Three-Dimensional Surgical Planning and Simulation to Improve Surgical

Int. J. Oral Maxillofac. Surg. 2017; 46: 586–589

http://dx.doi.org/10.1016/j.ijom.2017.01.020, available online at http://www.sciencedirect.com

Technical Note

Cosmetic Surgery

1,2

A. Valls-Ontan˜ o´ n , C. Mezquida-

1 1,2

Fernańdez , R. Guijarro-Martıńez , Three-dimensional surgical 1,2 F. Hernańdez-Alfaro

Institute of Maxillofacial Surgery, Teknon

Medical Centre, Barcelona, Spain;

planning and simulation to Department of Oral and Maxillofacial

Surgery, Universitat Internacional de

Catalunya, Sant Cugat del Valle`s, Barcelona,

improve surgical accuracy and Spain reduce invasiveness of

cranioplasties

A. Valls-Ontanõń, C. Mezquida-Fernańdez, R. Guijarro-Martıńez, F. Hernańdez-

Alfaro: Three-dimensional surgical planning and simulation to improve surgical

accuracy and reduce invasiveness of cranioplasties. Int. J. Oral Maxillofac. Surg.

2017; 46: 586–589. ã 2017 International Association of Oral and Maxillofacial

Abstract. Patients with too large a frontal prominence may suffer discomfort and

subsequent self-esteem problems. The case of a 29-year-old male with a prominent

forehead is presented. After three-dimensional (3D) virtual simulation of the

procedure, a stereolithographic model of the skull and a surgical cutting guide were

fabricated. The forehead recontouring and reconstruction procedure was performed

under general anaesthesia and the postoperative course was uneventful. At the

12-month postoperative follow-up, clinical and radiographic documentation

conﬁrmed softening of the frontal prominence from 14.48 mm to 8.56 mm, a

Key words: frontal sinus; frontal bone; fore-

nasofrontal angle increase of 22 , and overall high patient satisfaction. The

head; cone beam computed tomography; sur-

proposed workﬂow results in greater surgical precision, shorter reconstruction

gical planning software; surgical cutting guide;

times, reduced patient morbidity due to a reduced risk of dural exposure cranioplasty; aesthetic surgery; feminization.

and postoperative infection, and overall higher predictability and patient

satisfaction. Available online 21 February 2017

Comprehensive aesthetic analysis of the or thick supraorbital ridges. Consequent- come pneumatized and reach their full size

upper facial third entails consideration of ly, the nasofrontal angle is often acute in at puberty. Lee et al. described frontal

three key-areas: the frontal sinus promi- men, while it is much more obtuse in sinus anatomy and sex variations from

nence, the superciliary and supraorbital women in response to very little — if computed tomography (CT) scan images

ridge, and the nasoglabellar angle. In par- any — brow fullness. and concluded that males have greater

ticular, a prominent frontal vault is an The frontal sinuses are the last facial dimensions in most frontal sinus measure-

inherent masculine characteristic that sinuses to achieve complete development. ments: male foreheads were characterized

may be due to large frontal sinuses and/ After slow progressive growth, they be- by a more acute nasofrontal angle (119.9

Three-dimensional surgical planning and simulation to improve surgical accuracy and reduce invasiveness of cranioplasties 587

vs. 133.5 ), a steeper posterior forehead

inclination (À7.2 vs. À3.5 ), and a wider

glabella (44.4 mm vs. 33.9 mm), frequent-

ly protruding beyond the ideal forehead

slope line (51% vs. 30%).

According to the classiﬁcation of Urken

et al., an abnormally large frontal sinus

may be due to three different conditions:

hypersinus, pneumosinus dilatans, and

pneumocele. A hypersinus is an enlarged

frontal sinus that does not extend beyond

the normal limits of the frontal bone and

has normal wall thickness. Pneumosinus

dilatans is a situation where the sinus

expands abnormally beyond the normal

limits of the frontal bone, yet the bony

walls of the sinus are of normal thickness.

Finally, an aerated sinus with variable

thinning of its walls characterizes a pneu-

mocele. This condition differs from the

two previous ones in that it is considered a

pathological status secondary to a sinus

drainage disturbance. Fig. 1. Preoperative and postoperative pictures illustrating the successful result.

