Unilateral medial dislocation of the temporomandibular joint

We present our experience of the rare condition of unilateral medial dislocation of the temporomandibular joint (TMJ) in 11 patients with head trauma who had received a direct lateral blow on the chin. The diagnosis was made by direct coronal CT of the TMJ performed from 6 h to 7 days following the injury. In 6 patients, subcondylar fracture of the ipsilateral mandibular ramus was also demonstrated. A second CT performed 11-16 months following the first one demonstrated pseudoarthrosis of the fractured ramus in these 6 patients. The second CT was identical to the first in the remaining 5 patients with pure dislocation of the condyle. All patients suffered from severe disability of the TMJ. The maximal vertical distance between the upper and lower incisors in patients with uncomplicated dislocation ranged between 8 and 12 mm. In cases with complicated medial condylar dislocation with fracture and pseudoarthrosis of the mandibular ramus, this distance ranged between 16 and 25 mm, probably because of additional movement in the area of the pseudoarthrosis. The maximal vertical distance between the incisors was compared with a control group of 20 normal adults who had values from 40 to 52 mm. Medial unilateral dislocation of the TMJ can appear in two forms: uncomplicated or complicated, with pseudoarthrosis of the ipsilateral mandibular ramus.