Swelling of the metacarpophalangeal (MP) joint area in the rheumatoid hand results from articular and periarticular causes. Ultrasonography (7.5MHz) was used to demonstrate the location and extent of synovitis and effusion in the palmar aspect of 90 swollen MP joints in 30 rheumatoid patients.
The flexor tendon sheath in the swollen MP joint area was significantly thicker than that in the control group in the index, long and ring fingers. Swelling of the palmar capsule was noted in 12 joints (13%), synovial proliferation around flexor tendons in 21 joints (23%), and thickening of flexor tendon itself due to synovial invasion in 26 joints (29%) . In 12 MP joints with trigger phenomenon, 10 were caused by synovial thickening within the flexor tendon sheath and 2 by joint incongruity due to bone destruction.
Our findings suggest that ultrasonography is a easy and noninvasive method that can be utilized to detect the lesions in MP joint areas in early rheumatoid patients. In the treatment of trigger finger, the lesion can be confirmed objectively and accurately by the ultrasound measurement and the appropriate surgical approach can be determined preoperatively.
