:65–74 16 Gokkulakrishnan S, Singh S, Sharma A, Shahi AK. An analysis of postoperative Non comparative Chapter 5 complications and efficacy of 3-D miniplates in fixation of mandibular fractures. Dent Res J 2012;9:414-21. 17 Thomas Lee, Raja Sawhney, Yadranko Ducic. Miniplate Fixation of Fractures of the Non comparative Symphyseal and Parasymphyseal Regions of the Mandible. JAMA Facial Plast Surg. 2013;15(2):121-125. 18 Guruprasad Yadavalli, P Hema Mythily, Jayaprasad N Shetty. Clinical evaluation of Non comparative mandibular angle fractures with teeth in fracture line, treated with stable internal fixation. Indian J Stomatol 2011;2(4):216-21 19 R. Balasundaram, Kavitha Nanjundan. Locking plates and locking screws for Non comparative management of mandibular fractures. IOSR Journal of Dental and Medical Sciences 2018;17(2):38-42 20 Mahmoud E. Khalifa, Emad F. Essa and Rafic R. Pedar. Different Treatment Non comparative modalities for anterior mandibular fractures (A retrospective study). J Am Sci 2017;13(6):22-29

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REFERENCE

1. Lucca M., Shastri K., McKenzie W., Kraus J., Finkelman M., Wein R. Comparison of treatment outcomes associated with early versus late treatment of mandible fractures: A retrospective chart review and analysis. J Oral Maxillofac Surg 2010;68(10):2484–8. Doi: 10.1016/j.joms.2010.01.024. 2. Gutta R., Tracy K., Johnson C., James LE., Krishnan DG., Marciani RD. Outcomes of mandible fracture treatment at an academic tertiary hospital: A 5-year analysis. J Oral Maxillofac Surg 2014;72(3):550–8. Doi: 10.1016/j.joms.2013.09.005. 3. Malanchuk VO., Kopchak A V. Risk factors for development of infection in patients with mandibular fractures located in the tooth-bearing area. J Cranio-Maxillofacial Surg 2007;35(1):57–62. Doi: 10.1016/j.jcms.2006.07.865. 4. Mathog RH., Toma V., Clayman L., Wolf S. Nonunion of the mandible: an analysis of contributing factors. J Oral Maxillofac Surg 2000;58(7):746-52; discussion 752-3. Doi: 10.1053/joms.2000.7258. 5. Feller KU., Schneider M., Hlawitschka M., Pfeifer G., Lauer G., Eckelt U. Analysis of complications in fractures of the mandibular angle - A study with finite element computation and evaluation of data of 277 patients. J Cranio-Maxillofacial Surg 2003;31(5):290–5. Doi: 10.1016/S1010-5182(03)00015-5. 6. Gerbino G., Roccia F., De Gioanni PP., Berrone S. Maxillofacial trauma in the elderly. 5 J Oral Maxillofac Surg 1999;57(7):777-82; discussion 782-3. 7. Passeri LA., Ellis E., Sinn DP. Relationship of substance abuse to complications with mandibular fractures. J Oral Maxillofac Surg 1993;51(1):22–5. 8. Sauerbier S., Schön R., Otten JE., Schmelzeisen R., Gutwald R. The development of plate osteosynthesis for the treatment of fractures of the mandibular body - A literature review. J Cranio-Maxillofacial Surg 2008;36(5):251–9. Doi: 10.1016/j. jcms.2007.08.011. 9. Haug RH., Street CC., Goltz M. Does plate adaptation affect stability? A biomechanical comparison of locking and nonlocking plates. J Oral Maxillofac Surg 2002;60(11):1319–26. 10. Saikrishna D., Shetty SK., Marimallappa TR. A comparison between 2.0-mm standard and 2.0-mm locking miniplates in the management of mandibular fractures. J Maxillofac Oral Surg 2009;8(2):145–9. Doi: 10.1007/s12663-009-0036- 5. 11. Yang L., Patil PM. Comparative evaluation of 2.0 mm locking plate system vs 2.0 mm non-locking plate system for mandibular angle fracture fixation: a prospective randomized study. Eur Rev Med Pharmacol Sci 2015;19(4):552–6. 12. Collins CP., Pirinjian-Leonard G., Tolas A., Alcalde R. A prospective randomized clinical trial comparing 2.0-mm locking plates to 2.0-mm standard plates in treatment of mandible fractures. J Oral Maxillofac Surg 2004;62(11):1392–5. Doi: 10.1016/j.joms.2004.04.020. 13. Singh V., Kumar I., Bhagol A. Comparative evaluation of 2.0-mm locking plate

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system vs 2.0-mm nonlocking plate system for mandibular fracture: a prospective randomized study. Int J Oral Maxillofac Surg 2011;40(4):372–7. Doi: 10.1016/j. ijom.2010.11.012. 14. Chrcanovic BRR. Locking versus non-locking plate fixation in the management of mandibular fractures: a meta-analysis. Int J Oral Maxillofac Surg 2014;43(10):1243– 50. Doi: 10.1016/j.ijom.2014.07.014. 15. Zhan S., Jiang Y., Cheng Z., Ye J. A meta-analysis comparing the 2.0-mm locking plate system with the 2.0-mm nonlocking plate system in treatment of mandible fractures. J Craniofac Surg 2014;25(6):2094–7. Doi: 10.1097/ SCS.0000000000001018. 16. Wusiman P., Tuerxun J., Yaolidaxi B., Moming A. Locking Plate System Versus Standard Plate Fixation in the Management of Mandibular Fractures. J Craniofac Surg 2017;28(6):1456–61. Doi: 10.1097/SCS.0000000000003857. 17. Moher D., Liberati A., Tetzlaff J., Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 2009;339(jul21 1):b2535– b2535. Doi: 10.1136/bmj.b2535. 18. Shea BJ., Reeves BC., Wells G., Thuku M., Hamel C., Moran J., et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non- randomised studies of healthcare interventions, or both. Bmj 2017;4008:j4008. Doi: 10.1136/bmj.j4008. 19. Higgins JPT., Altman DG., Gotzsche PC., Juni P., Moher D., Oxman AD., et al. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials. Bmj 2011;343(oct18 2):d5928–d5928. Doi: 10.1136/bmj.d5928. 20. Slim K., Nini E., Forestier D., Kwiatkowski F., Panis Y., Chipponi J. Methodological index for non-randomized studies (Minors): Development and validation of a new instrument. ANZ J Surg 2003;73(9):712–6. Doi: 10.1046/j.1445-2197.2003.02748.x. 21. Jadad AR., Moore RA., Carroll D., Jenkinson C., Reynolds DJM., Gavaghan DJ., et al. Assessing the quality of reports of randomized clinical trials: Is blinding necessary? Control Clin Trials 1996;17(1):1–12. Doi: 10.1016/0197-2456(95)00134- 4. 22. Giri KY., Sahu P., Rastogi S., Dandriyal R., Mall S., Singh AP., et al. Bite Force Evaluation of Conventional Plating System Versus Locking Plating System for Mandibular Fracture. J Maxillofac Oral Surg 2015;14(4):972–8. Doi: 10.1007/ s12663-015-0764-7. 23. Rastogi S., Reddy MP., Swarup AG., Swarup D., Choudhury R. Assessment of Bite Force in Patients Treated with 20-mm Traditional Miniplates versus 2.0-mm Locking Plates for Mandibular Fracture. Craniomaxillofacial Trauma Reconstr 2016;9(1):62–8. Doi: 10.1055/s-0035-1563697. 24. Kumar I., Singh V., Singh A., Arora V., Bajaj A. Comparative evaluation of 2.0-mm locking plate system vs. 2.0-mm nonlocking plate system for mandibular fractures- -a retrospective study. Oral Maxillofac Surg 2013;17(4):287–91. Doi: 10.1007/ s10006-012-0377-y.

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25. Kumar BP., Kumar KAJ., Venkatesh V., Mohan AP., Ramesh K., Mallikarjun K. Study of Efficacy and the Comparison Between 2.0 mm Locking Plating System and 2.0 mm Standard Plating System in Mandibular Fractures. J Maxillofac Oral Surg 2015;14(3):799–807. Doi: 10.1007/s12663-014-0718-5. 26. Shaik M., Subba Raju T., Rao NK., Reddy CK. Effectiveness of 2.0 mm Standard and 2.0 mm Locking Miniplates in Management of Mandibular Fractures: A Clinical Comparative Study. J Maxillofac Oral Surg 2014;13(1):47–52. Doi: 10.1007/s12663- 012-0443-x. 27. Saha R., Ebenezer V., Balakrishnan R., Kumar S., Mani M., Vivek M. A comparison between locking plates and miniplates in fixation of mandibular fractures. Biomed Pharmacol J 2015;8SE(october Spl Edition):799–804. Doi: 10.13005/bpj/786. 28. Bhatt K., Arya S., Bhutia O., Pandey S., Roychoudhury A. Retrospective study of mandibular angle fractures treated with three different fixation systems. Natl J Maxillofac Surg 2015;6(1):31. Doi: 10.4103/0975-5950.168229. 29. Ali A., Chandra J., Rao SB. Comparison of Locking Titanium Miniplates and Conventional Titanium Miniplates in Treatment of Mandibular Fractures. Sch J Dent Sci 2016;3(9):257–63. Doi: 10.21276/sjds.2016.3.9.4. 30. Wakeel S., Bhat A., Shah AA., Khaliq IU. INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH A COMPARATIVE STUDY OF 2MM LOCKING PLATE SYSTEM V / S NON LOCKING PLATE IN MANDIBULAR FRACTURE Dr Syeed 5 Wakeel Dr Abrar Bhat Dr Ajaz A . Shah Dr Mohammed Israr Ul Khaliq *. Int J Sci Res 2018;7(1):530–2. 31. Agarwal M., Mohammad S., Singh RK., Singh V. Prospective randomized clinical trial comparing bite force in 2-mm locking plates versus 2-mm standard plates in treatment of mandibular fractures. J Oral Maxillofac Surg 2011;69(7):1995–2000. Doi: 10.1016/j.joms.2010.10.014. 32. Ramesh B., Kortashetti S., Umashankar G., Ramesh B. COMPARISION OF LOCKING PLATE AND CONVENTIONAL PLATE IN TREATMENT OF MANDIBULAR FRACTURE. Int J Curr Res Rev 2011;03(11):179–83. 33. Verma A., Sachdeva A., Yadav S. Versatility of Locking Plates Over Conventional Miniplates In Mandibular Fractures. J Innov Dent 2011;1(1):1–5. 34. Kumar S., Gattumeedhi SR., Sankhla B., Garg A., Ingle E., Dagli N., et al. Comparative evaluation of bite forces in patients after treatment of mandibular fractures with miniplate osteosynthesis and internal locking miniplate osteosynthesis. J Int Soc Prev Community Dent 2014;4(Suppl 1):S26-31. Doi: 10.4103/2231-0762.144575. 35. Jain MK., Sankar K., Ramesh C., Bhatta R. Management of mandibular interforaminal fractures using 3 dimensional locking and standard titanium miniplates - a comparative preliminary report of 10 cases. J Craniomaxillofac Surg 2012;40(8):e475-8. Doi: 10.1016/j.jcms.2012.03.007. 36. Vashistha A., Singh M., Chaudhary M., Agarwal N., Kaur G. Comparison of 2 mm single locking miniplates versus 2 mm two non-locking miniplates in symphysis and parasymphysis fracture of mandible. J Oral Biol Craniofacial Res 2017;7(1):42– 8. Doi: 10.1016/j.jobcr.2016.01.001.

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37. Seemann R., Frerich B., Muller S., Koenke R., Ploder O., Schicho K., et al. Comparison of locking and nonlocking plates in the treatment of mandibular condyle fractures. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009;108(3):328–34. Doi: 10.1016/j.tripleo.2009.04.026. 38. Camino Junior R., Moraes RB., Landes C., Luz JGC. Comparison of a 2.0-mm locking system with conventional 2.0- and 2.4-mm systems in the treatment of mandibular fractures: a randomized controlled trial. Oral Maxillofac Surg 2017;21(3):327–34. Doi: 10.1007/s10006-017-0636-z. 39. Kumar KN., Bhushan SN., Kumar KB., Sudheer A., Prameela S., Patnaik A. A Prospective Randomized Study on Comparison of 2.0mm Non-Locking Titanium Plates versus Locking Titanium Plates (1.8mm and 2.3mm) System for Mandibular Fracture. J Med Sci Clin Res 2017;5(11):30435–43. Doi: 10.18535/jmscr/v5i11.105. 40. Passi D., Singhal D., Kacker D., Gupta R., Singh M., Agarwal P. Comparative Evaluaton of 3- Dimensional Non Locking Versus 2- Dimensional Locking Matrix Miniplate Osteosynthesis in Mandibular Fracture Treatment : a Prospective Study and Clinica ... Research Article Comparative Evaluaton of 3-Dimensional 3 Dimensional. Int J Curr Res 2017;9(7):54092–5. 41. Baig Muqeet, Prasad Katitha R. Fixation of Mandibular Fractures- A Comparative Study Between 2 . 0 mm Locking Plates and Screws and 2.5 mm Conventional Miniplates and Screws. Int J Clin Dent Sci 2011;2(4):63–8. 42. Goyal M., Marya K., Chawla S., Pandey R. Mandibular Osteosynthesis: A Comparative Evaluation of Two Different Fixation Systems Using 2.0 mm Titanium Miniplates & 3-D Locking Plates. J Maxillofac Oral Surg 2011;10(4):316–20. Doi: 10.1007/s12663-011-0242-9. 43. Singh RK., Chand S., Pal US., Das SK., Sinha VP. Matrix miniplate versus locking miniplate in the management of displaced mandibular angle fractures. Natl J Maxillofac Surg 2013;4(2):225–8. Doi: 10.4103/0975-5950.127656. 44. Zhang J., Wang X., Wu R-HR-H., Zhuang Q-WQ-W., Gu QP., Meng J. Comparative evaluation of 2.3 mm locking plate system vs conventional 2.0 mm non locking plate system for mandibular condyle fracture fixation: a seven year retrospective study. Eur Rev Med Pharmacol Sci 2015;19(5):712–8. 45. Elsayed SAA., Mohamed FII., Khalifa GAA. Clinical outcomes of three different types of hardware for the treatment of mandibular angle fractures: A comparative retrospective study. Int J Oral Maxillofac Surg 2015;44(10):1260–7. Doi: 10.1016/j. ijom.2015.07.005. 46. Singh A., Arunkumar K V. Standard 3D Titanium Miniplate Versus Locking 3D Miniplate in Fracture of Mandible: A Prospective Comparative Study. J Maxillofac Oral Surg 2016;15(2):164–72. Doi: 10.1007/s12663-015-0817-y. 47. Strasz M., Wolschner R., Schopper C., Pöschl WP., Perisanidis C., Wick F., et al. Miniplate osteosynthesis for mandibular angle fractures - A retrospective comparative study of 3 concepts in a temporal cohort. J Cranio-Maxillofacial Surg 2016;44(1):56–61. Doi: 10.1016/j.jcms.2015.10.012. 48. George D., Suresh V., Narayanan SR., Yuvaraj V., Balaji T., Jude NJ. Comparative

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Study Between Titanium Mini Plates And 3 Dimensional Titanium Plates With Locking Screws Using Bite Force Evaluation For Management Of Anterior Mandibular Fractures. J Sci Dent 2016;6(2):7–16. 49. Holaiel WN., Elprince N., Fahmy MH. Matrix Miniplate versus Locking Miniplate in the Management of Displaced Mandibular Angle Fractures. Int J Sci Res 2017;6(3):261–9. 50. Aggarwal S., Singh M., Modi P., Walia E., Aggarwal R. Comparison of 3D plate and locking plate in treatment of mandibular fracture—a clinical study. Oral Maxillofac Surg 2017;21(4):383–90. Doi: 10.1007/s10006-017-0642-1. 51. Budhraja NJ., Shenoi RS., Badjate SJ., Bang KO., Ingole PD., Kolte VS. Three- dimensional Locking Plate and Conventional Miniplates in the Treatment of Mandibular Anterior Fractures. Ann Maxillofac Surg 2017;8(1):73–7. Doi: 10.4103/ ams.ams_175_17. 52. Zeng X., Zhang Y., Kwong JSW., Zhang C., Li S., Sun F., et al. The methodological quality assessment tools for preclinical and clinical studies, systematic review and meta-analysis, and clinical practice guideline: A systematic review. J Evid Based Med 2015;8(1):2–10. Doi: 10.1111/jebm.12141. 53. Ehrenfeld M., Manson PN., Prein J. Principles of Internal Fixation of the Craniomaxillofacial Skeleton. Trauma and Orthognathic Surgery. Georg Thieme Verlag; 2012. 5 54. Kim MY., Kim CH., Han SJ., Lee JH. A comparison of three treatment methods for fractures of the mandibular angle. Int J Oral Maxillofac Surg 2016;45(7):878–83. Doi: 10.1016/j.ijom.2016.02.013. 55. Al-Moraissi EA. One miniplate compared with two in the fixation of isolated fractures of the mandibular angle. Br J Oral Maxillofac Surg 2015;53(8):690–8. Doi: 10.1016/j.bjoms.2015.05.006.

