|Year : 2020 | Volume
| Issue : 2 | Page : 89-92
Facial nerve preservation in transmasseteric antero-parotid approach for open reduction and internal fixation of mandibular subcondylar fracture
Can Ilker Demir, Emrah Kagan Yasar, Kivanc Emre Davun, Aykut Gok, Murat Sahin Alagoz
Department of Plastic, Reconstructive and Aesthetic Surgery, Faculty of Medicine, Kocaeli University, Kocaeli, Turkey
|Date of Submission||27-May-2019|
|Date of Acceptance||08-Jul-2019|
|Date of Web Publication||18-Mar-2020|
Dr. Can Ilker Demir
Department of Plastic, Reconstructive and Aesthetic Surgery, Faculty of Medicine, Kocaeli University, Derince, Kocaeli
Source of Support: None, Conflict of Interest: None
Objective: Mandibular condylar fracture has an incidence rate between 14 and 48% of all mandibular fractures. Rigid fixation along with open reduction internal fixation is so far the most successful method to ensure the mandible stays in its natural anatomy. Facial nerve injury is the most feared complication for open reduction methods. We aimed to explain the surgical method using transmasseteric antero-parotid approach in mandibular condylar fractures, through which the buccal branch of the facial nerve is explored and maintained. Material and Methods: Since April 2015 to February 2018, the 12 patients (age range 19-42 years) with 15 fractures were treated with open reduction and internal fixation with transmasseteric antero-parotid approach. There were 9 male and 3 female patients. All patients were reviewed 2 weeks, 4 weeks, 3 months and 6 months after surgery. The clinical follow-up examinations included dental occlusion, maximum mouth opening (interincisal distance), weakness of the facial nerve, postoperatively complications (hematoma, infection,fistula,seroma) and salivary leak. Results: Infection, hematoma, fistula or seroma complications were not observed in any of our cases. The postoperative occlusal relationship was well restored in 11 patients. One patient with bilateral subcondylar fracture had unsatisfactory dental occlusion with anterior open bite. There was no permanent facial nerve palsy. All patients were satisfied with results. Conclusion: In mandibular condylar and subcondylar fractures, the transmasseteric antero-parotid approach is a reliable method that can ensure sufficient exposure and osteosynthesis.
Keywords: Facial nerve, mandibular fracture, open reduction, internal fixation
|How to cite this article:|
Demir CI, Yasar EK, Davun KE, Gok A, Alagoz MS. Facial nerve preservation in transmasseteric antero-parotid approach for open reduction and internal fixation of mandibular subcondylar fracture. Turk J Plast Surg 2020;28:89-92
|How to cite this URL:|
Demir CI, Yasar EK, Davun KE, Gok A, Alagoz MS. Facial nerve preservation in transmasseteric antero-parotid approach for open reduction and internal fixation of mandibular subcondylar fracture. Turk J Plast Surg [serial online] 2020 [cited 2020 Mar 28];28:89-92. Available from: http://www.turkjplastsurg.org/text.asp?2020/28/2/89/280990
| Introduction|| |
Mandibular condylar fracture has an incidence rate between 14% and 48% of all mandibular fractures, and the optimal treatment is controversial despite the common aim of reconstruction of the anatomical position and preservation of function.,, Rigid fixation with open reduction internal fixation is currently the most successful method to ensure the mandible retains its natural anatomy. Rigid fixation is performed by open surgery and using certain approaches, which include transparotid, intraoral, preauricular, and retromandibular approaches. When using these methods, however, the inability to identify and sufficiently protect the facial nerve in the patient may affect the outcome of the operation. Facial nerve injury is the most common complication. Wilson et al. pioneered an operative approach, the transmasseteric antero-parotid approach (TMAPA), which minimized the risk of this complication. In this paper, we describe our experience of mandibular condylar fractures repair using the TMAPA in which the buccal branch of the facial nerve is explored and maintained.
| Materials and Methods|| |
Twelve patients were treated with open reduction and internal fixation with TMAPA from April 2015 to February 2018 at our center. Inclusion criteria were: displaced subcondylar fracture; more than 30° of angulation at the fracture site; occlusion disturbances; and/or fragment fracture. Exclusion criteria were: patients younger than 18 years; those who presented with high or intracapsular condylar fracture; undisplaced fractures; shortening of the ramus <5 mm; <30° of angulation at the fracture site; and those who did not consent to the procedure. The patients who required open reduction but did not accept the procedure were treated by intermaxillary fixation using the arch bar. Computed tomography (CT) was used to assess preoperatively, to evaluate the degree of displacement, and to measure the shortening of the ramus. Mean delay between fracture time and surgery was 3 days. All patients consumed a soft diet for 4 weeks and underwent immediate mouth opening and closing exercises and received physiotherapy for 4 weeks' postoperatively.
All patients were reviewed at 2 weeks, 4 weeks, 3 months, and 6 months after surgery. The clinical follow-up examinations included dental occlusion, maximum mouth opening measured by interincisal distance, weakness of the facial nerve, assessment for postoperative complications including hematoma, infection, fistula and/or seroma and salivary leak. The radiologic follow-up examinations consisted of CT to assess the position of plates and bone healing, 2 weeks' and 6 months' postoperatively.
