2017-18 HSC Section 3 Green Book

The Journal of Craniofacial Surgery • Volume 25, Number 1, January 2014

Subcondylar Mandible Fractures

ankylosis of the TMJ secondary to forced immobilization during MMF. 29 Although the etiology of ankylosis is not completely under- stood, it is hypothesized that trauma leading to intracapsular hema- toma results in fibrosis and excessive bone formation, ultimately causing hypomobility of the affected side. 30,31 Given the current hypothesis, we believe that ankylosis of the TMJ is a manifestation of direct injury within the joint capsule or the condylar head itself. It is imperative to point out that as a result, there should be a lower risk for ankylosis in subcondylar fractures compared with fractures of the condylar head. Therefore, we advo- cate to closely examine the position of the fracture line relative to the joint capsule and to use a longer period of MMF if there is no involvement of the condylar head, disk, or capsule. It is our experi- ence that a longer period of MMF results in better union of the frac- tured segments with no increase in the incidence of ankylosis. In a nondisplaced fracture or minimally displaced fracture with a func- tional occlusion, we recommend 4 to 6 weeks of MMF followed by 2 to 3 weeks of guiding elastics (Fig. 2). The same treatment applies in the case of a nondisplaced bilateral fracture. However, this scenario is less common because the force parameters to cause the bilateral fracture are often greater and tend to displace the frac- ture fragments, significantly necessitating ORIF. 32 Open reduction with internal fixation is generally used in complex mandibular fractures that necessitate direct anatomic re- duction. This approach allows the surgeon to access the fracture directly via a preauricular, submandibular, retromandibular trans- parotid, or retromandibular transmasseteric incision. 33 However, the major risk in treating subcondylar fractures with ORIF is the poten- tial to damage the facial nerve. Both permanent and transient paresthesias are reported in the literature, although most cases after ORIF seem to be transient. 34,35 In addition, scarring at the surgical site may embody a cosmetic burden to the patient, leading to dissat- isfaction despite functionally successful results. Hypertrophic scars in particular are most perceivable and result in 7.5% of scars gener- ated by ORIF. 34 Conversely, the benefit of achieving a superior ana- tomic reduction and thereby better functional outcome makes ORIF desirable in more complex cases. Patients are also able to mobilize the injury site directly after surgery and avoid a prolonged period of MMF. Open reduction with internal fixation is thus indicated for patients lacking functional occlusion with a displaced fracture not amenable to an endoscopic technique. In these cases, we believe that the functional outcome achievable through open reduction outweighs the procedure's operative risks, which can also be miti- gated with facial nerve monitoring. The goal of ORIF is to provide optimal fracture reduction while minimizing damage to the facial nerve. We do this using the following approach. First, an incision is made 8 mm anterior to the standard preauricular incision that would normally be on the Open Reduction With Internal Fixation

addition, we recognized that there are significant variations in clin- ical practice that can often dictate care. It is important for the cra- niofacial surgeon to be facile with all 3 approaches discussed in this article. It is also pertinent to state that, with proper facial nerve monitoring, the open transparotid approach is safe and reliable and it can allow for surgical comfort to potentially achieve direct ana- tomic reduction when indicated in nearly all subcondylar fractures. Closed Reduction Closed reduction has historically been the standard treatment option for subcondylar fractures of the mandible. 7 Its widespread use is attributed to the idea that closed reduction results in fewer complications with similar functional and esthetic outcomes com- pared with ORIF. For instance, complications such as facial nerve damage and excessive scarring are significantly decreased because of the noninvasive nature of this approach. 23 However, as high- lighted by the ongoing debate, a consensus regarding outcomes be- tween open and closed reduction is not evident in the literature. In short, some studies conclude that both approaches produce roughly similar results, 10,13,24,25 whereas others have associated an array of unfavorable outcomes with closed reduction. 4,16,26,27 These include facial asymmetry, deviation upon mouth opening, skeletal maloc- clusion, and chronic pain of the TMJ. 14,16,28 The fact that many of these parameters lack standardization in time course of treatment further obscures the debate. Larger studies with consistent parameters are needed to reassess outcomes with the surgical techniques and technology present today. However, it is unlikely that a trial large enough will deliver granular evidence to conclusively quell this debate. Another controversial point regarding closed reduction is the length of time a patient should spend in MMF. Many surgeons choose to apply fixation for a very short period (ie, 2 wk) to avoid FIGURE 1. Postoperative CT of a subcondylar fracture of the mandible. A, Sigmoid notch line; B, oblique line connecting the sigmoid notch and the masseteric tuberosity.

FIGURE 2. A, Computed tomography showing bilateral nondisplaced fracture of the subcondylar mandible. B, Maxillomandibular fixation.

© 2014 Mutaz B. Habal, MD

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