Practical Tips for Open Reduction and Internal Fixation of Mandibular Subcondylar Fracture

Abstract

Mandibular subcondylar fractures are fractures below the most inferior point of the sigmoid notch. The reported incidence is 25% to 35%, depending on the study. Unlike most facial fractures, mandibular condyle fractures are due to indirect trauma. Typically, direct forces (i.e., trauma) to symphysis and/or parasymphysis will generate indirect forces. Transmitting the indirect forces (i.e., trauma) often results in mandibular condyle fracture/s. Several classification systems have been proposed. However, the most commonly used classification divides the mandibular condyle into three areas: (1) condylar head, (2) condylar neck, and (3) subcondyle. Condylar head fractures are located at the level of the temporomandibular joint (TMJ) capsule (i.e., intracapsular or diacapitular). Condylar neck fractures extend from the TMJ capsule superiorly to the level of the sigmoid notch inferiorly. Subcondylar fractures are below the sigmoid notch. Appropriate treatment of a mandibular condyle fracture re-establishes pre-injury occlusion, vertical facial height, speech, and mastication. There are various treatment approaches: (1) soft diet, (2) closed reduction (CR) with maxillomandibular fixation (MMF), and/or (3) open reduction and internal fixation (ORIF). The purpose of this chapter is to review pearls and pitfalls for ORIF of mandibular condyle/ subcondylar fractures.

Practical Tips

Preoperative Consideration

• The gold standard for diagnosing mandibular condyle/subcondylar fractures is computed tomography (CT) scans without contrast.

• Always look for concomitant mandibular fractures.

• Identifying fracture/s (1) location (head, neck, or subcondyle), (2) angulation, (3) dislocation, and/or (4) comminution will help to formulate the surgical plan.

• To avoid long-term functional complications such as cross and/or open bite, consider ORIF for fracture/s causes >2 mm shortening of the and/or angulated ≥30° (Fig. 11.1).

Fig. 11.1

Algorithm for management of mandibular condylar process fracture

Intraoperative Consideration

• The main surgical approaches for mandibular condyle/ subcondylar fractures are (1) preauricular, (2) high submandibular, (3) retromandibular, or (4) endoscopic (Fig. 11.2).

• The pre-auricular approach provides limited exposure to the condylar neck and subcondylar fractures. The pre-auricular approach is advised to treat condylar neck fractures.

• The high submandibular approach provides adequate exposure to condylar neck and subcondylar fractures. However, the risk of the marginal mandibular branch of the facial nerve injury is high because the incision lies immediately on top of the nerve (Fig. 11.3).

• Retromandibular approach has three modifications: (1) transparotid, (2) anteroparotid, and (3) retroparotid approaches.

• Anteroparotid and transparotid approaches have a lower incidence of facial nerve injury than retroparotid.

• The retromandibular approach provides direct and broad access to the condylar neck and subcondylar fractures. To minimize facial nerve injury, consider using a hand-held nerve stimulator to help localize the nerve branches.

• Do not use muscle relaxants while approaching the fracture.

• Once the buccal and marginal mandibular branches are identified, carefully dissect them with a McCabe nerve dissector.

• Once the fracture is exposed, ask the anesthetist to provide a muscle relaxant. Minimizing muscle pull will help with fracture mobilization and reduction.

• Do not use intermaxillary fixation (IMF) because it prevents proper fracture reduction.

• Careful alignment of the fracture segments with good anatomic reduction is important.

• Consider following Myers Lines of Osteosynthesis for more stable fixation (Fig. 11.4).

• Fixation can be done with (1) 2 mini plates following Myers lines of Osteosynthesis, (2) trapezoidal plate (best long-term results), or (3) geometric 3D plate.

• Always pay attention to the assistant during retraction to prevent neuropraxic injury with excessive pressure.

• Careful closure of the parotid-masseteric fascia with watertight closure will prevent the formation of sialocele.

• Consider cosmetic skin suturing technique; up to 8% of patients complain of postoperative scarring.

Fig. 11.2

Different surgical approaches for ORIF of mandibular condylar fractures

Fig. 11.3

High submandibular approach. Notice the location of the marginal mandibular branch

Fig. 11.4

Lines of compression and tension of the condylar process

Postoperative Consideration

• Transient facial nerve paresis is common. It should resolve within 3 to 6 months.

• Sialocele is a rare complication, and it can be managed conservatively with aspiration/pressure, a scopolamine patch, and a Botox injection.

Pearls

• Consider open reduction and internal fixation (ORIF) to prevent long-term functional complications.

• For accurate nerve stimulation results, avoid muscle relaxants while approaching the fracture. In contrast, to help fracture reduction, muscle relaxants are advised.

Pitfalls

• Intra-operative intermaxillary fixation (IMF) is not recommended, as it will hinder accurate fracture reduction.

• Avoid nerve injury due to retraction by paying attention to the retraction technique.