Synovial chondromatosis is a rare, self-limited and benign condition characterized by metaplasia of synovial lining of a joint, tendon sheath or bursa; leading to the formation of multiple cartilaginous loose bodies. It is also called articular chondrosis or synovial chondrosis. It may be classified into 2 types; intra-articular and extrarticular or para-articular types. Most common joint to be affected is the knee followed by hip, shoulder, elbow, ankle and wrist. Primary synovial chondromatosis develop without any underlying cause and secondary chondromatosis develop in those patients suffering from long standing osteoarthritis.
It usually occurs in the third to fifth decade and the males are twice more frequently affected than females. Rarely, it may also develop in bursae and soft tissue.
Trauma may be a cause as it is seen mainly in weight bearing major joints and in joints of the dominant upper limb. Infection is thought to be another cause.
Patients usually present with monoarticular pain, swelling and stiffness of insidious onset. Later on
they may complain of recurrent locking and effusion, multiple palpable loose bodies, reduced range of movement and crepitus may be demonstrated.
Multiple round or oval cartilaginous loose bodies may be seen intra-articularly. The cartilaginous loose bodies have a ‘popcorn’ or ‘rings and arcs’ appearance on x-ray. Changes suggestive of osteoarthritis may be found. In 25-30% of cases calcification is absent and CT scan may be helpful in detection of unmineralized loose bodies. MRI may show multiple signal voids and is helpful in identifying the precise location of loose bodies whether loose or attached, whether intrasynovial or extrasynovial. Loose bodies show intermediate or low signal on T1 and high signal in T2. Gradient echo images will enhance the signal voids.
On gross examination, synovium shows diffuse or focal involvement with multiple nodules which range in size from 1mm to several centimeters. Microscopy reveals focal or diffuse hyaline cartilaginous metaplasia of synovium. Milgram in 1977 described 3 phases; active intrasynovial disease (metaplasia without chondromas), transitional phase (metaplasia with loose bodies) and quiescent intrasynovial disease (loose bodies without metaplasia). Nodules may calcify or ossify. Rarely, sarcomatous transformation has been reported. Giant synovial chondromatosis is a variant where the size of one or multiple chondromas has attained sizes larger than 1cm.
Includes osteoarthritis, neuropathic arthritis, rheumatoid arthritis, osteochondritis dissecans, recurrent dislocations leading to osteochondral fracture, pseudogout, synovial sarcoma, lipoma arborescence, chondrosarcoma and tumor calcinosis.
Arthroscopic or open removal of loose bodies with partial or near total synoviectomy is the treatment of choice. Arthroplasty is an option is patient presents with advanced cartilage destruction. Arthroscopy may show snow storm appearance due to multiple intra-articular and synovial chondromata. Local recurrence may occur in 3-23%.
Copyright @Dr Rajesh Purushothaman, Associate Professor, Government Medical College, Kozhikode, Kerala, India