Medial patellofemoral ligament injury following acute transient dislocation of the patella: MR findings with surgical correlation in 14 patients.

PURPOSE The purpose of this study was to determine the accuracy of MRI in determining both the extent and the location of injury to the medial patellofemoral ligament (MPFL). METHOD MR findings were compared to the surgical results of 14 consecutive patients who experienced transient patellar dislocation. Two musculoskeletal radiologists, blinded to the surgical results, retrospectively reviewed the MR studies, and a consensus reading was obtained. RESULTS Surgery demonstrated complete disruption of the MPFL in 7 of 14 patients (50%), with stretching or partial tearing of the MPFL in the remaining 7 (50%) patients. MRI was 85% sensitive and 70% accurate in detecting MPFL disruption. Vastus medialis obliquus muscle elevation was present in 12 of 14 (85%). CONCLUSION MRI accurately depicts both the extent and the location of MPFL injury following transient patellar dislocation and can therefore play a significant role in directing surgical management of these patients.