93 Khulan or Mongolian wild ass (equus hemionus hemionus pallas) , Credit: Hureelen/ Ganbayar Urtnasan CHAPTER 6

A TREATMENT PROTOCOL FOR FRACTURES OF THE EDENTULOUS MANDIBLE

Enkh-Orchlon Batbayar, Ruud R.M.Bos, Baucke van Minnen J Oral Maxillofac Surg. 2018 Oct;76(10):2151-2160. https://doi.org/10.1016/j.joms.2018.04.010. Epub 2018 Apr 14. Chapter 6

ABSTRACT

Purpose. The incidence of fractures of edentulous mandibles is relatively low. The knowledge about the management of these fractured edentulous mandibles relies heavily upon case reports and observational studies. Based on current literature, we compiled a treatment protocol for fractures of the edentulous mandible and hypothesized that this protocol results in fewer complications.

Patients and Methods. We conducted a retrospective cohort study of edentulous patients with a mandibular fracture. The predictor variable was the fulfillment of the treatment protocol (yes, no). The outcome variables were postoperative complications and reoperation. Demographic variables of patients were collected from patient’s records. A chi-square test was used for statistical analysis between predictor and outcome variables.

Results. Of 61 edentulous mandibular fractures (36 patients), 53 fractures were treated according to the protocol and 8 were not. Four complications were observed first group in the (complication rate 4/53=7.5%) and four in the second group (complication rate 4/8=50%). The fracture treatments that followed the protocol had a significantly (p=.001, OR=.082) lower postoperative complication rate, and needed fewer reoperations (p=.0001, OR=.019) compared with the treatments that did not follow the protocol.

Conclusion. The results of this study show that following the compiled treatment protocol for fractures of edentulous mandibles significantly reduces postoperative complications and reoperations.

96 A Treatment Protocol for Fractures of the Edentulous Mandible

INTRODUCTION

The incidence of fractures of edentulous atrophic mandibles is relatively low. 1 The knowledge about the management of these fractures relies heavily upon case reports and observational or retrospective studies.2 Moreover, a systematic Cochrane review did not provide sufficient evidence for the best treatment of these fractures and concluded that treatment decisions are mainly based on clinician’s experience.6

Several factors need to be considered to treat patients with edentulous mandibular fractures, such as comorbidities, age, fracture type and particularly residual bone height at the fracture site. Some clinicians state that it is preferable to treat severely atrophic mandibular fractures with a combination of an autogenous bone graft and a load bearing plate.8,9 However, different theories have been proposed regarding the use of load-sharing or load- bearing principles in these fractures. Load-bearing plates without bone graft are advocated by some authors because this method is less invasive.4,5,9

Based on current literature and with our experiences, we compiled a treatment protocol (Fig.1) for fractures of the edentulous mandible. The aim of this study was to evaluate the effect of the treatment protocol for edentulous mandibular fractures on complication rates and number of reoperations. 6

METHODS

In a retrospective cohort study, we included all edentulous mandibular fracture cases which were treated at Department of Oral and Maxillofacial Surgery, University Medical Center Groningen, the Netherlands from January 2007 to December 2016. Due to its retrospective nature, this study was exempted of approval by the ethical review board of the University Medical Center Groningen. Edentulous individuals that received surgical or non-surgical treatment for a mandibular fracture were included. Patients were excluded who received initial treatment at other hospitals, when pre or post treatment radiographs were missing, and when follow-up was less than three months.

Based on the type of fracture and the height of the mandible, a treatment protocol was compiled (Fig 1).3,8,10–13 This protocol was not consistently applied to all cases during the study period. The total population of patients

97 Chapter 6 Treatment protocol protocol Treatment Fig 1.

98 A Treatment Protocol for Fractures of the Edentulous Mandible

was divided into two groups dependent on whether the treatment protocol was followed or not. The predictor variable was the fulfillment of the treatment protocol (followed, not followed) and the outcome variables were postoperative complications (yes, no) and reoperations (yes, no).

The following information was obtained from the electronic database of the university hospital: age, gender, comorbidities, wearing of dentures (regular or implant-retained), smoking habits, alcohol and drug addiction, concomitant fracture(s), cause of trauma, fracture location, fracture type and dislocation, treatment protocol, treatment modalities, type of fixation materials, vertical bone height, hospitalization time, follow-up duration, post-treatment complications, and reoperations. All patients received perioperative prophylactic antibiotics of variable duration.

Observed complications were recorded and divided into major and minor complications. Major complications included those that require reoperation. All other complications that were treated without surgical intervention were classified as minor. The vertical height of the fracture site was measured in millimeters from upper to lower border using a panoramic radiograph. The condylar fractures were classified using the classification of Loukota et al.14

AO (Arbeitsgemeinschaft für Osteosynthesefragen) terminology was used 6 for defining the fracture types.15 A simple fracture has a single fracture line producing 2 fracture fragments. A comminuted fracture has multiple fracture lines in the same anatomic location resulting in multiple fragments of bone. In an incomplete fracture, the fractures do not extend through both the buccal and the lingual cortices, as well as the alveolar and basal borders. In such cases, the fracture will be nondisplaced and nonmobile. Displacement: the fracture fragments are not anatomically aligned. Displacement is graded roughly as minimal, moderate and severe. However, there is no universally accepted definition for these terms.

Data were statistically analysed with IBM SPSS version 23.0.03 software. Statistical significance was set at p< .05 and the chi-square exact test was used to analyze differences.

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RESULTS

Demographics of patients and fractures

During the study period, 42 edentulous patients with a mandibular fracture were identified. Six patients were excluded: in four patients follow-up was less than three months, from one patient radiographs were missing, and one patient was not intitially treated in our hospital. A total of 36 patients who had 61 mandibular fractures were included this study. Patients’ mean age was 66±13 years (range 42-95 years). Nineteen (52.8%) patients were male, and 17 (47.2%) female. A mean follow-up was 6.3±4 months (range 3-21 months).

Fractures were caused by falls (n=9, 25%), assaults (n=8, 22%), vehicle accidents, including motor vehicles, bicycle and electronic bicycle (n=6, 16%). In seven (19%) patients the fracture occurred after the insertion of a dental implant, and in one patient (3%) the mandible fractured due to infection of a transmandibular implant which had been implanted 25 years before. The remaining patients had pathologic fractures due to osteomyelitis (n=2, 6%), fracture due to a complicated third molar extraction (n=1, 3%), spontaneous fracture during chewing with an ill-fitting denture (n=1, 3%), and fracture due to a collision with a cow (n=1, 3%).

Table 1. Fracture characteristics (n=61) Mean vertical bone 13.1±6.5 mm height* n (%) Location Parasymphyseal 22 (36.1) Body 16 (26.2) Angle 5 (8.2) Ramus 2 (3.3) High condyle 13 (21.5) Low condyle 3 (5.0) Type Simple 54 (88.5) Comminuted 4 (6.5) Incomplete 3 (5.0) Displacement No 31 (51.0) Yes 30 (49.0) Vertical bone ≤10 mm 19 (44.0) height (mm)* >10 mm 24 (56.0) Complications No 53 (87.0) Minor 1 (1.5) Major 7 (11.5) Reoperation Yes 5 (8.2) No 56 (91.8) *Ramus and condylar fractures (18 fractures) were not counted

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A Treatment Protocol for Fractures of the Edentulous Mandible

Concomitant fractures were present in 10 patients (27.8%). Of these patients, 4 patients had polytrauma (long bone fractures), 3 had maxillary fractures, 2 had fractures of the maxillary sinus, and 1 had orbital an orbital floor fracture. Comorbidities occurred in 40 patients (83.4%). Hypertension, alcohol and drug abuse, chronic obstructive pulmonary disease, osteoporosis, and malnutrition were most frequently observed.

Mandibular fractures were mostly located in the parasymphyseal region, followed by the body region. General characteristics of fractures are shown in Table 1. Before treatment 19 patients did not wear any prosthesis, 15 patients had a removable denture, and two patients had implant-supported dentures.

In total, eight fracture cases occurred after the insertion of implants (iatrogenic). After the fractures were treated, six of the patients received a new implant- supported prosthesis using the remaining implants or a new prosthesis after insertion of a new implant near the fracture location (Fig 2).

Treatment modalities

Of 61 fractures, 31(51%) underwent open reduction and internal fixation (ORIF). The remaining 30 fractures were treated in a closed manner (Table 2). In total, 27 treatments used load-sharing plates (2.0 mm mini-plates), 11 6

Table 2. Treatment modalities according to the treatment protocol (n=61) Treatment protocol Bone Bone Low High Non Non Displaced height height > condylar condylar displaced displaced Implant Variables ≤10 mm 10 mm fracture fracture and non- Implant related (n=12) (n=17) (n=4) or Ramus mobility or related fracture (n=14) incomplete fracture (n=1) (n=6) (n=7) Bone graft 6 (50%) 1 (6%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 1 (100%) and load bearing plate Treatment Load 4 (33%) 16 (94%) 3 (75%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) modalities sharing or load bearing plate only Closed 2 (17%) 0 (0%) 1 (25%) 14 (100%) 6 (100%) 7 (100%) 0 (0%) Yes 3a (25%) 3b (18%) 0 (0%) 0 (0%) 0 (0%) 1c (14%) 1d (100%) Complication No 9 (75%) 14 (82%) 4 (100%) 14 (100%) 6 (100%) 6 (86%) 0 (0%) Re-operation Yes 3 (25%) 1 (6%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 1 (100%) No 9 (75%) 16 (94%) 4 (100%) 14 (100%) 6 (100%) 5 (100%) 0 (0%) Protocol Yes 5 (42%) 17 (100%) 4(100%) 14(100%) 6 (100%) 7 (100%) 0 (0%) followed No 7 (58%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 1 (100%) a Non-union (n=2), re-dislocation of the fracture (n=1) b Osteomyelitis (n=1), wound dehiscence (n=1), plate fracture (n=1) c Pseudarthrosis (n=1) d Osteomyelitis (n=1)

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C Fig 2. A, Postoperative panoramic radiograph after insertion of 3 implants in a severely atrophic mandible. B, Fracture in the left parasymphyseal area (arrow) with loss of 1 implant 1 month later. C, Result 8 months after closed treatment and insertion of a new implant.

102 A Treatment Protocol for Fractures of the Edentulous Mandible

treatments used load-bearing plates (2.3 mm, n=8; Pape-Gerlach, n=2; or 2.7mm, n=1), and a combination of load-bearing and load-sharing plates were used in 3 cases (2.3 mm plus 2.0 mm). Bone grafts were used in 8 fractures in combination with load-bearing plates and circum-mandibular wiring. All bone grafts were harvested from the iliac crest and positioned along the lower border of the fracture. In 24 (77.5%) fractures, reduction was achieved by manual reduction, and 7 fractures (22.5%) were reduced by repositioning forceps. After treatment, 7 patients did not wear a denture until the end of follow-up. Twelve patients had a new removable partial denture, 5 patients used their old removable partial denture, 11 patients had implant-supported denture, and 1 patient underwent a Rohner procedure.16,17 Patients started to wear their prosthesis at a mean of 4.5±3.5 months after treatment.

Treatment protocol

In 8 out of 61 fractures (13%), treatment was not performed according to the protocol. In all 8 fractures, the vertical bone height was less than 10 mm or less (Table 3). Among them, 4 fractures were treated with ORIF without bone grafts. Two fractures underwent fixation with a load-bearing plate and with a bone graft but not with a sufficient number of screws (Fig 3). Two cases were treated in a closed manner. In 1 case this was because the patient refused to undergo an operation, and in the second case the patient’s general health condition 6 was a strict contraindication for surgery.

Table 3. Characteristics of fractures in which the treatment protocol was not followed № Gender/ Fracture Vertical Management Comment Complications Age (years) location bone height (mm) 1 Male, 61 Body 5.00 2.3 mm plate Bone graft was necessary Non-union with plate loosening 2 Male, 61 Body 5.08 2.3 mm plate and Bone graft was necessary Non-union with 2.00 mm plates screw loosening 3 Male, 74 Para- 7.70 Bone graft with Bone graft was done, but 2 Re-dislocation of symphysis 2.3 mm plate screws on the proximal side the fracture of fracture 4 Female, 73 Para- 5.00 Bone graft with Bone graft was done, but 2 Osteomyelitis symphysis Pape-Gerlach screws on the proximal plates side of fracture 5 Female, 72 Body 5.00 2.0 mm plates Bone graft and load bearing No plate was necessary 6 Female, 79 Body 8.00 2.7 mm plate Bone graft was necessary No 7 Female, 85 Body 9.10 Closed Bone graft and load bearing No plate was necessary 8 Female, 65 Body 8.75 Closed Bone graft and load bearing No plate was necessary

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Chapter 6

A B Fig 3. A, Postoperative panoramic radiograph showing the right-sided body fracture of a severely atrophic mandible with fixated a bone graft, 2.3 mm plate, and circum-mandibular wiring. B, Redislocation of the fracture (arrow) probably occurred because only 2 screws had been inserted on the proximal side of the fracture

Complication and reoperation

Of 61 fractures, 53 did not show any complications. Complications occurred in 8 fractures (13%). One originally nondisplaced implant-related fracture of an edentulous irradiated mandible became displaced during follow-up. The patient did not undergo surgery because there were no complaints. Therefore, this case was classified as a minor complication. Major complications occurred in 7 fracture cases, including osteomyelitis (n=2), nonunion (n=2), wound dehiscence (n=1), plate fracture (n=1), and redislocation of the fracture (n=1). Of the complications, 4 occurred in the group in which the treatment protocol was correctly followed (complication rate, 7.5% [4 of 53]); the remaining 4 complications occurred in the group of fractures not treated according to the protocol (complication rate, 50% [4 of 8]). As shown in Table 4, complications occurred significantly more often when the fracture treatment was not performed according to the protocol.

A total of 19 fractures occurred in severely atrophic (≤10 mm) mandibles. In 11 of these fractures, the treatment protocol was followed and no complications occurred. However, in 8 fractures the treatment protocol was not followed, and major complications occurred in 4 of them (50%). A significant difference was found between these two groups (p=.018, OR=2, 95% CI 2:4).

104 A Treatment Protocol for Fractures of the Edentulous Mandible

Table 4. Two-by-two table between the fulfillment of protocol and complications Complication Total Protocol Yes No Yes 4 (7.5%) 49 (92.5%) 53 (100%) No 4 (50%) 4 (50%) 8 (100%) Total 8 (13%) 53 (87%) 61 (100%)

P value .001, OR=.082 (95% CI, .015:.456)

Table 5. Two-by-two Table between the fulfillment of protocol and reoperations Re-operation Total Protocol Yes No Yes 1 (2%) 52 (98%) 53 (100%) No 4 (50%) 4 (50%) 8 (100%) Total 5 (8%) 56 (92%) 61 (100%) P value .0001, OR=.019 (95% CI, .002:.215)

Of 8 compilations, 5 resulted in an indication for reoperation. Of these fractures,

2 originally underwent fixation with bone grafts and load-bearing plates (Fig 3), 2 underwent fixation without bone grafts and both load-bearing and load- sharing plates (Fig 4), and 1 underwent fixation with a load-sharing plate only.

Table 5 shows that significantly fewer reoperations were necessary when the protocol was followed.

Confounders 6

The possible confounding factors for complications are summarized in Table 6. No association between complication and potential confounders was found.