While the chief patient complaint is an

annoying prominent forehead, related

symptoms include local painful pressure, CAT scanner; Imaging Sciences Interna- orbital rim were exposed, both supraorbit-

nasal bleeding, anosmia, diplopia, and tional, Inc., Hatﬁeld, PA, USA) and al neurovascular bundles were dissected

headache. In women with bossing fore- showed diffuse enlargement of both fron- carefully. The limits of the frontal sinus

heads, substantial aesthetic disharmony tal sinuses. No signs of intracranial or were marked on the anterior cortical wall

1–3

and facial masculinization may result. orbital involvement were detected. Simi- with the help of the prefabricated surgical

Likewise, men with too large a frontal larly, a sinus pathology was ruled out. cutting guide (Fig. 2). Then, the anterior

prominence may refer to discomfort and Metric analysis was performed at the fa- wall was removed integrally using a pie-

self-esteem problems. Surgical reshaping cial midline. The frontal sinus height, zoelectric device (Implant Center 2; Sate-

of the upper facial third is an effective width, and depth measured 36.47 mm, lec-Acteon Group, Tuttlingen, Germany)

solution to the aforementioned clinical 58.84 mm, and 14.58 mm, respectively. (Fig. 3). The tip of the piezoelectric saw

and psychological symptoms. The thickness of the anterior table was was inclined obliquely at an angle greater

The aim of this article is to describe a 2.24 mm. Despite mild thinning of the than 45 to the bone surface, taking care to

speciﬁc workﬂow for three-dimensional anterior cortical wall, the anatomical de- avoid any perforations and subsequent

(3D) planning and execution of forehead formity was categorized as a pneumosinus dural exposure. The mucosa of the sinus

recontouring and reconstruction, to ana- dilatans owing to frontal sinus expansion was removed, and both frontonasal ducts

lyze its advantages and limitations, and to beyond the normal limits of the frontal and frontal sinuses were obliterated with

discuss potential possibilities for future bone with signs or symptoms of sinus ﬁbre-reinforced calcium phosphate (Nor-

improvement. drainage disturbance. ian CRS; Synthes Inc., West Chester, PA,

Primary DICOM ﬁles (digital imaging USA). The previously removed anterior

and communications in medicine) from wall fragment was meticulously sculpted

Methods

the CBCT analysis were imported into and ﬂattened with a surgical burr (round

A 29-year-old male was referred to the speciﬁc treatment planning software (Sim- cutting, 6-mm diameter head) and then

department of oral and maxillofacial sur- Plant O&O version 13.0; Dentsply, Leu- repositioned. The sharp edges of the repo-

gery of a tertiary hospital complaining of a ven, Belgium). After careful manual

prominent forehead and self-esteem pro- segmentation of the raw dataset, the 3D

blems related to his facial appearance skull model of the patient was exported in .

(Fig. 1). The patient was otherwise asymp- stl (stereolithography ﬁle) format in order

tomatic and denied any symptoms consis- to fabricate a stereolithographic model.

tent with sinus disease. The remainder of The complete forehead recontouring and

his medical history was unremarkable, reconstruction procedure was simulated

with no history of trauma, infectious rhi- virtually. The virtual plan was reproduced

nitis, or allergies. in the stereolithographic skull model, and

Physical examination revealed a prom- a surgical cutting template was fabricated.

inent frontal vault and an acute nasofrontal Under general anaesthesia, the frontal

angle. Otorhinolaryngological, ophthal- bossing was reached through a coronal

mological, hormonal, and neurological approach. The incision was performed in Fig. 2. Intraoperative picture: limits of the

examinations were normal. an oblique fashion in order to preserve the frontal sinus marked on the anterior cortical

A cone beam computed tomography maximum amount of hair follicles. Once wall with the help of the prefabricated surgical

(CBCT) examination was performed (i- the frontal bone, glabella, and superior cutting guide.

588 Valls-Ontan˜o´n et al.

surface matching. To this effect, the ante- anatomy. Individuals can be classiﬁed into

rior and middle cranial fossae served as two major categories based on their fore-

reference landmarks. Two- and three-di- head anatomy. Group I comprises sub-

mensional morphometric comparisons jects with a thick cortical bone over the

(Fig. 4) revealed softening of the frontal frontal bulge, the sinuses meanwhile being

bossing from 14.48 mm to 8.56 mm, and of normal or small size. In these patients,

an increase in the nasofrontal angle from sculpting using a burr without penetrating

110 to 132 . the frontal sinus is sufﬁcient. Group II

comprises subjects in whom the frontal

protuberance is associated with compara-

Discussion

Fig. 3. Intraoperative picture: frontal bone tively thin bone over the frontal sinuses. In

anterior wall osteotomy.

