Alloplastic Or Homograft Implantation for Nasal Reconstruction

INTERUNIVERSITY-INTERDEPARTMENTAL PROGRAMME OF POSTGRADUATE STUDIES IN DISEASES OF THE NOSE, SKULL BASE & FACE

Department of Medicine University of Patras Department of Medicine NKUA

Alloplastic or Homograft Implantation for Nasal Reconstruction

ALIKI-KONSTANTINA D. DROSOU

M.Sc. Thesis

March 2021 Patras

Supervisor : Professor Nikolaos S. Mastronikolis

ΔΙΙΔΡΥΜΑΤΙΚΟ ΔΙΑΤΜΗΜΑΤΙΚΟ ΠΡΟΓΡΑΜΜΑ ΜΕΤΑΠΤΥΧΙΑΚΩΝ ΣΠΟΥΔΩΝ ΠΑΘΗΣΕΙΣ ΡΙΝΟΣ, ΒΑΣΗΣ ΚΡΑΝΙΟΥ ΚΑΙ ΠΡΟΣΩΠΙΚΗΣ ΧΩΡΑΣ

Τμήμα Ιατρικής Πανεπιστημίου Πατρών Τμήμα Ιατρικής ΕΚΠΑ

Alloplastic or Homograft Implantation for Nasal Reconstruction

ΑΛΙΚΗ-ΚΩΝΣΤΑΝΤΙΝΑ Δ. ΔΡΟΣΟΥ

ΜΕΤΑΠΤΥΧΙΑΚΗ ΔΙΠΛΩΜΑΤΙΚΗ ΕΡΓΑΣΙΑ

ΜΑΡΤΙΟΣ 2021 ΠΑΤΡΑ

Επιβλέπων : Καθηγητής Νικόλαος Σ. Μαστρονικολής

THREE MEMBER EXAMINATION COMMITTEE

Mastronikolis Nikolaos, Professor of Otorhinolaryngology (Supervisor) Danielidis Vassilios, Professor of Otorhinolaryngology Naxakis Stefanos, Professor of Otorhinolaryngology

ACKNOWLEDGEMENTS

I would like to thank my thesis supervisor, Professor Nikolaos S. Mastronikolis for giving me the opportunity to realize this project and for his continuous support and guidance during this Master Thesis. My sincerest appreciation to Professor Vassilios Danielidis and Professor Stefanos Naxakis from the Department of Otorhinolaryngology, for generously and selflessly teaching me a vast amount of their knowledge and experience. I am also indebted to my husband, Medical Physicist Dimitrios N. Georgakopoulos, M.Sc., for his invaluable advice on the proper structure of this thesis.

CONTENTS

ABSTRACT………………………………………………………………………...... vi ΠΕΡΙΛΗΨΗ…………………………………………...……….………………….....vii

Chapter 1……………………………………….……………………………...1 INTRODUCTION………………………………………………………………...... 1 1.1. Autografts ...... ………………...... 2 1.1.1 Septal Cartilage ...... 2 1.1.2 Conchal Cartilage...………………………………………………….……...….5 1.1.3 Costal Cartilage………………………………………….…...…...………...... 6 1.1.4 Bone as Implant Material……………….…………...…...... 8 1.1.5 Characteristics of the Ideal Implant...... ………………..….10 1.2. Homologous Grafts………………………………………...... 12 1.2.1 Surgical Technique……………….……...…………...... 13 1.2.1.1Columellar Strut ...... 13 1.2.1.2Dorsal Nasal Graft...... 14 1.2.1.3Laboratory Study...... 15 1.2.1.4Clinical Study ...... 15 1.2.2 Irradiated Costal Cartilage.….…………...... ………....……….………...15 1.2.3 Acellular Dermis…………………………………………………...... …...….19 1.3 Alloplastic Implants……………………………………………...... 22 1.4 Materials…….……………………………………………………...... ….24 1.4.1 Silicone…………………………………………………………...... …….24 1.4.2 Polytetrafluoroethylene…………...………………...... ………. .31 1.4.2.1Proplast…………...………………………...... 31 1.4.2.2Gore-Tex ...... ……………....39 1.4.3 Polyethylenes.………………………………………………………...... 46 1.4.3.1Chin Implants ...... …………………………………………………………….48 1.4.3.2Malar Implants ...... …………..……………………………………………….49 1.4.3.3Nasal Implants ...... …………..……………………………………………….49 1.4.3.4Ear Reconstruction …………………………………………………………...50 1.4.3.5Orbital Reconstruction.……………………………………………………….50 1.4.3.6Cranial Applications....……………………………………………………….50

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1.5 Polyesters and Polyamides...... …………………………………………...51 1.6 The Future….……...... ………………………………………………...... 52

Chapter 2...... ……………………………………………57 INTRODUCTION...... 57 2.1 Types of Grafts...... ………………………….……..58 2.2 Autologous Grafts...... ………………………………………..59 2.2.1 Autologous Septal Cartilage Grafts...... ……………………………….61 2.2.2 Autologous Auricular Cartilage Grafts…………………………………….....61 2.2.3 Autologous Costal Cartilage Grafts..………………………………………....61 2.2.4 Autologous Bone Grafts.………………………………………………...... 62 2.3 Homologous Cartilage Grafts....………………...... …………………………66 2.4 Heterologous Cartilage Grafts (Xenografts)...... 68 2.5 Alloplastic Implants...... 69 2.5.1 Silicone Implants...... 69 2.5.2 Mersilene Implants...... 70 2.5.3 E-PTFE...... 70

Chapter 3.……………………………...... ……………….....72 INTRODUCTION...... 72 3.1. Definitions...... ……...…………………………………………………..…....72 3.2. Literature Experience...... ……………………..…………………….....72 3.2.1 Grafts...... …...…....……………...…...72 3.2.2 Implants...... 73 3.2.3 Mersilene Mesh Utilization Cases...... ………………..…...75 3.2.4 Silastic………...... ……………………………………..…76 3.2.5 Gore-Tex……………...... 76 3.3. Why we want to use Implants...... 77 3.4. Clinical Situations Calling for Implants…………………………………...... 78 3.5. Graft Alternative Strategies...... 78

Chapter 4 – Connection to the Present...... 83

Conclusions...... 94 REFERENCES...... 95

ABSTRACT

Reconstructive and aesthetic rhinoplasty commonly requires utilizing implants to recreate nasal contour or strengthen the support for the nasal frame and soft tissues. Implants are divided into three main categories: autografts, homografts and alloplasts. Each aforementioned group is characterized by notable benefits and deficits. An ideal implantable material must possess biocompatibility, strength and elasticity. The material should be unable of inducing inflammatory reactions, be carcinogenic, delicate in mechanical strain, inflexible, and non-sterile. Several surgeons would argue that autografts should be the dominant choice for nasal reconstruction and regeneration.

Autogenous tissue has long been advocated as the mainstay for nasal implants and is most commonly employed for structural and augmentation grafting in the nasal tip, as well as for dorsal malformations. However, the finite availability and non-predictable absorption of both autologous and homologous implants have made newer alloplastic implants imported to crucial considerations for dorsal augmentation.

Conservative surgeons believe in making natural-appearing, well-supported, well- balanced noses. Conclusively, often the need to add something to create projection, balance, or support is desired.

ΠΕΡΙΛΗΨΗ

Η επανορθωτική και αισθητική ρινοπλαστική συχνά χρησιμοποιεί εμφυτεύματα προς αναδημιουργία του ρινικού περιγράμματος ή την ενδυνάμωση του ρινικού πλαισίου και των μαλακών ιστών. Τα εμφυτεύματα χωρίζονται σε τρεις κύριες κατηγορίες : Αυτομοσχεύματα, ομομοσχεύματα και αλλοπλαστικά μοσχεύματα. Όλες οι παραπάνω κατηγορίες χαρακτηρίζονται από τα πλεονεκτήματα και τα μειονεκτήματα τους. Ένα ιδανικό υλικό εμφύτευσης θα πρέπει να κατέχει τις εξής ιδιότητες : βιοσυμβατότητα, ισχύ και ελαστικότητα, αλλά ταυτόχρονα να μην προκαλεί φλεγμονώδεις αντιδράσεις, καρκινογενέσεις, να μην είναι ευαίσθητο στην μηχανική καταπόνηση, άκαμπτο και μη- αποστειρωμένο. Πολλοί χειρουργοί διατείνονται πως τα αυτομοσχεύματα πρέπει να είναι η κύρια επιλογή όσον αφορά την ρινική αναδόμηση και αναγέννηση.

Ο αυτογενής ιστός θεωρείται ο στυλοβάτης των ρινικών εμφυτευμάτων και χρησιμοποιείται συχνότερα στην δομική και αυξητική μεταμόσχευση του ρινικού άκρου, όπως επίσης και στις ραχιαίες δυσπλασίες. Παρόλα αυτά, η πεπερασμένη διαθεσιμότητα και η μη-προβλέψιμη απορρόφηση τόσο των αυτόλογων όσο και των ομόλογων εμφυτευμάτων έχουν φέρει τα νεότερα αλλοπλαστικά εμφυτεύματα σε καίρια θέση όσον αφορά την υπάρχουσα θεώρηση για την ενίσχυση της ρινικής ράχης.

Συντηρητικοί χειρουργοί θεωρούν ότι οι παρεμβάσεις στην μύτη πρέπει να προσδίδουν ένα αποτέλεσμα που να φαίνεται φυσικό και να είναι αρκούντως στηριγμένο και ισορροπημένο. Συμπερασματικά, είναι συχνή η ανάγκη της πρόσθεσης κάποιου υλικού, για την δημιουργία προσεκβολής ή την παροχή ισορροπίας ή στήριξης.

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CHAPTER 1

INTRODUCTION

Reconstructive and aesthetic rhinoplasty often requires the use of implants to recreate nasal contour or strengthen the support for the nasal frame and soft tissues. So far, there are many implants in our quiver, which are separated into three main categories: autografts, homografts and alloplasts. Autografts can be procured from the same patient, which comprise cartilage, bone, dermis, fat, and fascia. Homografts, which include cartilage, bone, and dermis, are materials harvested from donors of the same species. Alloplasts are used as implants and involve a broad group of synthetic and semisynthetic materials. A fourth and relatively small group of implantable materials, xenografts, are extracted from other species, just as bovine collagen.

Each aforementioned group of graft is characterized by notable pros and cons. However, there is still a controversy about which material is superior and will last until a category of alloplastic implants will cover the basic needs of the ultimate implant. An ideal implantable material must have biocompatibility, strength and elasticity. The material should not be capable of inducing inflammatory reactions, carcinogenic, delicate in mechanical strain, inflexible, and non-sterile.

Some factors that determine the choice of material for a particular occasion are the surgical needs, the choice of the patient, the preference and the experience of the surgeon. Many would argue that autografts should be the dominant choice for nasal reconstruction and regeneration. However, situations arise in which collecting an implant is impractical or worsens the morbidity of a procedure in a patient with a deteriorating medical condition. In addition, there may not be enough autonomous material to meet the patient's surgical needs. For these conditions, the implant materials are a sufficient substitute for the autografts. The location of the implant should also be considered when choosing a graft. Implants for relatively immobile dorsum may be less absorbed than those placed at the tip of the nose[1].

1.1 AUTOGRAFTS

Autologous tissue is the most ideal material for implantation. Biocompatibility is unsurpassed and the risk of infection and extrusion is much lower with autologous materials compared to alloplasts[2]. Autograft cartilage is the most frequently utilized material in rhinoplasty and holds for the gold standard against which all others are compared. Autogenous grafts have been the chosen material for nasal augmentation and reconstruction for numerous years. On availability, the patient’s own nasal septal cartilage is thought to be the preferred implant for nasal implantation. Septal cartilage autografts are mostly adequate for tip support and augmentation. Auricular cartilage is another disposable alternative material and is an appropriate implant for tip grafts and lower lateral cartilage onlay grafts. However, its demerit is that it owns some degree of remodeling and resorption, but prompt no immune response or biocompatibility problems.

The cartilage for the reconstruction of the nose can be collected from the diaphragm, the nasal conchae or the rib. The bone can also be taken from the diaphragm, calvarium or rib. The soft tissue can be transported to the area using various flaps or free flaps, as well as skin and fat grafts. Autologous materials offer the obvious advantage of unsurpassed biocompatibility, but they cause morbidity in the donor area and can be absorbed over time. The cartilage has the additional disadvantage of possible distortion or deformation. Limited cartilage supply from the diaphragm and ear can also be a problem.

1.1.1 SEPTAL CARTILAGE

Septal cartilage is the graft of choice for a nasal tip transplant[3-5]. The septal cartilage is usually stronger and stiffer than the conch cartilage. It is easier to carve and shape because it is more durable. Until now, only the concha has been utilized as a donor site, because its redeployment does not produce an unwanted secondary deformity. The size of the obtainable graft depends on the individual concha. Therefore, it is more practical to subtract the anterior skin and the full-thickness of the conchal cartilage down to the posterior perichondrium in toto, and transport it to a separate table where the perichondro-cutaneous graft is stripped. Magnification is important for this purpose, but it does not consist as a prerequisite. If the entire concha subtracted, then the donor bed is skin grafted.

Tardy et al.[6], documented a number of successful septal cartilage implants placed during rhinoplasty, which they followed for nearly two decades. Fresh cartilage autografts are being transplanted to the nose recipient site from donor areas in the nasal septum. For the past 17 years autograft cartilage has been used exclusively to support, accentuate, enlarge, and recontour nasal disharmonies resulting from congenital, traumatic, and iatrogenic disabilities.

Over 2,000 autogenous cartilage grafts have been implanted during this period, with predictable and positive early, as well as more critically, long-term results. The loss of any autogenous graft due to early infection or host rejection is unknown. Complications, which have been sparse and relative in nature, have originated from operator errors in graft contouring, fashioning, and inaccurate or imprecise host pocket preparation, preventable errors whose incidence diminishes with experience, acquired skills, and artistic conceptualization. No significant complications have been presented from the inherent unique properties of the cartilage autograft itself.

Autogenous cartilage grafts constitute a nearly ideal implant for the special requirements of nasal tissues. Cartilage flexibility can be retained and exploited for firm support and contouring, or this inherent springiness may be restricted and southed by multiple cross-hatching incisions or gentle morsalization. Ultimately, and most critically, the long-term fate of autogenous cartilage is well documented.

Strong bias for cartilage autografts is based on unique tissue biocompatibility, freedom from absorption and warping (when properly sculptured) of even small fragments of autografts, the ease of placement within accurate tissue pockets in the nose, the supportive structural characteristics of intact autografts, and the neo-chondrogenic potential for growth in children. Most significantly, if a cartilage autograft is unsuccessful for any reason in the patient (a rare occurrence), little tissue damage occurs, therefore extracting minimal penalty from the host tissues. Secondary reconstruction may then be rapidly planned and instituted without delay.

In nasal plastic and reconstructive surgery, cartilage autografts from the nasal septum are exerted on an increasingly regular basis to ameliorate proportions (e.g. support tip projection, expunge minor deficits, enlarge disharmonic angles, regularize nasal irregularities) and produce the necessary support in primary rhinoplasty, revision rhinoplasty, and nasal reconstructions. The nasal refinements provided by cartilage

autografts intensify the satisfaction derived by both the patient and the surgeon, while promising long-term safety and stability.

In revision rhinoplasty, common deficiencies encountered include loss of tip and alar support, contour deficiencies, soft tissue depressions, and saddle deformities. Contoured cartilage autografts serve well for safe, predictable repair of these largely iatrogenic deficiencies.

In nasal reconstructive procedures, customarily created by congenital, traumatic, or infectious processes, cartilage autografts from the ear or rib are of utmost importance (septal cartilage is commonly absent or deficient in the majority of these patients). Septal perforations which should be repaired (not all do) may be reliably closed and remanufactured with composite flaps from the sublabial mucosal layer, incorporating a disc of auricular cartilage for supersession of the absent septal cartilage.

Since the ideal nasal implant, whether natural or artificial, does not yet exist, the reconstructive surgeon must select a material which fulfills the reconstructive need, possesses high tissue biocompatibility, and does no harm to the patient.

Because of its unique characteristics, the cartilage autograft fulfills these criteria better than any other currently available. For over 17 years the cartilage autograft is being utilized exclusively in nasal reconstruction, with gratifying results. No major complications have been experienced, while a wide variety of nasal defects and disharmonies have been restricted.

The septal cartilage is commonly used for struts, batten grafts, lateral crural grafts, lateral crural strut grafts, and spreader grafts. This cartilage is also an excellent material for shield tip grafts and buttress grafts that add projection or length and definition to the nasal tip. Dorsal augmentation can be done using septal cartilage. Single or multi- layer implants attached with absorbable sutures can be used for different degrees of growth. A radial graft can be formed with bruised septal cartilage to improve the deep nasofrontal angle and enlarge the acute nasolabial angle in the form of a plumping graft. Cartilage compression can accelerate the onset and severity of cartilage absorption[7]. Septal cartilage is also our choice for strut grafting for tip support and for caudal septal grafting to enhance the length and support of the nose.

Septal cartilage can be collected by various approaches. Regardless of the method chosen, the amount of cartilage to be collected must be commensurate with the amount of cartilage required for inoculation. Also, at least 1.5 cm of dorsal and caudal septal cartilage must be maintained to achieve adequate nasal support. Should the grade of cartilaginous hump resection be considered before harvesting the diaphragm; if extra cartilage extends, the support may be disrupted. The cartilage can then be carved and damaged for a precise contour to match the surrounding tissue. The implant must be sutured in place.

1.1.2 CONCHAL CARTILAGE

Conchal cartilage is a different site for collecting an autograft and yields about 4 cm2 of cartilage as well as the perichondrium. Composite implants including skin, cartilage and perichondrium can be used to reconstruct the nasal tip, repair alar retraction and repair septal perforation (perichondrocutaneous implants)[8,9].

The free perichondrium can be used to cover an implant above the tip of the nose in patients with thin skin. Conchal cartilage is a suitable substitute for septal cartilage, grafts when the septum has been previously collected. Due to its more fragile nature, conchal cartilage may be more demanding to carve than septal cartilage. Αdditionally, the conchal cartilage is hollow and more flexible than the quadrilateral cartilage. Similar to septal cartilage, conchal grafts can be used as a single-layer implant or sewn together to increase volume. Conchal cartilage is suitable for improving the contour of the nasal tip or as an onlay implant. However, the septal or rib cartilage is more durable and offers more support. Previous extensive auricular cartilage collection may not allow further conchal cartilage collection. Other contraindications are systemic diseases, like collagen vascular disease, rheumatic disease, or immune disorders involving the auricle, such as lupus, polychondritis, sarcoidosis, and Wegener's granulomas. Careful preoperative examination and investigation will show the surgeon which ear to choose for the cartilage harvesting. Complete removal of conchal cartilage can lead to mild medialization of the pinna. For this reason, if it is not asymmetrical, the most obvious ear should be chosen for harvesting. In addition, for the patient who has a history of sleeping on one side of the head only, the contralateral conchal cartilage should be collected.

Several cartilage harvesting techniques have been described[10,11]. The posterior approach is considered the preferred. The posterior approach avoids incisions in the anterior surface of the ear and should be used when the postauricular area is to be exposed for other reasons (e.g., during otoplasty or rhytidectomy) or if the patient is predisposed to keloid scars. Conchal cartilage is considered the implant of choice for most non-structural grafting needs when the septal cartilage is not available.

1.1.3 COSTAL CARTILAGE

Saddle-nose deformities or severe structural defects usually need to be corrected with larger implants, such as rib cartilage. Costal cartilage provides sufficient amounts of cartilage for almost all structural defects of the nose that may occur. Converging ribs five and six or seven and eight are the preferred ribs for harvesting, so that we can use them in nasal implantation. Disadvantages of using this implant include the possibility of distortion and absorption[12], possible pneumothorax and postoperative ache[13].

A study of the behavior of maintained animal cartilage implants in humans presented fresh autogenous costal cartilage as a control in one volunteer. When this autograft was removed two months later histological examination revealed considerable surface absorption. Surface absorption was found to be frequently occurred and in certain circumstances it may be of clinical importance.

On the incidence of transplanted cartilage there were areas lid by perichondrium, that sheltered the underlying cartilage, and others were not. In the latter case, invasion, erosion, or absorption was present.

Absorption degree varied considerably among specimens and often between surfaces in the same specimen. Absorption was larger in the specimens, while loose tissue superseding the absorbed cartilage conflicts the dense enveloping fibrous layer.

It is of utmost significance that the picture is often the same whether the graft has been transplanted recently or has been in the tissues for many years. It is evident that even in the earliest specimens the absorptive process is no longer active; it is of prompt initiation and of short duration, and is accomplished within a few weeks of transplantation.

A further possibility is that the absorption is the natural reaction of host tissue towards any graft or implant and represents an effort to vascularize or remove it. In dead

cartilage the absorptive process keeps on, stimulated perhaps by the antigenic activity of the material absorbed; in surviving grafts it soon ceases. However, this does not explain the considerable variation in the process severity.

Whatever the cause, it is of no clinical importance so long as the graft is reasonably thick. But when diced cartilage is utilized there might be an appreciable diminution in the graft bulk and the smaller the dices the greater will be the total loss. Unfortunately, it is not possible to estimate this beforehand; if the erosion is limited to pitting of the surface there will be no loss in bulk, but if whole surfaces have been removed, there may be a significant volume loss. The absorptive process seemed to be of short duration and to be completed within a few weeks after transplantation. The degree of absorption varied widely; when severe it could result in a significant diminution in the bulk of the graft.

In elderly patients, cartilage calcification can make engraving and shaping almost impossible. Therefore, rib cartilage harvesting in the elderly should be avoided. Sculpting techniques that try to remove equal proportions of cartilage from all rib surfaces have been associated with less distortion[13]. Unpredictable distortion continues to be the major issue related to cartilage implantation, regardless of cautious technique. The costal cartilage should be used mainly as a strut graft for the nose that does not support an edge or for dorsal augmentation in patients with saddle deformity. Implant attachment can reduce the risk of misalignment and distortion[14].

Autogenous rib cartilage grafts have gained widespread use in rhinoplasty as dorsal onlay grafts and columellar struts. Nevertheless, the serviceableness of rib as a donor site has been narrowed by complications in postoperative cartilage warping. The internal stabilization of autogenous rib cartilage grafts with K-wires effectively prevents graft warpage.

Furthermore, the wide variety of autogenous and alloplastic materials for rhinoplasty, attests to the fact that the ideal grafting material has not been found. Alloplasts are prone to extrusion and infection; bone is difficult to shape, requires fixation, and may resorb; and rib cartilage has a tendency to warp.

It is generally preferred that autogenous septal cartilage are utilized for mild deficiencies in projection of the tip and dorsum. However, for more severe deformities, a sufficient quantity of septal cartilage is commonly lacking because of large grafting

requirements or previous septoplasty. There are large available quantities, ease of carving, and lack of postoperative resorption. However, warping has remained a significant obstacle, since it cannot be controlled, in order to allow rib cartilage to be the ideal nasal graft.

