Fig 1.

A preoperative cross-sectional view of the right knee on magnetic resonance imaging shows scarring at the anterior aspect of the medial patellofemoral ligament (MPFL). A subchondral loose body is seen between the medial patellar facet and medial femoral condyle. The articular cartilage of the medial facet is commonly injured after patellar dislocation. Magnetic resonance imaging is used to confirm injury to the MPFL and diagnose any associated pathology. Plain radiographs of the knee should also be obtained including anteroposterior, lateral, and axial patellar views.