Radiological evaluation with CT or CBCT these cases, an anterior wall frontal bone

permits a comprehensive evaluation of the osteotomy is required, and the anterior

sitioned anterior wall bone were polished patient’s anatomy (sinus size and wall wall of the forehead sinus must be set

with the same burr in order to achieve a thickness) and sinus pathology in order back, repositioned, and secured. Needless

smooth continuity with the margins of the to select the appropriate surgical tech- to say, group II surgery entails substan-

resection. Furthermore, the excessively nique and anticipate potential complica- tially greater technical complexity and

prominent supraorbital ridges were recon- tions. Furthermore, DICOM data subsequent risk of complications. It is

toured, taking care to avoid the supraor- processing with appropriate third-party important to point out that most patients’

bital neurovascular bundles. After software enables virtual simulation of frontal sinus anatomy falls into group II,

haemostasis revision, standard closure of the surgical procedure and .stl ﬁle expor- such that a detailed surgical plan is abso-

1–3,8,9

the coronal approach in two layers was tation in order to fabricate anatomical lutely mandatory.

completed: the scalp was closed with 3–0 models and/or surgical guides. In the While an endoscopic approach is pos-

Vicryl sutures (Ethicon, Sommerville, NJ, authors’ experience, these guides enable sible in order to avoid the classical stan-

USA) and the skin with 3–0 Prolene accurate delimitation of the surgical defect dard or modiﬁed coronal approaches and

sutures (Ethicon, Sommerville, NJ, USA). on the anterior cortical wall, thereby fa- the subsequent risk of large scars or alo-

A compressive forehead dressing and cilitating the procedure and reducing the pecia, this minimally invasive technique

two active drains were maintained for operative time, and improve the ﬁnal out- is best suited for properly selected group I

24 h. In addition, a closed-circuit cold- patients.

come globally.

water mask (17 C) was worn during the Recently, the development of surgical Technically, the authors prefer execut-

ﬁrst postoperative day. Standard antibiotic navigation systems has provided real-time ing the osteotomy of the anterior wall of

and anti-inﬂammatory prophylaxis was intraoperative guidance based on a preop- the frontal sinus with a piezoelectric de-

prescribed for 1 week. eratively simulated treatment plan. More- vice because it offers excellent control of

over, the rapidly developing technologies the direction of the cut and minimizes the

for 3D visualization, interactive localiza- risk of dural exposure. In the case reported

Results

tion, and point mapping enable the precise herein, the anterior wall of the frontal

The postoperative course was uneventful. identiﬁcation and preservation of critical sinus was removed in one piece and recon-

No complications such as alopecia, hae- areas. It is logical to expect that the incor- toured carefully before repositioning. Al-

matoma, or contour deformities occurred, poration of these simulation-guided navi- ternatively, the anterior cortical wall can

1,3,8

and a pleasing aesthetic result was gation systems into the clinical routine be fragmented into several pieces. In

achieved. will further improve the accuracy of cra- any case, gentle manipulation of the frag-

At the 12-month follow-up, the patient niofacial reconstructions and reproduc- mented bone and preservation of the peri-

remained satisﬁed with the outcome and ibility of the surgical plan, and will osteum are essential in order to avoid

did not wish any further surgery (Fig. 1). A minimize the need for intraoperative im- irregularities in forehead contour. Should

control CBCT scan was obtained in order provisation and the risk of complications. ﬂattening of the frontal bone lead to an

to evaluate the postoperative outcome. Several surgical techniques have been excess of overlying forehead skin and

The ﬁles were exported to Dolphin Imag- described for forehead recontouring and brow ptosis, a concomitant brow lift

8,9

ing 3D version 11.8 software (Dolphin reconstruction in particular. The most through the same coronal approach can

Imaging & Management Solutions, Chats- suitable procedure remains the preference be considered.

worth, CA, USA) to superimpose the pre- of the clinician based on personal experi- As mentioned previously, detailed pre-

and postoperative datasets by means of ence and the patient’s speciﬁc forehead operative analysis with CT or CBCT helps

the surgeon anticipate potential sinus

drainage problems. When the frontonasal

duct is involved, it is essential to re-estab-

lish an appropriate drainage. However,

there is no consensus regarding the man-

agement of the healthy mucosa. Some

authors advocate removing the sinus mu-

cosa and obliterating the lumen with fat or

galea grafts, autologous, homologous, or

heterologous bone grafts, and even allo-

plastic materials such as methylmethacry-

Fig. 4. Superimposition images where grey represents the preoperative data and green the

late. Nevertheless, most authors prefer to

postoperative data (12 months).

keep the mucosa intact, always avoiding

Three-dimensional surgical planning and simulation to improve surgical accuracy and reduce invasiveness of cranioplasties 589

mucosal engagement between bone frag- Acknowledgements. The authors would and analysis of the upper airway: a system-

ments and maintaining the patency of the like to thank every staff member at the atic review of the literature. Int J Oral Max-

frontonasal duct to prevent mucocele for- Institute of Maxillofacial Surgery, Teknon illofac Surg 2011; :1227–37.

7. Ricci JA, Desai NS, Vendemia N. Correction

mation in the frontal sinus. Medical Centre, Barcelona, for their ad-

of a contour deformity associated with fron-

In conclusion, speciﬁc DICOM-proces- ministrative and clinical support.

tal pneumosinus dilatans using surgical nav-

sing software enables a comprehensive 3D

igation technology. J Oral Maxillofac Surg

diagnostic analysis, simulation of the sur-

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