Mandible Fractures
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Direct answer
The mandible fractures most often at the condyle, angle, body and symphysis, with road accidents and assaults the usual mechanisms. Diagnosis rests on pain, swelling, deranged occlusion, a step deformity, lip paraesthesia and mobile segments on orthopantomogram. Management is reduction — anatomical and occlusal — followed by fixation, closed with intermaxillary fixation or open with miniplates along Champy's ideal lines, after airway priorities.
What you must remember
- Sites: the condyle and angle are most commonly fractured — many series rank the condyle first — and since the mandible is a ring, paired fractures such as symphysis with contralateral condyle are frequent; a chin bruise always prompts condylar examination.
- Features: pain, swelling, trismus; deranged occlusion — the most important functional sign; a step in the occlusal plane or lower border, mobile fragments, crepitus, sublingual haematoma and lower lip paraesthesia.
- In condylar fractures the chin deviates towards the fractured side on opening from loss of lateral pterygoid action, with premature molar contact and open bite when bilateral.
- Favourability depends on the fracture line relative to muscle pull: a slope that resists the elevators is favourable; one permitting displacement is unfavourable.
- Imaging and management: orthopantomogram with a posteroanterior view is the basic pair, CT for condylar and complex injuries; after trauma assessment — bilateral anterior fractures threaten the airway — reduce to restore occlusion and fix by closed intermaxillary fixation with arch bars or wires, or open plating along Champy's ideal osteosynthesis lines, which follow tension trajectories and permit early opening.
- Most condylar fractures are managed conservatively or with brief elastic traction; paediatric ones conservatively to avoid ankylosis and growth arrest.
- Complications: malocclusion, malunion and non-union, infection from the compound intraoral wound, nerve injury, plate exposure and ankylosis after childhood injury.
Common confusion
The deviation signs are the classic trap: in a unilateral condylar fracture the chin deviates towards the injured side on opening, whereas in unilateral dislocation it deviates away from the affected joint — one fact separates two frequently mixed questions. Favourable-unfavourable slopes are memorised blindly; the test is always the direction of muscle pull — whether the elevators drag the fragments apart or jam them together.
Exam-focused takeaway
Write the long answer in the order aetiology, sites with a ring diagram, clinical features, classification, imaging, closed versus open management and complications. Viva examiners ask the commonest site, why the chin deviates towards a fractured condyle, what Champy's lines represent and when intermaxillary fixation is preferred. During postings, study the radiograph before the surgeon comments and check occlusion yourself — when to operate a condyle and when to mobilise it is the real content.
Frequently asked questions
Which is the commonest site of mandible fracture?
The condyle and angle lead in most series, with the condyle first in many — always image both condyles when the chin is injured.
Why does the chin deviate towards a condylar fracture?
The lateral pterygoid of the fractured side cannot pull its condyle forward, so the normal side dominates rotation and the midline swings towards the injury on opening.
What are Champy's lines of osteosynthesis?
The ideal trajectories along which miniplates neutralise tension and compression forces — along the external oblique ridge at the angle, the lower border at the symphysis — allowing stable fixation and early movement.
When is closed intermaxillary fixation preferred?
For favourably aligned fractures, condylar fractures in elastic traction, children, or where open reduction is contraindicated by patient factors or facilities.
Why are mandible fractures prone to infection?
Most are compound into the mouth through torn mucosa, contaminating the fracture line with oral flora — mandating antibiotics, hygiene and sound fixation.