Synovialchondromatose

Synovial chondromatosis, also known as synovial chondrometaplasia or synovial osteochondromatosis, is a rare benign condition characterized by metaplastic formation of cartilaginous nodules within the synovial membrane of joints, bursae, or tendon sheaths. In this condition, nodules may detach to form loose bodies that accumulate within the joint space. Disease can be classified as primary, occurring without an underlying joint disorder, or secondary, arising in the context of preexisting joint disease such as osteoarthritis, inflammatory synovitis, or trauma.

Clinically, synovial chondromatosis most often affects middle-aged adults and commonly involves a single large joint, especially the knee, though other joints can be involved. Patients typically present with gradual onset joint pain, swelling, and reduced range of motion. Mechanical symptoms such as joint locking or catching may occur due to loose bodies. Recurrence after treatment is possible, particularly if synovial tissue is not completely removed or if the underlying joint pathology persists.

Diagnosis relies on imaging and tissue analysis. Plain radiographs commonly show multiple calcified or ossified loose bodies within the joint; early disease may lack calcifications. Magnetic resonance imaging is useful to detect noncalcified cartilaginous nodules and assess synovial proliferation. Computed tomography can better delineate calcified bodies. Definitive diagnosis is made histologically, with nodules composed of hyaline cartilage arising from the synovial membrane.

Treatment generally involves surgical removal of loose bodies with synovectomy. Arthroscopic approaches are often used for accessible joints, while open procedures may be required for extensive disease. Complete synovectomy reduces recurrence risk, particularly in primary disease. Prognosis is favorable with appropriate therapy, though recurrence can occur and malignant transformation to chondrosarcoma is rare but reported in longstanding cases.