An adolescent boy visited an orthopedic clinic for bilateral knee pain after a soccer game. He did not report trauma, fever or previous joint or back problems. He was a member of the school football team for two years, actively running and jumping in training. The pain appeared occasionally during the last month after matches and subsided with rest. His medical and family history was free of significant diseases. On examination, both knees had mild swelling, tenderness, and prominent tibial tubercles with normal range of motion. X-rays showed bone fragments around the tibia in both knees with soft tissue swelling.