Fracture dislocation of the ankle with posterior tibial tendon entrapment within the tibiofibular interosseous space: A case report

In rare cases of ankle fracture dislocation, the posterior tibial muscle tendon (TP tendon) is incarcerated between the tibia and fibula, thereby impeding reduction. Here we describe a case that presented with such a condition, in which ankle reduction was achieved and surgical repair of the incarcerated TP was delayed. The subject was a 30-year-old male who sustained a fracture dislocation of the left ankle (AO:44-C1.3) in a motorbike accident. After repairing the ankle dislocation, external fixation was performed and osteosynthesis was conducted 10 days after the injury. Plate fixation for the fibula fracture and tight rope fixation for the separation between the tibia and fibula were performed; however, internal fixation for the medial malleolus fracture was delayed because the skin on the medial side of the ankle was in poor condition. One month after the injury, osteosynthesis of the medial malleolus was performed, and the TP tendon was identified in the fracture site. After removing the incarcerated tendon, good reduction of the medial malleolus was achieved, and thus, internal fixation and wound closure could be performed. Re-examination revealed that the TP tendon had an abnormal course. After 3 months, upon re-exposing the entire length of the TP tendon, the TP tendon was incarcerated between the tibia and fibula. To date, although several cases have been reported regarding TP tendon incarceration caused by fracture dislocation of the ankle, no study has reported the anatomical repair of the ankle, regardless of tendon incarceration. In our case, rotational displacement of the medial malleolus fracture remained when the second surgery was completed; however, the presence of some type of incarcerated tissue was suspected. Because leaving the incarcerated TP tendon untreated can cause irreversible long-term complications, early anatomical repair is recommended.