The purpose of this study is to evaluate the incidence, location, and associated findings of extensor mechanism injuries in the setting of tibiofemoral knee dislocations.
Methods: A retrospective search for patients with previous knee dislocation and MRI of the knee was made during a 5-year period. Images were evaluated for abnormalities commonly seen in patellar instability. Patellar and quadriceps tendon integrity were also evaluated.
Results: A total of 14 patients were included in the study. Medial patellofemoral ligament injuries were identified in 10 patients (71%) with tibiofemoral dislocation. As in patients with previous patellar dislocation, medial patellofemoral ligament injuries commonly occurred at the femoral attachment of the ligament. Medial patellofemoral ligament injuries correlated well with vastus medialis oblique elevation. Patellar tendon injuries were less common identified in only 5 patients (36%).
Conclusions: Medial patellofemoral ligament injuries can be associated with tibiofemoral knee dislocations. In addition, patellar tendon injuries can also occur, although these are usually partial tears.