Clinical manifestations of synovial cysts.

Although synovial cysts are most commonly associated with rheumatoid arthritis and osteoarthritis, they may occur in many other conditions. The clinical manifestations of these cysts are numerous and may result from pressure, dissection or acute rupture. Vascular phenomena occur when popliteal cysts compress vessels, and result in venous stasis with subsequent lower extremity edema or thrombophlebitis. Rarely, popliteal cysts may cause arterial compromise with intermittent claudication. Neurological sequelae include pain, paresthesia, sensory loss, and muscle weakness or atrophy. When synovial cysts occur as mass lesions they may mimic popliteal aneurysms or hematomas, adenopathy, tumors or even inguinal hernias. Cutaneous joint fistulas, septic arthritis or osteomyelitis, and spinal cord and bladder compression are examples of other infrequent complications. Awareness of the heterogeneous manifestations of synovial cysts may enable clinicians to avoid unnecessary diagnostic studies and delay in appropriate management. Arthrography remains the definitive diagnostic procedure of choice, although ultrasound testing may be useful.