DISCUSSION

The aim of the current study was to assess the importance of following a treatment protocol for fractures of the edentulous mandible. The results of this study suggest that fractures of edentulous mandibles treated according to the treatment protocol have fewer complications. The treatment protocol (shown in Fig. 1) was compiled based on current literature and retrospecitvely applied to our total cohort. This protocol supports the strategy of an invasive approach (i.e. bone grafting combined with load bearing plate) for fractures of the atrophic mandible with a height of 10 mm or lower, and a less invasive for fractures of the edentulous mandible with sufficient bone height of more than 10 mm.

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B Fig 4. A, Postoperative panoramic radiograph showing fixation of severely atrophic mandibular fractures using load-bearing and load-sharing plates without bone grafts. After 1.5 months, redislocation (arrows) occurred. B, Open reduction and internal fixation after reoperation with autogenous bone grafts and load-bearing plates in same patient.

The treatment protocol was not followed in a total of eight fractures although in all these fractures bone height was less than 10 mm. Four of them presented major complications such as nonunion, osteomyelitis and re-dislocation of the fracture. Nonunion and osteomyelitis is the most common complication when fractures of severely atrophic mandibles are treated without bone grafts.2,3 Furthermore, several studies have shown the importance of the number of screws on each side of the fracture.10,11,18 These studies suggested that at

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A Treatment Protocol for Fractures of the Edentulous Mandible

Table 6. Potential confounders of complication Variables Complications P value* Yes No n (%)a n (%)a Gender Male 5 (26) 14 (74) .408 (n=36 Patients) Female 2 (12) 15 (88) Co-morbidity** Yes 4 (13) 26 (87) .073 (n=36 Patients) No 3 (50) 3 (50) Concomitant Yes 4 (40) 6 (60) .076 fracture No 3 (12) 23 (88) (n=36 Patients)

Bone height at <10 mm 4 (17) 15 (83) >.99 fracture line >10 mm 4 (21) 20 (79) (n=43 fractures) Fracture location b Anterior 7 (18) 31 (82) .143 (n=61 Fractures) Posterior 1 (4) 22 (96) Fracture Yes 6 (20) 24 (80) .147 Displacement No 2 (7) 29 (93) (n=61 Fractures) Fracture type Simple 6 (11) 48 (89) .067 (n=61 Fractures) Complex 2 (50) 2 (50) Incomplete 0 (0) 3 (100) Fracture fixation Load 3 (18) 14 (82) .851 (n=31 Fractures) sharing Load 3 (27) 8 (73) bearing Both 1 (33) 2 (67) Bone graft Yes 2 (25) 6 (75) .581 No 6 (11) 47 (89) 6 a Row percentage b Anterior (symphyseal, parasymphyseal, body), Posterior (angle, ramus, condyle) *Results of Chi square test (exact procedure) **American Society of Anesthesiologists classification III.

least 3 screws should be used on both sides of a fracture. In our study, 2 of the complications occurred probably because of lack of at least 3 screws at the proximal side of the fracture (2 screws inserted).

Fractures of the edentulous mandible with more than 10 mm bone height at the fracture site were mainly treated with ORIF without bone grafts. However, one pathologic fracture with a continuity defect was treated with load-bearing osteosynthesis with an autogenous bone graft. In fractures higher than 10 mm bone height, load-sharing plates can be used without bone graft in cases with good interfragmentary stability, while load-bearing plates can be used without bone graft in cases without sufficient interfragmentary stability.

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In our study 19 out of 61 fractures occurred in severely atrophic (<10 mm) mandibles. The severely atrophic mandibles that were not treated according to the protocol presented major complications twice as often as fractures treated according to the protocol.

Fractures of the atrophic mandible occurring after implant insertion are rarely reported.19,20,12 In the current study, eight mandibular fractures occurred after the insertion of an implant. All these fractures were treated closed, except one severely dislocated fracture case. This shows that closed treatment can result in uncomplicated healing in case there is no or just minor dislocation, and there is even agreement among some authors, who suggest closed treatment for implant related fractures of atrophic mandibles.12,21 One severely dislocated fracture after implant placement was initially treated with an autogenous bone graft and load bearing plate. However, because of osteomyelitis, this case needed re-operation through a Rohner procedure.16,17 Eventually, 3/4 of these patients received an implant-supported prosthesis on the remaining implants or after re-insertion of an implant. High condylar fractures and non-displaced or incomplete fractures were all treated closed, and no complications were observed.

A possible limitation of the current study is that the vertical height at the fracture site was measured using the OPG, which may result in magnification error. However, as this applied to both groups this should not affect the results of the study. Another limitation of this study could result from its retrospective design. On the other hand this study is based on a relatively high number of patients, compared to other reports on the treatment of fractures of the edentulous mandible. Furthermore, possible confounders were assessed that might explain postoperative complications.

Notwithstanding these limitations, the results of this study show that following the compiled treatment protocol for fractures of edentulous mandibles significantly reduces postoperative complications and reoperations.

108 A Treatment Protocol for Fractures of the Edentulous Mandible

REFERENCES

1. Ellis E, Moos KF, El-Attar A: Ten years of mandibular fractures: An analysis of 2,137 cases. Oral Surgery, Oral Med Oral Pathol 59: 120, 1985. 2. Tiwana PS, Abraham MS, Kushner GM, Alpert B: Management of Atrophic Edentulous Mandibular Fractures: The Case for Primary Reconstruction With Immediate Bone Grafting. J Oral Maxillofac Surg 67: 882, 2009. 3. Luhr HG, Reidick T, Merten HA: Results of treatment of fractures of the atrophic edentulous mandible by compression plating: A retrospective evaluation of 84 consecutive cases. J Oral Maxillofac Surg 54: 250, 1996. 4. Clayman L, Rossi E: Fixation of atrophic edentulous mandible fractures by bone plating at the inferior border. J Oral Maxillofac Surg 70: 883, 2012. 5. Mugino H, Takagi S, Oya R, Nakamura S, Ikemura K: Miniplate osteosynthesis of fractures of the edentulous mandible. Clin Oral Investig 9: 58, 2005. 6. Nasser M, Fedorowicz Z, Ebadifar A: Management of the fractured edentulous atrophic mandible. Cochrane Database Syst Rev, 2007. 7. Melo AR, Aguiar Soares Carneiro SC De, Leal JLF, Vasconcelos BCDE: Fracture of the atrophic mandible: Case series and critical review. J Oral Maxillofac Surg 69: 1430, 2011. 8. Ellis E, Price C: Treatment Protocol for Fractures of the Atrophic Mandible. J Oral Maxillofac Surg 66: 421, 2008. 9. Castro-Núñez J, Cunningham LL, Sickels JE Van: Atrophic Mandible Fractures: Are Bone Grafts Necessary? An Update. J Oral Maxillofac Surg: 1, 2017. 6 10. Haug RH: The effects of screw number and length on two methods of tension band plating. J Oral Maxillofac Surg 51: 159, 1993. 11. Haug RH: Effect of screw number on reconstruction plating. Oral Surgery, Oral Med Oral Pathol 75: 664, 1993. 12. Raghoebar GM, Stellingsma K, Batenburg RHK, Vissink A: Etiology and management of mandibular fractures associated with endosteal implants in the atrophic mandible. Oral Surgery, Oral Med Oral Pathol Oral Radiol Endodontology 89: 553, 2000. 13. Dijkstra PU, Stegenga B, Bont LGM de, Bos RRM: Function impairment and pain after closed treatment of fractures of the mandibular condyle. J Trauma 59: 424, 2005. 14. Loukota RA, Eckelt U, Bont L De, Rasse M: Subclassification of fractures of the condylar process of the mandible. Br J Oral Maxillofac Surg 43: 72, 2005. 15. AO Surgery Reference Glossary. Available at: https://www2.aofoundation. org/wps/portal/!ut/p/a1/04_Sj9CPykssy0xPLMnMz0vMAfGjzOKN_ A0M3D2DDbz9_UMMDRyDXQ3dw9wMDAwCTYEKIoEKDHAAR wO8-sMMofpxKXA0J85-PBYQ0F-QGxoa6qioCAAtJLPL/dl5/d5/ L2dJQSEvUUt3QS80Sm1FL1o2XzJPMDBHSVMwS09PVDEwQVNFMUdWRj

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AwMEU3/?soloState=true&. 16. Rohner D, Bucher P, Hammer B: Prefabricated fibular flaps for reconstruction of defects of the maxillofacial skeleton: planning, technique, and long-term experience. Int J Oral Maxillofac Implants 28: e221, 2013. 17. Schepers RH, Raghoebar GM, Vissink A, Lahoda LU, Meer WJ Van Der, Roodenburg JL, Reintsema H, Witjes MJ: Fully 3-dimensional digitally planned reconstruction of a mandible with a free vascularized fibula and immediate placement of an implant- supported prosthetic construction. Head Neck 35, 2013. 18. Pereira-Filho VA, Silva BN da, Nunes Reis JM, Spin-Neto R, Real Gabrielli MF, Monnazzi MS: Effect of the number of screws on the stability of locking mandibular reconstruction plates. Int J Oral Maxillofac Surg 42: 732, 2013. 19. Meijer HJA, Raghoebar GM, Visser A: Mandibular Fracture Caused by Peri-Implant Bone Loss: Report of a Case. J Periodontol 74: 1067, 2003. 20. Almasri M, El-Hakim M: Fracture of the anterior segment of the atrophic mandible related to dental implants. Int J Oral Maxillofac Surg 41: 646, 2012. 21. Tolman DE, Keller MSDEE: Management of Mandibular Fractures in Patients With Endosseous Implants. Int J Oral Maxillofac Implant 6:

110 A Treatment Protocol for Fractures of the Edentulous Mandible

111 The black-tailed gazelle (Gazella subgutturosa), Credit: Hureelen/ Ganbayar Urtnasan CHAPTER 7

QUANTITATIVE 3-DIMENSIONAL COMPUTED TOMOGRAPHY MEASUREMENTS PROVIDE A PRECISE DIAGNOSIS OF FRACTURES OF THE MANDIBULAR CONDYLAR PROCESS

Enkh-Orchlon Batbayar, Nick Assink, Joep Kraeima, Anne Meesters, Ruud R.M.Bos, Arjan Vissink, Max Witjes, Baucke van Minnen Submitted Chapter 7

Abstract

As 2D quantitative measurements are often insufficient, a standardized 3D quantitative measurement method was developed to analyze mandibular condylar fractures, correlate the results with the mandibular condylar fracture classifications of Loukota and Spiessl & Schroll and clinical parameters.

Thirty-two patients with a unilateral mandibular condylar fracture were evaluated using OPT, 2D (CB)CT images and 3D imaging to measure the extent of the fractures. The maximum mouth opening (MMO) was measured. Ramus height loss could be measured only in OPT, but not in 2D CT images. The Intraclass Correlation Coefficient was excellent in the 3D measurements. In the Loukota classification, condylar neck fractures had the largest median 3D displacement and the highest rotations of the fracture fragments. The largest fracture volume was observed in base fractures. According to the Spiessl & Schroll classification, type V fractures had the largest median 3D displacement and the highest rotation in the X-axis and Z-axis. Type I fractures had the largest fracture volume.

We found a moderate negative correlation between MMO and 3D displacement and rotation on Z-axis. 2D quantitative analysis of condylar fractures is limited, imprecise and not reproducible, while quantitative 3D measurements provide extensive, precise, objective and reproducible information.

114 Q3DCT measurements of mandibular condylar fractures

Introduction

Fractures of the condylar process represent 29-52% of all mandibular fractures. However, there is a lack of consensus on treatment of these fractures1–5. Generally speaking, practitioners chose one of two treatment modalities for condylar fractures: Surgical (open) treatment or conservative (closed) treatment4,6. The choice of treatment modality can be based on the classification and characteristics of the fracture4, but in practice this choice is usually based on the training, experience and skills of the surgeon. To overcome these differences in approach, several classification systems for condylar fractures have been proposed7–10, of which the classifications of Loukota11,12 and Spiessl & Schroll13 are most widely used.

To diagnose and classify condylar fractures, practitioners frequently use conventional two-dimensional (2D) imaging, such as panoramic radiographs (OPT) and Towne projections. Based on these radiographs, fracture characteristics such as ramus height loss and deviation of the condylar head are measured to decide on the preferred treatment modalities14–17. However, Kommers et al.18 questioned the reliability of measuring the ramus height loss of fractures of the condylar process on OPT. Additionally, others showed that measurements on conventional 2D imaging are highly observer-dependent and vary with patient positioning when taking X-rays19–23.

Despite the efforts of several authors, no consensus has been reached on clinically relevant universal classification and subsequent treatment choices 7 of condylar fractures. This situation continued even after the introduction of computed tomography (CT)7,9,24. Such a classification is needed because the description of condylar fractures is currently dependent on 2D slices of CT images, while the availability of conventional 2D images like OPT and Towne is rapidly declining due to the introduction of low dose CT and the conebeam CT (CBCT)7. Even though CT and CBCT can display the anatomy in 3D, most CT data are still viewed in 2D slices. A major drawback of the use of 2D CT images is that the assessment of condylar fractures with this type of radiograph is also dependent on the skills of the clinician who analyses these 2D CT images and can vary depending on the CT characteristics such as resolution, slice thickness and field of view7. Moreover, measurements such as the estimated loss of ramus height and deviation of the condylar head are not reliable if they are based on 2D CT images7.

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Nowadays, quantitative three-dimensional (3D) CT measurements are used for diagnosis and classification of fractures of the tibial plateau, acetabulum, and radial heads25–27. These measurements have been proven reliable and have provided insight into the multidirectional aspects of these fractures based on this detailed information about fracture extent25–27. Therefore, the aim of this study was to develop a standardized 3D quantitative measurement method for mandibular condyle fractures with high inter-user reliability, to correlate the obtained results with the Loukota11,12 and Spiessl & Schroll13 classifications and with clinical parameters as ramus height loss and maximum mouth opening.

Materials and methods

Study population

All consecutive patients that were diagnosed with a unilateral mandibular condylar fracture with or without concomitant other mandibular fractures at University Medical Center Groningen between 2015-2018 were reviewed. Patients whose diagnosis was confirmed with CBCT or CT with a maximum slice thickness of 1 mm were included. Exclusion criteria were a bilateral condylar fracture and unavailability of a diagnostic CT or CBCT scan.

Fracture classification and clinical parameters

To classify the condylar fractures, based on the preoperative standard 2D format CT or CBCT scans in axial, coronal, and sagittal reconstructions, the classifications according to Loukota11,12 and Spiessl & Schroll13 were used.

Due to the retrospective nature of this study, not all 32 eligible cases were completely documented with respect to clinical parameters. Maximum Mouth Opening (MMO) measurements (from incisor to incisor) were available from 20 patients. These measurements consisted of MMO scores in mm on the same day (±1 day) that the CT or CBCT scan was taken.

In patients whose OPT and/or Towne projections were taken at the same time as the CT scan (±1 day), 2D measurements were made of ramus height loss and deviation of the fracture. Ramus height loss (2D measurement) was measured in millimeters, and deviation was measured in degrees according to the method described by Palmieri et al17.

116 Q3DCT measurements of mandibular condylar fractures

Fig 1. A 3D representation of a segmented fractured condyle (red) and mandible (blue), which is based on the CT scan, superimposed on the CT slices.

Segmentation and 3D model

Of all included patients, the CT or CBCT files were imported into the Mimics Medical software package (Version 21.0, Materialise, Leuven, Belgium) to create a 3D bone model of the skull and each part of the fractured mandible. The segmentation process was performed using a default bone threshold (Hounsfield Unit ≥ 226) followed by manual optimization by a trained observer 7 (E.O.B). All the segmented models were given a different color (Fig 1).

Next, the condylar fracture was virtually reduced to its anatomical position in 3-matic Medical (version 13.0; Materialise, Leuven, Belgium). As a guide for reduction, the contralateral non-fractured side was mirrored and aligned with the affected side (Fig 2).

3D measurements

To measure the condylar fracture extent, the following new 3D measurements were used: 3D displacement, the volume of the fracture fragment and the rotation of the fracture fragment.

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Fig 2. Workflow of virtual reduction of the fracture using a 3D model. A, segmented condylar fracture fragment (green) from the mandible (blue). B, template mirrored from non-fractured contralateral condyle (gray). C, fractured condyle is aligned according to the template. D, virtually reduced model with the fracture fragment after reduction (orange).