Inner consolidation of rib grafts with K-wires should, at least theoretically, impede warping. However, it is still unknown if there exists a clinically applicable enzymatic alteration technique, which could reduce cartilage warping as well. The timing of cartilage warping remains a subject of debate. The non-existence of detectable warping suggests that K-wire stabilization prevents both early (within days) and late (within months) warping. Longer follow-up is of necessity to determine whether this benefit extends to years or not .

Ultimately, the internal stabilization of rib cartilage grafts with K-wires effectively prevents graft warpage. This technique is valuable in the rhinoplasty patient who requires a columellar strut or a dorsal onlay graft fashioned from autogenous rib cartilage.

1.1.4 BONE AS IMPLANT MATERIAL

The boat-like configuration is the desired design for grafting to re-create the dorsal anatomy and allowing coverage with an adjacent nasal anatomy[15]. The complication rate in primary cases, such as cosmetic improvement of the platyrrhine nose is low, while materials can be carved and placed to look and feel quite natural. The infection risk necessitating removal rises significantly in revision cases, where the surgeon must weigh such factors as skin thickness, technical difficulty, and their own experience carefully before proceeding with any implant.

Bone is a viable alternative to cartilage for dorsal nasal augmentation[16,17]. Reconstruction of nasal skeletal support for acquired defects has become increasingly necessary since the number of traumatic and post-surgical cases rises. The ideal material should fulfill the criteria of stability, strength, and durability. Increasingly, however, the reconstructive surgeon is operating on the nose for the third or fourth time and the status of donor sites may have been compromised by previous surgeons. That is why autogenous bone has been used in reconstructive rhinoplasty.

Carter first described the use of rib for repairing osseous defects, and “Macomder and Dingman” later used iliac crest as an alternative. These two donor sites have a number of defects. Pneumothoraxes have been reported with rib grafts and both rib and iliac crest donor sites are associated with significant postoperative pain. Due to these limitations, the calvarium has received considerable attention as a source of osseous bulk.

The cranium has numerous superiorities as a donor site. These include being in the same operative field, as well as resulting in minimum visual scar or functional malformation. The inpatient hospitalization is shorter than in cases in which hip or rib grafts are used. Ultimately, membranous bone resorbs less than endochondral bone. The latter fact is perhaps the most important reason for use of calvarial grafts. These results have been confirmed clinically by several authors. Their results have found split calvarial grafts to be quite resilient to resorption when utilized in a variety of maxillofacial locations.

Malformations in the osteocartilaginous framework frequently met, incorporate saddle- nose, nasal tip ptosis, and nasal valve collapse. The use of split calvarial grafts in correcting of saddle-nose deformities has been previously announced. When multiple structural malformations exist, however, it would be advantageous to use a single grafting material that can be fashioned to specific dimensions. Cartilage is the most frequent material for this purpose.

Split calvarium (membrane) is less likely to be absorbed than the iliac crest (endochondral)[18,19]. Due to the calvarium being harvested from similar operative field and considerable postoperative pain followed by osteotomies, split calvarium is the implant of choice when bone is used for dorsal growth. Risks associated with calvarium harvesting include cranial cavity penetration, rupture of a major venous sinus, brain damage, and postoperative cranial depression[20,21].

The bone used in the nose can create an unbreakable structure. Although the implant is usually well tolerated and poorly absorbed, the abnormal nasal appearance and difficulty in shaping the implant make the calvarial bone a not-so-ideal implant. It is necessary to do the fixation well, so that the implant maintains its position and reduces the risk of absorption[22].

1.1.5 CHARACTERISTICS OF THE “IDEAL” IMPLANT

The ideal nasal implant does not exist. Despite the fact that some implant choices display most of the qualities of the ideal implant, no implant satisfies all requirements. The characteristics of the ideal nasal implant ought to be: economical, disposable, inert, not toxic or carcinogenic, sterilizable, carvable, easily obscured, supply volume and mechanical subvention. Additionally, the ideal implant should interact in favor of surrounding tissues, preserving its form over time, resist trauma, infection and extrusion, and abide easy to subtract.

Autografts indulge most requirements of the ideal nasal implant. Some of their numerous benefits; no disease transmission or biocompatibility issues, low rates of infection, resorption, rejection, and extrusion, favorable graft–host interactions, and minimal inflammatory response elicited.

Cartilage is the autologous tissue of choice for nasal reconstruction. Cartilaginous autografts are able to be harvested from the septum, concha, or rib. Cartilage can purvey both volume and structural support. It may be easily sliced, crushed, or molded to the coveted size and shape. Resorption rate is generally low.

Like cartilage, bone can be utilized for structural grafting. Limitations of bone grafts comprise their rigidity and susceptibility to fracture. Yet another drawback is the requirement for a prolonged period of immobilization to allow for graft fixation.

When bone grafting is utilized, the surgeon has several donor site options which entail calvarium, rib, and iliac crest. Calvarial bone is preferred for several reasons: it can be prepped in the same operative field, graft harvest imparts minimal donor site morbidity, and finally, calvarium provides membranous bone. Membranous bone is known for its superiority in grafting due to the fact that endochondral bone possesses a greater predilection for resorption. Drawbacks of calvarial grafts include rigidity, susceptibility to fracture, an unnatural feel, and a tendency to create a noticeable step-off. Also notable are the uncommon but possibly serious donor site complications of intracranial sequelae or brain injury.

For all of its relative constraints, endochondral bone can also be used in nasal reconstruction. It is dispensable for harvest from the rib or iliac crest. A noteworthy drawback of endochondral bone is the larger resorption compared to membranous bone.

Particular donor site morbidity of iliac crest grafting incorporates substantial donor site pain and diminished mobility postoperatively. These drawbacks have bordered the commerciality of iliac crest as a donor site. Today, iliac crest bone grafting is infrequently utilized in nasal reconstruction.

Homografts comprise another option for nasal grafting material. Irradiated rib cartilage and cadaveric dermal grafts have been utilized as nasal implants with consistent and dependable results for numerous years. Homografts are the materials of choice by some nasal surgeons. Rib cartilage that has been subjected to radiation is ingathered from cadavers and chiefly utilized for structural grafting. To eradicate potential pathogens, it is irradiated with 30 to 40 kGy of ionizing radiation. The benefits of irradiated rib cartilage include low infection and extrusion rates, minimum host immunogenic response, and no reports of disease transmission associated. Its restrictions subsume a susceptibility to warp over time and a variable resorption rate when used in the head and neck region. Low absorption rates have been mentioned on the incidence of nasal implantation. As previously described, for autologous rib cartilage grafting, to minimize the risk of warping, the perichondrium and outer cortex of rib should be subtracted and the technique of symmetric carving should be employed.

A noteworthy vantage of cadaveric dermal grafting includes its favorable safety and compatibility profiles. In the 15 years since it was presented, there have been no reports of graft rejection or infection transmission. The drawbacks of this material are its inability to provide structural support and its high resorption rate. Volume reduction of 30% to 80% at 1 year has been reported.

Autologous implants maintain the role of preferred material for nasal implantation. These autografts also possess constraints, however, including resorption, donor site morbidity, warping, increased operative time, and insufficient donor material.

The pore size of an implant affects tissue–graft interaction in two main ways: the potential for bacterial colonization and fibrovascular host tissue ingrowth. Bacteria can enter pores larger than 1 mm in diameter. When pores exceed the size of 100 mm, important host tissue ingrowth occurs, which is significant for the following reasons: infection control and implant consolidation. Moreover, it reduces dead voids and enables the carriage of inflammatory cells to contravene bacterial colonization and

possible infection. Additionally, implant migration or extrusion is diminished by tissue ingrowth, which stabilizes the implant with respect to the surrounding tissues.

Silicone has been the most frequently used solid facial implant in the last decades. It is used in the nose for soft-tissue enlargement but it cannot provide structural support.

Meshed implants comprise of several polymers that are disseminated with big empty voids. Meshed implants offer several benefits, such as ease of customization in size and shape. Unlike silicon, graft–tissue interaction is extensive. Host tissue ingrowth of the implant imparts stability and also diminishes infection. Polyamide mesh (Supramid) is one of the first meshed nasal implants. Nevertheless, with this material high rates of absorption have occurred, resulting in not being contemplated as a viable implant nasal vent anymore. Polyester mesh (Mersilene) is more resistant to the resorption seen with polyamide mesh.

Porous materials interdigitate sturdy synthetic polymer with voids. The relative proportion of empty space is generally smaller with porous implants in comparison to meshed implants. That is why, porous implants bridge the gap between solid and meshed materials. Implant porosity allows host tissue ingrowth to supply consistency with respect to surrounding tissues, but not so much ingrowth that implant subtraction is overly difficult.

Porous high-density polyethylene (PHDPE) (Medpor, Porex) is made with a fusion litigation at high temperature and pressure. Additionally, PHDPE has been used extensively both as a nasal implant and in other areas of the face for chin and malar enlargement and for orbital reconstruction. It is carvable and may be casted as preferred, after placing it in hot water. Once cooled, the implant maintains shape. In soft-tissue enlargement and structural countenance it is telling and secure, while bone absorption is minimal under-graft.

1.2 HOMOLOGOUS GRAFTS

Many reconstructive surgeons choose autologous materials as implants. However, difficult situations arise when collecting this tissue may be harmful to the patient, or the tissue is not large enough to correct the defect. Homografts are a different solution

that is viable. Also, alloplastic materials have been used successfully to enlarge the nose and be used as another alternative, less acceptable of course, compared to autografts.

Fresh or preserved cartilage homografts have been utilized in large quantities by nasal surgeons throughout this century[6]. Their usage has gradually diminished because of unpredictable behavior and progressive absorption or replacement by fibrous tissue. Enthusiasm is still present in some centers for irradiated cartilage homografts, but clinical and experimental reports have not been uniform in their support for the long- term applicability of this material.

Homologous bone, cartilage and skin grafts reduce the morbidity of the donor site, however significant absorption has been reported. Toriumi et al.[23], examined the long- term absorption rates of demineralized bone split rib implants. The average absorption rate after just 2 years was greater than 80%. The results obtained using homologous tissue may also be unpredictable. Over time, the surface structure of the implant material may change, causing deformation of the overlying soft tissue. Despite these deficiencies that may occur, irradiated cadaveric costal cartilage serves as a suitable substitute for autologous rib cartilage. Many things can be done in an effort to reduce the risk of warping and distortion. Gunter et al.[14] described the use of K-wire insertion into a grafted cartilage to prevent such changes over time.

1.2.1 SURGICAL TECHNIQUE

1.2.1.1 Columellar Strut

Through an open rhinoplasty approach, a soft-tissue pocket is dissected between the medial crura and the nasal spine. The nasal spine is removed with a rongeur. A hole is drilled just lateral to the maxillary midline, to a depth of 10 to 12 mm and lies parallel to and 2 to 3 mm inferior to the nasal floor; thereby avoiding the incisive foramen. A K-wire is inserted 25 mm into a soft silicone block and cut to leave 10 mm exposed. The block is carved into a 2x3x35 mm strut, and the exposed end of the K-wire is placed in the maxillary drill hole. The desired tip projection is assessed by advancing and suturing the medial crura to the strut. Any excess strut projecting anterior to the domes is trimmed, establishing the final strut length.

After harvesting the rib cartilage by sub-perichondrial dissection, gross carving of the graft is performed with no.10 blade. If only a columellar strut is needed, a floating rib is harvested. However, if a dorsal onlay graft is also required, then more cephalad ribs are selected. With the rib cartilage stabilized in the previously described jig, a longitudinal hole is drilled in the center of the graft with a smooth 0,028-in K-wire. The 0,028-in K-wire is replaced with a threaded 0,035-in wire, stopping 3 to 4 mm short of the distal end. The cartilage is carved to the proper final dimensions by the silicone strut as a template, and the exposed end of the K-wire is trimmed to 10 mm in length. The thickness of the strut is only enough to keep the K-wire from being exposed.

The finished strut is placed in the pocket between the medial crura, positioning the exposed end of the K-wire in the maxillary drill hole. Then the medial crura are sutured to the strut to establish the desired nasal tip projection, and the K-wire is bent at its junction with the strut to make the appropriate nasolabial angle. If a nasal dorsal deficiency is present, a dorsal onlay graft is placed, as described below. The skin is redraped, and dorsal height, tip projection, and tip rotation are assessed before closure.

1.2.1.2 Dorsal Nasal Graft

The nasal dorsum is undermined through an open rhinoplasty approach. The cartilaginous portion of the appropriate rib(s) is harvested. We initially used the ninth and tenth ribs in all patients. However, we now conceal the chest incision in women by utilizing a medial inframammary fold incision to harvest the sixth, seventh, and/or eighth ribs. After gross carving, the cartilage is centrally penetrated with a smooth 0,028-in K-wire, which is replaced with a threaded 0,035-in K-wire. The graft, which is carved to the same dimensions as the silicone sizer, is anatomically contoured to a canoe shape with the widest portion at the osteo-cartilaginous junction. The K-wire is trimmed flush with the end of the graft. The graft is sutured to the nasal dorsum at the septal angle and the superior margin of the upper lateral cartilages. Additional graft fixation is achieved with a smooth 0,028-in K-wire placed percutaneously through the graft into the nasal root. Prior placement of a columellar strut does not affect the positioning or fixation of the dorsal onlay graft. The percutaneous K-wire is removed with the external splint 1 week postoperatively.

1.2.1.3 Laboratory Study

A mean of 2,2 degrees of contortion was noted in the K-wires grafts compared to 8,9 degrees in control group, suggesting that inner consolidation of rib cartilage with K- wires minimizes twisting (p<0,001). Most warping occurred within the first quarter after sculpting, while minimal changes occurred after 5 days.

1.2.1.4 Clinical Study

Over a mean follow-up period of 13,5 months, graft warping was not observed in any patient. Good to excellent aesthetic results were reported in all patients, although one patient did experience mild displacement of a dorsal onlay graft at the radix. Extrusion of the K-wire through the palate occurred in three of the first nine columellar struts at 6 weeks, 6 months, and 9 months postoperatively. The extruded K-wires were removed in the office without difficulty and without compromise of the aesthetic results. This complication prompted an alteration in surgical technique. Specifically, a threaded 0,035-in K-wire replaced the smooth one previously utilized, the maxillary drill hole was placed parallel to the nasal floor, and the columellar K-wire was bent at the graft- maxillary interface. These changes resulted in more secure K-wire fixation and no subsequent K-wire extrusions. No extrusions occurred in the dorsal nasal grafts, but one graft required removal at 6 months due to postoperative infection with partial graft resorption.

Three patients with columellar strut grafts complained of postoperative pain and numbness of the anterior palatal mucosa in the central incisor area. In two patients, the K-wire was removed at 15 and 18 months, respectively, resulting in complete relief of the symptoms. In the remaining patient, the symptoms resolved spontaneously over a 6-month period. One patient underwent root canal of a central incisor at 2 months postoperatively, presumably secondary to misdirection of the maxillary drill hole.

1.2.2 IRRADIATED COSTAL CARTILAGE

Shaving equal amounts of cartilage from all surfaces of a graft can reduce the risk of graft deformity and distortion. All perichondrium should be removed to further reduce

the chance of cartilage deformity. Many surgeons have used irradiated costal cartilage grafts successfully for dorsal nasal augmentation[24-26].

Irradiated costal cartilage (ICC) grafts were first used by Dingman and Grabb in 1961. Successful long-term results in more than 600 patients have been published since. Similar results with minimal absorption (0–1.4%) have been published over the years by numerous authors. In spite of the initial reports, several authors, mentioned a high warping potential, even when the carving was performed according to Gibson’s principle of balanced cross-sections. This resulted in confusion about, and possibly underutilization of this graft source.

Open approach was utilized in 39 patients (60%). Homologous costal cartilage allografts were procured from prescreened donors, dehydrated, sterilized by γ-rays, rehydrated in 0.9% NaCl and packed in vacuum-sealed bags. Grafts of choice were 5 or 7 cm, while solely the rib core parts were utilized in order to stunt contorting. All the perichondrium was removed and the graft was soaked in sterile saline for half an hour before shaping. Shaping was done by scalpel carving. Ultimately, the graft was left for an additional 10 min in saline in order to audit for any twanging twists. Any acutely warped cartilage was then either reshaped or discarded, as necessary.

Grafts were used in several shapes: elliptical dorsal grafts, hearth-shaped tip grafts, spreader grafts, segments for septum reconstruction, L-shaped profile grafts, leaf- shaped lower lateral cartilage grafts, chopped-diced grafts, batten grafts for the columella and septum, butterfly grafts to support upper lateral cartilages, and smaller leaflets for nasolabial angle augmentation. Spreader, batten, and tip grafts were rectified by 5/0 prolene sutures. Dorsal grafts were tied up by only a snugly fitting pouch and plaster cast.

The mean value of the follow-up period was 33 months (range, 6–49 months) in the 59 patients that could be followed. Serial photographs were taken at one, three and six months and then every six months to assess the amount of any possible resorption and warping. No resorption that affected the success or outcome of the operation was recorded in any of the patients. Both aesthetic and functional results were more than satisfactory, and no further surgical procedure was required in any but one of the patients. Minor complications occurred in three other patients (4.6%). No infections were presented.

ICC constitutes a trully reliable and versatile material for septorhinoplasty. It could be utilized for any type of cartilage nasal malformation, ranging from a lamellar dome enlargement graft to a thick dorsal graft for saddle deformity. It was easy to manipulate and shape and permitted suture lodgement for secure fixation. None of the dreadful complications presented to any significant extent: there was zero resorption and little warping (1.3%) or extrusion (1.3%). This was in concordance with previously published data.

Several variables have been postulated to affect the resorption rate of ICC. Raised resorption rates in irradiated cartilage compared to thiomerosal-preserved cartilage resulted in proposing that technique and irradiation duration may sway graft absorption. It seems that irradiation somehow obstructs infiltration of the graft by viable host cells. Another factor is the infection present, which may motivate total resorption if it is not treated properly. In a reevaluation study it was highlighted that ICC used in facial reconstruction was successful at first, but resorbed significantly when follow-up periods were extended from 5 to 16 years. Fibrous tissue substitution of the resorbed cartilage affects the final success of rebuilding as proportionate fibrosis might retain the cosmetic and functional results, particularly in the nose. This latter finding might explain the discrepancy between the long-term results of Dingman and Grabb and other authors. In fact, the onset of resorption in cartilage after many years, is unexpected, and results of animal studies point out that resorption already presents within three to four weeks of implantation. It should be highlighted that resorption is not a specific problem related to ICC, as cartilage autografts and autogenous bone grafts utilized in nasal reconstruction do also have a variable resorption rate. Similar long-term resorption of septal cartilage does occur following septoplasty, possibly related to trauma/ischemia- induced alterations in the life cycle of chondrocytes. Although the follow-up period is relatively short, no resorption was observed.

Warping is the second biggest problem related to costal cartilage utilization in rhinoplasty. The incidence percentage of warping differentiates within the literature, from 0 to 14.8%. Clinically, it has been postulated that ICC warps less than autogenous costal cartilage and warping happens between 10 and 21 days post-implantation. Nevertheless, it was recently denoted that radiation has no effect on the warping potential of costal cartilage. Warping is presumably most related to the cartilage carving technique.

Warping could be totally eliminated by one of the following manners:

(1) Total perichondrium removal,

(2) Grafts carving from the straightest segment of the rib,

(3) Use of only the core part of the rib and discarding the peripheral struts,

(4) Shaving the segment in a balanced fashion while thinning,

(5) Moisting the prepared segment in saline for 10 min to check for an acute warping before implantation, and

(6) Preparing and placing the graft in a manner that ensures visual compensation should any warping take place.

The costal cartilage allografts were very resistant to infection and extrusion, unlike all other non-biologic alloplastic materials used in rhinoplasty. This is a blatant merit as such complications with high-density porous polyethylene or silicone implants are catastrophic and uneasy to manipulate in the nose. Single exposure was related to an over-long dorsal graft with a spiculate extremity that perforated the mucosa at the membranous ration of the columella. Therefore, it seems that complications with ICC are less dramatic and easier to handle.

Additionally, contemporary septoplasty commonly requires the use of a wide range of grafts, forcing surgeons to find a generous source of cartilage. Irradiated costal cartilage allografts may be a non-invasive way of obtaining cartilage grafts when autogenous septal cartilage is either insufficient or inadequate. It provides a grafting material that is safe and versatile.

Use of this material should be restricted to the dorsum. Significant absorption appears to result from implantation in the mobile nasal tip[27]. Cadaveric rib cartilage comes from donors who must meet the same criteria as organ donation, screening for Venereal disease research laboratory (VDRL), hepatitis B, human immunodeficiency virus (HIV), tuberculosis, and slow virus testing. The selected donor rib is then exposed to 60 kGy γ-rays to eradicate cellular and viral pathogens. The reason these implants are well tolerated is because their relative acellular makeup triggers a minimal immune response in the transplant patient. Cadaveric rib transplants are ideal for elderly patients

who require minimal operating time and morbidity at the donor site. In addition, the rib of an elderly patient can be calcified, making it difficult to form. The success of implantation and maintenance of the implant volume appears to be related to the implant site. The nasal dorsum seems to tolerate implantation well, most likely due to its relative immobility[24,26].

Resorption rates of ICC might also alternate according to the recipient site. Grafts lodged in sites that exposed to regular muscular activity or constant pressure appear to be absorbed earlier. In this respect, the nasal dorsum consists of a fine location while the columella does not.

Rib cartilage, whether autologous or homologous, must therefore be maintained for dorsal nasal growth where it has the best chance of maintaining its volume over time. Long-term studies are needed to more accurately determine the absorption rates of these grafts.

1.2.3 ACELLULAR DERMIS (ALLODERM)

Acellular dermis (AlloDerm) is an ideal camouflage material, the use of which is intended for skin graft replacement in burn victims[28]. Cicatrix and shriveling are the main long-term aftermath of meshed split-thickness autografting for full-thickness skin impairment. In dermis absence, ripe fibroblasts exude collagen in the differentiated impairment pattern. The use of an acellular dermal matrix processed from human allograft skin (AlloDerm) in the treatment of a full-thickness burn injury is illustrated. The proceeding technique leads to an acellular dermal matrix with canonical collagen organization and bundling and an intact basement membrane complex. In these patients, AlloDerm exhibited a high percentage uptake and supported an overlying meshed split- thickness skin autograft, simultaneously applied. The clinical observations of the uptake were confirmed with histological and evaluation of biopsies with electron microscopy which showed host cell infiltration and neovascularization of the AlloDerm. No specific immune response was observed, either by histology or by lymphocyte proliferation assay. By providing a dermal replacement, the grafted dermal matrix allowed utilization of a thin, widely meshed autograft from the donor site, without the unwanted scarring and contracture at the wound site frequently resulting in

this technique. If effect, this approach would markedly diminish the donor skin quantity required for split-thickness autografts in full-thickness burn injuries.

Burn therapy is vastly dependable in fulfilling the permanent skin replacement in extensive full- and deep partial-thickness impairments. The procedure of using a meshed split-thickness skin graft (STSG) accomplishes wound closure, but is commonly related to scarring and contracture of the wound site. Moreover, trauma may result from a plague yielding at the donor site. The scarring and contracture degree of the grafted wound correlates inversely with the dermis quantity delivered in a STSG. However, harvesting a thicker STSG results in enlarged morbidity at the donor site. Moreover, patients with massive bums have limited donor sites; therefore, dermal transplantation ought to be retained to a minimum to allow for repeated harvesting and hasten closure.

