Knee Pain Following a Ski Injury

CASE: A 13-year-old boy presented to the ski clinic following a fall and a possible twisting of his right knee. He was not able to bear any weight on his right leg and was experiencing pain in the medial aspect of his right knee. His past medical and surgical histories were unremarkable and he was otherwise in good health. Physical examination revealed no ecchymosis or effusion. He had moderate tenderness over the medial femoral condyle. Stress valgus test did not reveal any laxity, but caused significant pain. Plain radiography was performed (Fig. 1). How do you interpret his radiographs? A. Enchondroma of the medial distal femur. B. Nonossifying fibroma of the medial distal femur. C. Osteoid osteoma of the medial distal femur. D. Salter-Harris type II fracture of the distal femur.