A 55-year-old lady presented in the outpatient clinic, with the complaints of mechanical knee pain of three-year duration. Radiographs (Fig. 1) of the knee were suggestive of multiple loose radio-opaque calcified bodies around the knee joint.

Fig. 1.

Anteroposterior and lateral radiographs of knee. Multiple loose calcified bodies are seen within it (asterisks).

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The radiographs are pathognomonic of Synovial Osteochondromatosis, an atypical neoplastic disease, with an occurrence rate of 1 in 100,000 people.1 People are likely to get affected by Synovial Osteochondromatosis in their 3rd to 5th decades of life, occurs almost 2 times more frequently in men than women. The pathogenesis includes hyperplastic metaplasia of connective tissue where hyaline cartilage gets calcified into multiple intra-articular loose bodies in synovial tissues, within the joint, bursa or tendon sheaths. Though knee is mostly affected, hip, shoulder, ankle, elbow, and wrist joints can also be affected. Joint swelling and tenderness, locking, pain, restrictions of range of motion in affected joints are some common clinical features. This disease has potential to transform into chondrosarcoma, in very few cases.2 Surgical excision of the chondromal nodules and synovectomy are the mainstay of treatment to prevent late degenerative transformation. Overall with a reported recurrence of 3–60% in primary disease, the recurrence rate goes below 10% after surgery.1,2