3D displacement. 3D displacement of the fracture is the difference between the fractured and the reduced position of the condyle. This was assessed using 3-matic Medical and Matlab (R2014B, Mathworks, Natick, Massachussetts, US) software. The extent of displacement/dislocation of the fragment(s) of the condyle was determined by calculating the 3D displacement along the X, Y, and Z axes. To calculate the 3D displacement, the fracture was virtually reduced in the 3D model, as described above (Fig 2). For each point on the surface of the 3D model, a difference in Euclidian distance between the fractured and reduced position was calculated in millimeters (mm). This 3D displacement of each part of the fragment is presented as a distance map in Fig 3, and was calculated as follows:

3D displacement = 6 ∑*78(𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆* ∗ 𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑*) 6 ∑* (𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆*) + 𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 Volume of fracture fragment. The volume of the fracture fragment is the actual size of the fractured part of the condylar process. It was calculated in cubic millimeters (mm3) using 3-matic Medical.

3D rotations. 3D rotation is a rotation of the fractured fragment of condyle in the X, Y, and Z axes. This was assessed using the same software (3-matic Medical and Matlab). This measurement was calculated in degrees (°). Because the

118 Q3DCT measurements of mandibular condylar fractures

Fig 3. Measurements of ramus height loss and 3D displacement. (a), ramus height loss measurement on panoramic: loss of vertical height is the difference between non-fractured (A’-B’) side and fractured side (A*-B*). 3D displacement of fractured condyle fragment after (b) and before (c) virtual reduction. The two fragments (d) were imported into MATLAB software, after which a quantitative map of the displacement was calculated (e).

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orientation of the mandible within the original CT scan is greatly influenced by the positioning of the patient in the scanner, a standardized axis was defined using three landmarks on the bilateral lingulae of the mandible (Fig 4). This method has good reproducibility28.

Deviation in axial alignment was described as the rotation difference along the Y-axis between the fragment and its original position, whereas the rotation difference along the Y-axis described the deviation in coronal alignment (Fig 5).

Reproducibility and statistical analysis

The condylar fractures were classified by two independent observers (E-O.B and R.B). Consensus was reached after discussion, without need of a third observer. Ramus bone height loss (2D) was measured by the same observers on the OPT.

Fig 4. Defined standardized axis of the mandible. The axes was defined by using three points: the uppermost part of left lingual (B), and the uppermost and lowermost parts of the right lingula (C).

120 Q3DCT measurements of mandibular condylar fractures

Fig 5. Fracture alignment in three views: (a) anterior-posterior, (b) medio-lateral, and (c) cranial- caudal. X (red), Y (green), and Z (blue) axes are shown in different colors.

7 3D displacement and 3D rotation were measured by one observer first (E-O.B) in all 32 included patients. To assess the reproducibility, the 3D measurements were then performed by another independent observer (N.A.) in 10 patients, selected by E-O.B, so that all types of condylar fractures were represented.

All statistical analyses were performed using IBM SPSS Statistics for Windows, Version 23.0 (Armonk, NY: IBM Corp.) software. Reproducibility was calculated using the Intraclass Correlation Coefficient (ICC), with a two-way random, single measurements model with the absolute agreement.

Normality of the data distribution was tested with the Kolmogorov-Smirnov test, and median and interquartile range (IQR) were reported for not normally distributed variables, and means and standard deviation (SD) for normally

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distributed variables. The Kruskal-Wallis test was used to compare the results of the measurements (MMO, ramus height loss, and 3D) with the fracture classifications (Loukota and Spiessl & Schroll). The correlation between MMO and measurements (ramus height loss and 3D) was determined using Spearman’s correlation test. Statistical significance was set at P<0.05.

Results

Descriptives

In total, 32 patients with unilateral condylar fractures met the inclusion criteria. Median age was 29 (21;50) years, and 23 (72%) patients were male. In total 9 patients (29%) had condyle fractures concomitant with other mandibular fractures: parasymphyseal (n=7), body (n=1), and angle (n=1). The median number of fracture fragments of the condyle was 1 (1;3). Mean MMO was 22.0±7.6 mm. A Towne projection was not available for any of the 32 included patients, so measurement of deviation was not possible; OPT were available for 8 patients.

According to the Loukota classification of condylar fractures, 9 patients had diacapitular fractures (type A, n=4; type B, n=3, type C, n=2), 5 patients had neck fractures, and 18 patients had base fractures. According to the Spiessl & Schroll classification, 9 patients had non-displaced fractures of the condyle (type I, n=9), 8 patients had low condylar fractures with displacement (type II, n=8), 6 patients had low condylar fractures with dislocation (type IV, n=6), 3 patients had high condylar fractures with dislocation (type 5, n=3), and 6 patients had intracapsular or diacapitular fractures (type 6A, n=4; 6B, n=2). The type III fracture was not observed in the study.

The median (IQR) of the overall 3D displacement of the condylar fractures was 5.3 mm (2.3;8.6). Median of the rotations for the fractures was: X-axis, 5.4° (-1.3;59.1); Y-axis, -0.8°(-9.2;4.5); Z-axis, 4.8° (1.1;12.0).

Eight of 32 patients had a pre-operative OPT, and ramus height loss was measured in these patients only. Median loss of height was 5.7 mm (1.6;8.2).

122 Q3DCT measurements of mandibular condylar fractures

Reproducibility

The Intraclass Correlation Coefficient (ICC) for the validation of the Loukota classification was 0.98 (95% CI, 0.96;0.99), and of the Spiessl & Schroll classification was 0.99 (95% CI, 0.93;0.98).

The ICC for reproducibility of the ramus height loss (2D) measurement was 0.86 (95% CI, 0.45;0.97) between the two observers.

The ICC for 3D displacement measurement was 0.98 (95% CI, 0.86;0.99), and the fracture rotation measurements were X-axis 0.99 (95% CI, 0.96;0.98), Y-axis 0.96 (95% CI, 0.84;0.99), and Z-axis 0.98 (95% CI, 0.95;0.99).

Clinical parameters by diacapitular fractures (Loukota classification)

In total 9 patients had diacapitular fractures of the mandibular condyle: 4 patients had type A fractures, 3 patients had type B fractures and 2 patients type C fractures. Because no OPT was available, ramus height loss was could not be measured in any of the diacapitular fractures. MMO was scored higher in type A (n=4, 24.5 mm) and type B (n=2, 26.5 mm) fractures and lowest in type C fractures (n=1, 9.0 mm).

3D measurements by diacapitular fractures (Loukota classification)

The larger 3D displacement was measured in (n=2, 10.3 mm) type C fractures followed by type A (n=4, 8.3 mm) and type B (n=2, 1.3 mm) fractures. The type 7 C diacapitular fractures had greater rotation on the X and Z axis (n=2, 25.8°, and 13.8°) compared to type A (n=4, 10.2°, and 7.5°) and type B (n=2, 1.3°, and 4.1°) fractures. The mean volumes of the fracture fragments were 693 mm for type A fractures, 851 mm3 for type B fractures and 761 mm3 for type C fractures.

Clinical parameters by condylar process fractures (Loukota classification)

Ramus height loss was measured only in the condylar base fractures (n=8); and the median was 5.7 mm (16;8.2). Therefore, no comparison between the classes was performed.

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Table 1. Measurements according to the Loukota classification

Variables Diacapitular Diacapitular Diacapitular Diacapitular Neck Base P

Type A Type B Type C Overall value*

MMO 23.5±10.9 26.5±12.0 9.0 22.2±10.9 16.5±5.0 24.1±4.9 0.235

[mm; mean±SD]

Ramus height loss - - - - - 5.7 -

[mm; median (1.6;8.2)

( IQR)]

3D displacement 8.3 (3.7;12.1) 1.3 10.3 (8.8;10.3) 6.1 10.7 5.0 0.117

[mm; median (0.0;1.3) (2.1;11.2) (2.8;15.1) (1.9;5.9)

( IQR)]

Rotation X 10.2 (2.2;15.8) 1.6 25.8 5.8 6.3 (1.9;35) 4.5 0.880

[degrees; median (0.0;1.6) (19.9;25.8) (1.1;18.1) (2.1;4.5)

( IQR)] Y -9.8 0.9 -1.5 -1.5 -3.6 -0.1 0.498

(-10.1;-3.5) (0.6;0.9) (-2.1;-1.5) (-9.8;0.7) (-17.6;18.3) (-1.5;7.9)

Z 7.5 (4.8;10.8) 4.1 13.8 (6.8;13.8) 6.8 19.7 2.1 0.187

(2.6;4.1) (4.4;10.5) (0.4;64.6) (0.4;9.0)

Volume 693±440 851±201 761±72 761±298 2140±626 2226±571 0.001

[mm3;mean±SD]

*Based on Kruskal-Wallis test

MMO was documented in 21 patients with condyle fractures, consisting of diacapitular fractures (n=7), neck fractures (n=4), and base fractures (n=10). Higher mean MMO was observed in the base fractures (24.1 mm) and diacapitular (22.2 mm) fractures, and lower mean MMO in the neck fractures (16.5 mm) fractures (Table 1).

3D measurements of condylar process fractures (Loukota classification)

Condylar neck fractures had the largest median 3D displacement (n=5, 10.7 mm) compared to the diacapitular (n=9, 6.1 mm) and base fractures (n=18, 5.0

124 Q3DCT measurements of mandibular condylar fractures

Table 2. Measurements according to the Spiessl & Schroll classification

Variables Type I Type II Type VI Type V Type VI A Type P

VI B value*

MMO 23.5±6.7 26.3±6.1 21.4±7.1 12.0±4.2 23.5±10.9 18.0 0.354

[mm; mean±SD]

Ramus height loss 0.143

[mm; median ( IQR)]

3D displacement 2.3 5.4 6.8 11.9 8.3 3.5 0.013

[mm; median ( IQR)] (1.3;4.1) (2.0;6.2) (4.6;11.2) (8.8;11.9) (3.7;12.1) (1.3;3.5)

Rotation X 2.4 4.3 9.4 31.8 10.2 1.0 0.021

[degrees; (0.7;4.5) (1.7;8.4) (5.3;13.0) (19.9;31.8) (2.2;15.8) (0.0;1.0)

median ( IQR)] Y 0.1 6.3 -13.0 0.0 -9.8 3.9 0.031

(-2.6;1.9) (-6.7;11.9) (-16.4;-2.0) (-2.1;0.0) (-10.1;-3.5) (0.6;3.9)

Z 1.4 5.8 8.6 20.8 7.5 4.8 0.173

(0.4;3.1) (0.3;14.6) (0.3-24.2) (6.8;20.8) (4.8;10.8) (2.6;4.8)

Volume 2291±826 2151±392 1950±575 1244±838 693±440 793±247 0.002

[mm3; mean ±SD]

* Based on Kruskal-Wallis test

mm) of the condyle, but a statistically significant difference was not observed 7 between the classes.

Condylar neck fractures had the highest median rotation on all three axes; X-axis 6.3°, Y-axis -3.6° and Z-axis 19.7°. The rotation of the fracture fragments did not differ between the Loukota classes. The mean volume of the fracture fragment was as follows: diacapitular 761 mm3, neck 2140 mm3, and base 2226 mm3. A significantly larger volume of the fragment was observed in base fractures compared to diacapitular and neck fractures.

Clinical parameters according to the Spiessl & Schroll classification

The ramus height loss was measured in following fracture types only: Type I, II, and IV. High loss of ramus was measured in type IV fractures (n=4, 8.1 mm)

125 Chapter 7

and type II fracture (n=1, 6.2 mm) whereas low in the type I fractures (n=3, 1.0 mm).

MMO was measured in 21 patients. Higher MMO was measured in type II (n=3, 25 mm) and type IV (n=5, 25 mm) fractures, followed by type VI A (n=4, 24.5 mm), type I (n=6, 23 mm), type VI B (n=1, 18 mm), and type V (n=2, 12 mm).

3D measurements according to the Spiessl & Schroll classification

The largest median of 3D displacement was observed in type V (n=3, 11.9mm) fractures followed by type VI A (n=4, 8.3 mm), type IV (n=6, 6.8 mm), type II (n=8, 5.4 mm), type 6 B (n=2, 3.5 mm), and type I (n=9, 2.3 mm). The 3D displacement differed significantly in between the fracture types.

The highest rotation on X and Z-axis was observed in the type V fractures (31.8°, 20.8°). Type IV fractures had the highest rotation on Y-axis (-13°). Fracture rotation varied in the other types of condylar fractures (Table 2). Significantly higher fracture rotations were observed in the type V fractures (X and Y-axis).

Table 3. Correlation between maximum mouth opening (MMO) and parameters

Parameters MMO

Spearman’s correlation P value

coefficient

Ramus height loss 0.57 0.23

3D displacement -0.41 0.05*

Rotation X-axis -0.27 0.23

Y-axis -0.54 0.82

Z-axis -0.56 0.01*

Volume -0.12 0.59

*Statistically significant results (Spearman’s correlation)

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Q3DCT measurements of mandibular condylar fractures

The largest mean volume of the fracture fragment was observed in type I (2291 mm3) and the smallest volume in VI A (693 mm3) fractures. A significant difference was observed between the fracture types.

Correlations between clinical parameters and 3D measurements

The correlations between MMO and ramus height loss and 3D measurements are shown in Table 3. A statistically significant negative correlation was observed between MMO and 3D displacement (-0.41, p=0.05), and rotation in the Z-axis (-0.560, p=0.01).

Discussion

The quantitative 3D CT measurement method we have described here expands the classification by Loukota and Spiessl & Schroll quantitatively. This 3D method provides precise and detailed information about fractures of the condylar process, and the reproducibility is excellent.

In a previous study, the repeatability of the 2D measurement of ramus height loss measurement was reported to be excellent using OPT18. In our study, however, the 2D reproducibility was good only for ramus height loss measured on OPT. This discrepancy could be related to the difficulty in finding the highest point (reference point) of the condylar head in the fractured side on an OPT in case of severely displaced and dislocated fractures (Fig 2) due to rotational movements of the fracture fragments. 7

Measurement was impossible on 2D reconstructed CT and CBCT images, which was previously reported by Neff et al.7. Our study supports this finding. Results varied depending on the slices which were chosen forthe measurements. Ramus height loss can be measured on the OPT with only fair reproducibility. Moreover, this provides limited information about fracture severity. In contrast to ramus height loss measurement based on OPT images, the 3D displacement measurements of the fracture of the condylar process are precise and hardly observer-depended.

The best of our knowledge, this study provides the first objective description of reproducible measurement of displacement and rotation of any condylar fracture. We found the largest fracture 3D displacement and rotations in

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the condylar neck and diacapitular fractures according to the Loukota classification, and in the dislocated high condylar and diacapitular fractures without loss of ramus height according to the Spiessl & Schroll classification (type V and type VI A). A possible explanation could be the attachment of the lateral pterygoid muscle to the condylar neck and condylar head. Although the 3D measurements are precise, objective and reproducible, it is not known at this point whether the large 3D displacement and rotation of the condylar neck and diacapitular fractures are clinically relevance or not. To answer this question a prospective study that takes into account additional clinical variables such as lateral excursion of mandible, pain, as well as mandibular function impairment, is needed.

Limitations of this retrospective study were missing data about MMO as well as Towne projections and OPT. Within these limitations, we found a low negative correlation between MMO and 3D displacement and moderate correlation with rotation on the Z-axis. A possible interpretation is that the 3D displacement or rotation on the Z-axis, regardless of fracture classification, might be inversely related to the mouth opening. As this mouth opening was measured when the CT scans were taken, i.e. shortly after trauma, the importance of this initial mouth opening parameter to final functional outcome is unclear.

Compared to the Spiessl & Schrol classification of condylar fractures, the classification of Loukota et al., which was proposed as an aid for making treatment decisions,12 is simplified. For example, Loukota does not take displacement, dislocation and deviation of the fractures into account, whereas these aspects are included in the Spiessl & Schroll classification. Another consideration is that many languages do not differentiate between displacement and dislocation, which makes it difficult to translate these terms. Therefore these two concepts must be clearly defined: dislocation means that the condyle is outside the fossa; displacement indicates the separation between the fracture fragments6. Based on the 3D measurements, it is possible to quantify the dislocation, displacement and deviation in the X, Y, and Z-axes.

