A Rare Co-Existing of Hip and Knee Joint’s Synovial Chondromatosis: A Case Report

A 29-year-old male patient presented to our clinic with progressively worsening bilateral hip pain, right knee pain and swelling. The hip and knee pain started about 3 months ago and increased over time. Pain of the hip joints was spreading bilaterally to the trochanteric regions. The characteristic of the pain was mechanical. He did not feel pain while sleeping. Prolonged sitting or standing caused the hip to lock. Previously, he had received analgesic medications but there had been no significant improvement. There was no pain in any other joint, and there was no history of disease or trauma associated with the hip and knee. Physical examination revealed an antalgic gait and the patient had visibly swollen right popliteal fossa. The motion of the right hip joint was limited and painful in all directions, whereas lumbar and left hip joint motions were unrestricted. He could fully extend his knee, but flexion was restricted to only 120 degrees. Radiography of the pelvis and knee indicated a narrowing joint space, and there were erosions on the acetabular side of the joint and multiple soft tissue calcifications outside the joint capsule of the right knee. Magnetic resonance imaging (MRI) of the bilateral hip revealed findings consistent with synovial chondromatosis, which filled the joint space completely and MRI of the knee revealed expanded sinovium that contained osteochondromas, which were hypointense in all sequences (Figure 1). Orthopedic surgical procedures including arthroscopic debridement were planned with symptomatic right hip and right knee joints. Synovial osteochondromatosis is a rare benign condition characterized by the formation of multiple nodules of hyaline cartilage within the sub-synovial connective tissue (1). The condition is generally monoarticular and involves the knee in more than 50% of the cases (2). The other common joints involved are hip, elbow, shoulder and ankle. In the literature, Kose et al. (3) presented a unilateral hip joint synovial osteochondromatosis case, Mackenzie et al. (4) presented Fatih Bagcier, Ayhan Kul, Emine Esra Ergul, Akin Erdal