Fig. (5) 27 year old male patient with knee pain following an acute rotational valgus injury. A) Axial PD (proton density) fat saturated MR image, demonstrating edema (high signal) on the outer aspect of the lateral femoral condyle and at the inferomedial aspect of the patella, signifying a recent transient lateral patellar dislocation (open arrows). B) and C) sagittal and coronal PD MR images demonstrating a displaced and medially migrated osteochondral fracture fragment (arrows). The donor site from the lateral femoral condyle is also clearly shown (arrow heads). D) Post-surgical AP radiograph of the knee, demonstrating that the osteochondral fragment has been surgically reduced and fixed into an anatomic position (arrow).