With regard to the validation of the Loukota classification, disagreement between the observers occurred with two condylar fractures. The first observer judged these two fractures to be a base fracture, whereas the second observer judged them to be a neck fracture of the condyle. Regarding the classification of Spiessl & Schroll, the disagreement also occurred with the same patients. The disagreement involving the first fracture was due to discrepancy in assessing

128 Q3DCT measurements of mandibular condylar fractures

low and high condylar fractures, which was a similar problem with the Loukota classification (neck and base). The disagreement on the second fracture regarding the classification results from a discrepancy in assessing type I and type II displacement of the condylar fractures. There is no clear objective cut-off between these two types. Similar disagreement on the assessment of the condylar fracture classification was reported previously regarding neck and base fractures29. Together with the classification systems of Loukota and Spiessl & Schroll, the results from the quantitative 3D measurements in the present study have contributed to the objective description of condylar fractures.

The volume measurement of the fragment(s) of condylar fractures has not yet been included in any classification. This measurement not only enables visualization of the fragmentation, but also provides information about the extent and inter-fragmentary stability of the fracture. It also allows an estimation of the dimensions of the osteosynthesis materials to be chosen for fixation. Although these measurements can now be done with the 3D method, it is unclear whether this would be helpful in the clinical setting.

In conclusion, quantitative 3D measurements provide precise, objective and reproducible information about the condylar fracture with regard to volume, dislocation and rotation of fragments, with excellent reproducibility. The quantitative 3D measurements enable surgeons to classify the fractures more exactly in accordance with the classification of Loukota and Spiessl & Schroll. Further research should be conducted with 3D quantitative measurements to determine if this method could be used to support treatment choice, and, 7 more importantly, to predict the functional outcome of condylar fractures.

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References

1. Iida S., Kogo M., Sugiura T., Mima T., Matsuya T. Retrospective analysis of 1502 patients with facial fractures. Int J Oral Maxillofac Surg 2001;30(4):286–90. Doi: 10.1054/ijom.2001.0056. 2. Jensen T., Jensen J., Nørholt SE., Dahl M., Lenk-Hansen L., Svensson P. Open Reduction and Rigid Internal Fixation of Mandibular Condylar Fractures by an Intraoral Approach: A Long-Term Follow-Up Study of 15 Patients. J Oral Maxillofac Surg 2006;64(12):1771–9. Doi: 10.1016/j.joms.2005.12.069. 3. Boffano P., Roccia F., Zavattero E., Dediol E., Uglešić V., Kovačič Ž., et al. European Maxillofacial Trauma (EURMAT) project: A multicentre and prospective study. J Cranio-Maxillofacial Surg 2015;43(1):62–70. Doi: 10.1016/j.jcms.2014.10.011. 4. Neff A., Chossegros C., Blanc JL., Champsaur P., Cheynet F., Devauchelle B., et al. Position paper from the IBRA Symposium on Surgery of the Head - The 2nd International Symposium for Condylar Fracture Osteosynthesis, Marseille, France 2012. J Cranio-Maxillofacial Surg 2014;42(7):1234–49. Doi: 10.1016/j. jcms.2014.03.005. 5. Zhou HH., Liu Q., Cheng G., Li ZB. Aetiology, pattern and treatment of mandibular condylar fractures in 549 patients: A 22-year retrospective study. J Cranio- Maxillofacial Surg 2013;41(1):34–41. Doi: 10.1016/j.jcms.2012.05.007. 6. Bos RR., Ward Booth RP., de Bont LG. Mandibular condyle fractures: a consensus. Br J Oral Maxillofac Surg 1999;37:87–9. Doi: 10.1016/S0266-4356(98)90014-6. 7. Neff A., Cornelius CP., Rasse M., Torre DD., Audigé L. The comprehensive AOCMF classification system: Condylar process fractures - Level 3 tutorial. Craniomaxillofacial Trauma Reconstr 2014;7(7):S44–58. Doi: 10.1055/s-0034- 1389559. 8. He D., Yang C., Chen M., Zhang X., Qiu Y., Yang X., et al. Traumatic temporomandibular joint ankylosis: Our classification and treatment experience.J Oral Maxillofac Surg 2011;69(6):1600–7. Doi: 10.1016/j.joms.2010.07.070. 9. He D., Yang C., Chen M., Jiang B., Wang B. Intracapsular Condylar Fracture of the Mandible: Our Classification and Open Treatment Experience. J Oral Maxillofac Surg 2009;67(8):1672–9. Doi: 10.1016/j.joms.2009.02.012. 10. Lindahl L. Condylar fractures of the mandible. Int J Oral Surg 1977;6(1):12–21. Doi: 10.1016/S0300-9785(77)80067-7. 11. Loukota RA., Eckelt U., De Bont L., Rasse M. Subclassification of fractures of the condylar process of the mandible. Br J Oral Maxillofac Surg 2005;43(1):72–3. Doi: 10.1016/j.bjoms.2004.08.018. 12. Loukota RA., Neff A., Rasse M. Nomenclature/classification of fractures ofthe mandibular condylar head. Br J Oral Maxillofac Surg 2010;48(6):477–8. Doi: 10.1016/j.bjoms.2009.08.036. 13. Spiessl B., Schroll K. Gelenkfortsatz-und Kieferköpfchenfrakturen. Spezielle Frakturen-und Luxationslehre. Band l/1: Gesichtsschädel ed. Stuttgart New York:

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Georg Thieme Verlag; n.d. 14. Bhagol A., Singh V., Kumar I., Verma A. Prospective evaluation of a new classification system for the management of mandibular subcondylar fractures. J Oral Maxillofac Surg 2011;69(4):1159–65. Doi: 10.1016/j.joms.2010.05.050. 15. Schneider M., Erasmus F., Gerlach KL., Kuhlisch E., Loukota RA., Rasse M., et al. Open Reduction and Internal Fixation Versus Closed Treatment and Mandibulomaxillary Fixation of Fractures of the Mandibular Condylar Process: A Randomized, Prospective, Multicenter Study With Special Evaluation of Fracture Level. J Oral Maxillofac Surg 2008;66(12):2537–44. Doi: 10.1016/j. joms.2008.06.107. 16. Widmark G., Bågenholm T., Kahnberg KE., Lindahl L. Open reduction of subcondylar fractures A study of functional rehabilitation. Int J Oral Maxillofac Surg 1996;25(2):107–11. Doi: 10.1016/S0901-5027(96)80052-X. 17. Palmieri C., Ellis III E., Throckmorton GS. Mandibular motion after treatment of unilateral condylar process fractures. J Oral Maxillofac Surg 1999;57:764–75. 18. Kommers S., Moghimi M., Ven L Van De., Forouzanfar T. Is radiological shortening of the ramus a reliable guide to operative management of unilateral fractures of the mandibular condyle? Br J Oral Maxillofac Surg 2014;52(6):491–5. Doi: 10.1016/j. bjoms.2014.04.008. 19. Uysal T., Sisman Y., Kurt G., Ramoglu SI. Condylar and ramal vertical asymmetry in unilateral and bilateral posterior crossbite patients and a normal occlusion sample. Am J Orthod Dentofac Orthop 2009;136(1):37–43. Doi: 10.1016/j. ajodo.2007.06.019. 20. Sadat-Khonsari R., Fenske C., Behfar L., Bauss O. Panoramic radiography: Effects of head alignment on the vertical dimension of the mandibular ramus and condyle region. Eur J Orthod 2012;34(2):164–9. Doi: 10.1093/ejo/cjq175. 21. Wyatt DL., Farman AG., Orbell GM., Silveira AM., Scarfe WC. Accuracy of dimensional and angular measurements from panoramic and lateral oblique 7 radiographs. Dentomaxillofacial Radiol 1995;24(4):225–31. Doi: 10.1259/ dmfr.24.4.9161166. 22. Xie Q., Soikkonen K., Wolf J., Mattila K., Gong M., Ainamo A. Effect of head positioning in panoramic radiography on vertical measurements: an in vitro study. Dentomaxillofacial Radiol 1996;25(2):61–6. Doi: 10.1259/dmfr.25.2.9446974. 23. Nunes R., Lara Y., Crivelaro G. Common positioning errors in panoramic radiography: A review. Imaging Sci Dent 2014;44(1):1–6. Doi: 10.5624/isd.2014.44.1.1. 24. Zhou Z., Li Z., Ren J., He M., Huang Y., Tian W., et al. Digital diagnosis and treatment of mandibular condylar fractures based on Extensible Neuro imaging Archive Toolkit (XNAT). PLoS One 2018;13(2):e0192831. Doi: 10.1371/journal. pone.0192831. 25. Guitton TG., Werf HJ Van Der., Ring D. Quantitative three-dimensional computed tomography measurement of radial head fractures. J Shoulder Elb Surg 2010;19(7):973–7. Doi: 10.1016/j.jse.2010.03.013.

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26. De Muinck Keizer RJO., Meijer DT., Van Der Gronde BATD., Teunis T., Stufkens SAS., Kerkhoffs GM., et al. Articular gap and step-off revisited: 3D quantification of operative reduction for posterior malleolar fragments. J Orthop Trauma 2016;30(12):670–5. Doi: 10.1097/BOT.0000000000000676. 27. Mellema JJ., Janssen SJ., Guitton TG., Ring D. Quantitative 3-dimensional computed tomography measurements of coronoid fractures. J Hand Surg Am 2015;40(3):526–33. Doi: 10.1016/j.jhsa.2014.07.059. 28. Fariña R., Bravo R., Villanueva R., Valladares S., Hinojosa A., Martinez B. Measuring the condylar unit in condylar hyperplasia: from the sigmoid notch or from the mandibular lingula? Int J Oral Maxillofac Surg 2017;46(7):857–60. Doi: 10.1016/j. ijom.2017.03.004. 29. Kommers SC., Boffano P., Forouzanfar T. Consensus or controversy? the classification and treatment decision-making by 491 maxillofacial surgeons from around the world in three cases of a unilateral mandibular condyle fracture. J Cranio-Maxillofacial Surg 2015;43(10):1952–60. Doi: 10.1016/j.jcms.2015.08.031.

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133 Wild reindeer (Rangifer tarandus Linnaeus), Credit: Hureelen/ Ganbayar Urtnasan CHAPTER 8

GENERAL DISCUSSION Chapter 8

This thesis describes ways to optimize the treatment of fractures of the mandible by investigating several steps in fracture diagnosis and treatment.

Fracture reduction techniques

Anatomic reduction is an essential step in the treatment of fractures. Especially when the load-sharing principles according to Champy are used, interfragmentary stability is an important factor for uneventful healing as the combination of fracture reduction and plate fixation in the tensile zone (=upper border) provides the stability of the fracture.

Intermaxillary fixation (IMF) is historically used to reduce the fracture fragments and to restore occlusion. However, in some mandibular fractures, IMF is not enough to achieve adequate reduction of fracture fragments. In chapter 2 several other methods to improve alignment of fracture fragments were proposed. It appears that the use of reduction forceps makes the treatment quicker and easier. Clear evidence that reduction forceps have an advantage over other fracture reduction techniques is lacking. The study described in chapter 3 provided extra knowledge regarding this topic.

The results of this chapter indicate that a fracture of the mandible reduced with the aid of reduction forceps resulted in better fracture alignment and less postoperative complications than those reduced without the help of the reduction forceps. The scoring of the postoperative fracture alignment (assessed on panoramic and Towne) in the study is somewhat counterintuitive in case of angle fractures because mandibular angle fractures often do not show a perfect alignment of the fracture fragments in the initial postoperative radiographic and adjusts over time by muscle action. On the other hand, to overcome this limitation we assessed fracture alignment on postoperative radiographs along with the occlusal state of the patients. Another limitation of the study was the retrospective design. Standardization of the surgeon or reduction technique selection was not possible. The group of mandibular fractures studied was a representative sample of the mandibular fractures treated during the inclusion period. As these fractures are treated by several surgeons during out of office hours the surgeons could not select patients or fractures. Therefore, the results of this study can be generalized to other surgeons as well.

136 General discussion

The results of Chapter 2 and 3 clearly indicate that there is a need for further development of reduction forceps of mandibular fractures. Therefore, after careful analysis of existing techniques and reduction forceps, we have produced a set of three reduction forceps, one for the anterior part and a left and a right one for the posterior part of the mandible and tested their feasibility clinically (Chapter 4). The feasibility test revealed that these two designs are suitable for the reduction of most mandibular fractures. However, this initial feasibility test showed that a reduction forceps is not always suitable for the reduction of oblique, flat fractures of the mandible. Further adjustments and testing of the forceps designed for the angle region is planned to overcome these drawbacks.

The use of locking plate systems.

After sufficient reduction of mandibular fractures is achieved by either reduction forceps or other techniques, fixation is performed using osteosynthesis materials. Osteosynthesis is nowadays achieved by either lag screws or different plates and screws, depending on the fracture characteristics, location, and surgeons’ preferences. Besides the dimensions of the plates and screws, the osteosynthesis may vary in a locking and non-locking mechanism. It is presumed that the locking plates system is superior to the non-locking plate system with regard to stability, and postoperative complications. However, the meta-analysis described in Chapter 5 demonstrated that a locking plate system is only superior to a non-locking plate system concerning the postoperative need for IMF in the early and intermediate period after treatment. The cause for this finding is not obvious and may be explained by subjective choices of the surgeon instead of the locking or non-locking system. Moreover, the quality of the included studies was moderate and even low, because they did not report randomization, concealment of allocation and blinding of participants, 8 surgeons and outcome assessors. Although blinding of the surgeons is not possible when these two plate systems are compared, other quality characteristics could be improved in future studies.

Furthermore, most of the included studies in the review described in Chapter 5 do not take into account plate dimension, number of plates, plate design, and fracture fixation principles (Champy vs. AO) when comparing the locking and non-locking plate systems. This means that, besides locking and non- locking characteristics of the plate systems, other potential confounders are not considered in these studies. Consequently, the meta-analysis included

137 Chapter 8

only studies which compared plates as similar as possible with regard to plate dimensions and design, and fixation principles.

Treatment of fractures of the edentulous mandible

While a variety of treatment protocols for fractures of the edentulous mandible have been suggested, a generally accepted consensus has not been reached, particularly not for the treatment of severely atrophic mandibles with a bone height of equal or less than 10 mm. The study described in Chapter 6 demonstrates a practically applicable clinical flowchart/protocol for the fracture of the edentulous mandible. The protocol was developed according to the best evidence available, but due to the low number of included patients and diversity of fractures, the level of evidence is low. On the other hand, if others would start to use this a guideline, and evaluate outcomes there will be hopefully stronger evidence in the future.

The protocol cannot be extrapolated to all patients. For instance, most edentulous patients are seniors, which tend to have a variety of systemic diseases and health-related complications. From this perspective, conservative or closed treatment is preferable in geriatric patients with health issues which could decrease the chance of morbidity and mortality. One should bear in mind that this issue is not taken into account in the protocol. Moreover, in general, the treatment protocol is one of the options for improving the quality of care. Yet, following the protocol does not prevent each and every complication that could occur. The bottom line is that the ”Groningen protocol” significantly reduces postoperative complications and reoperations in the treatment of the fractures of the edentulous mandible.

3D measurements of condylar process fractures of the mandible

A comprehensive classification scheme for fractures should meet several requirements1. It must have a logical and systematic structure, and provide an accurate demonstration of the possible complexity of the fracture, as well as provide therapeutically relevant information about the fracture. The widely known mandibular condylar fracture classification by Loukota and Spiessl & Schroll are logically structured and differentiate the lower regions (viz. base) and higher condylar neck regions, but somewhat lack to fulfill the above-stated requirements. The displacement and dislocation of the condylar fractures which demonstrate the fracture extent and severity are not considered

138 General discussion

in Loukota’s classification whereas it is included in the Spiessl & Schroll classification. According to the Spiessl & Schroll classification, dislocation is diagnosed in case the condylar head is out of the fossa while displacement is diagnosed in case the condylar head is within the fossa while there is displacement at the fracture site. However, the displacement extent is vaguely defined. The difference between fractures with (type II and III) or without (type I) considerable displacement is not clear, and the outcome may likely differ from surgeon to surgeon. Moreover, these classifications do not give enough information on which the choice for one or another treatment can be based. Clinical decision making is also often based on unreliable 2D measurements such as ramus height loss (measured in OPT) and deviation of the fractures (measured in Towne)2,3. The 2D measurements are user dependent and have low reproducibility. Therefore, there is need for improvement of the measuring method in order to get to a correct classification.

