Fracture Fridays: Mandible fractures

The Case

A 14 year old male was tackled while playing football and has pain along the angle of his jaw. He can open and close his mouth without pain. He does have pain to palpation along the body of the mandible adjacent to 2nd/3rd left inferior molars. There are no loose teeth and he feels that they are in normal alignment. He can bite down on a tongue depressor, and feels pain at same site when you flick the tongue depressor and it vibrates. He wants to know if he has a mandible fracture?

from learningradiology.com

Diagnosis

Fortunately his X-Rays were read as normal. Before moving on take a look at this representation of mandible anatomy.

The jaw!

In the Pediatric ED the peak incidence 16-20 year. As you might expect males are 3:1. In patients less than <10 years old the condyles are the most common location, whereas in those >10 years old you see fractures of the symphysis, body, and/or ramus. Multiple fractures are seen in 40-60% – These are more common when patients are >13 years old. C spine injuries are also seen in <1% whereas dental injuries are much more common – 20-30%. Fractures of the condyle and symphysis are seen more often in falls and motor vehcile accidents, whereas assaults/blunt trauma lead to fractures of the body and angle. In adults the fracture breakdown by cause is:

MVC 40%
Assault 40%
Fall 10%
Sports 5%
Other 5%

What exam findings can help diagnose a mandibular fracture?

Tenderness over fracture site
Malocclusion
Bruising in floor of mouth
Mucosal/gingival lacerations
Chin deviation
Pain when opening/closing mouth
Inability to bite down on a tongue depressor
Tooth fracture
Lip numbness (inferior alveolar nerve injury)

Pro-Tip: Bleeding /lacerations along the alveolar ridge suggests an open mandibular fracture

Are chin lacerations associated with fractures of the mandible?

Yes according to Hubbard et al 1995. In a prospective series of 45 children with chin lacs 24% had mandible fractures on panorex Xrays. I haven’t seen this in my practice – and many of these were nondisplaced. I also don’t have panorex films readily available. So take this as you will.

Management

Imaging

Usually diagnosed with plain Xrays or panorex. 3 view plain films are equally sensitive in detecting fractures as panorex. According to Posnick et al 1995 CTs are not superior to plain films (at least in children). Charalambous et al 2005 performed a prospective study of 280 adults with possible mandible fracture, all of which got Xrays – lateral-oblique and PA. The radiologist was blinded to clinical probability of a fracture. Ultimately 65 had a fracture. the authors then derived a decision rule that identified 5 parameters with a Sensitivity of 100% and specificity of 39% that may eliminate the need for radiography if the patient lacks all 5 findings:

Malocclusion
Trismus
Broken teeth
Pain with mouth closed
Step-off deformity

Though your mileage may vary – this study was done in adults, and I still advocate for X-Rays. However, if the patient does have one of the above findings, and has normal X-Rays and can eat and talk I don’t rush them to the CT scanner as they patient may have a non-operative non-displaced fracture that wouldn’t necessarily change management significantly.

Fracture of the body of the mandible

Treatment

If needed, surgery should be done within 5 days of injury followed by immobilization for 3-4 weeks (adults 6-8 weeks). Unilateral condyle fractures with no malocclusion can be treated conservatively with analgesia, soft diet, and 1-2 week follow-up Xrays. With malocculsion 7-10 days of immobilization is recommended. Bilateral condyle fractures should be splinted, as permanent malocclusion may be warranted. Non-displaced fractures of the symphysis, body and angle can be managed conservatively. Displaced/opne fractures need surgery (generally plates).