The contingent use of allograft donor skin as an abiding skin replacement in full- thickness burns is narrowed by its immunogenic properties. Allograft skin grafts will routinely take to a full-thickness wound, but are finally rejected. Immune response to allograft is directed vastly contrary to the epidermis cells and the endothelial and fibroblast cells in the dermis. The non-cellular components of dermis, consisting mostly of extracellular matrix proteins and collagen, has been shewed to be relatively nonimmunogenic. The complexity of subtracting the immunogenic cells from the nonimmunogenic dermis of allograft skin has previously limited its use to provisional coverage of full-thickness burns.

The early clinical and histological observations of a processed acellular dermal matrix (Allo-Derm) grafted simultaneously with an overlying meshed STSG in two patients is being described. The acellular dermal matrix was produced from fresh human cadaver skin by a carefully controlled process that subtracted the epidermis and the cells from the dermis without changing the extracellular matrix structure and the basement membrane complex. The AlloDerm was intended to provide a nonimmunogenic template to enlarge the dermal component of a widely meshed STSG grafted to an excised full-thickness burn.

Furthermore, one of the steps used in the AlloDerm process has been displayed, via an independent contract laboratory, to inactivate a concentrated suspension of HIV. While not ensuring viral sterility, this stands for an added safeguard.

A homogenized extract of the AlloDerm graft was tested for its capacity to stimulate lymphocytes isolated from the patient at day 0 and day 60 following grafting. Both the test and the grafted AlloDerm were from the same donor. Stimulation was evaluated by incorporation of [3H]thymidine. Positive controls such as phytohaemagglutinin and pokeweed mitogen were utilized. No stimulation of sensitized lymphocytes has been detected for any grafted patient.

Conclusively, the need to replace skin lost through injury is of utmost importance in extensively burned patients with limited donor site capacity. Skin can be procured from deceased donors, however, the inevitable rejection of allogeneic skin has narrowed its major use to short-term coverage of burn wounds. The allograft ought to be changed every few days to prevent the development of a rejection response and subsequent necrosis of the wound bed.

It has been demonstrated that a grafted acellular dermal matrix (AlloDerm) shall support fibroblast infiltration, neovascularization and epithelialization in the absence of an inflammatory response. This approach has given attention on the matrix rather than the viable cell components of skin as the major dermal deficit in full-thickness skin loss. The immunological complications related to grafting dermis that includes allogeneic cells may be bypassed by utilizing an acellular matrix scaffolding into which the patient’s own cells can migrate.

Findings indicate that supplemental dermis commissioned by the acellular allograft dermal matrix can eventually meliorate the healing characteristics of a meshed autograft. The clinically pertinent implication is the possibility for closure of a widely burned patient using minimum autograft skin, although concluding in a skin cover whose quality is superior to that typically gained with extensively meshed, thin autografts with their tendency for scarring and contracture.

In the case of rhinoplasty, this material is used especially to cover the dorsal nasal abnormalities in the patient the thin-skinned rhinoplasty. Its special advantage is its immediate availability and the fact that it is well tolerated. There are no long-term data on the implant absorption process. If, on the other hand, there is partial absorption, it can be replaced with a thin layer of scar tissue to maintain a smooth nasal dorsum1. AlloDerm can alternatively be used for the fascia or perichondrium to cover soft tissues and in addition can be used as an adjunct in mucosal regeneration procedures to close

perforations in the diaphragm. In addition, AlloDerm combines well with cartilage or bone grafts to create a smooth dorsal nasal contour in patients with thin skin.

1.3 ALLOPLASTIC IMPLANTS

The implantation of synthetic material in the nose must be done with special care. A major risk factor for any nasal implant placement is early postoperative or long-term insufficiency. In general, any synthetic material used to reconstruct the nose should be intended for the relatively immobile dorsal dorsum and should be considered as a final solution after examination of autologous and homologous implants. Costantino[29] outlined four concepts to consider when designing an alloplastic implant: porosity, particle formation, elemental makeup, and location.

Implantable materials have pores of various sizes and can range from less than 20 μm to several hundred μm. Pores allow tissue growth. The larger the pore, the faster the growth. Pores also allow bacteria to enter. However, this is not necessarily a problem, especially if the pores are large enough to allow macrophages to enter (50 μm)[30].

Porous hydroxyapatite (IP200), created by conversion of the Poritidae porites exoskeleton, has pores averaging 230 pm and pore interconnections averaging 190 pm in diameter. Furthermore, colonial reef building coral of the family Poritidue are noteworthy for the highly interconnected porosity of their exoskeletons. The microstructure of the hexacorallium genus porites seems to be likely to interstitial cortical bone. The sturdy carcass and pore network both constitute continuous and interconnected domains. The solid components of the implant framework average 75 μm and their interconnections average 95 μm. The pores average 230 μm diameter and their interconnections average 190 μm diameter. A lookalike between implant pore diameter and the average human osteon diameter of 190 μm is highlighted. The solid volume fraction of implant is 33% and its pore volume fraction is 67%. In human cortical bone, approximately two thirds is osteonic and one third is interstitial with a cement line forming a canalicular barrier between the two components. A similarity between implant pore volume fraction and cortex osteonic volume fraction is additionally highlighted.

The mean width of IP200 (75.9 μm), the implant framework, approximates the 75-95 μm range reported in the literature. If the mean width of bone (78.5 μm) is idealized as a hemiosteon, and the mean width of soft tissue (27.1 μm) is idealized as a Haversian canal, a mean osteon diameter of 184.1 μm can be estimated, which is approximately the normal diameter of secondary osteons. The mean bone thickness at 3 months was 74 μm, for an average regenerative apposition rate of 0.8 μm/day. When a lag phase is permitted, this datum is compatible with appositional rates of 1.0 - 1.4 μm /day reported in normal canine cortical bone remodeling.

Quite large pores (> 100 μm) theoretically allow the growth of bone and fibrous tissue, which further stabilizes the implant. Solid silicone implants, for example, have no pores and therefore are not easily penetrated by bacteria and tissue growth. Stabilization therefore depends on capsule formation and infection can occur at any time. An unfortunate continuation of silicone rubber implants can also be the deformation of the overlying tissues, as a consequence of the formation of a thick capsule.

A major concern for implants placed in flexible areas is the formation of particles. Some particulate materials from 20 to 60 μm that are relatively inert can phagocytose. However, ingestion leads to the death of macrophages and subsequent release of several inflammatory agents, which are responsible for chronic inflammation. Particles > 60 μm in diameter may not be phagocytosed. Immunocomplex formation may also be a factor contributing to a significant immune response in the region.

There is no perfect implant. New biomaterials continue to be invented and researched in order to meet the strict criteria necessary to facilitate a surgeon using implants. An implant must be inactive and not cause inflammation or allergy, be non-carcinogenic, have mechanical strength, be easily modified, be configurable and be sterile. The preferred materials are those that resemble human tissue next to the proposed implant site[29]. For example, silicone is similar to carbon, which is one of the body's main constituents. For this reason, silicone has been widely used as an implant due to its relative non-reactivity.

Success depends on the location of the implants. Regardless of biocompatibility, the agile areas of the body are vulnerable to a higher risk of failure. The tip of the nose should be taken as a mobile unit and therefore should not undergo alloplastic implantation. The dorsum of the nose and premaxilla are considered relatively stable

areas and are more suitable for alloplast enhancement. It is often difficult to have a successful dorsum transplant, especially if the implant is not covered by a sufficient amount of skin and soft tissue, which provides an adequate blood supply to the area.

Alloplastic nasal implants are divided into several categories: polymers, metal, ceramic and injectable. Polymers are the largest category. All the above materials have been used with a different outcome on the nose. However, alloplastic implants are considered to be the third choice after autologous or homologous implants.

1.4 MATERIALS

A polymer is composed of large chains of subunits, which are repeated. Carbon, hydrogen and oxygen are the main ingredients, but there are exceptions. The length of the chains, as well as the number of intersections between them, are related to the stability of the material. If the material is stable enough, then it is less likely to break[31]. The best known polymers used as nasal implants are silicone, polytetrafluoroethylene (PTFE) and polyethylenes.

1.4.1 SILICONE

Silicone refers to a group of polymers, the basic element of which is silicon. Silica,

SiO2, when polymerized with methyl groups, forms silicone. The final shape of the material is affected by the extension of the length and the intersection of the polymer. The result is the progressive formation of silicone gel and silicone rubber. The shape of the material plays an important role in the acceptance by the host tissues. Silicone rubber has no pores and therefore does not form particles. The primary use of silicone gel is for breast augmentation surgery, but also to improve the nasal contour in cured form[32].

Silastic Medical Adhesive Silicone Type A is a translucent, non-flowing, soft silicone paste for bonding silicone elastomer to itself and other synthetics. It is now usual to utilize custom-made soft silicone elastomer implants made from the curing of silicone adhesive spread on a nasal cast model. This model is obtained from an alginate

impression of the patient’s nose. These implants have a ventral surface of the exact concave contour conforming to the convex surface of the patient’s nose.

The litigation of making silicone elastomer nasal implants out of silicone adhesive is pretty simple. These implants are formed from a nasal cast model acquired from an alginate impression of the nose. The two preliminary steps in making a nasal implant are taking the impression and making the cast.

Custom-made nasal implants of soft silicone elastomer types I and II are used for identical aesthetic purposes as primary enlargement rhinoplasty with huge success. The usage of these implants is desirable in most patients who want increased dorsal profile and/or tip projection. The preoperative considerations for using these implants are the choice of the patients and the implant size. Initially, this type of implant can be practiced on patients whose skin is fairly thinned, particularly in the lobule. Based on experience in Asian nose enlargement with similar, fairly thinned lobular skin texture as that of Caucasians, there were no cases of implant extrusion if these soft implants were small enough to not produce excessive tension. Nevertheless, for postoperative and posttraumatic nasal malformations, due to scarring, reduced vascularity, and skin thinning, the implant should be lidded with autogenous of allogeneic fascia. Moreover, the implant size should be small enough to ameliorate the dorsum, specifically the tip. That is due to the fact that there always exists the possibility of the subcutaneous tissue thinning following implantation.

Custom-made nasal implants of soft silicone elastomer types I and II have the following advantages: Initially, the ventral surface of the implant may be contoured accurately from the patient’s own nasal model so that it blends in smoothly with the various configurations of the patient’s existing nasal framework, specifically for subtle contour nasal deficits. Secondly, implants avoid having a prototype nose for everyone, which happens commonly after nasal enlargement with commercially dispensable prefabricated silicone implants that have the same configuration of the dorsal profile. Third, the combination of the following two factors – an exact concave undersurface of the implant adapting to the nose and use of porous sheet or perforating the implant with multiple holes to allow for tissue ingrowth and subsequent periosteal fixation – stabilizes the implant in the midline of the nose, thus preventing malposition and extrusion. Ultimately, there is no need for trimming of these custom-made implants at

the time of surgery. As a result, operation time is diminished to minimum. These custom-made implants are also more cost-effective.

When nasal enlargement is perforated with implants fashioned from a piece of solid silicone block or commercially disposable prefabricated implants, the accurate sculpturing of the ventral surface of the implant in order to conform to the convex contour of the nose is commonly hard to reach, raising the possibility for malposition and extrusion.

Silicone rubber or Silastic is relatively unlikely to elicit an inflammatory response from the recipient, because it has no pores and is quite stable. This material has been widely used for back, edge and premaxillary augmentation[22,33-36]. The medical grade silicones are almost the unique alloplastic materials acceptable as a resident subdermal implant in the areas where softness and lack of reaction are quintessential.

The major reason for the use of the medical grade silicones is their ability to be implanted sub-dermally without causing intolerable foreign body reactions. An important quality for an implant material and one which is often overlooked, is its capability to resist attack by the body. The body is capable of disintegrating almost any implanted organic material. Some plastics can withstand the body for long periods, but few, if any, are completely impervious to such attack. At present, there is no indication that the body can break down a silicone. There is no known organism, plant or animal, macro- or microscopic, that can metabolize a silicone. There are indications that phagocytes can engulf tiny amounts of silicone fluid injected into the tissues and carry them away from the injection site; but there is no indication that any metabolism of these droplets occurs. There is no evidence that medical grade silicone rubber is susceptible to phagocytic attack.

The applications of silicones to maxillofacial surgery are multitudinous. Silicone rubber is used for straightening the dorsum of the nose and for building out the chin in cases of micrognathia. By using medical grade silicone rubber adhesive, it is possible to adhere Dacron cloth to the chin implant. This cloth then acts as a stroma for tissue ingrowth, holding the prosthesis in place.

Silicone rubber blocks and thin films are used, with and without adhered Dacron, for repair of blow-out fractures of the orbit. Silicone rubber ear armatures are dispensable, eliminating the problems involved in obtaining and shaping rib cartilage. Erosion

through the skin is, of course, no better with a silicone rubber ear prosthesis than with one of rib cartilage. It should be borne in mind, however, that an exposed silicone rubber implant does not necessarily mean the loss of the implant. There are several reports of such exposures, due to surgical or traumatic misadventures, which have been followed by healing without problems, sometimes even spontaneously. This has occurred in many areas of the body. Such healing does not always occur, of course, but the reports are frequent enough to warrant conservative optimism when problems of the kind are encountered.

Medical grade silicone rubber burr hole covers are available to prevent the sunken appearance of skin over these areas. Whole or partial mandibular prostheses made of hard silicone rubber have been researched. Some of these have been used merely to hold the tissues until the bone may be replaced; others have been more resident. They have been made with and without metallic support. Moreover, silicone rubber has been utilized to prevent the reformation of ankylosis of the tempo-mandibular joint, being subtracted from the joint after all healing had happened.

Room temperature vulcanizing medical grade silicone rubber can be used by the surgeon to create custom made implants for repair of forehead and zygoma depression and for making obturators for cleft palates. In the latter case the catalyzed but still liquid material is simply placed into the cleft and permitted to set up, which is a matter of a few minutes. It has also been used to make external prostheses for replacement of missing ears, noses, large facial areas, etc. Recently a stronger and more translucent material has been developed specifically for external maxillofacial prostheses and is being tested by a number of prosthetists. A pressure sensitive silicone adhesive is used to adhere these to the skin.

Finally, the use of silicone implants for the correction of velopharyngeal insufficiencies has been reported. Several forms of the silicones have been used for this purpose, including carved blocks, shreds and the injection of a soft room-temperature- vulcanizing silicone rubber.

Their apparently successful use in extended contact with these varied tissues focused the attention of many surgeons on the fact that perhaps a material had finally been found that had tissue compatibility, and which was soft and rubbery enough to be used as a soft tissue replacement.

The reduced possibility of bacterial colonization is due to the non-porous composition of the silicone, but on the other hand it does not allow the growth of tissues. This underdevelopment can lead to displacement of the implant and capsule formation around the implant. However, if the capsule is infiltrated by bacteria, it prevents the penetration of antibiotics and thus the implant may be deformed. The risk of graft rejection is real and it has been reported that it can occur up to 20 years after implantation[37-39].

The early prostheses for enlargement rhinoplasty were made of excessively hard materials such as ivory. Other materials were introduced afterwards, such as acrylic resin, silicone and silicone rubber. Unfortunately, these compounds were either too hard or too soft: it was often technically difficult to fashion the implant to the adequate shape and to obtain a good fit of the prosthesis over the nasal bones. The operations could also be time-consuming: for this reason attempts were made to pre-construct I- and L- shaped implants which could be easily adjusted by trimming and several models are now commercially dispensable. The surgical results were commonly unpredictable and far too many of these implants extruded themselves or had to be subtracted as a set procedure for various reasons such as infection, undue mobility or even fragmentation.

Anatomically speaking, the nose can be separated into various parts: the root, tip, dorsum columella and columellar base. The combination and relationship of skin, muscle, bone and cartilage give each segment a different degree of stretch and movement. For this reason, a prosthesis that is uniformly hard might be just as unwanted as one that is uniformly soft. Accordingly, and in order to minimize the risk of extrusion, there was a new type of nasal prosthesis developed, that incorporates surgical silicone rubber of varying degrees of hardness. This is disposable in 3 different models.

Type I

In which only the tip is made of soft silicone rubber the rest being of harder silicone.

Type II

In which both the tip and the dorsum are made of soft silicone rubber.

Type III

In which almost the whole implant is made of soft silicone rubber, with the exception of a small segment of harder silicone over the root of the nose.

These implants have a curved dorsal outline (in cross section view) that permits the prosthesis to lie firmly over the nasal bones. The lower end of the columellar strut has an oval-shaped ball of soft silicone that can be inserted into the depressor septi muscle to augment the nasolabial angle or alternatively may be subtracted to give support in patients with a long columella. The prosthesis is dispensable in a variety of sizes. If required, the columella section of the L-shaped implant may be trimmed away and the prosthesis is then converted into a simple I-shaped bridge line implant.

Indications for Choice of Implant Type

Type I

This type is the most effective for treatment of the conventional saddle nose. Only the tissues over the dorsum of the nose are lifted and the internal pressure created is absorbed by the softness of the prosthesis in order to procreate a natural looking tip. The same design of prosthesis can be utilized to lift only the nasal tip. For correction of nasal distortion due to a cleft lip, the ball of an L-shaped prosthesis may be inserted into the depressor septi nasi muscle to raise the nasolabial angle and elevate the nose tip.

Type II

This type in which the tip and dorsum of the implant are soft may be used in cases where there is scar tissue over the tip or dorsum of the nose, following a fractured nasal bone or disfigurement after a disastrous rhinoplasty. In such cases the capability of the scarred skin to stretch is very low, so that any implant will inevitably rise the internal pressures in the undermined tissues: but a soft prosthesis may resorb pressure and blocks disfigurement and extrusion of the implant.

Type III

This type is particularly useful in correcting the convex nose (American Indian nose) or hump nose when a natural well-balanced nose can be created without resorting to an osteotomy.

Selection of the correct I- or L-shaped prosthesis, according to its structural design is quintessential before operation using profile photographs and xero-radiographs to show the nasal bones, cartilaginous dorsum, alar cartilages, nasolabial angle, nose size and general configuration. If the correct type and design of prosthesis is chosen, an anatomically natural-looking nose may be achieved utilizing a relatively simple and safe surgical technique.

Silicone is commonly used for combined dorsum and tip augmentation, and has been used extensively for rhinoplasty in the Asian race[36]. Of the many forms of aesthetic surgery, augmentation rhinoplasty generates the most interest for Japanese surgeons, since a Roman nose signifies a beautiful face in Japan. This sense of beauty has necessarily encouraged them to develop methods and implants that generally have led to satisfactory results.

However, in the course of all these developments, it is inevitable that some complications can arise postoperatively. Considering that the complications are not only common, but also form the fundamental problems in enlargement rhinoplasty with foreign implants, corresponding techniques in their treatment will be expanded as the manual of nasal complications from implants is added to by other authors in the future.

The advantage of silicone rubber is that it is easily carvable and autoclavable. The method of inserting the silicone depends on its use. Patients should be aware of the risks involved with these implants. However, solid silicone does not belong to the same category as breast implant gel, but is an ideal material for chin augmentation. The silicone used in Asian patients undergoing augmentation rhinoplasty has been crowned with success. These patients, due to thicker skin, can better support an alloplastic implant than patients with thinner skin. However, if possible, it is preferable to use autologous or homologous materials.

1.4.2 POLYTETRAFLUOROETHYLENE

The most notable PTFE implant materials are Teflon, Proplast, and Gore-Tex (most widely used PTFE nose implant material), all of which consist of fluorine–carbon polymers. In spite of the absence of fluorine or fluorinelike substances in the body, the polymer bond is very strong and therefore stable.

1.4.2.1 PROPLAST

Proplast is a black-colored, fairly rigid and easily visible through thin skin implant material, making its use impractical in dorsal nasal augmentation[40,41]. Proplast was produced as a low modulus stabilization interface for prosthetic reconstruction and exhibits the following features:

1. Biocompatibility as conferred by in vitro and in vivo testing of organic and inorganic ingredients.

2. Appropriate porosity between 70 and 90 % volume, pore size ranging from 100 to 500 μm, and dendritic pore interconnections greater than 200 μm in diameter to accommodate rapid ingrowth of tissue throughout

3. Resiliency and low modulus for uniform and smooth transfer of load stress between prosthesis and surrounding and ingrown tissues.

Proplast is procreated from polytetrafluoroethylene (Teflon) and vitreous or glassy carbon fiber. The gross physical appearance is that of resilient sponge felt. Chemical and thermal stability permits firm fusion of 0.5 to 5 mm coatings to metallic prostheses. A coated Proplast prosthesis, or bulk material itself, can be sterilized by routine steam autoclaving. Proplast materials were initially estimated after plugs had been implanted in canine long bones, canine mandibular alveolar ridges, and primate alveolar ridges. Dense mature collagen was found throughout the entire substance of bony plugs and alveolar ridge enlargements by routine histologic examination from 12 weeks to 1 year after implantation.

The treatment given with endosseous blade vents was judged to be successful 12 to 48 months postoperatively. Reasons for failure; lack of initial stabilization of the implant, operative errors, and inability to obtain adequate slot depth. In terms of design, three

types of mandibular Proplast blade-vent implant were used: prototype, design No. 1, and design No. 2. Prototype Proplast blades consisted of various commercial blades coated with Proplast. The coating was vulnerable to shearing and/or compression at the time of blade placement. One of the three cases treated with this design was judged to be successful 36 months postoperatively.

Design No. 1 was constructed so that Proplast coating was inset within the body of the blade and protected from shearing by a rigid metallic framework (AISI 316 L stainless steel). The buccolingual width of the blade was approximately 3 mm, non-tapering. In most instances, looseness prevailed at the time of operation, resulting in early failure of the implant. In successful cases, mobility diminished during the first few postoperative weeks as ingrowth of tissue and subsequent calcification occurred in the pores of the Proplast. Three of seven cases were considered to be successful 30 months postoperatively. Splinting was perforated with all implants of the No. 1 design to increase implant stability but proved unhelpful.

Design No. 2 was instituted as a result of undesirable thickness (3 mm) and lack of tapering and initial stability of design No. 1. Total buccolingual width of design No. 2 was 2 mm, with superior-inferior tapering. Highly polished neck and head, a longer neck, and rounded margins were insignificant changes. Four patients with implants of design No. 2 have sufficient functionality 12-21 months post-operatively.

Temporomandibular prosthesis is the eldest clinical application of Proplast utilized as a porous coating material. Nine cases of temporomandibular joint disease were in necessity of surgical reconstruction. In all instances, reconstruction was performed through a Proplast-coated ticonium prosthesis. In seven cases, ankylosis was involved, and in six of them the condition was bilateral.