The study described in Chapter 7 aimed to develop a standardized quantitative 3D measurement method for mandibular condylar fractures and to correlate the obtained results with the Loukota and Spiessl & Schroll classification. The obtained results from the 3D measurements provide additional quantitative information about fracture extent and severity of the condylar fractures with excellent reproducibility. Due to the retrospective design of the study, we are not able to compare the 3D measurements of the condylar fractures with the outcome of the treatment chosen. At this point, the 3D measurements cannot dictate which therapy should be chosen. There is ongoing debate on which fractures should be treated open or closed. Decision making seems to be based mainly on surgeons opinion, surgeons experience, and facilities for treatment. Despite several attempts to set up randomized clinical trials in order to prove which fractures should be treated closed or open, there still is discussion. The great variation in fracture presentation introduces so 8 many confounding factors influencing the outcome of treatment that, to our honest knowledge, there is no scientific evidence for any treatment protocol so far except absolute indications as given by Zide and Kent4. Possibly and hopefully, an exact classification based on reproducible 3D measurement will provide criteria to choose objectively for surgical or non-surgical treatment in an individual case.

139 Chapter 8

Future perspectives

This thesis tries to contribute to optimization of the mandibular fracture treatment, although the outcome of the treatment is generally appreciated as favorable and relatively uncomplicated. In addition to the subjects in this thesis, there is abundant room for further research to enhance the treatment of mandibular fractures as suggested below. As long as there is room for improvement, the time needed for treatment may be reduced, duration of hospitalization may be reduced, and time from trauma to resuming daily activities of the patient may be reduced.

As for the open treatment, a plate should be adapted to the surface of the underlying bone when used to fix fractures at varying anatomical positions. This process may take some time when the surgeon is unexperienced. In addition, repeated bending of the plate can fatigue the plate and increases the chance of a fracture of the plate. Therefore, a pre-bent (pre-shaped) plate could help to overcome these issues. A pilot study was conducted in our department to test the feasibility of pre-bent plate for mandibular angle fractures. To do that, first, manually bent plates were postoperatively segmented and reconstructed from postoperative CBCT scan (7 patients). Second, the anatomical shape of healthy (non-fractured) mandibular angles were analyzed using 3D models which were manufactured from CBCT scans as well (19 patients). The preliminary results of this study showed that the variation of the manually bent plates was very large and it was not feasible to use these data to determine average contouring of a pre-bent angle plate. Conversely, the anatomical shape of the intact mandibular angle turns out to have less variation which made it feasible to design a pre-bent angle plate. Further studies should prove the clinical relevance of this development.

Biodegradable osteosyntheses generally have less mechanical properties than titanium ones. The mechanical demand for the osteosynthesis may theoretically be lower after a very precise reduction which enhances interfragmentary stabiliby. Reduction with reduction forceps will help in the precise reduction. It is worthwhile to test degradable osteosyntheses for mandibular fracture fixation after precise reduction with reduction forceps, especially when using sonic weld fixation as measured by Buijs et al.5 Sonic weld fixation provides considerable more rigidity in comparison with a combination of degradable plate and screw fixation.

140 General discussion

The treatment protocol for fractures of the edentulous mandible (Chapter 5) illustrated the importance of compiling/developing a protocol. Also, quantitative 3D analyzes of fractures of the condylar process (Chapter 6) provide accurate information about the fracture extent allowing a reliable classifications. The results of these studies support the idea to define a protocol for fractures of the condylar process in reference to the quantitative characteristics of the fracture. Clinical results may bring the ongoing discussion on open vs. closed treatment to an end. For now it seems that the outcome of treatment of condylar process fractures is more a problem for some surgeons than for most of the patients.

Last but not least, an alternative approach to improve mandibular fracture care is to pay more attention to the patients’ appreciation of proposed treatment and treatment outcome. A patient will hardly be able to determine for open or closed treatment protocols. He/she is depended on the information the surgeon provides him/her or which the patient gathers in other way. It is well known that patients can be very content with the treatment and the treatment outcome while the surgeon is not, vice versa. It seems worthwhile to measure the quality of life (QOL) of mandibular trauma patients. These measurements may help in determining the best treatment option for individual patients. A patient seems more concerned about the ability to chew and speak without complaints after the treatment; his/hers least concern is how the fracture is reduced or fixated. Therefore, the treatment outcome may be improved by learning from patients’ expectations6,7.

141 Chapter 8

REFERENCES

1. Buitrago-Téllez CH., Audigé L., Strong B., Gawelin P., Hirsch J., Ehrenfeld M., et al. A comprehensive classification of mandibular fractures: a preliminary agreement validation study. Int J Oral Maxillofac Surg 2008;37(12):1080–8. Doi: 10.1016/j. ijom.2008.06.008. 2. Palmieri C., Ellis III E., Throckmorton GS. Mandibular motion after treatment of unilateral condylar process fractures. J Oral Maxillofac Surg 1999;57:764–75. 3. Kommers S., Moghimi M., Ven L Van De., Forouzanfar T. Is radiological shortening of the ramus a reliable guide to operative management of unilateral fractures of the mandibular condyle? Br J Oral Maxillofac Surg 2014;52(6):491–5. Doi: 10.1016/j. bjoms.2014.04.008. 4. Zide F., Kent JN. Indications for Open Reduction of Mandibular Condyle Fractures 1983:89–98. 5. Buijs GJ., Houwen EB Van Der., Bos RRM. Mechanical Strength and Stiffness of the Biodegradable SonicWeld Rx Osteofixation System.YJOMS 2009;67(4):782–7. Doi: 10.1016/j.joms.2008.07.022. 6. Suk M., Daigl M., Buckley RE., Lorich DG., Helfet DL., Hanson B. Outcomes after orthopedic trauma: Are we meeting patient expectations?-A prospective, multicenter cohort study in 203 patients. J Orthop Surg 2017;25(1):1–8. Doi: 10.1177/2309499016684089. 7. Laferton JAC., Kube T., Salzmann S., Auer CJ., Shedden-Mora MC. Patients’ expectations regarding medical treatment: A critical review of concepts and their assessment. Front Psychol 2017;8(FEB):1–12. Doi: 10.3389/fpsyg.2017.00233.

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143 Argal (ovis ammon linnaeus) , Credit: Otgonbayar Baatargal CHAPTER 9

SUMMARY Chapter 9

Mandibular fractures are the most common injuries of the craniofacial region, and postoperative complications after surgical treatment occur in 20-26% of patients. The cause of these postoperative complications is related to poor fracture reduction, improper fixation, the severity of the trauma, fracture location and type, and general health conditions. Historically, numerous innovations have contributed to the improvement of mandibular fracture treatment. Although the outcome of mandibular fracture management is looked upon as satisfactorily, there still is room for improvement (Chapter 1). Therefore, the general aim of this thesis was to assess ways to improve mandibular fracture reduction and fixation by reviewing available fracture reduction methods, analyzing the effect of reduction forceps on postoperative complications, developing sophisticated reduction forceps, to analyze the added value of locking plate systems versus non-locking plate systems, compiling a treatment protocol for fractures of the edentulous mandible, and analyzing the difference between characteristics of condylar process fractures based on 2D respectively 3D imaging.

The study described in Chapter 2 reviews mandibular fracture reduction methods other than intermaxillary fixation. There are three basic approaches currently being used to reduce fractures of the mandible. First, reduction forceps. Quick and adequate reduction of fractures seems possible with reduction forceps resulting in anatomic repositioning and shorter operation time. Several modifications and new designs of the forceps have been proposed in the literature, but there is no reduction forceps available so far that really functions in the posterior region through an intraoral approach. Second, elastic rubber bands or metal wire loops fixed on screws placed across both sides of the fractured parts. Third, a vacuum-formed splint or 3D printed splint after computer-guided mandibular fracture reduction. These two methods are rather time-consuming. They have been used mainly in severely displaced fractures. Overall, the aforementioned fracture reduction methods are favorable in the dentate part of the mandible. A satisfying intraorally applicable solution for the posterior part of the mandible is not yet available.

The study described in Chapter 3 analyzed the added value of using reduction forceps in the treatment of mandibular fractures. For this study, a total of 131 consecutive patients with 252 mandibular fractures were included. In 54 patients the mandibular fractures were reduced without the aid of reduction forceps while in 77 patients the fractures were reduced with the aid of a reduction forceps. Fractures reduced with the aid of the forceps had a better postoperative fracture alignment. The overall complication rate was higher

146 Summary

in the group of fractures reduced without the aid of forceps (17%) than in the forceps-aided group (7%). Taken together, these findings highlight the potential usefulness of reduction forceps in the reduction and fixation of mandibular fractures. Moreover, the findings clearly indicate that there is a need for reduction forceps that are suitable for use in the posterior part of the mandible.

The study described in Chapter 4 was undertaken to design, develop and evaluate new fracture reduction forceps for use in the treatment of mandibular fractures. We designed and developed three fracture reduction forceps, one for the (para)symphyseal area and a right and left one for the posterior region. The forceps were developed based on extensive morphological analysis and with respect to the drawbacks of currently available reduction forceps. Each forceps has a unique design which makes it applicable in the predetermined region of the mandible. This set of three reduction forceps is applicable for the reduction of almost any fracture of the anterior as well as the posterior region of the mandible. However, in cases of very oblique, flat fractures without sufficient interfragmentary stability reduction with any kind of forceps may be impossible due to sliding of the fractured parts.

The study described in Chapter 5 systematically reviewed the postoperative complications (including infection, hardware failure, and need for intermaxillary fixation) of mandibular fractures fixated with locking and non-locking plate systems, and critically assessed the methodological quality of the currently available systematic reviews. The quality of the included studies was evaluated with relevant assessment tools with regard to their study types and results were summarized. In total 33 studies, and 3 existing systematic reviews were revealed. The included studies had a large variety of comparison of different locking and non-locking plates, and the overall quality was poor. The comparison of these two plate systems was possible only 16 studies. The results of those studies suggested that locking plates are superior only concerning the need for intermaxillary fixation in the early and intermediate postoperative period although this may very well be explained by the surgeon 9 habits and not because it was indispensable. In addition, the methodological qualities of the existing systematic reviews on the topic were low, which indicated that the current review was meaningful.

The study described in Chapter 6 compiled the obtainable knowledge about the treatment of fractures of the edentulous mandible. On the bases of the

147 Chapter 9

current literate and our own experience, we compiled a treatment protocol for fractures of the edentulous mandible and hypothesized that this protocol would result in fewer complications. In total 42 consecutive edentulous patients with mandibular fractures were identified of whom 36 patients with 61 fractures met the inclusion criteria. The mean age of the patients was 66±13 years, and 19 were men (52.8%). Of 61 fractures, 19 were severely atrophic mandibles (≤10 mm), 24 were atrophic mandibles (>10 mm), 16 were fractures of the condyle, and 2 were ramus fractures. Among these fractures, the treatment protocol was followed in a total of 53 fractures, and the complication rate in this group was 7.5 % (4 of 53). The treatment protocol was not followed in 8 fractures, and the complication rate was 50% (4 of 8). The reoperation rate was 2% (1 of 53) in the first group and 50% (4 of 8) in the second group. These results suggest that following the compiled treatment protocol for fractures of edentulous mandibles significantly reduces postoperative complications and as well as reoperations.

The study described in Chapter 7 analyzed unilateral fractures of the condylar process in 32 patients using 3D measurements (3D displacement and rotations). The results were correlated with commonly used condylar fracture classifications of Loukota and Spiessl & Schroll. It was found that according to the Loukota classification, condylar neck and diacapitular fractures had the largest median 3D displacement as well as highest rotation of fracture fragments. With regard to Spiessl & Schroll classification, high condylar fractures with dislocation (type V) and diacapitular fracture (type VI) had the largest median of 3D displacement and also higher rotation in comparison to other types. It is possible that these higher 3D displacement and rotations are the result of attachment of the lateral pterygoid muscle to the condylar neck and head. Although the 3D measurements are precise, objective and reproducible, it is not known at this point whether the large 3D displacement and rotation of the condylar neck and diacapitular fractures have a clinical relevance or not. Moreover, we found a low negative correlation between MMO and 3D displacement and moderate correlation with rotation on the Z-axis. In other words, regardless of fracture classifications, the higher the 3D displacement or rotation on the Z-axis, the smaller the mouth opening was.

148 Summary

CONCLUSION

The research described in this thesis has shown that optimization of treatment of mandibular fractures is possible although the outcome of mandibular fracture management is generally looked upon as satisfactorily. This study provides the first comprehensive assessment of fracture reduction forceps. The results show that there is an added value of using forceps in the treatment of mandibular fractures. The fracture alignment is better, the complication rate is lower and the operation time is shorter. Three reduction forceps have been developed for the mandible that allow to reduce almost any mandibular fracture through an intraoral approach.

Despite the lack of appropriate studies included in the systematic review, the locking plate systems only have a significant impact on the postoperative need for intermaxillary fixation although this may well be caused by the preference of the surgeons and not by the choice of IMF.

With respect to treatment of fractures of the edentulous mandible, the proposed treatment protocol is not strongly evidence based, but based on the best available data in the literature plus clinical experiences within the UMCG. Strictly following the protocol described can be considered as best practice. The rate of complications and reoperations will decrease. Consequent use of the protocol and evaluation of results will extend the knowledge regarding this topic.

An important aspect of optimizing the treatment of condylar process fractures may be exact diagnosis and classification. Quantitative 3D measurements provide precise, objective, and reproducible information about condylar fractures. It allows the surgeon to classify the fractures exactly when, for instance, using the classification of Loukota or Spiessl & Schroll. The 3D measurements may well influence the choice for one or another treatment modality. However, further studies that focus on clinical parameters and the comparison of treatment modalities are needed to determine the true indication 9 for open respectively closed treatment.

149 White-tailed eagle (Haliaeetus albicilla), Credit: Hureelen/ Ganbayar Urtnasan CHAPTER 10

NEDERLANDSE SAMENVATTING

(SUMMARY IN DUTCH) Chapter 10

Fracturen van de onderkaak behoren tot de meest voorkomende letsels van het craniofaciale gebied. Postoperatieve complicaties na chirurgische interventie komen voor bij 20-26% van alle patiënten. Deze postoperatieve complicaties worden gerelateerd aan matige fractuurrepositie, onjuiste fixatie, de ernst van het trauma, lokalisatie en type fractuur, en de algemene gezondheidsstatus van de patiënt. Talloze innovaties vanuit het verleden hebben bijgedragen aan de verbetering van behandeling van fracturen van de onderkaak. Hoewel de resultaten van behandeling over het algemeen als tevredenstellend worden beschouwd, is er toch nog steeds ruimte voor verbetering. Het algemene doel van dit proefschrift was dan ook om mogelijkheden te onderzoeken om repositie en fixatie van mandibulafracturen te verbeteren door bestaande repositiemethoden te onderzoeken, het effect van het gebruik van repositieklemmen op postoperatieve complicaties te analyseren, slimme repositieklemmen te ontwikkelen, de waarde van locking platen versus non-locking platen te analyseren, een behandelprotocol voor fracturen van de edentate onderkaak samen te stellen en om het verschil te onderzoeken tussen diagnostiek van fracturen van de processus condylaris bij analyse met behulp van 2D, respectievelijk 3D diagnostiek.

In hoofdstuk 2 worden repositiemethoden van mandibulafracturen anders dan intermaxillaire fixatie beschreven. Tegenwoordig worden drie basistechnieken toegepast om fracturen van de onderkaak te reponeren. Allereerst repositieklemmen. Snelle en adequate repositie van fracturen blijkt mogelijk met behulp van repositieklemmen resulterend in anatomische reductie en kortere operatietijd. In de literatuur worden diverse modificaties en nieuwe ontwerpen voor repositieklemmen voorgesteld, maar er bestaat geen goed functionerende repositieklem voor fracturen van posterieure delen van de mandibula via intraorale benadering. Ten tweede elastieken of metalen draden aangebracht op schroeven, geplaatst ter weerszijden van een fractuur. Ten derde een vacuümgevormde spalk of een 3D geprinte spalk na computergestuurde repositie van mandibulafracturen. Deze laatste twee methoden zijn tamelijk tijdrovend. Zij zijn voornamelijk toegepast bij ernstig gedisloceerde fracturen. De hiervoor genoemde repositiemethoden werken vooral bij betande onderkaken. Een bevredigende, intraoraal toepasbare oplossing voor de posterieure delen van de onderkaak is nog niet beschikbaar.

