Mandibular fractures are relatively common especially among young men. Although traditionally the mandible and base of skull are thought to form a complete bony ring, interrupted only by the TMJs. This should mean that the mandible should fracture in two places (akin to the bony pelvis) making single fractures uncommon, but this in fact not the case, with ~40% of fractures being unifocal.

Epidemiology

After the nasal bones, the mandible is considered the second most common site of facial fractures. Aetiology and demographics will vary significantly depending on the population demographics and with where patients present. In the setting of a trauma centre in New Zealand, 90% of patients are male, with 64% between the ages of 15 and 29 ²:

• assault: 50%

• intimate partner violence

• motor vehicle accident (MVA): 10%

• fall: 15%

• sport: 15%

• other: 10%

Clinical presentation

Presenting complaints will include ³:

• pain

• chin paresthaesia (damage to the mental nerve, a terminal branch of the inferior alveolar nerve)

• malocclusion

• trismus

• dental damage

• abnormal mobility

• laceration of the skin of the external acoustic meatus

Pathology

Location

• angle: 20-33% ^1-3

• body / horizontal branch: 15-25%

• condyle or neck: 15-36%  (see: TMJ trauma)

• parasymphyseal: 14-15%

• ramus: 5%

• coronoid process: 1-3%

• alveolar ridge: 2%

Unifocal fractures are common, accounting for approximately 40% of all mandibular fractures ¹:

• multifocal: 60% ¹

• unifocal: 40%

  • simple: 25%

  • comminuted: 10%

  • associated with condylar subluxation: 5%

Subtypes

• guardsman fracture

• flail mandible

Treatment and prognosis

Treatment can be conservative or involve formal reduction (which may be open or closed). Closed reduction may be supported with intermaxillary fixation or splints (ORIF).

Complications

• osteomyelitis

• permanent malocclusion ³

• permanent paraesthesia