Proplast II is composed of PTFE linked to aluminum oxide fibers and hydroxyapatite, to give it a white color and to allow for bone compatibility, respectively[42]. Proplast II entails greater rigidity and permeability compared to Proplast, permitting raised tissue ingrowth. Raised porosity might as well be due to its fragmentation torque and severe inflammatory reactions when subjected to shearing-type forces as shown with substitution of the temporomandibular joint (TMJ)[43-52].

Polytetrafluoroethylene (PTFE) implants, marketed as Proplast-Teflon interpositional implants, were extensively utilized for reconstruction of the temporomandibular joint

(TMJ) after meniscectomy. The aim of this alloplastic material was to interpose a stable material between the condyle and the fossa to maintain vertical dimension and to supply a barrier to adhesions and ankylosis. Since its widespread use in the early and mid-80s PTFE implants have been subtracted from the market because of severe bony erosion of both fossa and condyle. Multiple cases have been reported showing the severity of the erosive response as a result of an exuberant foreign body inflammatory reaction. Severe bone erosion within the temporomandibular joint reconstructed with polytetrafluoroethylene implants is a well-recognized phenomenon. Although erosion into the middle cranial fossa has been stated, this is a report of a case of cerebrospinal fluid leak noted at the time of PTFE implant subtraction and its subsequent management. Perforation and reconstruction of the contralateral fossa is reported as well. The contralateral joint also demonstrated a large perforation of the fossa but without dural violation. Maxillofacial surgeons ought to be prepared to reconstruct the TMJ at the time of subtraction of the implant material and the surrounding reactive tissue and carry out bony reconstruction with autogenous bone as well as to manage violation of the dura mater of the temporal lobe. Neurosurgical consultation is of necessity.

A case of bilateral, large glenoid fossa perforations secondary to a chronic inflammatory reaction to PTFE (Proplast-Teflon) implants in TMJs is stated. On one side, a CSF leak was encountered. Management of it with a temporalis myofascial flap and resorbable gelatin sponge is reported. The contralateral perforation was managed by autogenous bone grafts of the fossa. The surgeon and the patient must be prepared for the possibility of such problems associated with subtraction of these implants and for the reconstruction of soft tissue as well as bone that may be imperative.

The surgical management of internal derangements involving the temporomandibular joint (TMJ) involves simple meniscectomy, meniscus repair and repositioning, and the insertion of either alloplastic or autogenous implants designed to work as disk prostheses. Alloplastic implants can either be resident or extractable. Alloplastic implants composed of a laminate of Proplast with nonporous Teflon, silicone, and Silastic have been used for permanent TMJ implants. The imaging results (conventional radiography, tomography, Computed Tomography, and Magnetic Resonance) of 34 joints were studied, that were operated on later with failed, permanent Proplast implants, and the findings with pathologic data in each case were correlated.

Patients chosen where those who had undergone temporomandibular meniscectomy and interpositional arthroplasty with resident Proplast-Teflon implants. The implants had been in place for 4-54 months. Clinical indications for postoperative imaging involved restricted joint motion, joint pain , bothersome joint noises (crepitus) during movement, preauricular swelling, regional lymphadenopathy, malocclusion either acquired or altered since implant surgery, and clinically evident facial deformity. MRI was performed. Closed-mouth sagittal MR projections, 500-800/20/2 (TR/TE/excitations), were produced with a 3-mm slice thickness, 1-mm interspace gap, 256 x 256 matrix, and 12-cm field of view. Coronal images (Time of Repetition = 500- 800) were obtained when intraarticular soft-tissue masses and bony destruction or findings suggesting avascular necrosis of the mandibular condyle were observed on sagittal views. In some cases, there was a need of a study with unenhanced, thin-section (1 .5 x 1 .5 mm thick), axial CT followed by generation of three-dimensional images and mandibular disarticulation for viewing of the condylar changes. The clinical indications for imaging were made disposable to the radiologist interpreting the imaging studies.

Surgical implant retrieval, involving joint debridement and resection of granulatomous tissue and devitalized bone, was perforated in all cases. The mandibular condyles were inspected for areas of articular cartilage erosion, osseous destruction, granulomatous ingrowth into the marrow space, and articular surface collapse. Devitalized bone and granulomatous tissue were subtracted and submitted for routine histology. Bids to ablate the granulomatous tissue margins when direct condylar and/or temporal bone infiltration by the granuloma occurred, were performed. Augmented regional lymph nodes were biopsied and submitted for histology.

Radiographic findings involved side-to-side asymmetry in mandibular condyle size and shape, condylar malformation in previously operated joints, and deviation of the chin toward an implant-containing joint. Tomography assured the presence of abnormal condylar morphology in all joints containing Proplast implants. Condylar findings, observed in various combinations within the same joints, involved focal articular surface erosions, raised radiographic density or sclerosis, articular surface collapse, and fragmentation. Intra-articular calcifications were observed as well.

Hypointense, intraarticular soft-tissue masses were observed with MRI. Implant irregularities (involving disruption of the implant articular surface; implant delamination and raised MR signal, suggesting soft-tissue ingrowth; and fragmentation) were observed as well. Furthermore, erosion of the articular surface of the mandibular condyle was present as well as areas of decreased signal within the condylar marrow. Decreased condylar marrow signal was interpreted to represent granulomatous marrow involvement when such signal was observed in conjunction with focal erosion and/or destruction of the adjacent bony cortex by a soft-tissue mass. Avascular necrosis was suggested by the loss of marrow signal along with osseous malformation and/or collapse without adjacent cortical destruction, or by the extension of the amount of signal loss, osseous collapse, and malformation beyond the margins of the soft-tissue mass within the articular space.

Surgical results and histology were made dispensable. Intra-articular foreign-body granulomas were present in all. Implant erosion, delamination, and granulomatous ingrowth and/or fragmentation were found in most of the joints. Granulomatous condylar destruction and either focal or generalized granulomatous ingrowth into the condylar marrow were encountered in few cases. Focal or generalized osseous collapse or resorption of the condyle without surgical evidence of granulomatous ingrowth into the marrow was encountered in 35% of the joints and interpreted to represent avascular necrosis. Articular bearing-surface cartilage was either focally or extensively eroded from all condyles exhibiting alterations of marrow signal. Focal glenoid fossa erosion and perforation by the granulomas were met in all six joints in which the diagnosis was indicated by either preoperative tomography or MRI. Few granulomas had eroded through the temporal bone to the dura of the middle cranial fossa, without infiltrating the dura.

Complications associated with alloplastic TMJ implant surgery have been reported throughout the years. Studies with conventional radiography, tomography, and CT describe complications consisting of profound bony remodeling and destruction but do not identify avascular necrosis in special. Avascular necrosis of the condyle is a common complication of failed Proplast implant surgery and frequently leads to severe structural malformations. Diagnosis of avascular necrosis has important implications for the management of patients, due to the fact that facial malformation and unstable malocclusion were frequently encountered associated complications of avascular

necrosis. Avascular necrosis may result in collapse of the mandibular condyle and condylar neck (proximal mandible) leading to open bite with bilateral disease or crossbite and chin deviation toward the collapsed side (unilateral disease) as the jaw is pulled posteriorly and upward by the muscles of mastication.

MRI is an extensively accepted imaging procedure for diagnosis of avascular necrosis of bone and internal derangements of the TMJ due to the increased soft-tissue contrast resolution that makes this imaging tool perfect for researching the complications related to fizzled TMJ operation as far as soft-tissue and marrow-space are concerned. Diminished condylar marrow signal may be interpreted confidently to represent avascular necrosis when marrow signal changes go along by osseous malformation, articular surface collapse without either adjacent cortical destruction or outspread of an intra-articular mass inside the marrow space. In addition to avascular necrosis, the differential diagnosis of diminished marrow signal on T1-weighted images involves marrow infiltration (granulomatous and neoplastic), marrow fibrosis, and osseous sclerosis. T2-weighted images may also be helpful in differentiating early stages of avascular necrosis from other entities.

Submentovertex and anteroposterior jaw-protruded skull radiographs, along with TMJ tomograms, supply critical ancillary information regarding soft-tissue calcification and subtle cortical infractions involving the temporal bone and mandible, frequently presented in conjunction with these implant complications. Radiographs indicate important alterations in side-to-side facial and mandibular condyle symmetry. Tomograms and conventional radiographs are crucial when local MRI signal is lost because of magnetic field interference from metallic anchoring screws. CT may also supply osseous detail that may escape detection with MRI. Either conventional radiography and tomography or CT provides adequate ancillary osseous detail in most cases, and only rarely would both techniques be required.

The basic pathophysiology associated with failed Proplast implants seems to be a foreign-body response derived from mechanical breakdown of the Proplast-Teflon laminate. Primate research suggests that the foreign-body reaction quickly destroys articular structures. Direct granulomatous ingrowth into the condylar marrow might be observed and seems to precede the development of avascular necrosis. The granuloma

may extend directly into adjacent soft tissues, including lymphatics, and result in regional lymphadenopathy.

Screening patients with retained Proplast TMJ implants with submentovertex and anteroposterior jaw-protruded radiographs, closed- and open-mouth lateral TMJ tomograms, and surface-coil MRI images is highly recommended. The complications associated with permanent implants warrant the clinical and radiologic evaluation of these patients.

History and testing

The evolvent of some alloplastic materials to sustitut the TMJ disk and condyle/fossa relationship has been based on instinct or empiricism and clinical urgency rather than sound biomechanical data. Two materials that have been widely utilized for replacement of the disk, are silicone rubber and Proplast-Teflon sheeting; the first was utilized as a short- or long-term apparatus, while the second was only used as a resident apparatus. In the mid-80’s enthralling short-term alloplast disk substitution results rapidly led to long-term TMJ surgical revision problems. Silicone rubber, once thought as the “gold standard,” and Proplast-Teflon II sheeting were accepted for disk substitutions by a vast number of surgeons. However, since 1985 a increasing number of clinical and animal studies on alloplastic disk substitution have stated biomechanical apparatus setback with microscopic corruption debris that causes a macrophage and foreign body giant cell (FBGC) counteraction with related pain, bone absorption, hypomobility, and malocclusion.

In the past, controversy existed in the surgical community regarding to the biomechanics of this joint, that is, whether the TMJ was load bearing. Only recently TMJ simulators have been designed and constructed to assist with understanding the mechanics of this joint and the determination of loads, which may create implant failure. In vitro biomechanical wear testing of Proplast-Teflon-InterPositional-Implants under loads that were thought to be predictive of both normal and abnormal TMJ forces were perforated. The results indicated an early failure rate with a predicted in vivo service life of ≤ 3 years. Unfortunately, these and other in vivo animal studies, which also presented rapid implant failure, were perforated after the marketing of the implant. To guard against future deficiencies in device testing and evaluation, professionals

should become knowledgeable in joint biomechanics and material behavior testing under load. There are 5 phases of testing of a loaded alloplast device before general use.

Phase 1 is a proceeding in which applicant materials meet or overdraw minimum standards for lab decay trial. Wear debris can be gathered for biocompatibility testing in animals.

Phase 2 is an in vitro proceeding with joint simulators for the recommended apparatus scheme. If loads, contact area, and frequency are known, in vivo service life predictions can be evaluated from the results of in vitro wear testing. Intrinsic factors such as unfavorable bone remodeling are not predictable.

Phase 3 focuses on biocompatibility animal trials for designation of tissue or cell toxicity and counteractions under perfunctory burden. Nevertheless, animal model problems involve uncontrollable device loading, unknown device load history, compromised design integrity from small animal anatomy, and necessary device miniaturization, which makes extrapolation to the human situation difficult. However, animal testing must bring the device and material to failure status to allow the study of mechanisms of failure, the effects of wear debris, prosthesis stability, and the subsequent biologic result.

Phase 4 is limited clinical trials before marketing to estimate all in vivo end-use conditions with patient monitoring and examination of explanted devices due to the fact that results vary as to implant sites. For instance, animal and clinical results of implants used as a condylar cap without disk removal may not be representative of the implants used as a disk replacement. In the first use, the function of the implant is primarily rotation with the implant moving with condyle and disk, whereas in the second use, the function of the condyle on the implant is rotation and sliding. The presence or absence of load is critical. Proplast and silicone rubber have perforated well as an unloaded facial enlargement material, while Teflon or Silastic is an excellent orbital floor repair material, but under load, these devices cannot withstand the rigors of TMJ loading.

1.4.2.2 GORE-TEX

Gore-Tex has been used widely as a vascular graft and as a facial implant. Subcutaneous augmentation material (SAM) was approved in 1993 for use in facial (including nasal)

augmentation[53]. Gore-Tex is a derivative (by polymerization) of Teflon, made up of repeating units of carbon bound to fluorine, a structure that results in its stability. The material’s interweaving fibrillar makeup along with relatively small pores (22 μm) permits the stabilizing tissue ingrowth without importantly inhibiting subtraction if necessary[54]. Moreover, it is also hydrophobic, which inhibits bacterial adherence and reduces the severity of tissue ingrowth thereby facilitating its removal. In the rabbit model, Gore-Tex has been shown to elicit minimal inflammation when evaluated grossly and histologically[55,56]. The material abides relatively inert as a result of its highly strong carbon–fluorine bonding, despite that fluorine is not detected normally within human tissue.

Gore-Tex implants have been used for various applications in facial plastic surgery but have found significant success when used to enlarge the nasal dorsum[15,57-62]. The use of expanded polytetrafluoroethylene (Gore-Tex) in rhinoplasty, based on chart and photographic reviews, is reviewed, after Gore-Tex implantation rhinoplasties. The results were assessed according to the follow-up notes in the chart reflecting patients’ and surgeon’s comments and full preoperative and postoperative photographic documentation. In all occasions, patient indulgence was enunciated in terms of aesthetic and functional result. Patient impressions were confirmed by critical assessment during follow-up. The implants presented excellent stability and tissue tolerance. Complications requiring subtraction occurred in 2.7 % of implants placed. Gore-Tex is an exquisite alternative to autografts as far as rhinoplasty is concerned, except for the nasal tip, columella, or problems in which rectifications would demand stiffness of the implanted material. Nasal tip or columellar sites do not lay ample soft-tissue coverage, permitting the implant to set near the surgical incision. Due to the fact that this creates additional risk of implant extrusion, such locations were avoided in the series of patients.

Despite autologous cartilage or bone having always been thought of as the gold standard for nasal grafting, one may face situations in which autogenous bone or cartilage is either less wanted or in limited supply, as is commonly the case with revision rhinoplasty. The exhaustive list of alloplasts previously used in rhinoplasty – aluminum, platinum, cork, silver, fingernails, stones from the Black Sea, duck’s breastbone, toothbrush handles, injected petroleum jelly, injected paraffin, ivory, porcelain, gold, and more recently Silastic, Proplast, Medpor, Mersilene, and Supramid

– is itself testimony to the interest that has persisted in the search for an acceptable alloplast for nasal implantation.

Gore-Tex (expanded polytetrafluoroethylene, or ePTFE) is a polymer of carbon bound to fluorine that is extruded under pressure through a dye to procreate a microporous synthetic that is a weave of PTFE nodules and thin flexible PTFE fibrils. The pore size, which ranges from 10 to 30 microns, permits for limited tissue ingrowth and stabilization of the implant while simultaneously allowing easy removal if necessary.

Millions of vascular grafts placed without a single reported case of bioincompatibility have long ago established the reliability of the product. Gore-Tex soft-tissue patches have found multiple applications in facial plastic and reconstructive surgery. Whereas the long-term efficacy of Gore-Tex implants has been well established in vascular surgery, the more recent experience in facial plastic and reconstructive surgery is comparatively limited. Although initial reports within the literature have been optimistic, there remains a natural reluctance on behalf of all surgeons to accept alloplastic nasal implants, based largely on complications such as resorption, extrusion, and infection that have plagued other “promising” implants in the past. It may well be that owing to the thin skin-soft-tissue envelope, which is easily disrupted, the subcutaneous plane of the nose represents a “low threshold” area, where implant materials well tolerated elsewhere in the body fare less well. This finding underscores the need for ongoing evaluation and reporting of long-term results with the introduction of any new implant.

The ideal implant should exhibit a high degree of biocompatibility, have exquisite handling characteristics (easy to insert and to remove, pliable) low complications rates, and excellent long-term stability. It should convey a natural look and feel, and ultimately be readily disposable and relatively inexpensive.

Autologous tissue will of course remain the standard against which all alloplasts will be compared in terms of biocompatibility and complication rates. Unquestionably for minor malformations including the nasal tip, columellar retraction, nasal valve collapse, or other deficits in which correction would require rigidity of the grafted or implanted material, autogenous cartilage is still preferable for use as a shield graft, columellar strut, or spreader graft.

For correction of localized depressions of the lateral wall or malformations of the nasal dorsum as well as for effacement of an overly acute nasolabial angle with a premaxillary plumping filler, Gore-Tex as an alloplast has been found to be even a more preferable material to autografts. Moreover, there are circumstances in which the quantity of autologous tissue disposable might be insufficient for a specific malformation, or a patient may object to a second operative site, in which case an alloplast may need to be considered.

Numerous alloplasts have been utilized in the past. Silastic (solid medial grade silicone rubber), although biocompatible, is not incorporated into the surrounding tissues and consequently has been plagued by unacceptably high rates of migration, extrusion, and infection when used in nasal reconstruction.

Medpore is a very rigid, biocompatible material that has been successfully utilized as an onlay implant for facial reconstruction in several sites. Further studies are necessary in order to estimate its practical application in the nasal surgery. Furthermore, long- term follow-up studies with Supramid used as a facial implant have showed inexplicable resorption of the implant. Mersilene, although not noted for resorption, is like Supramid stabilized by extensive tissue ingrowth and therefore may be difficult to remove when necessary as well.

The incidence of infectious complications reported within the literature relating to the use of Gore-Tex in rhinoplasty is consistently quite low. Complications have been analyzed as related to surgical technique and biological phenomena. While autologous tissue keeps being the gold standard against which all implants ought to be compared, both bone and cartilage have been reported to undergo resorption as well as changes in shape and contour.

As an alloplast, Gore-Tex has numerous appealing characteristics, as bourne out within the literature. It is biocompatible, non-allergenic, and noncarcinogenic. It has exquisite handling features, it is easily inserted and subtracted. As a result, the inevitable revisions that may be required for either over- or under-enlargement would be expected to be simpler than in cases in which autogenous grafts have been utilized. Gore-Tex has been reported to have an acceptably low rate of infection or migration and is without the problems of resorption. Furthermore, due to the pliable nature of the material, it conveys well the character of the underlying tissues, feeling firm over bone but not so

over the supratip cartilaginous dorsum. The resorption absence supplies larger predictability of the final outcome. Is Gore-Tex the ideal alloplast for use in nasal augmentation? What remains to be answered at this point in only the test of time. Based on experience and results, Gore-Tex appears to be an exquisite material for implantation in rhinoplasty.

Deep wrinkles and folds are commonly not completely or permanently corrected with face lifting, fat or collagen injections, chemical peel, and other known procedures. A resident implant, well tolerated by human tissues, might be useful as an isolated or associated procedure. An expanded synthetic polymer known as Gore-Tex expanded polytetrafluoroethylene soft-tissue patch is readily disposable and is easy to utilize to approximate and correct defects; it also may be used as a filler or to substitute other prostheses in order to obtain better projection of frontal, orbital, malar, and chin areas.

Polytetrafluoroethylene is an expanded polymer. Nodules of the material are interconnected by means of a multidirectional fibril structure, giving it great strength. Expansion causes spaces in the structure and thus the capability of ingrowth when it is implanted in living tissue. The average fibril length is 22 μm. From a physicochemical point of view, this product is one of the most inert known today. It is non-allergenic and non-carcinogenic, and its absence of foreign-body response and strength have rapidly made it a valid organic substitute. As early as 1969, it was distributed in the form of vascular grafts, resulting in more than two decades of historical data.

More recently, Gore-Tex e-PTFE has been manufactured in the form of sutures and patches of various dimensions (50 to 600 cm2) and thicknesses (1 and 2 mm). These patches were found applicable in general, cardiovascular, and uro-gynecologic surgery (closure of parietal wall defects, correction of cardiovascular malformations, hernia repairs, and other soft-tissue reconstructions of the viscera) as well as plastic surgery.

Manipulation of the Gore-Tex soft-tissue patch is really simple and rapid. The patch is extemporaneously cut prior to surgery to the required dimensions using a pair of sharp scissors. Implants thus obtained are optimally in the form of either patches or strips. If there is a need for greater projection (such as for the malar area), it is possible to superimpose two or three layers using one or two transfixing sutures. The knot should be properly secured so as to prevent a stair-stepping effect of the layers. This unwanted effect may also be prevented when the implants are located under thin skin by crushing

the edges of the implants with a flat instrument. Nevertheless, it should be highlighted, that crushing the edges might close the pores of the patch and ultimately affect tissue ingrowth. The implant should then be handled with extra care, since it will retain the memory of any untimely pinching or pulling.

The implant may be placed either by tunneling of by choosing a discrete access site a certain distance from the desired point of projection (buccal access or behind the hairline). The implant must be passed through with the greatest of care, totally avoiding wrinkling the edges, which would cause inharmonious results. There are special instruments designed for this purpose that allow both placing the implant without damaging it and keeping it in place using a transfixing cutaneous needle as the instrument is withdrawn. In placing a patch directly during open access (face lifting, for example), it is easy to place using several peripheral sutures.

Prophylactic antibiotic therapy is not necessary, and pieces of graft that are not used can be re-sterilized up to 10 times using steam or gas techniques. To prevent contamination, clean gloves or atraumatic instruments should be used to handle the implant.

A sheet of Gore-Tex soft-tissue patch can be used to correct inhomogeneities in a poor rhinoplasty. This type of implant is difficult to do due to the fact that there is no room for even the slightest imperfection. The laying in place of the implant is a delicate operation because of the limited access routes for rhinoplasty.

Ease of handling, suppleness, and biologic tolerance of Gore-Tex soft-tissue patch bring a quick and elegant solution to requests for correction of insufficiencies of projection or of hollows in the facial structures. The improvement is immediate at the price of a very discrete access route and a very rapid intervention, often done under local anesthesia.

This procedure cannot be thought of as a unique resolution of all problems of facial rejuvenation. The implant performs better in association with most of the routine surgical techniques than by itself. It may be that poor results are due to excessive or insufficient employment.

Several materials have been utilized in nasal surgery, varying from autogenous, to homogenous, and alloplastic grafts. Autogenous cartilage abides the perfect graft

material; nevertheless, there are occasions in which an alternative or an additional grafting material is of necessity. Homogenous materials have demonstrated significant resorption. Alloplastic grafts have offered varying degrees of success but have resulted in significant complications as well. Gore-Tex has incurred widespread research and clinical application in several surgical fields with marked success.

In performing rhinoplastic procedures, the surgeon is often coping with malformations in need of grafting. This may range from small, localized surface deficits or inhomogeneities to severe nasal dorsal saddle deformities. Autogenous cartilage remains the ideal grafting material and alone has withstood the scrutiny of time. Sometimes alternative grafting material is desirable for numerous reasons. Autogenous grafts may warp and become distorted. Harvesting might require a distant donor site, prolonging the procedure, raising the incidence of postoperative morbidity, and possibly procreating a cosmetic malformation at a distant site. Commonly, an adequate quantity of autogenous material is not readily disposable, and homogeneous or alloplastic implants are required.

