A Case of Baker’s Cyst with Synovial Chondromatosis of Knee

Synovial chondromatosis is a benign condition which arises from synovial membrane or bursae around the joints. Joint abnormalities in the form of arthritic or mechanical conditions such as detachment of osseocartilaginous fragments from the articular surface are its secondary associations. Rarely there maybe involvement of the Baker’s cyst. Here we report a case in which a 60-year-old female came with complaints of pain, swelling and restriction of movement of right knee joint for the past one year. After careful clinical and radiological examination, it was diagnosed as Baker’s cyst complicated by synovial chondromatosis. After the diagnosis the patient underwent the following procedures: open synovectomy, cyst removal and thorough joint debridement. Synovial chondromatosis was confirmed histopathologically. Secondary synovial chondromatosis has features of osteoarthritic changes, lack of extensive synovial proliferation and complicated Baker's cyst which is not seen in primary synovial chondromatosis. Synovial chondromatosis (SC) is caused by metaplasia of the synovium into chondrocytes and is a rare benign disorder.[1,2] Primary synovial chondromatosis (PSC) is a self-limited process that occurs in an otherwise normal joint.[3] When synovial chondromatosis develops in a joint previously affected with disease, often posttraumatic or degenerative osteoarthritis, it is called as secondary synovial chondromatosis.[4] SC may involve any joint, but the most common joint involved is knee joint followed by hip joint, and small joints of the hand and wrist. Least involvement is seen in elbow and shoulder joint. [5] The disease is categorised into three phases according to Milligram classification: active intrasynovial disease without any loose bodies observed in the early phase, active disease and loose bodies observed in the transitional phase, and multiple loose bodies without any intrasynovial disease observed in the late phase. In orthopaedic practice, popliteal cysts are common occurrence; many of them are associated with degenerative or rheumatoid arthritis. The differential diagnoses become more complex when loose bodies and calcifications are noted within the joint on a radiograph. Here in, we are presenting a case of Baker’s cyst with synovial chondromatosis of knee treated by surgical excision and confirmed by histopathology.