Under general anesthesia, a preauricular incision was performed in such a way that it extended downward, in a curvilinear manner, in the skin crease [Figure 1]a. Harvesting the flap in the subdermal plane, superficial to the musculoaponeurotic layer, extends to the parotid gland and its anterior border. Then, the parotid gland was withdrawn toward the posterior. Under loupe magnification, the buccal nerve was identified and maintained inside the fatty tissue on the superficial surface of the masseter muscle. There was no need to use a nerve stimulator. The nerve was retracted superiorly to facilitate exposure of the masseter muscle, which was split in the direction of the fibers [Figure 1]b. After performing an incision on the periosteum of the mandibular ramus, the site of the fracture was then visible on the subperiosteal plane [Figure 1]c. The assistant then applied firm downward intraoral pressure to the ipsilateral third molar to depress the mandible. The fracture was then reduced and fixed, using screws and 2 mL plates [Figure 1]d. Occlusion and mobility of the joint were checked, and the skin was closed with nonresorbable sutures. A Hemovac drain was applied which was subsequently removed on the 1st day postoperatively. All patients were placed under intermaxillary fixation for 5 days [Figure 2]. The details of the surgical technique can be found in the following Video 1.
|Figure 1: (a) The skin flap is elevated to expose the anterior border of the parotid gland. (b) The buccal nerve is identified and preserved on the surface of masseter muscle. (c) The masseter muscle is split in the direction of its fibers, which run parallel to the anterior edge of mandibular ramus. (d) Fixation is performed after reduction of the fracture|
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|Figure 2: Illustration of the relevant anatomical structures: m-masseter muscle; b-the mandible; n-the masseter muscle|
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| Results|| |
The 12 patients were aged from 19 to 42 years, and 9 were male, with a total of 15 fractures. The distribution according to the pattern of subcondylar fractures was: eight patients with isolated unilateral subcondylar fracture, two patients with contralateral parasymphyseal fracture, one patient with bilateral subcondylar fracture, and one patient with, unilateral multiple fragment subcondylar fracture.
There were no complications due to infection, hematoma, fistula, or seroma in any of the patients. The postoperative maximum interincisal distance was 38–46 mm after 6 months. The postoperative occlusal relationship was well restored in 11 (91.7%) of the patients. One patient with bilateral subcondylar fracture had unsatisfactory dental occlusion with anterior open bite. Transient facial nerve palsy in the region served by the buccal nerve was observed in two patients, which resolved spontaneously within 3 months' postoperatively. There was no permanent facial nerve palsy. Postoperative radiologic examination (CT) showed a successful reduction in the correct anatomic position in 11 (91.7%) patients. One patient with unilateral multiple fragment subcondylar fracture had an incorrect anatomic position which did not require revision surgery. After all operations, functional occlusion and reduction of the condyles were good. The radiologic examinations are given in [Figure 3] and [Figure 4].
|Figure 3: Preoperative and postoperative radiologic examination of one of the patients|
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|Figure 4: Preoperative and postoperative 3D computed tomography examination of one of the patients|
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| Discussion|| |
Insufficient treatment of condylar fractures in the mandible may lead to complications including limited jaw movements, facial deformity, occlusion disorder, and temporomandibular joint ankylosis., The risks of these complications are even higher in cases with displaced fractures and where they are not internally fixed, insufficiently fixed, or where the surgical operation is not performed. Early mobilization is essential to ensure the full functioning of the temporomandibular joint in cases of mandibular condyle fractures. Early mobilization, however, can only be attained by rigid fixation which, in turn, are dependent on open surgical intervention with accompanying retromandibular, submandibular, and preauricular incisions., However, not identifying the facial nerve in these patients leads to insufficient exploration and may affect the outcome of the operation with attendant facial nerve injury.
Different nerve injuries may be caused depending on the method of incision used. Retromandibular and submandibular incisions carry the risk of injury to the marginal mandibular nerve. Preauricular incision carries the risk of injury to the temporal and zygomatic nerves. In one study, the risk of injury to the facial nerve with the preauricular incision method was reported to vary between 3.2% and 42.9%. A second study reported 30% occurrence of temporary facial nerve injury with the retromandibular incision method.,,, The TMAPA technique allows the exploration of the fracture site from between the buccal and marginal mandibular nerves, which presents the least risk of surgical nerve injury. Once the parotid gland is reduced to the rear, the buccal nerve is identified on the masseter muscle surface, which then allows the prevention of nerve damage, both temporary and permanent, by reducing the buccal nerve gently. The risk of deficits after a buccal nerve injury that might occur is low, due to the high cross-anastomosis ratio between the buccal nerve and the zygomatic nerve at 87%–100%., In our cases, we identified and maintained the buccal nerve and performed the dissection far from the marginal mandibular nerve. Thus, no nerve damage occurred in any of our cases.
A further risk during mandibular subcondylar fracture repair surgery is parotid gland injury, usually in the form of parotid fistula formation. This may necessitate later removal of the plate screws due to infection risk in the fistula.,, In our cases, we explored the fracture site at the front border of the parotid gland, from the masseter muscle, which allowed us to perform the operation with a reduced risk of fistula formation, as we avoided the parotid gland and managed to fix the masseter muscle. Rigid fixation requires sufficient exposure of the fracture site, and when using submandibular and retromandibular incision methods, this degree of exposure can only be achieved by excessive retraction, which also increases the risk of the facial nerve and parotid gland damage. The last possible complication results from the difficulty in inserting the screw due to the structures that adhere to the mandible, which usually necessitate using an intraoral incision method or an endoscope. In our cases, we ensured sufficient exposure of the fracture site at the mandibular condyle by very carefully retracting the parotid gland.
| Conclusion|| |
The TMAPA technique preserves the parotid gland and the facial nerve more than other techniques. Thus, it has a reduced risk of complications after surgery in mandibular condylar fractures. In mandibular condylar and subcondylar fractures, TMAPA is a reliable method that can ensure safe and sufficient fracture site exposure and osteosynthesis.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]