Medial Patellofemoral Ligament Tear Associated with an Intra-articular Axial Spilt Osteochondral Fracture of the Lateral Femoral Condyle: a "Knee Trap-door" Fracture.

INTRODUCTION: Medial patellofemoral ligament (MPFL) prevents lateral dislocation of the patella and acts as a major stabilizer. The tear could be associated with osteochondral avulsion fractures; however, intra-articular split fractures are not seen. Here, we present one unusual case of such a presentation.

CASE REPORT: A 16-year-old male presented with a history of recurrent patellar dislocation and inability to bear weight following the last episode. The patient was diagnosed with an MPFL tear with an unusual intra-articular femoral condyle split fracture. The case had significant improvement in functional scores post-surgery.

CONCLUSION: In physically active populations, twisting of the knee could result in an MPFL tear, leading to recurrent patellar dislocation. The treatment remains ligament reconstruction, open, or arthroscopic. Associated intra-articular fractures are very rare with such injuries and need to be addressed due to the high rate of non-union.