Evaluation of facial nerve following open reduction and internal fixation of subcondylar fracture through retromandibular transparotid approach.

The objective of this study was to evaluate any damage to the facial nerve after a retromandibular transparotid approach for open reduction and internal fixation (ORIF) of a subcondylar fracture. We studied 38 patients with 44 subcondylar fractures (3 bilateral and 38 unilateral) treated by ORIF through a retromandibular transparotid approach. All patients were followed up for 6 months. Postoperative function of the facial nerve was evaluated within 24h of operation, and at 1, 3, and 12 weeks, and 6 months. Variables including type of fracture, degree of mouth opening, postoperative occlusion, lateral excursion of the mandible, and aesthetic outcome were also monitored. Nine of the 44 fractures resulted in transient facial nerve palsy (20%). Branches of the facial nerve that were involved were the buccal (n=7), marginal mandibular (n=2), and zygomatic (n=1). In the group with lateral displacement, 2/15 showed signs of weakness, whereas when the fracture was medially displaced or dislocated 7/23 showed signs of weakness. Of the 9 sites affected, 7 had resolved within 3 months, and the remaining 2 resolved within 6 months. The mean (range) time to recovery of function was 12 weeks (3-6 months). There was no case of permanent nerve palsy. The retromandibular transparotid approach to ORIF does not permanently damage the branches of the facial nerve. Temporary palsy, though common, resolves in 3-6 months. Postoperative occlusion, mouth opening, and lateral excursion of the mandible were within the reference ranges. We had no infections, or fractured plates, or hypertrophic or keloid scars.