Several implant materials have been utilized in nasal surgery. These involve both homogeneous materials and allografts. The homogeneous implants, which include cadaveric irradiated or freeze-dried bone or cartilage, have showed important and unpredictable resorption. They may transform the nose into a rigid, irregular structure susceptible to even minor trauma. Several synthetic materials have been used as well. These include silicone, Mersilene mesh, polyethylene, methyl methacrylate, Supramid mesh, Teflon, Proplast, and hydroxyapatite. All of those materials have offered varying degrees of success but have resulted in significant complications as well. The problems are related to foreign-body reactions, material rigidity, encapsulation, infections, and instability after placement with extrusion. A thin covering of nasal skin and frequency of trauma tend to potentiate these problems.

Gore-Tex is composed of nodules of solid polytetrafluoroethylene interconnected by thin flexible fibrils of polytetrafluoroethylene characterized by a microporous architecture (10 to 30 μm pore size). Much information concerning the biophysical properties of the available Gore-Tex grafts, such as strength, durability, porosity, and healing properties, was accrued between 1971 and 1976 from clinical and experimental studies. It was studied initially in animals and distributed clinically in the form of

vascular grafts. Since then, there is extensive literature describing success in vascular surgery, with more than 5 million vascular replacement procedures perforated without a reported case of rejection. More recently, Gore-Tex patches were produced and used for repair of abdominal wall defects, cardiovascular surgery, hernia repairs, ophthalmologic surgery, rectal/vaginal prolapse repair, chest-wall defects, and temporomandibular joint reconstructions, all demonstrating similar success.

Although autogenous septal cartilage remains the material of choice for grafting needed during rhinoplastic procedures, there are cases where an alternative or additional grafting material is required. This is particularly evident in revision cases when the septal cartilage has been previously harvested and is unavailable or is needed for support and reconstruction of the nasal tip. Other autogenous sources of cartilage, such as the auricle, have disadvantages such as donor-site morbidity, warping, fragility, brittleness, distortion of the material, and additional operating time.

Numerous synthetic implants have been used in the past. Reportedly, most alloplastic materials are complicated by migration and extrusion, foreign-body reaction, or infection. Attempts at removal in the face of infection can prove to be extremely difficult in some patients. In contrast, Gore-Tex soft-tissue patches were shown in animal studies to be the most biocompatible synthetic material to date. The material becomes permeated and surrounded by mature connective tissue, forming a strong supporting envelope for the material, yet the implant is easily removed because of the absence of surrounding tissue reaction. The success of the material as an implant is well documented in other areas, including vascular surgery, ophthalmologic surgery, and urologic surgery in millions of cases in over 20 years of clinical experience. In the reports of its use in facial cosmetic surgery, including rhinoplastic enlargement procedures, the short-term results supported the findings seen with other applications. The ideal balance of tissue ingrowth and resultant implant fixation, tissue compatibility, consistency similar to that of host tissue, structural integrity, and ease of manipulation, placement, and removal is found with Gore-Tex soft-tissue patch material. Finally, results demonstrate a high level of patient satisfaction.

Because of its natural appearance and ease of use as compared with rib cartilage or other autologous implants, Gore-Tex has become popular as a nasal implant. Subcutaneous Augmentation Material (SAM) is identical to the soft tissue patch and is

used specifically for facial plastic and reconstructive surgery. Furthermore, it can be easily carved and shaped to hide deficiencies in the nasal dorsum. The material is procreated in 1-, 2-, and 4-mm thickness, which may be beveled at its circumference to pair with surrounding tissue[56]. Due to its ease of use and natural appearance, it rapidly became the chosen alloplastic implant for many facial, plastic and reconstructive surgeons. Nevertheless, utilization of autologous materials when possible, is preferred.

1.4.3 POLYETHYLENES

Polyethylene implants are synthesized of a group of polymers with alternating aspects based on their length, density, and cross-linkages. Three alternative densities have been reported: low-, medium-, and high-density polymers[63]. The high-density ones are the most frequently used for reconstructive craniofacial surgery. Medpor and Plastipore are examples of high-density materials. They are flexible but retain shape when manipulated[64].

The Medpor porous polyethylene implant is a highly stable and somewhat flexible porous alloplast that has been reported to show quick tissue ingrowth into its pores. Implants are used for the chin, malar area, nasal, ear, and orbital reconstruction, as well as the correction of craniofacial contour malformations. Many of these implants are placed in areas long considered problematic such as areas of thin soft-tissue coverage, extensive scarring, and severe facial burns. Medpor is an exquisite alternative to existing implants. It is shapeable, strong yet flexible; stable; and it displays tissue ingrowth into its pores.

Facial harmony and balance are dictated by the facial skeleton that supports the overlying soft tissues. Minor corrections to improve the facial relationships are easily achieved with the use of implants. Recently, attention has turned to the development of porous implants. The primary benefit of porous materials is that they permit tissue ingrowth. Nowadays, many available porous implants have had a number of limitations that preclude their utility. Implant materials have been difficult to use, excessively brittle, abrasive to surrounding tissues, or lacking structural integrity. Medpor is a widely disposable alloplast, thus constituting an appealing alternative to other alloplasts and autogenous tissue.

The Medpor implant is made of a medical-grade, high-density polyethylene that is sintered to create a somewhat flexible framework of interconnecting pores. It has been shown to exhibit rapid tissue ingrowth into its pores with collagen deposition that ultimately forms a highly stable complex resistant to infection, exposure, and deformation by contractile forces. The mechanical properties are such that the implant is easy to shape and strong enough for utility in non-load-bearing regions of the craniofacial skeleton. Medpor is disposable as a sterile implant in blocks, preformed anatomical shapes, and on a custom basis.

Furthermore, Medpor has been available for clinical implantation since 1985. Since that time, its primary use has been for maxillofacial trauma reconstruction. Favorable results have been reported from hospitals affiliated with Johns Hopkins, Harvard, and the University of Southern California. Institutional experience with the implant consists of elective reconstructive surgery primarily for posttraumatic malformations and major facial burns.

Achieving the appropriate implant shape is a crucial step for a successful enlargement. With a little practice, Medpor is easy to shape. The implant may be cut with a pair of scissors or with a knife on a nylon block. Bending is facilitated by heating the implant in boiling saline. The heat allows for configuration of the implant to a new retained shape after cooling. Once the correct fit is established, fixation is perforated using sutures, K-wires, or screws. It is critical to feather the edges or to cover an inhomogeneous implant with a thin overlay, to obtain a smooth contour and to eliminate any possibly visible edges. As with any new implant, surgeons should familiarize themselves with the material and practice shaping the implant before surgery. Keys to success are to use as thin an implant as possible to optimize vascular ingrowth and to ensure that no undue pressure is exerted on the overlying skin.

The Medpor porous polyethylene implant has a unique combination of properties that gives it a significant advance over other available alloplasts: The implant is easy to shape; it is strong yet somewhat flexible; it is remarkably stable; and it exhibits tissue ingrowth into its pores. Polyethylene is a highly inert material that has a long history of use in the craniofacial skeleton; more than 30 years of patient follow-up have been reported. High-density polyethylene has a consistently benign response. Used frequently in orthopedic appliances, it has been a standard reference material for

biocompatibility testing. Moreover, it is a porous form of high-density polyethylene that is strong enough to resist deformation of the pores that are critical to vascularization of the implant and tissue ingrowth. The contiguous, large pore structure of the Medpor implant enables tissue fluid to circulate throughout the implant. Rapid vascularization of the implant accompanies soft tissue ingrowth. The pore size of Medpor is controlled so that more than 50% of the pores are larger than 150 μm. If the need arises to remove the implant, experience has shown that elevating the tissue from the implant is much like elevating periosteum from a bony surface.

1.4.3.1 Chin Implants

Medpor has a variety of applications in the facial skeleton. Chin implantation is one of the most frequent uses for a facial implant. The procedure is easy to perforate, with good results and low complication rate. The most frequently used material continues to be silicone. Complications outlined with use of a smooth-surfaced implant are bone resorption, shifting of the implant, and ptosis of the overlying soft tissue. Silicone chin implants are known to cause resorption of the underlying bone, an effect believed to be caused by mechanical pressure and by the active capsule that forms around all silicones. Osteointegration of an alloplast is a key principle in stabilizing orthopedic implants, and to date there have been no reports of bone resorption under Medpor implants. One of the major benefits of an implant that permits for tissue ingrowth is the fixation of the overlying chin pad to the implant. Following the placement of a silicone chin implant, ptosis of the implant and the chin pad can exacerbate a so-called "witches chin" malformation. Such silicone-associated deformities can be corrected with a structurally stable porous implant. If a small incision is contemplated, it is frequently easier to insert the implant after cutting the implant into two pieces, inserting each piece individually, and then reconnecting the pieces. The cut should be made so that the two pieces fit in a tongue-and-groove fashion. Fixation with a suture, screw, or a K-wire until tissue ingrowth has occurred is highly recommended.

1.4.3.2 Malar Implants

The use of a structurally stable implant with a high degree of tissue ingrowth is specifically important in the malar region. With an improved understanding of the cruciality of soft tissue attachments in facial rejuvenation and trauma reconstruction, the less than optimal effect of placing a smooth implant in the malar region is becoming blatant. In order to insert a malar implant, the soft tissue envelope is elevated off one of the main areas that suspends the midface. Placing a smooth implant into the pocket may interfere with the reattachment of the face, and the eventual ptosis of the soft tissue envelope may explain the drawn appearance of patients many years after malar enlargement. The capsular contracture that develops over a smooth-surfaced implant may further compound that effect. Although technically more demanding, the benefit of using an implant that allows for tissue ingrowth becomes clear. The Medpor implant eventually becomes fixed to the facial skeleton, and the ingrowth of the overlying soft tissue supports the soft tissue envelope of the face.

1.4.3.3 Nasal Implants

In the nose, Medpor has a number of useful applications. Enlargement of the nasal dorsum has a higher complication rate than implants placed in areas with larger soft tissue coverage. The soft tissue envelope of the nose is relatively thin, and the graft is subject to numerous external forces. Keys to success involve using an implant that is adequately shaped and fits into the pocket. A frequent pitfall with using a poor fitting silicone implant and compressing it into a tissue envelope is that, timely, the compressed portion of the implant will cause tissue erosion. The properties of Medpor make it a good choice as a dorsal onlay for reconstructive and aesthetic purposes. Available nasal shapes are easily modified for that aim. Thin onlays of Medpor, 0.85 mm in thickness, are particularly useful for areas that traditionally have been enlarged with autogenous tissue. Thin pieces may be utilized to augment or replace alar cartilages and prevent nasal airway collapse. In burn patients, thin pieces of Medpor have been used with success under mature skin grafts. Quick implant vascularization helps ensure stability. Collagen ingrowth into the implant add strength to it and a smooth surface, masking small contour inhomogeneities and rendering the implant almost invisible under the skin. Medpor should be used with caution in the columella

because the shear forces exerted on the implant by normal motion of the nose disrupt tissue ingrowth into the implant and predispose the implant to exposure.

1.4.3.4 Ear Reconstruction

Medpor has been demonstrated to have an important application in ear reconstruction. The development of the "pivoting helix" design that can fold against the head in event of externally applied pressure has changed the scope of alloplastic ear reconstruction. Keys to success involve ensuring an adequate vascular provision by using a temporoparietal fascial flap and by anchoring ends of the implant that might otherwise act as a spring and become exposed.

1.4.3.5 Orbital Reconstruction

Orbital floor reconstruction stays one of the most common applications for Medpor. The orbital floor can be rebuilt using thin or ultrathin sheets. The implant may also be stacked to effect volumetric changes. Stacking the implant anteriorly in the orbit tends to elevate the globe and correct vertical dystopia. Volumetric enlargement in the posterior aspect of the orbit tends to relocate the globe forward and correct for enophthalmos. The low incidence of Medpor-related complications in the orbit is noteworthy given the number of implants that have been placed in contact with open, contaminated facial sinuses. In an animal study, Medpor implants exposed to the maxillary sinus showed rapid tissue ingrowth and incomplete mucosalization of the exposed implant within 3 to 4 weeks. This is also consistent with both a previous case report and an animal study in privates in which exposed implants remained fixed and well vascularized.

1.4.3.6 Cranial Applications

Cranial onlay applications with Medpor are similar to chin and malar applications, and the benefits concentrate on the materials’ ease of use, tissue ingrowth, and implant stability. Complex shapes such as the supraorbital rim may frequently be reproduced using the flexblock implant. It was designed as an onlay for calvarial bone graft donor

sites, with a soft exterior and a series of conical ridges on its undersurface thus permitting easy bending, sufficient contour adaptability, and appropriate power. Cranial onlays are usually fixed with a suitable micro-screw system. Final contouring can be perforated in situ, and an ultrathin sheet of Medpor can be used as an overlay to eliminate any minor inhomogeneities or possibly visible implant edges. When a primary indication for a cranioplasty is the protection of the brain, or when there is a large cranial defect, flexblock alone does not supply sufficient strength. For those cases, a custom-fabricated Medpor implant might be more appropriate. Implant thickness can be specified, and the implant can be matched to fit a given deficit using computerized axial tomography or magnetic resonance imaging data.

Ultimately, Medpor implant is an exquisite alternative to existing materials utilized for facial contour correction. The implant material is easily shaped, strong yet somewhat flexible, noteworthily stable and it exhibits tissue ingrowth into its pores. Pore size ranging from 100 to 250 μm, permits significant soft tissue and bone ingrowth[65-68]. Due to its stiffness, the implant appears unnatural over the nasal dorsum.

1.5 POLYESTERS AND POLYAMIDES

Polyethylene terephthalate can be woven into a non-resorbable mesh referred to as Mersilene for dorsal, nasal and subnasal region implantation[69,70]. A detailed report on the complications observed is currently being prepared where the judicious use of Bioplastique with installation of the material to the proper depth in precise amounts is advocated.

The implant material allows for significant tissue ingrowth, maintaining implant position, but also making its removal difficult when necessary[71]. The mesh permits bacteria to grow within its fiber network, leading to significant problems with bacterial colonization, infection, and graft failure[72]. Due to these factors, it is not suggested to place over the nasal dorsum. Polyamides include a similar substance to Mersilene mesh with the trade name Supramid (Ethicon) mesh. Both have similar qualities and appearance. Supramid, however, will resorb leaving behind a fibrous shell to maintain some of the implant’s original volume.

1.6 The Future

Autologous, homologous, and alloplastic implants possess inherent strengths and weaknesses. Tissue-engineered autografts could possibly overcome the biocompatibility issues of alloplasts and the donor site morbidity and limited supply issues associated with autografts. Vacanti et al.[73,74] pioneered the development of xenograft tissue-engineered bovine cartilage grafts placed in immune-depleted mice.

An approach for tissue creation utilizing synthetic biocompatible and biodegradable polymers, onto which cells are seeded, as templates is reported. The delivery of chondrocytes on synthetic polymers configured to supply a large surface area for cell attachment and therefore to permit cell function and survival by diffusion of nutrients has resulted in the creation of macroscopic plates of up to 100 mg of new cartilage subcutaneously in animals. The approximate dimensions and configuration of the original templates were retained as new cartilage was formed and the polymers resorbed.

Prior reports have described new cartilage formation using isolated cell suspensions, cells attached to a naturally occurring matrix, or polypeptides derived from bone. This method differs in that synthetic biodegradable polymers are utilized as templates onto which chondrocytes are seeded and then implanted into an animal for the purpose of new cartilage formation. Reference to the polymer with its associated chondrocytes is performed as a cell-polymer construct. The employment of synthetic rather than naturally occurring polymers permits exact engineering of matrix configuration so that the biophysical limitations of mass transfer are satisfied, allowing formation of large three-dimensional masses of cartilage the size and shape of the original polymer construct.

The procedure constitutes of the following: Hyalin cartilage was obtained from the articular surfaces of newborn calf shoulders within 6 hours of sacrifice. The shoulders were washed in povidone-iodine 10% solution, and chondrocytes were harvested under sterile conditions using a technique described by Klagsbrun. The isolated cells were quantitated using a hemocytometer, and then the chondrocyte suspension was concentrated to 5x107 cells/cc. Next, braided threads of polyglactin 910, a 90:10 copolymer of glycolide and lactide, coated with polyglactin 370 and calcium stearate were cut into pieces of approximately 17 mm in length. A knot was placed at one end.

The suture material was unbraided distal to the knot to expose multiple fibers 14 μm in diameter.

Using the configuration, it was sustainable to create inter-fiber distances varying between 0 and 200 μm while keeping the unit intact. The synthetic bioabsorbable suture material is referred to as the polymer fiber.

Fifty polymer fibers were placed into tissue culture dishes 35 mm in size at a density of two polymer units per well. Each of 28 experimental fibers were seeded with 100 μl of the chondrocyte solution and kept 22 polymer fibers free from exposure to chondrocytes (the controls). One of the polymer fibers seeded with chondrocytes was contaminated during manipulations and was therefore discarded.

After 4 hours, 2 cc of a solution containing Hamm’s F-12 culture media and 10% fetal calf serum with L-glutamine (292 μg/cc), penicillin (100 U/cc), streptomycin (100 μg/cc), and ascorbic acid (5 μg/ml) was added to each well. A total of six fibers from each group (experimental and control) were evaluated in vitro for the presence and morphologic appearance of chondrocytes by phase-contrast microscopy and histochemical stains after incubation at 37oC for 3, 6, 11, 18, 21, and 24 days.

Thirty-seven of the remaining fibers (21 experimental and 16 control) were surgically implanted subcutaneously at the base of the neck in the dorsal midline of 37 male nude mice that were 4 to 5 weeks of age. Thirty-two of these implants (16 in experimental group A and 16 in control group A) were perforated after incubation for 3 days in vitro, whereas the remaining 5, all in experimental group B, were perforated after incubation for 10 days in vitro. Seven mice with implants (3 in experimental group A with chondrocytes incubated for 3 days, 1 in experimental group B with chondrocytes incubated for 10 days, and 3 in control group A) were sacrificed at each of the following intervals: 8, 18, 28, 49, and 81 days (35 total). Two additional mice, one experimental implanted after 3 days of incubation with chondrocytes and one control, were sacrificed at 168 days.

As another control, 10 mice were injected subcutaneously in the same region with 200- μl cell suspensions containing 5x105 chondrocytes without attachment to polymers. Five of these cell suspensions were injected immediately upon isolation of the chondrocytes, whereas the remaining five cell suspensions were injected after incubation of the chondrocytes in vitro for 3 days. These mice were sacrificed at the

same intervals of time as the experimental group, and the areas injected were evaluated histologically in the same manner as aforementioned for evidence of chondrocytes or cartilage. The data from the two experimental groups were combined for statistical analysis and compared with the control groups using the Fisher’s exact test.

After being implanted for specific periods of time, the implants were then excised following a tissue plane that easily separated the implant from the surrounding tissue and were fixed in 10% buffered formalin phosphate. In order to classify the type of collagen present in the specimens, immunohistochemistry was perforated utilizing antibodies to bovine collagen types I to IV. Hyalin cartilage, being different from other mammalian tissues in that it contains no type I collagen, is one of very few mammalian tissues containing type II collagen. The avidin-biotin-peroxidase technique was used. Chondrocytes in culture readily adhered to the polymer fibers in multiple layers and maintained a rounded configuration. This modulation has been related to the cell’s capability to reach normal differentiated functionality. In vitro, hematoxylin and eosin staining of the experimental specimens exhibited a basophilic matrix at 18, 21, and 24 days. Aldehyde fuschin-alcian blue stains of the same specimens highlighted the presence of sulfated glycosaminoglycans (GAGs). In contrast, histologic evaluation using hematoxylin and eosin stains reported no evidence of chondrocytes of chondroitin sulfate in the six in vitro control fibers. All polymer fibers in vitro (control and experimental) began to dissolve by day 27, which is comparable to their anticipated dissolution time interval.

On gross examination, the experimental polymer fibers were progressively replaced by cartilage, until only cartilage with very little evidence of polymer remained. The wet weights of the specimens raised gradually until day 49, after which time they remained stable, averaging from 60 to 70 mg. The surface of the newly formed cartilage was smooth in all specimens.

Histologic examination of these specimens using hematoxylin and eosin stains revealed evidence of cartilage formation in most of the experimental implants (statistically significant from the control groups using the Fisher’s exact test, p<0.01), with all specimens having been implanted for at least 28 days seeming very similar to normal human fetal cartilage. A mild inflammatory response, as evidenced by polymorphonuclear leukocytes and giant cells, noted in the day 8 specimens appeared

to be resolving in the day 18 and 28 specimens. The resolution of the inflammatory response correlated, at least temporally, with the disappearance of the polymers. Very little evidence of either inflammatory response or polymer remnants was noted in the day 49, 81, and 168 specimens. No lacunae were present in any day 8, 18, 28, or 49 specimens, whereas lacunae were observed in all day 81 and 168 specimens, indicating the progression from fetal to mature cartilage. A diminution in neovascularization was also noted in these specimens. Aldehyde fuschin-alcian blue staining of these specimens indicated the presence of sulfated glycosaminoglycans.

Type III collagen, generally seen only in immature mammalian hyaline cartilage, was reported with immunohistochemistry in the day 49 and earlier specimens but was not seen in later specimens. Type II collagen, remarkable in that it is found almost exclusively in mammalian hyaline cartilage, was not found in early specimens, that is, day 8, 18, or 28 specimens; Nevertheless, it was showed in specimens implanted 49 days or more. Type I collagen, detectable in most mammalian tissues but not found in mammalian hyalin cartilage, was not detected in any of the specimens. In the 16 polymer fiber control implants not containing chondrocytes, there was no evidence of cartilage formation histologically using the hematoxylin and eosin stain. A mild inflammatory response with polymorphonuclear leukocytes, giant cells, and fibroblasts was highlighted in these implants at days 8, 18, and 28, after which time no evidence of the implant was found. In the second control group, cartilage formation was not profound in any area injected with a suspension of chondrocytes.

Chondrocytes seeded onto appropriately configurated synthetic biodegradable polymers will adhere and perform differentiated function in vitro, as seen by matrix formation. Surgical implantation of this cell-polymer construct into an animal will result in the formation of new cartilage that matures with time, contains type II collagen, and retains the approximate configuration and dimensions of the original template. The new cartilage formed is seen as early as 8 days histologically, and both its wet weight and volume progressed until 49 days, after which time the size of the cartilage formed remained stable, although it matured histologically, as evidenced by the formation of lacunae. Moreover, the cell-polymer construct is critical in that either injection of free chondrocytes or implantation of the polymer fibers without attached chondrocytes does not result in cartilage formation. A diminution in neovascularization and fibrous tissue formation is correlated with the development of this cartilage formation.

This might mirror the juvenile cartilage’s procreation of an angiogenesis inhibitory factor.