In hoofdstuk 3 wordt de toegevoegde waarde beschreven van het gebruik van repositieklemmen voor de behandeling van mandibulafracturen. Bij 54 patiënten werden de onderkaakfracturen gereponeerd zonder gebruik te maken

152 Nederlandse samenvatting (Summary in Dutch)

van repositieklemmen. Bij 77 patiënten werden de fracturen gereponeerd met behulp van reductieklemmen. Fracturen gereponeerd met behulp van repositieklemmen hadden een betere postoperatieve stand. Het aantal complicaties was hoger in groep van fracturen die zonder repositieklemmen waren gereduceerd (17%) dan in de groep die met repositieklemmen waren gereduceerd (7%). Deze bevindingen laten zien dat het gebruik van repositieklemmen bij repositie en fixatie van onderkaakfracturen zinvol is. Bovendien blijkt dat er behoefte is aan repositieklemmen voor toepassing in posterieure delen van de onderkaak via een intraorale benadering.

De studie zoals beschreven in hoofdstuk 4 werd ondernomen om nieuwe repositieklemmen bij gebruik van behandeling van fracturen van de onderkaak te ontwerpen, te ontwikkelen en te evalueren. Er werden drie verschillend repositieklemmen ontworpen en ontwikkeld, één voor de (para)symphysis regio en een rechter en linker voor de posterieure delen van de onderkaak. Deze klemmen werden ontwikkeld na uitgebreide morfologische analyse van de mandibula en met in het achterhoofd de nadelen van de bestaande repositieklemmen. Elke klem heeft zijn eigen ontwerp waardoor die toepasbaar is in het gebied van de onderkaak waarvoor het is bedoeld. Met deze drie repositieklemmen kan nagenoeg elke breuk van de mandibula in zowel in het voorste als in het achterste gedeelte worden gereponeerd. Echter, in het geval van sterk oblique verlopende en niet vertande, gladde breuken, kan repositie met een klem mislukken vanwege afglijden van de fractuurdelen.

In hoofdstuk 5 wordt een systematische review beschreven van postoperatieve complicaties (inclusief infectie, osteosynthese falen en noodzaak voor aanbrengen van intermaxillaire fixatie) van fracturen van de mandibula gefixeerd met locking resp. non locking plaatsystemen. Tevens werd in deze studie de methodologische kwaliteit van de bestaande systematische reviews beschouwd. De kwaliteit van de geïncludeerde studies werd geëvalueerd met relevante controlemiddelen waarbij met name werd gekeken naar het type studie. De resultaten van deze kritische beschouwingen werden samengevat. In totaal werden 33 studies en drie bestaande systematische reviews geïncludeerd. De geïncludeerde studies vertoonden een grote variatie in vergelijking van verschillende locking en non-locking plaatsystemen. De kwaliteit van de studies was over het algemeen slecht. Uiteindelijk konden slechts 16 studies worden gebruikt om een vergelijk te trekken tussen locking 10 en non-locking plaatsystemen. De resultaten van die studies suggereren enige superioriteit van locking plaatsystemen alleen voor wat betreft de noodzaak om

153 Chapter 10

intermaxillaire fixatie aan te brengen in de eerste postoperatieve weken. Daarbij moet worden aangetekend dat onduidelijk is of dit daadwerkelijk geïndiceerd is dan wel dat dit wordt veroorzaakt door gewoonten of voorkeuren van de behandelend chirurg. Opgemerkt kan nog worden dat de methodologische kwaliteit van de bestaande systematische reviews betreffende dit onderwerp uitgesproken slecht zijn. Dit onderstreept nog eens de zin van deze studie.

In hoofdstuk 6 wordt beschikbare kennis samengevat omtrent de behandeling van fracturen van de edentate onderkaak. Op basis van de bestaande literatuur en onze eigen ervaring, werd een behandelprotocol voor fracturen van de edentate onderkaak samengesteld onder de hypothese dat volgen van dit protocol zou moeten resulteren in minder complicaties. In totaal 42 opeenvolgende edentate patiënten met fracturen van de mandibula werden geïdentificeerd van wie 36 met samen 61 fracturen voldeden aan de inclusiecriteria. De gemiddelde leeftijd van de patiënten was 66±13 jaar, 19 waren man (52,8%). Van de 61 fracturen, waren 19 ernstig atrofische onderkaken (≤10mm), 24 atrofische kaken (>10mm), 16 fracturen van de processus condylaris en2 fracturen van de ramus mandibulae. Het behandelprotocol zoals opgesteld bleek gevolgd bij 53 fracturen. De complicatieratio in deze groep was 7,5% (4 van 53). Bij 8 fracturen werd het behandelprotocol niet gevolgd. Bij deze groep was de complicatieratio 50% (4 van 8). De reoperatieratio was 2% (1 van 53) in de eerste groep en 50% (4 van 8) in de tweede groep. Deze resultaten tonen aan dat volgen van het voorgestelde behandelprotocol voor fracturen van de edentate onderkaak het aantal complicaties en reoperaties significant reduceert.

In hoofdstuk 7 wordt beschreven de analyse van unilaterale fracturen van de processus condylaris bij 32 patiënten waarbij gebruik werd gemaakt van 3D-metingen (3D verplaatsing en rotaties). De resultaten van deze metingen werden gecorreleerd aan bestaande condylaire fractuurclassificaties van resp. Loukota en Spiessl & Schroll. De bevinding was dat volgens de Loukota- classificatie condylaire halsfracturen en kaakkopfracturen de grootste mediane 3D-verplaatsing alsmede de grootste rotatie hadden. Volgens de Spiessl & Schroll-classificatie hadden hoge fracturen van de processus condylaris met dislocatie (type V) en kaakkopfracturen (type VI) de grootste gemiddelde 3D verplaatsing en de grootste rotatie in vergelijking met andere type fracturen van deze classificatie. Het lijkt aannemelijk dat deze grotere 3D-verplaatsing en de rotaties werden waargenomen vanwege de aanhechting van de musculus pterygoideus lateralis aan de condylaire hals- en kaakkop. Hoewel de

154 Nederlandse samenvatting (Summary in Dutch)

3D-bepalingen nauwkeurig, objectief en reproduceerbaar zijn, valt de klinische relevantie van de grote 3D-verplaatsing en rotatie van de processus condylaris en van kaakkopfracturen niet vast te stellen. Verder constateerden we lage negatieve correlatie tussen maximale mondopening en 3D-verplaatsing en bescheiden correlatie met rotatie om de Z-as. Met andere woorden, ongeacht de fractuurclassificatie, hoe groter de 3D-verplaatsing of rotatie om de Z-as, hoe kleiner de mondopening kan zijn.

CONCLUSIE

Het onderzoek zoals beschreven in dit proefschrift laat zien dat verbetering van behandeling van fracturen van de mandibula mogelijk is, ook al wordt het resultaat van de behandeling van mandibulafracturen over het algemeen beschouwd als tevredenstellend.

Dit proefschrift beschrijft de eerste uitgebreide beoordeling van fractuurrepositieklemmen. De resultaten laten zien dat er een toegevoegde waarde is voor het gebruik van repositieklemmen bij de behandeling van fracturen van de mandibula. De repositie is exacter, de complicatieratio lager en de operatietijd korter. Drie repositieklemmen zijn ontwikkeld voor de mandibula die het mogelijk maken nagenoeg elke mandibulafractuur te reponeren via een intraorale benadering.

Ondanks het gebrek aan adequate studies zoals geïncludeerd in de systematische review, hebben lockingplaatsystemen een significante invloed op de postoperatieve noodzaak tot intermaxillaire fixatie hoewel dit heel wel kan worden veroorzaakt door de voorkeur van de chirurgen en niet omdat intermaxillaire fixatie daadwerkelijk noodzakelijk was.

Wat betreft de behandeling van fracturen van de edentate onderkaak is het voorgestelde protocol niet heel overtuigend evidence-based, maar wel gebaseerd op de best beschikbare data in de literatuur en de ervaringen binnen het UMCG. Strikt volgen van het protocol kan worden beschouwd als best practice. Aantallen complicaties en reoperaties zullen afnemen. Consequent gebruik van het protocol zal de kennis omtrent dit onderwerp verdiepen. 10 Een belangrijk aspect van het verbeteren van de behandeling van fracturen van de processus condylaris kan zijn precieze diagnose en classificatie. Kwantitatieve

155 Chapter 10

3D-metingen verschaffen precieze, objectieve en reproduceerbare informatie over fracturen van de processus condylaris. Het verschaft de chirurg de mogelijkheid om de fracturen exact te classificeren, bijvoorbeeld door gebruik te maken van de classificatie volgens Loukota of Spiessl & Schroll. De 3D-metingen kunnen mogelijk van invloed zijn op de keuze van behandeling. Echter, vervolgstudies zijn nodig die nadruk leggen op klinische parameters en het vergelijk tussen behandelmodaliteiten om te kunnen bepalen wat de werkelijke indicatie is voor open resp. gesloten behandeling.

156 ACKNOWLEDGEMENTS

APPENDIX

CURRICULUM VITAE

Acknowledgements

Finally, after 4 years of study, numerous tense yet enjoyable days, I completed my thesis. It has been a professional and creative evolution for me, and I have drawn on the energy and knowledge of many people who are best in their own professional field. It seems like everybody I have interacted with positively influenced me to grow not only professionally also to become a good brother, son, father, husband, friend or just a simply better human being. But I could mention only a few in here. I am constantly aware of my good fortune to learn and get inspired from many remarkable people, professors, colleagues, and mentors. It is impossible to name everyone.

Prof.dr.R.R.M.Bos, dear Ruud, you are such an open, caring individual with good sense of humor. Thank you for being available almost every time when I needed you throughout my study. I am more than grateful for not only your guidance regards my research, but also for being helpful to all kinds of matters. Attending international congress which held in an occasion to your retirement was once in a lifetime opportunity for me. I wish all the best for you and Liesbeth.

Dr.B.van Minnen, dear Baucke, thank you for being one of the kindest people I have ever known. I really appreciate your time that you had spent to revise my manuscripts. Your critical point of view was always on point and improved my work to the next level. Even though your schedule was always tight, you had spared lots of your time, we even joked that my studies revision was your Saturday evening work. You never failed to encourage me. Most importantly, you always tried to be there to help me, even for my personal matters. We also thank you for visiting Anir shortly after she was born, the blanket you gifted was her favorite one. Thanks to you my commute to the UMCG became much more comfortable and faster.

Prof.dr.P.U.Dijkstra, dear Pieter, you always found a way to be on my side to encourage me. Your ability to simplify complicated statistics never failed to help me to find solutions. Thank you for your outstanding expertise and advice that was crucial to my thesis. You gave me the confidence to complete my work. I always left your room with a full of confidence after consultation regarding statistics and meta-analysis. Thank you for your kind and encouraging advice.

Prof.dr.A.Vissink, dear Arjan, Thank your critical comments and punctuality. You always responded promptly and work efficiently. Your precise revision

159 played a significant role in my work. No wonder your nickname is “Faster than your shadow”. It was delightful to work with you.

Prof.dr.G.M. Raghoebar, dear Gerry, I had an interview for this position with you and Ruud via Skype and it was a very pleasant experience. After coming here, I met you in person and you gave me an opportunity to assist you in surgeries. It was an exhilarating experience and thank you again for granting me the opportunity.

Prof.dr. F.K.L. Spijkervet, dear Fred, thank you for supporting me in every possible way. I always remember the day I was called to meet you and walking to your office very nervously. However, you congratulated me for having a daughter and gave her a cutlery set. It was a very unexpected pleasant meeting. My daughter loves to play with it for now and hopefully will use them properly soon.

Prof.dr.A,J.Moshage, dear Han, I cannot thank you enough for your diligent support for me and my fellow Mongolian students. I am deeply thankful for your contribution that enabled us to pursue our studies.

Prof.dr. M.J.H. Witjes, dear Max, working on the 3D project with you was such delight. Thanks to you, my environment, availability to work in 3D lab was very pleasant. We had a nice talk during the flight Eelde to Munich as we were ‘The Last of the Mohicans’ and I believe that experience has brought us closer.

Prof.dr.J.L.N. Roodenburg dear Jan, thank you for always showing interest in my country, culture and being kind to me every time we encountered. Every single of them has left me a good memory. I wish you the fullest life after your retirement.

Dr. R.H. Schepers, dear Rutger, I always remember the pleasant day of visiting your house shortly before we departed for the course in Amsterdam. I was able to see your children’s morning routine, breakfast, they were so adorable. More importantly, thank you so much for making it possible to test and shoot the image of the forceps for my study.

Dr.Konstantina Delli, dear Konstantina, you are very inspiring and hardworking person. Thank you for your advices in general and recommendation for my review.

160 Acknowledgements

Dr. N.B. van Bakelen, dear Nico, you have been a very good friend and advisor to me throughout my time in here. Thank you for sharing the information about companies and for discussing about rare trauma cases.

Dr.T.A.van der Meulen, dear Taco, my paranymph, one of the most hardworking people I ever known. I appreciate all advices and help you gave me during my PhD. You and your family are such an inspiration to me both personally and professionally. I used to look forward to our routine to share the stroopwafel during the coffee time and it is such a good memory. After all, everything might be turning out good thanks to your ritual before making coffee (inside joke). I wish all the best for you and your family, Ingeborg, Amelie, Jozua, and Hylke.

Dr.J.Kreaima, Drs B.J. Merema, Drs H.Glas, Drs A.M.L.Meesters, Drs N.Assink, dear Joep, Haye, Anne, Nick, friends in 3D LAB, I cannot thank you enough for your support and enthusiasm regards to my 3D project. It would not have been possible to complete it without your expertise.

L.Kempers, H.B. de Jonge, N.E. Geurts-Jaeger, K.A. de Vries-Moritz, R. van der Graaf, S. Wiersema, dear Lisa, Harrie, Nienke, Angelika, Ron, Fieke, the administration office, I am so grateful for your diligent support regards to my documentation and paper works. Your punctual work ethic, ability to work efficiently, and attentiveness have made my life and work here so much pleasant.

Mw.H.Groenewegen, dear Hester, thank you so much for your warm and inspirational conversations with me regarding almost everything. I was able to ask freely and learned so much from you. Even the matters regarding my wife and a baby. And also, thank you for your Dutch expertise for the phone calls that required Dutch.

Dr. J.I. Drouven-Kamstra, Dr.M.H.J. Doff, Drs.R.Rozema, dear Jolanda Michiel and Romke, Thank you for being very pleasant (former)officemates.

Drs.S.Malwand, dear Somaia, co-author of my study, thank you for your time and enthusiasms to finalize the forceps study.

Drs.A.J.Tuin, Drs F.J.Voskuil, Drs J.Boeve, dear Jorien, Floris, Koos, it was nice to attend the European Congress with you guys, especially the Bavarian evening was fun and enjoyable time. Thank you for the photos taken during my presentation.

161 Dr.J.Jansma, Dr.K.P.Schepman, Dr.S.A.H.J. de Visscher, dear Johan, Kees- Pieter, Sebastiaan, thank you for the friendly atmosphere in the department.

Prof Dr T.H.F.Halbertsma, dear Tjalling, I am more than grateful for your enthusiasm towards Mongolia. You may be even more knowledgeable about Mongolia than me. Thank you for being the bridge of the cooperation between MNUMS and RUG. Thank you for always supporting me and other Mongolian students and most importantly for sponsoring my thesis.

Prof. Yi Choong Kook, dear Prof.Yi, you are my life mentor. It was such rewarding years to work and learn alongside with you. We had such good memories in Ulaanbaatar. I am deeply grateful for your dedication to the development of young surgeons and medical service in Mongolia. I will try my best to follow your guidance, so your years in Mongolia will not be in vain.

Prof Lee Sang Hwy, you almost became one of my supervisors if I pursued my PhD in Mongolia. And I still think of you as one of my mentors. Thank you so much for letting me assist your surgeries, letting me learn from the expertise and for always being open to my requests.

Prof. Hee-Kyun Oh, Prof. Park Hong-Ju, Prof. Kook Min Suk, and Dr. Seunggon Jung. Dear Prof. Oh, thank you so much for being such a warm mentor and close friend. Every time when my wife, then girlfriend visited me in Korea, you treated us with good meals. Once, we had pleasure to meet and dine with your whole family and even went to the movie afterward. Dear Prof. Park, thank you for your support and guidance throughout my fellowship in Korea even though you were located and busy in the US. The memory of the trip to Jeju island with you was delightful. Dear Prof. Kook, I am so thankful for you taking care of me during my stay in Korea. You even made a space for me in your office which is a rare opportunity for a fellow student in Korea. I learned the principles of the trauma surgeries as well as orthognathic surgeries from you. And I will always be grateful for you. Dear Dr.Jung, you were in your final year of the residency when I was in Korea and always very kind towards me. Thank you for your attentiveness during my stay in Korea, and for the time both in Mongolia and Korea.

