Not the bees' knees

This x-ray fascinated us for a while. You don't really expect to see that much calcium where its not supposed to be! A lady presented with knee pain and a hx consistent with osteoarthritis. What could this be?

Ans: Synovial Chondromatosis

• basically calcification of synovium (metaplastic)
• occurs in men mostly
• Synovectomy if pain persists despite painkillers

Ref: Wheeless Ortho page and also Orthoinfo