This approach for creating new tissues differs from other approaches in that it utilizes a synthetic matrix to which cells adhere, supplying structural integrity as the implant engrafts and new tissue is created. Using synthetic as opposed to naturally occurring substances as matrices allows one the flexibility to alter physical properties and potentially facilitates reproducibility and scale-up. The configuration of the synthetic matrix may also be manipulated to vary the surface area disposable for cell attachment as well as to optimize the exposure of the attached cells to nutrients. The precise physical characteristics and configuration of the “optimal” polymer design have yet to be determined. The chemical environment surrounding a synthetic polymer might be affected in a controlled fashion as the polymer is hydrolyzed. The possibility exists to continuously deliver nutrients and hormones that may be incorporated into the polymer structure. Experiments suggest that the degree of cartilage generated in this manner is such that it might be feasible to alter the physical appearance of the recipients of such implants in a controlled and predictable fashion. This technology can be proven useful in plastic and reconstructive surgery as well as in replacing cartilage on articulating surfaces. It is also conceivable that employment of this approach utilizing different cell types may result in the generation of other tissue equivalents.

More recently, work has been done using autologous bioengineered cartilage grafts in rabbits[75]. Rabbit chondrocytes in vitro were cropped and cultivated, pursued by lodgement on polyglycolic acid nonwoven felt blended with poly-L-lactic acid. This porous, pre-shaped scaffold allowed for directed chondrocyte development into cartilage. The authors reported impressive short- and long-term results using these implants placed into the flank of the donor rabbits. Vast amounts of host specific cartilage may be procreated in such a way, that would have an important impact on future implantation protocols. Cartilage harvested in this manner would most certainly be more expensive than other alternatives, but the future may also supply more efficient and cost-effective methods for producing bioengineered implant materials.

CHAPTER 2

INTRODUCTION

Rhinoplasty implant usage is controversial. A vast variety of materials are employed in nasal surgery either for augmentation or for reconstruction. Autogenous tissue has long been advocated as the mainstay for nasal implants. Autogenous cartilage is mostly harnessed for structural and enlargement grafting in the nasal tip, as well as for dorsal malformations. However, confined disposability and non-predictable resorption of both autologous and homologous implants have made newer alloplastic implants imported to important considerations for dorsal augmentation.

Choosing the most suitable graft or implant material for soft tissue augmentation is a hard task. A vast variety of materials and techniques are exerted by outstanding surgeons who have equally compelling arguments for the materials utilized. No single material is suitable for all augmentation and nasal reconstruction cases. Each has its pros and cons. The surgeon’s own experience and personal preference play a significant role in the success of the utilized material.

The indications for nasal soft tissue augmentation are most often associated with depression over the cartilaginous or bony dorsum pyramid—the so-called saddle-nose disfigurement. This can occur in many degrees and as the result from various causes. This deformity can result from congenital abnormalities (e.g. aplasia of the nasal bones). It can be secondary to trauma, which can generate septal hematoma and cartilaginous necrosis or disarticulation of the upper lateral cartilages and resulting in dorsal depression. It can also result from atrogenic causes, such as overresection of the quadrangular cartilage in septoplasty surgery. Studies have shown that 39% of patients undergoing extensive septal reconstructive surgery independent of rhinoplasty surgery showed some degree of external malformation with time. Cartilaginous saddle-nose distortion in the middle one-third of the nose is frequently the consequence of radical septal surgery.

In a review of 153 revision rhinoplasties, authors have stated that 58 patients presented with defects in the bony dorsum and 91 presented with blemishes of the cartilaginous vault. Approximately 20% of the vices would be classified as saddle-nose deformities

requiring some degree of augmentation. Thus, augmentation of the bony or cartilaginous dorsum is not an infrequent consequence of rhinoplasty surgery[76].

In nasal augmentation, medial osteotomies are routinely performed to encourage a new blood supply. Noses in which multiple grafts have failed are managed with autogenous tissue or harvested, previously implanted polyamide mesh. A free graft of harvested polyamide is utilized as well in those cases in which a carved soft implant is indicated.

2.1 TYPES OF GRAFTS

The perfect graft to rectify dorsal prostrations would present the following qualities:

(1) host tolerance,

(2) remain unaltered over time,

(3) easily carved or molded,

(4) no transillumination or discoloration of supervening tissues,

(5) pliable,

(6) easily obtainable.

Grafts may be categorised as autologous grafts (from host’s own tissues), homologous grafts (from another individual), heterologous or xenografts (from a different species), and alloplastic or synthetic implants.

Biological materials are called grafts. These living or non-living tissues are incorporated into the host tissues or are completely replaced by the host tissues. Synthetic or alloplastic materials are synthetic organopolymers that are generally well tolerated by the host’s tissues. Synthetic materials called implants, maintain their characteristic composition into the tissues. Although their structure may be invaded by host tissues, the implant structures are neither altered nor removed by the host[77].

2.2 AUTOLOGOUS GRAFTS

Autologous grafts have been the implants of choice for nasal augmentation and reconstruction for more than a century[78]. Many surgeons prefer to use the patient’s own septal cartilage as the implant of choice for nasal reconstruction[79,80]. This cartilage is particularly useful for tip support and augmentation. However, that is not always available. Autologous cartilage may be cropped from the auricle or the rib.

Two main categories are provided for cartilage grafting: morphologic and hyaline. Septal cartilage is an example of morphologic cartilage. It has the advantage of keeping its shape when transplanted. Rib, or costal, cartilage is an example of hyaline cartilage. Hyaline cartilage has a system of interlocking stresses inherent in its molecular structure. There is a balance of internal elastic forces that resist distortion. Responsible for this property are the protein core and the glycosamine side chain are. Parallel force lines run through the cartilage circumference and react to the effects of the internal forces. Once the cartilage block is cut, the stress forces on that side of the cartilage are relieved, but they no longer counteract on the opposite side of the graft. This can result in implant warping and can be a disadvantage of its use. A technique can be used to minimize warping by shaving only scant amounts from the periphery of the graft, such that the outer restraining forces are not unfettered.

Unlike bone, little remodeling of cartilage takes place in a normal state. Chondrocytes are not replaced during adult life. The ability of cartilage to regenerate remains questionable.

Cartilage does enjoy some immunologic privilege. Cartilage cells possess antigens of the major H-antigen system. Cartilage grafts are antigenic and feebly immunologic due to the matrix proteoglycan that guards the chondrocyte from the afferent arm of the immune response, thereby stunting attack by immunoglobulins. Thus, there is no immune response or biocompatibility problem. Cartilage grafts, as compared with bone grafts, have been reported to have lower absorption rate and lower metabolic requirements for survival[81].

Living autogenous cartilage would be the perfect grafting material, since it rarely resorbs, if it was not so inclined to warping. Deformation results from the systole of the outer layer once the rib is sculpted so that the natural equilibrium is upset. In this, the fibrous perichondrium plays a minimal role.

Nevertheless, utilizing the principle of the balanced cross-section, entails the following: the distorting forces are balanced at all points along a cartilage graft as viewed in cross- section and thus, the cartilage graft it will not warp. Using this technique, no graft has twisted and none has shown any evidence of absorption. This technique may be agreeable as supplying grafts which do not twist, since any distortion would have manifested itself within the first few days or weeks. Nor is late absorption of the grafts to be feared; although absorption is the rule on any surface bared of perichondrium, this is of no clinical importance in large cartilage grafts. Only in the incidence of cartilage survival failure would resorption be important, which is sparse.

Resorption rates of septal cartilage grafts have been estimated as ranging from 12% to 50%[82]. Twenty physicians out of a total of 211 who utilized preserved grafts reported that there was only 10% absorption in 91% to 100% of the cases they implanted. There appears to be a clustering of the largest numbers of physicians demonstrating low absorption when autologous grafts were used as compared to when they used preserved grafts. The following histogram illustrates the number of physicians who have reported in 80% to 100% of their cases either 0% to 10% or 0% to 20% absorption of their cartilage grafts. It is therefore blatantly clear that most of the physicians had less absorption, and moreover, preservation of greater graft size when they used fresh autogenous cartilage compared to when they used the preserved.

Nevertheless, absorbed cartilage is commonly substituted by host fibrous tissue, making absorption clinically non-detectable.

2.2.1 AUTOLOGOUS SEPTAL CARTILAGE GRAFTS

Septal cartilage onlay grafts can be used to correct moderate saddle depressions. Sessions and Stallings[83] reported only 15% resorption after 1 year’s experience with this technique. Gunter and Rohrich[84] described an excellent technique of using septal cartilage as a frame graft and inserting autologous cartilage remnants underneath the frame to provide increased dorsal enlargement.

2.2.2 AUTOLOGOUS AURICULAR CARTILAGE GRAFTS

Autologous auricular cartilage grafts might substitute the corresponding septal cartilage. Inherent curvature makes them immensely practical for reparation of the nasal valve, thus shaping for utilization as onlay grafts. However, the deficit of demanding a second surgical site is discouraging.

Auricular cartilage may be located near the surface, since it does not need direct contact with bone or nasal cartilage. Perichondrium maintenance on the epiphany of the cartilage is a matter of controversy. Nevertheless, it superinduces stiffness. Beyond the age of 45 to 50 years, attention must be paid, since auricular cartilage becomes more brittle and easily fragmented.

2.2.3 AUTOLOGOUS COSTAL CARTILAGE GRAFTS

Autologous costal cartilage is commonly used for augmentation of large dorsal nasal defects and for columellar struts. It’s major deficit is the requirement of a second surgical site and being followed by a high morbidity degree. Gunter et al.[85] pointed out that the value of the rib as a donor site has been limited by difficulties with postoperative cartilage warping. Stabilizing the graft with longitudinal K-wire appears to eliminate warping and provides internal stabilization of the graft.

The appropriate sizer is selected is selected to direct rib carving. The cartilaginous portion of the appropriate ribs is harvested. Initially, the ninth and tenth ribs in all patients were utilized. However, it is concealed the chest incision in women by utilizing a medial inframammary fold incision to harvest the sixth, seventh, and/or eight ribs is appropriate. After gross carving, the cartilage is centrally penetrated with a smooth

0.028-in K-wire, which is replaced with a threaded 0.035-in K-wire. The graft, which is carved to the same dimensions as the silicone sizer, is anatomically contoured to a canoe shape with the widest portion at the osteo-cartilaginous junction. The K-wire is trimmed flush with the end of the graft. The graft is sutured to the nasal dorsum at the septal angle and the superior margin of the upper lateral cartilages. Additional graft fixation is achieved with a smooth 0.028-in K-wire placed percutaneously through the graft into the nasal root. Prior placement of a columellar strut does not affect the positioning or fixation of the dorsal onlay graft. The percutaneous K-wire is subtracted with the external splint 1 week postoperatively.

Over a 10-day study period, a mean of 2.2 degrees of warping was observed in the grafts with K-wires as compared with 8.9 degrees in the control group. This highlights that internal stabilization of rib cartilage grafts with K-wires significantly diminishes warping (p<0.001). Most warping occurred within the first 15 minutes after carving. Minimal changes occurred after 5 days. Moreover, at a mean follow-up period of 13.5 months, graft warping was not observed in any patient. The absence of detectable warping indicates that K-wire stabilization prevents both early (within days) and late (within months) warping. This technique is valuable in the rhinoplasty patient who requires a columellar strut or a dorsal onlay graft fashioned from autogenous rib cartilage.

Excellent results can be obtained with the use of autogenous costal cartilage to reconstruct the nasal dorsum. Partial resorption is thought to be related to trauma. Smaller implants appear to be more vulnerable to absorption than larger implants. Pressure on the cartilage implant due to tight nasal skin or contracting scar did not seem to alter the behavior or increase the graft absorption rate.

2.2.4 AUTOLOGOUS BONE GRAFTS

The use of septal bone grafts has been reported. Multiple small pieces of vomer and perpendicular plate were harvested and placed over the dorsum. Segments were ranging from 0.75 to 1.0 cm in length and approximately 2 mm in width. Smith reported on 25 cases with excellent results at 4 years follow-up, with no complications noted and no resorption detected.

Iliac crest grafts had frequently been used for nasal reconstruction when osseous material was required. However, this required a second surgical site that was often painful to patients. In addition, iliac bone grafts diminished in size over time and became more susceptible to fracture as the cancellous portion resorbed, leaving a partially collapsed cortex.

Recently, split calvarium bone grafts have gained popularity. These grafts are a large source of material for grafting and have the further advantage of providing excellent structural support and a high level of tolerance[86]. Several recent experimental studies have concluded that autogenous onlay bone grafts of membranous origin (cranial grafts), orthotopically placed, are less resorptive than those of endochondral origin (iliac crest graft), heterotopically placed. It remains unclear though, whether the superiority of the membranous bone grafts was a function of embryonic origin, graft morphology, graft orientation, or a combination of these. Despite the need of a second surgical site as a prerequisite, in contrast to iliac bone grafts, calvarium bone graft is cropped from the same operative field as the rhinoplasty. It was also demonstrated that there is a difference in resorption between membranous bone such as frontoparietal calvarium and endochondral bone such as iliac crest. Membranous bone (calvaria) grafts either persist in their entirety or increase in size, whereas endochondral bone (iliac) grafts resorb. This became obvious when grafts onlayed to rabbit’s skulls demonstrated significantly alternate patterns of graft resorption and deposition at identical evaluation times.

Contrasting grafts of membranous and endochondral origin with identical orientation and morphology, revealed statistically significant differences between all surface areas, volumes, and weights at both 1.5 and 3.0 months.

Full-thickness circular bone plugs were harvested from the frontal parietal calvaria (membranous bone) and the iliac crest (endochondral bone). The grafts were placed in either subcutaneous or subperiosteal pockets in the craniofacial region. In both recipient locations and for all time intervals evaluated, bi-cortical membranous bone retained or raised its volume while bi-cortical endochondral bone consistently resorbed. Despite the apparent difference, the significance of the difference is unspecified since no statistical evaluation of the data was performed.

On the other hand, contrasting uni-cortical endochondral bone with bi-cortical membranous bone demonstrated that bone of membranous embryonic origin, when orthotopically grafted, was superior to that of endochondral origin, heterotopically grafted, when placed on the skull. Nevertheless, there was no care taken for control or contrast reciprocal graft morphology or the orientation of the uni-cortical graft.

Inspection of the gross morphology of freshly harvested bone-graft specimens of rabbit calvaria and iliac crest involves a critical difference in the cortical to diploe ratio between them. Moreover, the bony architecture of the diploe in membranous bone is a dense honeycomb of relatively thick, compact bone that differs from the thin, non- interfacing spicules of compact bone found within the cancellous space of endochondral bone.

Cortical bone grafts are known to undergo osteoclastic resorption prior to appositional bone formation. The gross morphology of the graft may affect this process. Thus, in bi- cortical iliac grafts, the small, compact bone struts set in the cancellous portions of the endochondral bone are rapidly resorbed, thereby allowing inward collapse of the two relatively thin cortical plates. In contrast, a bi-cortical membranous calvarial graft, with a relative paucity of diploic space (cancellous equivalent) and thick, intra-diploe osseous struts mechanically resists this collapsing mechanism, thereby maintaining original volume and acting as a template for osteogenesis, i.e., osteoconduction.

Finally, uni-cortical endochondral grafts consist only of a single thin, cortical plate and small, compact osseous struts that transverse the cancellous space to retain graft surface area and height. In contrast, unicortical membranous bone has both a thicker cortical plate and thicker intra-diploe osseous struts. Thus, the relatively thin cortical plate and supports of the endochondral iliac crest graft are probably more susceptible to resorption prior to appositional bone formation, which results in a loss of bone height and surface area, than the more robust calvarial grafts.

Powell and Riley[87] reported resorption rates for calvarium bone within a range of 20 to 30%. Calvarium bone appears to be an excellent choice for subtotal and total nasal deformities and a reasonable alternative when sufficient cartilage is unavailable. However, it is not without drawbacks. These include increased surgical time and complexity, donor site morbidity, difficulty in shaping the graft, graft warpage, and resorption[88].

On the incidence of cells in human tissue grafts failure to survive transplantation, the graft structure inclines to resorption and substitution by connective tissue or mixed connective-tissue derivatives. Substitution may be quite slow, as in the case of cartilage and bone, or rapid, as in the case of muscle and fat grafts. Generally, deceased grafts composed largely of inanimate intercellular material incline to resorption more slowly than dead grafts composed largely of cellular elements. Exceptions to inclinations to fibrous tissue substitution of deceased grafts may occur when a dead bone graft is in contact with living bone, or when a deceased nerve graft is in accurate contact with living nerve. Therefore, it seems that bone and nerve own larger reparative strength than many other human tissues in that deceased bone and nerve grafts might be substituted in part, as the same type of tissue by infiltrating elements from the host bone and nerves.

Furthermore, the generally accepted point of view has been that the cells in autogenous bone grafts transplanted in contact with living bone die, and that the matrix of the graft serves as a scaffold which is invaded and replaced by ingrowing host cells from the adjacent host bone or from its periosteum. This conviction implies as well that the cells in autogenous bone grafts transplanted in contact with unlike tissues depart, and that the deceased graft structure is substituted by host fibrous tissue. The validity of this belief, however, is open to question since it is not consistent with certain observations regarding the behavior of bone grafts.

There is certainly a great deal of evidence suggesting that the host bone may replace those portions of a graft which fail to survive transplantation, and it seems that tile specific calcified structure of the graft is kept by surviving bone cells in the graft aided by cells from the adjacent host bone or its periosteum. The extent of this aid by "creeping substitution" from the host bone probably depends upon the number of surviving bone cells in the graft, and thus bone grafts might ultimately consist of surviving graft cells reinforced by replacement cells from the host bone.

Bone grafts which survived as bone after transplantation adjacent to unlike tissues originated from the vomer, nasal bones, and from the ethmoid. The former two are membranous bones, while the latter arises through endochondral ossification.

Nevertheless, a common characteristic of the vomer, nasal bones, and perpendicular plate of the ethmoid, is that there is hardly any evidence of bone regeneration when portions of these bones are subtracted.

Thus, it is possible that the cells in bone grafts which lack regenerative power are endowed with a tenacious capability to maintain their calcified matrix regardless of contact with bone, whereas the cells in bone grafts with regenerative powers do not seem to possess this ability unless the graft is adjacent to living bone.

Thus, bone cells at some point in their differentiation process must of have acquired different code scripts, that define later action under the conditions of free transplantation.

2.3 HOMOLOGOUS CARTILAGE GRAFTS

The human immunodeficiency virus (HIV) crisis has all but vanished the use of cartilage banks, where a surgeon would chemically sterilize with methiolate, alcohol, or other chemicals resected septal cartilage for use in subsequent patients. Today, most homograft cartilage is irradiated costal cartilage. Cartilage is acquired from donors meeting the criteria for organ donation. Specimens are tested for various viruses. The cartilage is then placed in sterile saline and exposed to 30-60 kGy g-waves to destroy cellular elements and pathogens, including viruses[89]. This approach has the advantage of ready availability and does not require an additional surgical harvesting site.

Absorption of homograft cartilage has long been cited as a major drawback to its use. Resorption often depends on the means of preservation of the cartilage. Studies have reported a 42% absorption of methiolate preserved cartilage, whereas irradiated cartilage has provided much greater survival rates[90].

The same authors reported experience with irradiated homograft costal cartilage implants, 22 of which were nasal; 1.4% had partial resorption, and 0% showed warping. These findings were consistent with those reported by Lefkovits[91] in which irradiated homograph costal cartilage was used in 27 patients; 83% had good to excellent results, 14% showed warping, and 0% demonstrated resorption[2]. Currently, irradiated costal cartilage harvested from human donors is the principal homograft material used in the nose.

Resorbed cartilage is to some extent replaced by fibrous tissue and might make the resorption unnoticeable. The role of perichondrium in the prevention of absorption has not been clearly shown. Authors have reported cartilage protection with intact overlying perichondrium in 25 cases followed from 2.5 months to 37 years. However, another study showed cartilage survival not to be related to the presence or absence of perichondrium. Peer showed that cartilage placed in an area of greater muscle activity or exposed to greater tensile forces tends to undergo more resorption. Cartilage grafts that have been crushed to facilitate contouring tend to undergo significantly more resorption as well.

Another alternative to native tissue for graft material is irradiated costal cartilage harvested from human donors. Homograft cartilage functions like a solid alloplast. Cartilage is obtained from donors who meet the criteria required for organ donation. The specimens are tested for VDRL, hepatitis B, HIV, tuberculosis, and slow viruses. They are then placed in sterile saline and exposed to 30-60 kGy gamma waves, destroying cellular elements and pathogens, including viruses. It is subtracted from sterile saline solution and placed in antibiotic solution immediately before using the implant. The cartilage is denuded of debris and the rough edges are smoothed with a knife. After this preparation, the antigenicity is very low and the resultant immune reaction is minimum. Systemic antibiotics are administered intra- and post-operatively.

Availability, relative low cost, and easy storage are among the benefits that characterize homograft rib cartilage. It is easily shaped and carved and may be used in areas where tissue strength is of importance for structural support, such as in improving nasal valve collapse or improvement of nasal tip projection. While resorption over time might prove to be problematic with this material, infection and extrusion rates have been generally low. Another major deficit in using this material is the public fear of disease transmission, although no such case has yet been reported.

Fibrous ingrowth may replace part of the resorbed homograft cartilage. There are indications that the reported varying graft resorption rates are related to graft location on the face. Implanted cartilage subject to recurrent trauma or mobility (with following inflammation) such as the tip, is more inclined to absorption than at fixed spots, like the dorsum. Nevertheless, the precise resorption rate of irradiated homograft costal cartilage is still unclear. Results from long-term follow-up studies range from minimum

resorption rate over an 11-year period to 75% resorption after 9 years and 100% resorption after 15 years. Another study looking at 122 patients with caudal septal, nasal valve, lateral onlay, alar rim, or dorsal onlay grafts reported only four cases of resorption over an average follow-up time of 15 months. Clinically evident resorption and warping of the cartilage graft becomes apparent by 3 or 4 months. Long-term follow-up studies of homograft cartilage shall determine the extent of its future use in nasal implantations.

Resorption is related to granulation tissue surrounding the implant, which undergoes transformation into a fibrous capsule that halts further resorption. Thus, it might be beneficiary to avoid utilizing systemic steroids in nasal surgery when homograft cartilage grafts are considered.

Homograft cartilage benefits are : no surgical site is needed in order to crop the grafts, and it does not occlude utilization of autogenous cartilage grafts at a later date. The disadvantages of homograft cartilage are a potential immunologic response (i.e., it is not tolerated as well as host tissue), it must be contoured and shaped, and it is susceptible to warping and resorption.

2.4 HETEROLOGOUS CARTILAGE GRAFTS (XENOGRAFTS)

Zyplast (Collagen Corporation, Palo Alto, CA) has been used as provisional implant to offer a veil in contour anomaly of the nasal dorsum during the convalescent period of rhinoplasty and to temporize before revision surgery. It also may be supportive to act as a spacer to prevent scar contracture of the nasal tissues before enlargement with a more long-lasting implant. The expense and transitory longevity are negative points for its use. Moreover, a skin test is fundamental before injection to identify patients who might be receptive to bovine collagen. Some surgeons prescribe two skin tests separated by 30 days to identify additional patients who might exhibit susceptibility.