Chang Seop Kim, Jaeik Choi, dear friends, I thank you for being good friends and your hospitality while I was in Korea.

162 Acknowledgements

N.Dijkstra-Teuling, dear Netty thank you for being a good friend. We had many inspirational and pleasant conversations during our coffee time at your place. Your stories about the Netherlands, UMCG and Dutch culture has been very informative and interesting.

Jan and Magda Meeuwissen, thank you for being warm hearted neighbors. Anir plays with the toys rigorously that you have given to her. It is indeed lovely that you are witnessing our daughter to grow.

Khaltar, Bolortungalag, Anand, and Anar, First of all, you are my closest extended family. Thank you so much for the life advises and good memories in the US. We talk about you constantly and treasure the time with you. Dear Haku, thank you for being such a cool brother and for your wisdom. Dear Boloroo, thank you very much for caring and loving us. Dear cousins, I watched you grow up and think like you are still young children. But I get surprised every time I see your pictures nowadays. We talk a lots about you and how cute you and your actions were. Anandaa, you played with me pretending to be a John Cena of WWF and we had so much fun. Anaraa, you were toothless for quite a bit and you had the cutest smile. Once you complimented the sandwich I made and said ‘this is the best sandwich I ever ate’. I never forget it. The next time when we meet, you might surprise us with your life stories. We cannot wait to see you again.

Uyanga and Misheel. Thank you for being the best roommates of my wife. We talk about you a lot and treasure the time we had with you. Thanks to you, I worried less about Otgoo. Dear Uyangaa, thanks for always believing and thinking the best of me and Otgoo. Your morning coffee made our mornings. Dear Mishka, thank you for being close to Otgoo. She talks about you fondly. Our walk to the lower Manhattan on a sunny day is one of the good memories we had in NYC.

Khurel and Khongorzul, dear Khurlee, you are and have been a father figure to our entire family. We look up to you and respect you deeply. Khongoroo, you are such a bright and positive person. I have so many good memories of you from my childhood. Thank you for making our visit to the UK comfortable and we had seen and experienced lots of good. Most importantly, you enabled me to pursue my PhD degree in the Netherlands. Wish you the best for you and my cousins, Galaa, Duluu, Och, and Ichko.

163 Itgel and Tungalag, dear friends, thank you for being a good friend since middle school and for the nice memories while I and Otgoo visited you on the way to the Netherlands. Thank you for sparing your time for us even though you were quite busy with work. I wish all the best for you and your children Indra and Irmuun.

Enkhee and Tsermaa, dear friends, you are my lifelong friends. My students’ years and all the adventures have always been shared with you. So, when I think of you, it is hard to include all the things I want to say in one paragraph. But one thing is for sure, thank you for being such an inspiring family and professionals. Otgoo and I adore you and you are in our conversations quite often. I wish you all the best for you and Khangal, Tsatsral.

Zen and Gandiimaa, dear Gandii, thank you for being such a good friend to my family. You have revised the first draft of the research proposal. You never failed to be there for Otgoo and me when we needed the most. Dear Zen, we ran into each other in Mongolia a lot when both of our significant others were in NYC together. Thanks for the drinks and time we shared. Warm wishes for your family and your children, Erdem, Ariya.

Tuya van Dodewaard, Tuyaa Perenlejchantsa, Thank you for being open and for your tips to adjust in the Netherlands. We thank your hospitality for making us feel at home when we visited your place. You are a great example to the Mongolian dentists. Thank you for being such hardworking and inspiring individuals.

Yanjmaa, the dear grandma, thank you for loving me unconditionally and raising me. You are my most beloved one.

Mart and Nyamsuren, dear grandmothers, Thank you for your love and affection. I acknowledge my deep sense of gratitude to you.

Batbayar and Tungalag. Dear dad and mom, I am more than grateful for your love and for the freedom you provided me growing up. I was able to find myself and pursue my path without interruption thanks to you. Without your support, love, I would not be here. Dad, thank you for your unwavering support and love. Mom, thank you for loving me and caring me and dedicating your everything.

Ariunbold and Oyunchimeg. dear parents, thank you so much for always being there for me, especially when I needed most. Dad, even though our lives were separated for a while, your love and affection never left my side like we

164 Acknowledgements

were never apart. Oyunaa, I am truly loved and cared by your unconditional love. Thank you for your sincere, heartfelt affection.

Nyamsambuu and Lkhagva, dear parents-in-law. Thank you for loving me like your very own son. Your love and support throughout the years have been irreplaceable and we cannot thank you enough for this.

Telmen, Ravjaa, and Itgel. I thank you for being my brothers, I am more than proud to be your big brother. Dear Temka, thank you for being the gentlest, kind hearted brother. Dear Tavhai, my memory of you being a young child and hiding behind mom is so vivid up to this day yet you are outgrowing me. Thank you for growing up to be good. Dear Itgel, your name is hope. And you came to us to bring all the goodness in the world.

Zaya and Zoljargal. I am grateful to have such two dashing, intelligent younger sisters. dear Zaya, you are so bright, hardworking and caring sister. Dear Zoloo, your cheerfulness, big hearted nature has always comforted me.

Tselmeg, Sodtsetseg, and Sonintsetseg. Dear cousins, Tseemee, we grew up together and made so many wonderful memories. Thank you for being family hearted man and for always arranging a family gatherings. I wish all the best to you and Saruul. Dear Sonio and Sodoo, thank you my lovey, kind-hearted cousins for your kindness. You are always there for everyone when your help is needed.

Tuul, Tumur, Mandakh, Bold, Sarantuya, Bolor, and their children. To my beloved family members, I am deeply grateful for your support and understanding up to this day. Your encouragement, warmth has played a tremendous part in my life.

Badam, Narangerel, Odgerel, Oyungerel, ‘’The late Jigjidsuren’’, Enkhbold, Batbaatar, Bayarbold, and Amarsanaa and their children. To my beloved family members, thank you for being awesome in-laws/friends. We have made much memories full of joys and adventures. I always thank your backing and for supporting me whenever I needed.

Ochbayar, Tsolmon, Uyanga, Khongorzul, Battsengel, Gan-Erdene, Ankhbayar, Munkhzaya, Alimaa, Ullziijargal, Nasanjargal, Bayarmaa, Shadavlonjid, and Amarbat. Dear friends from dental school and medical school, it was a valuable time for our student life. I have really appreciated your kind wishes and present when I headed to pursue my degree in the Netherlands.

165 Enkhbadrakh, Tsatsral, Naranbaatar, Tsolmon, Tuvshinbolor, Tuguldur, Bolorsaikhan, Enkhjargal, Gan-Od, Bolormaa, Erdene, Enkhmanlai, Naranbat, Erdenesuren, Saruul, Uyanga, Enkhtur, Tsolmon, Uguumur, Bayasgalan, Chaminbileg, Sodbayar, Undral, Amarsanaa, Solongo, Bat- Erdene, Anarkhuu. My partners in crime, I thank you for our fabulous memory and for being terrific friends. Thanks to you, my days have been much more cheerful with full of laughter.

Prof. Amarsaikhan and Prof.Ariuntuul. dear Amraa, thank you for helping me to build my career path with your advice, guidance and encouragement. It meant so much to me. I would not be who I am today without your guide. Dear Ariuntuul, your discipline and high-level of responsibility is something we all get inspired by and thrive to be. Thank you for your sincere, persistent support.

Dr.Ganjargal, Dr.Munkhdul, Dr.Tsengelsaikhan, Dr.Unurzul, Dr.Oyunkhishig and rest of the colleagues at school of dentistry, MNUMS. Thank you for being inspiring and outstanding colleagues. I appreciated your warm wishes before my departure.

Prof.Khentii, ’The late Prof.Davaanyam’, Prof.Uranchimeg, Dr.Davaakhuu, Dr.Batbayar and Dr.Davaadorj. Dear colleagues of the department of OMS, thank you for your support while I was a residence as well as a staff of the department, and your kind wishes.

Dr.Denis, Dr.Gantumur, Dr.Ayanga, Dr.Erdenetsogt, Dr.Baasandorj, Dr.Batsanaa, Dr.Onon, and Dr.Unurjargal. dear mentors and friends, thank you for your kind support during my residency, and best wishes.

Ganbayar, Buyanbadrakh, Otgonbayar. Thank you for supporting my thesis with your nice photographs of the threatened species in Mongolia.

Jambaperenlei, Delgersuren, Tsenguun. I am deeply grateful for meeting you here. You have helped and supported us tremendously. Thanks to you, our days were brighter and we always felt like at home in Groningen.

William, Ariuntuya. Thank you for your warm heart and hospitality. Thank you for always supporting us, fellow Mongolian students.

Benderya Batbayar, and Julia. I will always remember your kindness and support. Thank you very much.

166 Acknowledgements

Otgontsetseg, Altantsooj, Myagmarchuluun, Enkhmaa, Tsogtsolmaa, and Khulan. Dear friends, you were the first friends I made in Groningen. We had such a good time and memory together.

Enkhkhuyag, Bolorchimeg, Khurelbaatar, Bolor, Margad-Erdene, Tuyaral, Namsraijav, Davaasuren, Munkh-Erdene, Ariunaa, Tengis. Dear friends, it was always joyful to play basketball together and to hang out with you guys. I wish all the best for you and for your family.

To ‘’the seven’, Byambasuren, Oyuntugs, Turtushikh, Dulguun, Khosbayar, Saranchimeg, Ariuntuya, Batzorig, Altanzul, Namuunaa. ’We became almost extended family in here as we know each other so well, including our family members. Thank you for being amazing colleagues, friends. We have made such good memories here and will make much more in the future. Our coffee breaks were always full of conversations covering all kinds of subjects. Our holiday gatherings were always so much fun and eventful.

Anir, my little one, the joy of my life, daddy loves you so much and your cutest smile always fulfill my heart. You are our heaven on earth.

Otgongerel, My love, my life, my better half who believed in me more than I believed in myself. This thesis would never have been accomplished without your love, support, dedication and understanding. Thank you for being with me through the thick and thin of it all. I lack words to tell you how much you mean to me.

167 168 Appendix

Appendix

‘The ‘Khureelen’ (meaning ‘environment’ in Mongolian) project crew comprised of biologists, photographers, journalists and documentary filmmakers has been travelling through Mongolia since 2013 to create a repository where photos and videos of Mongolian nature, wildlife and animals are kept and to increase public awareness of endangered animal and wildlife nature of Mongolia. The photos which were included in this thesis used with permission of the authors. https://www.facebook.com/ProjectHureelen/ [email protected]

Description of the images.

Image 1 (Chapter 1).

Gobi bear Mazaalai (Ursus Arctos Gobiensis) is a critically endangered species existent only in Mongolia. Smaller compared to most members of the brown bear family, their average body length is 170 sm. Since the 1960s, mazaalai’s habitual range has seen fivefold decrease with under 30 mazaalais remaining throughout the Greater Gobi Strictly Protected Area (GGSPA). (Source: Oyu tolgoi LLC)

Image 2 (Chapter 2).

Siberian musk deer (Moschus moschiferus is very rare species which inhabits in dense forest covered with moss and lechen, and listed as vulnerable on the International Union for Conservation of Nature (IUCN) Red List. Due to excessive illegal hunting, the numbers were sharply reduced 44,000 (1970) to 6500 (2010). (Source: touristinfocenter.mn)

Image 3 (Chapter 3).

Pallas’s cat (Otocolobus manul), also called Manul is a small wild cat with a broad but fragmented distribution in the grasslands and mountain steppes of Central Asia. It is negatively affected by habitat degradation, prey base

169 decline, and hunting, and has therefore been classified as Near Threatened on the IUCN Red List since 2002. (Source: touristinfocenter.mn)

Image 4 (Chapter 4).

Snow leopard (Panthera unicia schreber) is listed as vulnerable on the IUCN Red List. The snow leopard inhabits high altitudes in extreme (more than 1000 meters above sea level) climates. In 2000, around 800-1500 leopards were recorded in Mongolia. Loss of wild prey base, land encroachment by the man with increasing livestock numbers, the leopard natural habitats invaded, leopards preying on livestock increases. The cubs were vulnerable, easily get washed away by floods, preyed upon by other predators. (Source: touristinfocenter.mn)

Image 5 (Chapter 5).

Takhi or Przewalski’s horse (equus przewalski ploiakov) is wild horse has never been domesticated thus making it the only speicie that is truly wild in the world. There are roughly 2,000 Takhi in the world right now, and the largest number of them live at Hustai National Park, within 60 miles of Mongolia’s capital, Ulaanbaatar. This park reintroduced Mongolian wild horses on June 5th, 1992 with the help of the Dutch Association FPPPH (Foundation for the Preservation and Protection of the Przewalski Horse). (Source:smithsonianmag.com)

Image 6 (Chapter 6).

Khulan or Mongolian wild ass (equus hemionus hemionus pallas) inhabits in desert and desert-steppe with mountains, hills and plains and valleys between them, and listed as near threated on the IUCN Red List. By 2003, the population decreased by 60% from 1997 (~15000). They are also still illegally hunted. Harsh winters with a lot of snow results in loss of pastures leading to high mortality. (Source: touristinfocenter.mn)

Image 7 (Chapter 7).

The black-tailed gazelle (Gazella subgutturosa) or the goitered gazelle is a cloven-hoofed animal, found in Southern Gobi and Great Lakes Depression among others. The species is listed as ‘vulnerable’ both in the International Union for Conservation of Nature and Mongolian Red List. According to an

170 Appendix

estimate done by the Ministry of Nature, Environment, and Tourism of Mongolia, around 25 thousand black-tailed gazelles existed throughout Mongolia in 2010. Hunting of this species is strictly prohibited since 1965. Due to increased human activities, their habitat has changed, often occupying higher altitudes, constantly moving from one place to another, sometimes covering dozens of km per day. It is also found in parts of Azerbaijan, Georgia, Iraq, and a few other countries. (Source: Oyu Tolgoi LLC).

Image 8 (Chapter 8).

Wild reindeer (Rangifer tarandus Linnaeus) inhabit in high mountain slopes (2300-3000 meters) and listed vulnerable on the IUCN Red List. In 1996, the total population was estimated to be 200-400 in Mongolia. (Source: touristinfocenter.mn)

Image 9 (Chapter 9).

Argal (ovis ammon linnaeus) is the largest species of wild sheep, and list as near threatened on the IUCN Red List. Argal inhabits gobi desert, forest steppe, and high mountains. By 2009, their population estimated 18000. (Source: touristinfocenter.mn)

Image 10 (Chapter 10).

White-tailed eagle (Haliaeetus albicilla) is a very large eagle widely distributed across Eurasia and listed the least concern on the IUCN Red List.

171 172 Curriculum Vitae

Curriculum vitae

Enkh-Orchlon Batbayar was born on 23 August 1985 in Ulaanbaatar, Mongolia. He graduated high school in 2003 (New Mongolia/Shine Mongol) in Ulaanbaatar, and enrolled into dental school at Health Sciences University of Mongolia (HSUM). After obtaining a dental degree (DMD) in 2009, he started a post-graduate program (MSc) in the same university. Thereafter, between 2011- 2014, he finished residency in Oral and Maxillofacial Surgery at Mongolian National University of Medical Sciences (MNUMS) and Yonsei-Friendship Hospital in Ulaanbaatar, under the supervisions of Prof.Khentii.L, and Prof.Yi Choong Kook (emeritus professor from Yonsei University, Seoul, South Korea). He was the recipient of a one-year fellowship of Asian Association of Oral and Maxillofacial Surgeons (AAOMS) and trained at Department of Oral and Maxillofacial Surgery (head: Prof. Hee-Kyun Oh), Chonnam National University (Gwangju, South Korea). In June 2015, he started his PhD research at the Department of Oral and Maxillofacial Surgery of the University Medical Center Groningen (UMCG), Groningen, the Netherlands. Enkh-Orchlon is married to Otgongerel Nyamsambuu and they have a daughter, Anir (2018).

173 Sponsoring