Acute dislocation of the proximal tibiofibular joint.

The patient was a 19-year-old female who reported an acute onset of lateral left knee pain while participating in a 3-legged race. The patient reported to the emergency department immediately following the injury. Observation revealed prominence along the lateral aspect of the knee. The patient was unable to bear weight on her left lower extremity and her symptoms were exacerbated with extension of the knee. Although the initial radiographs of the left knee and lower leg showed no apparent fracture, a widening of the interosseous space between the tibia and the fibula and an altered position of the fibular head were noted on the anterior to posterior radiographic view. On the lateral radiographic view there was anterior displacement of the left fibula compared to the right. These radiographic findings suggested an anterolateral dislocation of the fibular head, the diagnosis of which was confirmed upon the completion of axial computed tomography. Successful closed reduction was achieved and the patient was treated with a period of protected weight bearing on crutches, progressing to full weight bearing over 6 weeks. At 1 year following the injury, the patient was participating in all regular activities of daily living without pain or instability. Early detection and immediate reduction of an acute dislocation of the proximal tibiofibular joint are important to prevent long-term disability.