Purified acellular human dermal graft (AlloDerm, Life Cell Corporation, Woodlands, TX) is an acellular graft yielded from fresh human cadavers by a proceeding that extract the epidermis and the cells from the dermis without altering the extracellular architectures. Despite originally used as a dermal scaffolding for skin grafts in scalded

patients, it has been advocated as a dorsal onlay graft and for use as a draping graft in conjunction with other dorsal implants. The long-term resorption rate is unknown[2,92].

2.5 ALLOPLASTIC IMPLANTS

Maas et al.[2] proposed that the clinical efficacy of implant material over the long term is dependent on the perseverance of the material to chemical degradation such as by hydrolysis and other redox reactions, as well as physiologic cellular activity directed against the material. The penetration ability of the implant materials plays a crucial role in host tissue ingrowth and subsequent stabilization. Furthermore, such factors as thin skin overlying the implant, scarring of the tissue bed, and the architecture facilitating stabilization of the implant play influential roles in determining the longevity of the clinical result[2].

Absortive implants have a larger risk of immediate infection, as there is augmented surface area for bacteria cohesion. However, porous implants have less late-stage infections, as the fusion of host tissue into the implant pores allows entry to the site for immune response mediators[2].

The vast majority of alloplastic implants often used in nasal reconstruction are polymeric materials.

2.5.1 SILICONE IMPLANTS

Silicone implants have long been used to correct significant dorsal abnormalities. Tissue reaction to solid silicone implants is portrayed by a subdue fibrous tissue capsule without tissue ingrowth[93]. When a silicone implant is entered in the nasal dorsum, it is subject to trauma and mobilization. In spite of these implants having been used in vast numbers with excellent results, they are subject to moderate to intense ongoing inflammation, seroma formation, and extrusion. Extrusion rates for silicone implants have been reported as high as 10% for dorsal implants and 50% for columellar implants[94,95].

2.5.2 MERSILENE IMPLANTS

Mersilene is a polyethyleneterethalate, which is a meshed polymer. It enables fibrous tissue ingrowth, thus, more arduous to subtract. This material can be used as a draping graft over the dorsum or the nasal tip area, or it can be rolled for utilization for dorsal augmentation. The following technical aspects should be contemplated when using rolled mesh. First, it has tapered ends. Second, the implanted alloplast must be placed away from the incision, to minimize exposure. Third, medial osteotomies can increase fibrosis and help position the rolled mesh. Finally, caution must be exercised in utilizing this technique in revision rhinoplasties, where there is less vascularity over the nasal dorsum, to prevent difficulties in wound healing and implant extrusion. Gilmore[96] has proposed the use of alloplastic mesh as a “draping graft” to cover dorsal implant irregularities and more contouring uniformity.

2.5.3 E-PTFE

Broadened penetrable polytetrafluoroethylene (e-PTFE) is often used for nasal augmentation[97,98]. Gore-Tex constitutes an exquisite alternative to autogenous tissue due to its biocompatibility, ease of use, minimum infection rates and lack of ejection or absorption. Nevertheless, long-term success and complication rates are still lacking, and enormous numbers of patients with longer follow-up periods are required.

Gore-Tex is an expanded form of polytetrafluoroethylene developed by W. L. Gore in the late 1960s. It has a microporous architecture with pore sizes ranging from 10 to 30 μm, thus allowing for tissue ingrowth and stabilization of the graft while due to the lack of a significant inflammatory reaction, it allows easy subtraction when needed. Since 1972, Gore-Tex has been used without a reported case of rejection or carcinogenesis. It has been used extensively for hernia repairs, abdominal wall defects, and rectal and vaginal prolapses as well.

The complication rate is quite low in the literature. Complications such as infections or foreign body reactions can develop with the use of Gore-Tex, but resorption problems as well as changes in shape and contour met with cartilaginous or bony grafts do not occur. In the case of infections that do not response to antibiotic treatment, the Gore-

Tex implant should be subtracted. Tissue ingrowth and the inflammatory processes can make subtraction challenging.

In the case of nasal dorsum enlargement, Gore-Tex can be a suitable synthetic material, specifically in selected cases. It is useful for secondary touch-up procedures, which may be perforated as an office application with the patient under local anesthesia. Due to the fact that it is a foreign material, it possesses an average of 2.5% to 3% complication rate.

Although the implant is soft, resulting in a natural feel, it yields excellent support over the dorsum and can be utilized for tip grafts and even in the columellar area. The implant is handily contoured and comes in a variety of thicknesses, making it applicable to a variety of contouring problems. e-PTFE is considered the implant of choice for reconstructing modest to large dorsal flaws, since it is readily disposable, while reducing operative time as well, as no second surgical site is of necessity in order to crop a graft. The implant is handily contoured and very well tolerated by patients. When stacked autologous cartilage implants are utilized over the nasal dorsum, grafts can become dislodged, and deformities result when sunglasses or reading glasses are worn. This problem is much less likely with the solid alloplastic implant.

The implant can be easily situated through an internasal incision with the aid of chromic guide sutures affixed to a Keith needle to help in properly positioning the implants. The implant is first soaked in antibiotic solution before being placed; prophylactic antibiotics are proposed. When such implants are used, it may be proper to contemplate prescribing prophylactic antibiotics for patients who sustain dental work, in order to minimize the possibility of bacteria seeding the implant.

CHAPTER 3

INTRODUCTION

Conservative surgeons, believe in making natural-appearing, well-supported, well- balanced noses. As a result, often the need to add something to create projection, balance, or support is desired. The use of autologous septal cartilage is possible. There have been times, however, when there just is not enough septum to do the job. So, on occasion, the use of implants has been applied. Therefore, placing implants in the nose should be scrupulously avoid.

3.1 DEFINITIONS

Grafts are biologic materials, either living or non-living. They may be yielded from the host’s own tissues (autologous), derived from another individual of the same species (homologous), or derived from a different species (heterologous).

Implants are synthetic materials that have been authorized for implantation into the nose, and which keep their characteristic composition within the tissues.

Notwithstanding the fact that every article ever written about nasal reconstruction suggests that autologous grafts are superior, all the available surrogates, as well as those used not so long ago, which are no longer available, are outlined in the following.

3.2 LITERATURE EXPERIENCE

3.2.1 GRAFTS

Maas et al.[2] state that “autograft cartilage is the most commonly used material in rhinoplasty and remains the standard against which all others are compared.” There is compliance with this proposal among experts. When used to enlarge or support the nose, autogenous cartilage has proved to yield long-lasting clinical correction and to be very opposing to infection or extrusion[99]. Tardy[100] reports more than 6000 cartilage

autografts implanted, with zero rejection or infection rates: “uncommon complications … arise from technical errors that tend to zero as experience grows ... No important complications have presented from the inherent monadical cartilage properties itself.” However, the subject of technical errors is critical. Sheen and Tardy spend considerable amount of time discussing technical contemplations to ensure adequate blood supply, and avoidance of wrong positioning and visibility, the two most often problems with autografts.

3.2.2 IMPLANTS

The medical bibliography is teeming with articles developing the usage of one or another kind of new material. As time passes by, new implants continue to be developed, which would suggest that no one has been absolutely satisfied with the materials that were previously advanced. failures though, are not published with the same timeliness as are the initial successes.

Typically, articles that tout the utilization of one or another implant report complication rates of less than 5%[101-103].

One study claims that complications requiring removal occur in approximately 2.7% of implants. Thus, it appears that Gore-Tex is an excellent material for rhinoplasty.

Two points seem particularly relevant:

(1) six complications occurred in secondary patients and only one in primary cases, and (2) seven cases or 3.7 percent (7 of 189) needed implant subtraction due to infection or “soft-tissue reaction”. It would seem that the patient and the surgeon must be willing to accept a 2.5% infection rate possibility requiring subtraction within the first 3 years. This infection/extrusion rate stands in marked contrast to an expected infection rate of 0.1% using autogenous grafts, which rarely require removal. Therefore, Gore-Tex does present greater risk than autogenous grafts.

Another study reports that complications occurred in five patients out of 187 (2.6%). Three early and two delayed infections necessitated implant subtraction from patients that had compromised skin–soft tissue envelopes secondary to heavy smoking, cocaine abuse, or prior surgery. One case of an overly enlarged nasal dorsum and tip required

implant subtraction, diminution, and reinsertion. All implants were easily subtracted. No other complications involving implant extrusion or skin erosion have been reported. Medpor implants allow for fibrovascular ingrowth, that permits the implant to be stable. Porous polyethylene implants are well tolerated and supply an excellent material for nasal reconstruction.

One patient undergoing revision surgery developed erythema and swelling around an alar batten implant 2 weeks post-operatively and needed implant subtraction. A second patient, with a history of heavy tobacco use, developed erythema around an alar batten 3 weeks post-operatively and required implant removal. A third patient refused placement of Merocel packing. Postoperative edema of his marginal incisions progressed to erythema at 3 weeks and necessitated a unilateral alar batten subtraction. Two patients developed delayed infections (1%). One patient with a history of collagen vascular disease developed erythema around a dorsal implant 3 months postoperatively. The infection resolved after a course of oral antibiotics; nevertheless, when the erythema returned the patient was treated with intravenous antibiotics. The erythema again resolved but returned after cessation of antibiotics, and the dorsal implant was subtracted permanently. Another patient originally presented with a large cocaine-induced septal perforation and saddle nose malformation. At the patient’s request, only aesthetic reconstruction of the external nose using multiple PHDPE implants was perforated. Three months post-operatively, the patient presented to the clinic with erythema of the nasal dorsum and a central dorsal swelling. The patient stated that she had sustained a severe sunburn to the nose a week before noticing the swelling and redness. The patient was administered broad-spectrum intravenous antibiotics. After 48 h, the erythema had progressed to the nasal tip and subtraction of only the nasal dorsal tip implant was perforated through an external rhinoplasty approach. Sharp scissor dissection permitted easy subtraction of the implant without injury to the overlying nasal skin. This patient, has not withstanded another implant subtraction and had a moderate course for 28 months. No further surgical reconstruction has been requested at this time.

Another patient (0.5%) was dissatisfied with the revision rhinoplasty result 1 year postoperatively. She felt that the nasal bridge was too high and created a dorsal hump. Subsequently, the dorsal tip implant was electively subtracted through an external rhinoplasty, sculpted smaller, and reimported into the nasal dorsal pocket. The patient

had an unproblematic course and is delighted with the surgical result 22 months after revision. No other entanglements (including distortion, exposure or ejection, or skin corrosion) presented in any other individuals. Ultimately, another study reported that of 101 nasal Proplast implants, four implants were subtracted (approximately 4%): one LS implant and three DS implants.

Reports of complications often come from other investigators, citing their own experience with implants inserted by other surgeons.

Things change pretty quickly on the nasal implant scene. An intercomparison of two excellent review articles published only 10 years apart points this up extraordinarily. A review article in 1987 by Adams[104] can be compared with similarly scholarly reviews by Kridel and Kraus[105] and Maas et al.[2] in 1995 and 1997, respectively. The following divide the critiques of these materials into two categories: Then and Now.

Despite little, if any, harm has been performed by properly utilized liquid silicone injections, much legal hay has been made of this substance. Immunity from abruptly being declared illegal, posing both the manufacturer and the practitioner at large risk appears not to be offered to any alloplast. What about the fact that Silastic implants are still in use in the nose, even though it is well reported that “in nasal augmentation its use is limited. Thin-soft tissue coverage, constant movement of the nose, and frequent midface trauma lead to an unacceptably large incidence of dislodgment and extrusion.

3.2.3 MERSILENE MESH UTILIZATION CASES

Patient 1: Placed through a transfixion incision to enlarge the premaxillary area, the implant became infected within 1 month of surgery and driven to drought whenever the patient was not on antibiotics. The implant was ultimately removed without a problem.

Patient 2: Rolled to quickly augment a dorsum accidentally over-shortened using an osteotome, this implant stayed in place but eventually swelled a little, giving the patient the notion of money wastage on a rhinoplasty. The implant was removed non- problematically, and the nose reshaped with satisfactory outcome.

Patient 3: Placed to amend a slight mid–third unilateral depression, this implant began to exude a foul odor noticed by the patient. Although there was no clinical infection,

one could see the graft fibers protruding through the inter-cartilaginous incision site. At first revision, the incision was reopened and grafts removed within 3 mm of the incision. The problem recurred after many months, and the remainder had to be removed. The excisions were technically difficult in both instances. The final result was acceptable.

3.2.4 SILASTIC

Silastic was known to possibly be problematic in the tip and the dorsum, but may be acceptable in the premaxilla. Two such implants were placed. Both lasted about 5 years:

Patient 1: Positioned in a secondary rhinoplasty to protrude a nasal tip complex, the implant carried out the goal. Over the course of years, however, beginning months after insertion, foul drainage would occur from a small portion of the incision. Antibiotics worked for a time, but infection would always recur. Due to the fact that the patient loved the appearance, the implant was ultimately removed. The tip maintained in place, requiring no further actions.

Patient 2: This patient had not undergone surgery but did have a drug-induced septal perforation, and resultant loss of premaxillary support. Placement was similar to that used in patient 1. This patient did well until 5 years later, when she presented with asymptomatic exposure from the region of the hemitransfixion incision. The implant was subtracted, while no further action was of necessity.

3.2.5 GORE-TEX

Gore-Tex is currently in fashion in the literature. Eight implants have been placed. Three required removal, with the following results:

Patient 1: A 2-mm piece of reinforced Gore-Tex was placed into the nose of a male who had injured his nose in Vietnam. He had endured a rhinoplasty for an acute condition, leaving him with an over-shortened dorsum and valve collapse. The implant was placed through endonasal incisions. His airway had proceeded well for 1 year as his appearance improved. At that time, he began experiencing episodes of nasal swelling. The implant could be seen protruding from the inter-cartilaginous region on

the left side. The area was explored and the graft was reduced. He was provided with both oral and intravenous antibiotics consistent with cultures obtained. After several months without symptoms, the nasal swelling and erythema recurred. The implant was removed. No further actions were of necessity.

Patient 2: Rolled Gore-Tex was utilized to enlarge the pre-maxilla in a primary rhinoplasty. After an initial good result, the material instinctively became infected, resulting in foul drainage from the transfixion incision. The implant was removed after two interim successful courses of antibiotics. The nose has maintained its position.

Patient 3: Reinforced Gore-Tex was used as a spreader in a 55-year-old man who had had previous septoplasty, internal valve collapse and needed support in conjunction with his cosmetic/functional rhinoplasty. The grafts functioned nicely for about 12 months, after which a foul odor alerted to the extrusion of one of the grafts through the septal mucosa. He had a great deal of nasal dorsal and columellar swelling with these infections, and this was his greatest concern. Ultimately, despite antibiotics and graft trimming, the implants required removal. The swelling retreated, satisfying the patient.

Although no serious sequelae have resulted from the implant experiences, the resulting troublesome procedures do not seem to be worth the time saved or donor site morbidity saved. What about recipient site morbidity?

3.3 WHY WE WANT TO USE IMPLANTS—EVEN THOUGH THEY AREN’T GOOD FOR US

Sometimes, after getting all one can get out of the septum, one just doesn’t have enough material to build the nose one is looking for. One may not want to open the ear and try to fuss with crooked cartilage. One wants to be able to open a box and pull something out that one can comfortably shape into what one needs, which won’t take a lot of additional time, that will give the nose the volume or the support needed, and that will complete the procedure before the vaso-constrictor wears off, and the bleeding starts.

Despite the fact on nothing being wrong with that logic, as it stands, it is short-sighted. It will get a happy patient, but one could return some day not being as happy.

3.4 CLINICAL SITUATIONS CALLING FOR IMPLANTS

The consecutive five cases suggest specific situations in which grafts may be demanded.

Case 1: A revision rhinoplasty has been performed in a patient who has had a dorsal overreduction, but nothing is left in the septum.

Case 2: A primary rhinoplasty does not have enough good pieces of septum to make a big dorsal graft or to make the tip grafts.

Case 3: premaxilla enlargement.

Case 4: structure and lengthening, without enough septum.

Case 5: slight contour correction after a rhinoplasty.

3.5 GRAFT ALTERNATIVE STRATEGIES

Several alternating strategies for use of graft material might be contemplated. The consecutive suggestions are proposed for specific cases, such as the five described above.

1. Plan to take some other tissue: Let the patient know that you will need an alternative and plan to take what you think will be needed.

Applies in cases 1, 3, and 4.

2. Stretch two pieces of septum into one: Godfrey[106] presents a technique for splicing two lengths of septal cartilage together.

Both open and closed rhinoplasty approaches are utilized. The open approach affords excellent exposure for graft procurement, preparation of the recipient site, and fixation of the graft into that site, but the mortise/tenon method is independent of the rhinoplasty approach. The quantity of septal cartilage that is required for the enlargement is harvested sub-perichondrially in as few pieces as possible. Most full-thickness septal cartilage varies between 2 and 3 mm in thickness.

A dorsal pocket was deployed in order to host the graft. This is done sub-perichondrially as well as subperiosteally to as large a degree as possible in order to retain a thick soft tissue cover for the graft. A sizing template as described in the literature is fabricated. This diminishes both the amendment need of the graft pursuing assembly and the trauma to the graft from reiterated inductions into the dorsal pocket. Dimensions are tailored to the needs of each patient but, typically, about 4 cm is adequate to reconstitute the dorsal line. Widths vary from 0.6 to 1.0 cm and heights from 2 to 5 mm. The template is designed to begin at the radix and terminate at the cephalic margins of the alar cartilages.

The available cartilage pieces are carefully inspected and oriented in different directions to determine their best arrangement for duplication of the template. They are then carved to fit the template. The dorsal epiphany brinks of the grafts are circled with a blade and burr to finished circumscription. Only then are the mating joint surfaces fashioned. A biplanar mortise/tenon structure is sought; therefore, a V-shaped joint is preferred because it can be constructed rapidly. Approximately 5 mm of overlap (or joint length) seems ideal for the primary or transverse mortise: Less overlap compromises structural stability and more overlap wastes cartilage. The secondary or anterior/posterior mortise (tongue-in-groove) requires only 1-2 mm of overlap. Cleverness in joint design can be helpful where the basic shape of the disposable cartilage pieces make joint configurations other than the basic V shape less wasteful of cartilage. Regardless of the joint shape, the aim is a tight fitting nonlinear junction distributed over 5 mm or more along the long axis of the graft.

Once the joint configuration is selected, the primary mortise is carved into one piece of cartilage at right angles to the flat surface. This piece is then placed upon its mate-to- be and the two are stabilized with each other with needles or forceps. The second piece is then cut with the first acting as a guide for the knife. This assures proper fit at the joint. The mating edges of the corresponding pieces are then readily beveled and grooved freehand with a #15 blade to create the secondary (tongue-in-groove) mortise. Three simple 6-0 Prolene sutures are utilized to secure and stabilize the joints. Figure- of-eight sutures are unnecessary and practically unwanted since they block the snug fit of the joint. The compressive forces of the sutures are complemented by the mortise/tenon geometry and an impressively strong, stable structure is created.

Small-caliber taper needles are utilized because they minimize the risk of cartilage laceration. The short BV-1 needle "double-armed" on 6-0 Prolene disposable is preferred. Proper sequence of needle passage locates knots on the deep side of the graft. Loupe magnification and an adequate carving block have raised control and minimized operative time.

The structural integrity of the joint is tested with manual pressure on the united graft prior to its placement in the nose. On properly carved and sutured onset, the joint seems to be even stiffer and more resilient than the native cartilage. If such stiffness is lacking, the precision fit of the joint may require improvement. Additional fragments of cartilage are stacked and sutured beneath the mortised graft as needed to achieve the proper dorsal line height. Where this is highlighted, it might be necessary to modestly successively raise the width of deeper layers to procreate a gently rounded dorsal contour that integrates smoothly with the nasal pyramid. This prevents unwanted prominence of the graft edges.

Could work for cases 2 or 4.

3. Try a pericranial graft: Ioannides and Fossion[107] report this technique in which a covered incision can administer large quantities of effortless stackable firm tissue.

A free pericranium graft was cropped, the size of the defect. After preparation of the right parietal area a slightly curved incision was made through the scalp layers the pericranium being left intact. Obtuse dissection exempted the latter from all overlying layers scheduled to be cropped. The graft was outlined, sharply separated from the remaining pericranium and raised from the underlying calvarial bone with a periosteal elevator. The plague was shut in layers utilizing a medium sized Redon drain.

The defect was approached through an inter-cartilaginous incision and tunnelled over its entire surface. The pericranium graft was rolled up, adapted to the shape of the defect, inserted into the tunnel and secured with two 5.0 Prolene non-absorbable sutures. The intranasal incisions were closed with 4.0 Catgut. The nose was covered for two days with Steristrips over the dorsal or lateral nasal skin. In a case of a patient with sore nose the pericranial graft covered the whole nasal dorsum.

For all cases in which mesh would have worked, such as 1, 2, and 3.

4. Use of an autogenous rib: An exceptional report by Sherris and Kern[108] details the harvesting techniques as well as some of the uses for rib for dorsal grafts, columellar struts, and tip grafts. The extra incision should be non-problematic if the patient is prepared for it.

Excellent choice for cases 1, 3, and 4. Overkill, perhaps, for cases 2 and 5.

5. Alloderm utilization: Is it a graft or an implant? Yes, it comes in a box, but it is a biologic material and is incorporated into the host tissue. Although “the jury is still out” on this, it is believed it could be useful for premaxillary augmentation, dorsal enlargement, lateral wall fill, and perhaps tip grafting as well. It is not a structural graft.

Applies to cases 1, 2, 3, and 5.

6. Use autologous fat: Coleman[109] and others have refined the techniques of autologous fat transplantation to the point where long-term corrections of volume deficiency can be reliably amended. Fat is harvested by syringe and small cannulae, handled minimally, and injected through small needles or cannulae.

A wonderful technique for case 5, possibly an alternative to revision rhinoplasty in the first case.

7. Possibly try auricular cartilage: This material has not been mentioned until now. Endo et al.[110] reports 1200 cases of augmentation rhinoplasty in Japanese and detail the methods utilized for work off the troublesome cartilage spring.

Initially, a linear incision at the back of the ear is made and the cartilage graft is designed. Nevertheless, when so doing, it is crucial that the upper border of the graft never pass the superior crus of the anthelix in order to avoid an ear malformation.

The width of the cartilage graft is designed to be 3.8 mm, but the length depends on the individual case and ear size, although it generally ranges from 30 to 40 mm. Usually, we can obtain two pieces of cartilage graft, from one ear. However, if more than 3 pieces are needed, it is safer to excise an additional piece from the contralateral ear, because of the possibility of ear malformation. Thus, care must be exercised.

Successively, numerous transverse parallel incisions are made on the superficial side of the cartilage graft. The release of tension on one surface corrects the wave and makes

a straight line. The upper and lower edges of the cartilage are beveled on the side that will be adjacent to the skin.

Ultimately, stacked cartilage using a rim incision is inserted, but the number of stacked cartilages also depends on the individual case. The average number is two, but in the case of a severely flat nose, sometimes up to four pieces of cartilage are stacked up. In such case, no internal fixation is used.

