Understanding Synovial Chondromatosis: A Rare Cause of Shoulder Impingement.

Introduction: Synovial chondromatosis (SCM) is a benign neoplastic condition manifesting as multiple loose bodies within a joint cavity, usually affecting the knee and hip joints. It is a rare cause of shoulder joint pain. There is a challenge in diagnosing this condition, as early findings reveal non-ossified, radiolucent, cartilaginous loose bodies, which significantly delay the diagnosis. Surgical excision and synovectomy are the usual treatments. Here, we present an unusual case of SCM of the shoulder joint that was successfully treated with arthroscopic excision, with good functional outcome at the 12-month follow-up. Case Report: A 30-year-old male presented with complaints of left shoulder pain for 6 months, with a history of unknown origin. Pain was insidious in onset, characterized by a dull aching pain of mild-to-moderate intensity that worsened with throwing activities over the past 2-3 months. There were symptoms of locking and crepitus affecting daily activities. The physical examination revealed diffuse tenderness, and the range of motion was full with no obvious deformity. The clinical tests for impingement were positive, and the testing of rotator cuff integrity suggested no tear. Plain radiography was grossly normal except for some calcification seen medially. Magnetic resonance imaging demonstrated multiple loose bodies involving the subscapular recess, posterior and inferior aspect of the glenohumeral joint, and at the rotator interval, suggestive of SCM. The patient was surgically treated with arthroscopic excision, and multiple nodules were excised. Conclusion: There were no symptoms of recurrence at the 12-month follow-up.