Tardy[100] and Sheen[99] go into great detail on their handling of auricular cartilage so that it can yield either structure or contour reinstatement. Very useful for cases 1, 2, and 5. May work to provide length (case 4) for Sheen, but this is possibly a stretch for the ordinary surgeon.

CHAPTER 4

Since the future of the past described in p. 52 of the present thesis, constitutes the present, the following literature brings us up-to-date.

Pak et al.[111] indicated in 1998, that alloplastic nasal enlargement via silicone elastomer (Silastic) is performed quite often in Asia. Despite the fact that silicones are bio-inert, they have been implicated in a number of adverse reactions after implantation.

In the pass of time, it has been utilized with varying degrees of success worldwidely, and still retains its popularity material for nasal augmentation. Late complications have been reported, such as lymphadenopathy. Moreover, there is proof of small silicone particles migrating to the surrounding tissues from the Silastic materials within the joint prostheses and the lymphatic spread has been associated with lymphadenopathy, fever, and even lymphoma. Apart from displacement and angulation, numerous long-term complications have been recognized, the most frequent being delayed infection, erosion and extrusion while recurrent facial oedema and dorsal nasal cysts have been reported less commonly. In spite of the relatively low observed morbidity rate in alloplastic dorsal augmentation in Asian patients, it is advised that this implant should only be utilized really carefully on an individual basis. Alternatively, autogenous grafts, including bone, cartilage, fat or fascia should be preferred.

Moreover, Lovice et al.[112] in 1999 described the suitable implant material as one that ought to be biocompatible, strong, and elastic. Concurrent facial implants may be categorized into four groups: autografts, homografts, xenografts, and alloplasts. Autologous grafts are materials derived from the patient. Homografts refer to tissues obtained from a different donor of the same species. Xenografts imply that the biomaterial was harvested from another species. Xenografts are not used in rhinoplasty or nasal reconstruction and, therefore, will not be discussed further. Alloplasts are materials that are semisynthetic or entirely synthetic such as polymers etc.

In search of manners to correct the deviated nose, Emsen et al.[113] in 2008 stated that a complex cosmetic and functional problem, constitutes a challenge for the rhinoplasty surgeon. Despite the fact that corrections using a wide range of surgical techniques to straighten the nose and maximize nasal function have been proposed, recurrence is frequent due to the cartilage memory and scar contracture. Thus, in order to prevent

recurrence and retain the correction of the septum, a stable, strong, and permanent support with the ability to keep its given shape after placement on one or both sides of the septum is of utmost importance.

For this reason, the use of a personally-shaped graft in conjunction with high-density porous polyethylene (Medpor) was planned and utilized. Currently, Medpor is readily disposable on the market as a thin plain sheet (0.85 × 38 × 50 mm) that may be cut to an appropriate size for these grafts. Ingrowths of fibrous tissue inside and around Medpor stabilize the upper lateral cartilages and septum in their newly corrected position and retain the corrected/straightened position.

The technique involved the release of all the deforming forces; correction of the deformed parts of the septum, leaving an L-strut; straightening of the septum by scoring the concave sides and resecting edges and thick obstructing parts; performing osteotomies; and use of an E-M shape with Medpor armor graft to keep these corrections and overcome cartilage memory and scar contractures. E-shaped Medpor armor grafts were covered laterally with mucoperichondrial septal flaps and dorsally with upper lateral cartilages (sutured to each other). The grafts retain the corrected position and appearance, hence leaving the surgeon with no postoperative complications or recurrences. They provide strength on each side of the dorsal septum after correction of even the most difficult malformations. Due to the fact that all parts of the grafts were covered with septal mucosal flaps laterally and upper lateral cartilage above, as well as the non-contact with skin and subcutaneous tissues, there was no dorsal extrusion or irregularities observed, even in Caucasians. The use of Medpor is provided with the increased flexibility in graft design and dispensability.

The surgeon may in an easy and rapid manner modify the graft to the necessary and/or suggested shape without compromise. Due to the fact that Medpor is non-absorbable, fibrous tissue grows inside and around it, stabilizing the upper lateral cartilages and septum in their new corrected position and maintaining the corrected/straightened position. E-M shaped Medpor armor graft is safe, cheap, effective, reliable, reproducible, and ready for use. Moreover, these grafts provide both septal perfusion by mucoperichondrial flaps and septal framework confined by the limbs of E-M shape of the Medpor implant. The central E-M part ideally provided the natural dorsal curvature of the nose. The E-M shape also has role as a spreader and batten graft in

nose. In autogenous grafts, it is rather hard to shape the E-M, but this could be very easy with Medpor implants. Also, it avoids donor area problems and extra surgery for graft harvest.

Furthermore, Agostini et al.[114] in 2010 stated: there is no doubt whatsoever, that homografts and allogenic implants supply a simple, rapid and efficient method of enlargement compared to autografts, which involve additional surgical procedures, extra operating time, comorbidities and surgical skills; in contrast, rejection, infection, mobility, dislocation, exposure, and extrusion represent common surgery complications. Utilization of allografts for structural support of the nasal framework commonly results in failure due to these complications, thus necessitating removal and replacement with autografts. An exception is represented by skin substitutes: homologous acellular dermis and a dermal regenerative template may be utilized as a single layer or stacked in multiple layers, depending on the degree of soft-tissue replacement necessitated; these soft materials are used to camouflage autografts and rough surfaces from previous surgery but are not used for structural support. Nevertheless, most reports in the literature share incomplete follow-up of patients and no alloplastic implant has yet proved successful, while the complication rate matches that of autografts, which are less prone to be extruded.

In 1954, Peer noted that most allografts were constantly being buried by one group of surgeons and then constantly being revived by another group of surgeons after varying periods of time. In 1997, Collawn et al. discussed the raised utilization of autografts over allografts during a decade of experience. A wide range of implant materials are disposable in order to shape and enlarge the nose, but long-term retention and stability are poor and can depend on the recipient site as well: the nasal tip is more predisposed to complication due to its mobility; a surgical nose is predisposed to a higher complication rate because the impaired soft tissues are scarred, less vascularized, and thinned.

The rate of complications is insignificant compared with the irreversible tissue destruction that results in permanent malformation to the patient. Any complication rate, however small, cannot though justify a procedure that is possibly disfiguring to patients when a better alternative is available - the patient’s own tissues. Thus,

experience suggests that autografts are the material of choice in spite of their resulted imperfection or complications.

Additionally, Niechajev et al.[115] in 2012 reported that Medpor is a biocompatible implant material used as a skeleton substitute. Operation with Medpor in the facial region is a secure proceeding. Currently, Medpor seems to be the best alloplastic material dispensable as a facial bone substitute. It is long-lasting, with a low frequency complication rate, morbidity similar to procedures involving autologous grafts, and high overall patient satisfaction. Since reports on the long-term host tissue tolerance of Medpor are sparse, this study aimed to do so. Medpor is made from high-density polyethylene, with a fusion process to procreate a relatively pliant fuselage of ranging in size interconnecting pores. Polyethylene makes up approximately one-half of the implant volume(54 %), and the remaining pores are filled with air. The interconnecting, multidirectional pore structure of the implants allows quick ingrowth of vascularized tissue, with collagen deposition that ultimately forms a highly stable complex resistant to infection, exposure, and distortion by contractile strengths of the surrounding tissues. The firm nature of the material allows carving with a large scalpel blade without collapse of its pore structure.

Medpor is almost as hard as cancellous bone at room temperature but has thermoplastic abilities. When submerged in hot (82–100oC) sterile saline for several minutes, Medpor implants can be bent to the desired shape, which becomes permanent after cooling. Medpor sheets may be sliced, and thicker implants can be carved with a bone cutter or cutting burr. Medpor implants are invisible through overlying tissue. The Medpor surface is rough, allowing to anchor it to the tissues in a desired location. This implant is insoluble in tissue fluid, has long-term structure stability, and does not resorb. Due to its high-density properties, Medpor also has high tensile strength, which resists stress and fatigue. Medpor utilization in facial reconstruction has numerous advantages. General anesthesia is commonly not needed because the implant is available from the shelf. The time spent in the operating room is substantially shorter than for cases involving harvest of an autologous bone or cartilage graft, which also increases morbidity. Furthermore, autologous graft procedures have an unpredictable resorption rate, with consequent relapse and the risk of warping always present.

The silastic rubber, proplast, paraffin acrylic, Teflon and other materials used in rhinoplasty have always failed to fulfill promised expectations of long-term support and biocompatibility. The result has been either instant or ensuing host rejection, infection, and ejection, with a commonly serious series for the patient. Therefore, many experienced surgeons take a categorical stand never to use these materials. However, porous polyethylene is different. Its structure allows ingrowth. It becomes translucent and unified with the surrounding tissues. The major deficit considered by many surgeons is that it is not known how porous polyethylene is tolerated by the human body in the long term. This study provides such data concerning the biocompatibility of Medpor. Moreover, it appears to be the best alloplastic material dispensable as a facial bone alternative. It is long-lasting, with a low frequency of complications and morbidity similar to procedures involving autologous grafts and high overall patient satisfaction.

In order to fulfil part of the gap in the literature concerning the long-term complications after rhinoplasty, Alonso et al.[116] in 2013 published an article in which the authors claim that autogenous cartilage grafts or alloplastic implants can be used for nasal dorsum enlargement. Nevertheless, the potential for permanent damage to the skin and soft tissues as well as complications such as infection and extrusion of the implant make autogenous tissue augmentation preferable to alloplastic implantation. This short report scoped to delineate a monadic migration case of an alloplastic implant from the nose to the forehead, simulating a frontal sinus fistula, in order to partially fill the gap of scant literature concerning the long-term effects of these implant materials. This study describes a patient who developed a forehead cutaneous fistula caused by migration of an alloplastic implant. One of the major benefits of using alloplastic implants in the nose is the ease of use. Alloplasts require much less time in preparation of the pocket and sculpting when compared with autogenous tissue. The 3 most commonly used implants in rhinoplasty are Medpor, silicone, and expanded polytetrafluoroethylene (Gore-Tex). Medpor has been used in a variety of facial reconstructions since the 1980s. Other authors have suggested that Medpor is a much more versatile implant because it is easy to shape, flexible, remarkably stable, and exhibits rapid soft-tissue ingrowth. Furthermore, dislocation and migration have not yet been reported using this material. Nevertheless, a literature review showed extrusion and infection rates ranging from 2.8% to 7.4%, with the need for Medpor removal in this series. Nasal cyst formation

and implant migration have been reported after silicone enlargement; whereas, to our knowledge, there is no report in the literature of such complications with Medpor, including migration of a nasal dorsum Medpor implant to the forehead 10 years after a rhinoplasty, presenting as a local fistula. Thus, complication rates of such a procedure may be higher in a long-term evaluation than that initially reported.

In 2014, Kim et al.[117] referred to alloplastic materials in rhinoplasty. Silicone implants are not expensive, toxic or immunogenic, though they are bio-compatible, shapeable and chemically stable. Nevertheless, the imbroglio, comprize infection, capsular systole, ejection, implant displacement, and calcification. Numerous studies reported up to 36% of incidence of these intricacies. Gore-tex has been used by many practitioners for its good biocompatibility, no allergenic property, ease information, and structural stability. Gore-tex has 10 to 30 μm size pores and capillaries, collagen, and connective tissues, including fibroblasts, which grow into the pores, therefore, it has been attractive materials to surgeons due to low inflammatory response and capsular contracture. Various entanglements have been reported as far as the usage of Gore-tex in rhinoplasty is concerned. A 2006 multicenter evaluation of 853 patients in Korea found a 2.5% complication rate.

Due to its good tissue biocompatibility, ingrowth of connective tissue, and no donor site morbidity, porous high density polyethylene (pHDPE, Medpor), has been used in rhinoplasty since the 1980s, however, provoked controversy over its utilization due to ejection and infection drawbacks. All Medpor-related obstacles met in these revisional rhinoplasty cases originate from the usage of pHDPE as the columellar strut. Most authors indicate that pHDPE was used as a spreader graft, and that the complication rates were significantly lower compared to when pHDPE was used as a columellar strut. Based on their bivariate analysis, Winkler, et. al. reported that the relative risk of postoperative infection from the use of pHDPE as a columellar strut was 21.24%, being approximately 5 times higher than 4.11% shown with the use of expanded polytetrafluoroethylene as the dorsal onlay. This study authors experiences show that the surgical removal of Medpor was extremely complicated compared to that of other alloplastic materials. Although not included in the alloplastic materials, irradiated homologous costal cartilage (IHCC), acellular cadaveric dermis (Alloderm), and injectable fillers have also been used for augmentation rhinoplasty.

The clinical application of IHCC was first reported in 1961 and IHCC has since been applied as a substitute to autologous costal cartilage. There is no doubt that autogenous costal cartilage is the most stable material, however, because of its deficits including a lengthy operation time and a raised donor site morbidity, IHCC can be more attractive and recommendable. IHCC is typically required as a SEG for correcting short noses and utilized when not much autologous septal cartilage is dispensable. Nevertheless, infection in its entirety, is doubtlessly the most disastrous complication to melt adjacent septal cartilage. On the onset of infection, the surgical site needs to be reoperated immediately to subtract IHCC in order to stunt infection from ruining neighboring septum and other normal tissues.

Alloderm has been used in various reconstructive surgery since 1995, and there are numerous multivariate studies on complications in soft tissue reconstruction. The major complaints of Alloderm are bulkiness and depression of the tip and the dorsum. In specific cases, the use of Alloderm to camouflage the gap at the supratip is recommended. Injectable fillers are injected for enlargement of the nose, glabella, and nasolabial fold line. As early complications, skin necrosis may occur when particles block subdermal artery directly, vessels are damaged due to the use of needle, or vessels are compressed by the volume of filler. In most cases, however, late or delayed complications, develop, including granuloma, nodule and chronic repetitive suppurative infection. Naturally, several trauma treatments may be practised to ameliorate the entanglements. There are reports that adipose-derived stem cell therapy was used to treat nasal skin necrosis, and satisfactory results of healing were obtained.

A systematic review of 311 cases was published in 2017 by Fanous et al.[118]. Authors state that autografts are widely used in rhinoplasty. They are mostly exported from septal and auricular cartilages, and sparsely from costal cartilage. These grafts suffer virtually no infection. A major benefit of autogenous grafts is their excellent record of safety in both the short and long terms.

Alloplasts’s main demerit is the risk of infection. The current medical literature heavily favors autografts over alloplasts in nasal surgery. The synthetic implants are perceived by a majority of surgeons as dangerous, unpredictable or hard to use. Nevertheless, if we consider the esthetic result, alloplasts have some advantages: They do not undergo resorption, they do not curl, they look and feel reasonably natural (especially the soft

implants), they have no sharp edges, they are rarely displaced, they offer an unlimited supply of volume, form and consistency, they do not need a donor site, and they need a shorter surgical time. Although alloplasts carry certain risks and complications, they do have valuable advantages, especially in terms of producing predictable esthetic results. It is time that alloplasts be considered as an additional option and a helpful tool in the field of rhinoplasty.

As far as the utilization of spreader grafts in Asian patients is concerned, Li et al.[119] in 2018 stated that: porous high-density polyethylene (ie, Medpor; Stryker, Kalamazoo, MI) is an alloplastic material comprising of continuous interconnected spaces that allow for ingrowth of host tissue and neovascularization into the implant. Medpor has presented sufficient biocompatibility and strength for nasal surgery.

Autologous spreader grafts and a columellar strut may not be brewed with septal cartilage alone most of the times, creating the additional need for the patient’s costal cartilage. Despite its structural integrity and abundance, costal cartilage has been advised against for rhinoplasty. Costal cartilage has a tendency to warp in an estimated 6% of cases and involves a high rate of donor-site morbidities, including pneumothorax, pain, and scarring. Contrary to septal cartilage, cropping of costal cartilage needs general anesthesia, which involves longer operating and recovery times along with greater expense.

On the basis of its superior biocompatibility, autologous tissue generally is regarded as more preferable to alloplastic material for nasal augmentation. Western plastic surgeons most probably treat patients with sufficient, structurally sound nasal cartilage. Nevertheless, Eastern surgeons who routinely see Asian patients should contemplate alloplastic material as a suitable alternative. Medpor is nonallergenic, nonantigenic, and easily malleable. Nasal features in Asian patients include dense fibromuscular and fatty layers; hence, complications of alloplastic augmentation rhinoplasty are less common in these patients than in Caucasians. Investigators have highlighted exquisite long-term rhinoplasty results with Medpor. Medpor enables ingrowth of vascularized tissue for integration and stabilization of the implant. After formation of the implant complex, these features are associated with decreased rates of infection. However, extreme caution is recommended in the instance of Medpor being implanted in revisional rhinoplasty wherein soft tissue is traumatized, and the skin is slim and under stress.

Grafting with costal cartilage is expensive and is associated with donor-site complications and distortion at the recipient site. Silicone cannot withstand the tension created in nasal lengthening procedures that involve caudal rotation rhinoplasty with alloplastic transplantation that can be performed under local anesthesia in an outpatient setting.

In addition, in 2018, Yang et al.[120] demonstrated that a number of implant materials are available to the rhinoplasty surgeon that can be used to restore the inadequate structural integrity and volume. Autogenous implants represent the gold standard for human implantation in most cases, with the advantages of relatively high biocompatibility and lower infection risk. Dermofat or costal cartilage is utilized for dorsal augmentation, and septal or conchal cartilage is mainly used for reconstruction of the nasal tip. However, they carry drawbacks of donor site morbidity with limited quantity of available tissue and unpredictable resorption rates. Alternatively, alloplastic material, most notably silicone, is chosen over autografts due to its benefit of no harvest-related morbidity. Although they are easy to tailor to fit the specific need and concerns about resorption are also reduced, allografts are associated with higher risk of implant extrusion, mobility and infection. Despite such drawbacks, alloplastic materials have been used widely in Asians who have relatively lower amounts of cartilage to harvest.

Cross-linked acellular dermal matrices (ADM) have been introduced. It has reported that the implanted ADM has structural and biochemical properties by extra cellular matrix deposition and promoting tissue regeneration therefore, it is suitable for soft tissue augmentation procedures. It is thought to supply camouflage to the dorsal irregularity covering the osteocartilaginous frame work of the nose, and can also be utilized for dorsal augmentation alone or as a wrapping material for diced cartilage graft and other alloplastic implants.

Ideal implant material in augmentation rhinoplasty requires biocompatibility, potential for tissue integration and durability. It also must be easy to sculpt, resistant to trauma, infection and extrusion, inert and readily dispensable. Autogenous implants represent the gold standard for human implantation in most cases, with the benefits of high biocompatibility and lower infection rate. Tardy et al. reported no incidences of graft loss due to infection or rejection with their 17-year experiences in over 2000 cases of

autogenous cartilage grafts in rhinoplasty. Nevertheless, they carry the drawbacks of donor site morbidity with limited quantity of harvested tissue and the demonstrated resorption rates vary from 12 to 50%. ADM has recently been introduced as an alternative implant material for rhinoplasty. There is no donor site morbidity, which is a frequent problem encountered when utilizing autologous tissue. Moreover, as it is structurally stable and less resorptive, the contour of nasal dorsum is well retained. Additionally, compared to an alloplastic implant, ADM possesses benefits such as biocompatibility, neovascularization and minimized propensity to incite inflammation. It possesses the potential for early tissue integration and remodeling as well, which permit rare implant migration. It is also advantageous that the infection rate is low, handling is easy, and the appearance is more natural. It is a very useful surgical option especially for the patients who do not desire an alloplastic implant or who do not want a secondary surgical site. The novel cross-linked human ADM has relatively high biocompatibility and a lower infection rate as an autogenous material. It also has long- term structural integrity and durability after implantation as an alloplastic material.

Ultimately, in 2020, Bai et al.[121] illustrated that the L-shaped silicone implants seemed to bring better nasal mobility compared with expanded polytetrafluoroethylene (e- PTFE) after rhinoplasty. However, the implant lacked steadfastness due to the relocation of the nasal tip, which led to the entire nose, notably near the nasion. This leads to an unnatural nasal appearance. The present study aimed to improve the dynamic beauty of rhinoplasty by applying a new carving method of the prosthesis double ‘‘V’’ method.

The e-PTFE implants minimized the nasal mobility, whereas the silicone implants tended to result in a rigid nose. Hence, the present simple and effective modified carving technique in enlargement rhinoplasty may improve postoperative nasal mobility. In general, cartilage grafts are preferred in rhinoplasty. Autogenous grafts carry the minimum entanglement risk and may be cropped in large quantity. Nevertheless, there are many limitations that should be addressed, including unpredictable bending of nose, prolonged operation, significant donor site infection, and scarring. For all these complications, this method can be an attractive alternative for congenital nasal deformations, trauma or revision rhinoplasty.

Although it has great biocompatibility, it possesses numerous complications as well, such as extrusion, fistula, and high rigidity. Silicon and e-PTFE implants remain the materials of choice. Significant findings supplied strong evidence that the double ‘‘V’’ manner of carving prosthesis could raise nasal mobility and prevent the nose from relocating with the whole prosthesis. In case of e-PTFE implant, capillaries, collagen, and connective tissues including fibroblasts grow into the pores resulting in strong adherence with surrounding tissue.

Thus, the likelihood of nasal dislocation is smaller in an e-PTFE implant. This study designed a simple and effective double ‘‘V’’ carving manner of L-shaped silicon and e-PTFE. This method enhanced dynamic rhinoplasty outcomes by raising nasal mobility and improved patient satisfaction compared to traditional methods of rhinoplasty. Cosmetic surgeons, comprehend the patient’s requisition of a symmetrical, natural nose.

CONCLUSION

Loss of nasal structure and support often mandates the need for implant materials to improve nasal form and function. Autologous implants, most notably septal cartilage, are the nasal grafts to which all others should be compared. Other autologous materials, such as auricular cartilage, costal cartilage, calvarial bone, fascia, perichondrium, and dermis, are excellent materials for implantation in the nose. Both irradiated rib and acellular dermis constitute homologous alternatives and should therefore be contemplated for patients who may not connive at the extra morbidity related to graft cropping or who do not own sufficient amounts of autologous material. Although alloplastic implants are plentiful and easy to shape and provide a natural contour under the skin, these materials have the increased potential for complications and are therefore the least wanted materials to be utilized as a nasal graft. Their lodgement should be narrowed to the comparatively motionless nasal dorsum or premaxilla, while the patient ought to be thoroughly advised as far as the risk of infection or ejection of these materials is concerned. In the near future, bio-engineered cartilage shall become an additional option for nasal procedures that have graft materials as a prerequisite.

The use of autogenous cartilage material, preferably from the nasal septum, is still the graft of choice for nasal reconstruction. However, technical advances in yielding of alloplastic implants such as e-PTFE provide an enticing alternative when autogenous cartilage is finite. Graft and implant materials are very controversial. Their discussion always engenders strong opinions from those who favor one material over another. A vast variety of materials can be used successfully in nasal reconstruction when sound surgical principles are utilized in conjunction with good surgical technique.

Ultimately, the case is that grafts are highly superior to implants in the nose, and the use of implants should be assiduously averted. It has been tried to understand the existing consideration upon selection of an implant and interrupt that thought process with some alternating grafting proposals.

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