Rheumatoid arthritis is a synovial lesion. In the structures of the hand and wrist joints, the synovial layer of the tendon sheath surrounds the tendon, and synovial hyperplasia can affect the corresponding tendon structures, as can intra-articular synovial lesions. Involvement of the tendon sheath is very common and can precede the onset of symptoms of intra-articular lesions by several months. Synovitis of the tendon sheath can be painful, and erosion of the tendon by the proliferating synovial tissue can lead to tendon rupture. Treatment can relieve pain, especially before secondary changes in the surrounding tissues or tendon rupture, and can prevent deformities and impaired function. Therefore, synovectomy of the dorsal, metacarpal and fingers is usually the first procedure performed in patients with rheumatoid arthritis. Prophylactic synovectomy reveals that in approximately 50-70% of patients with synovitis, the tendon has been eroded by hyperplastic synovial tissue. Anatomy of the tendon and tendon sheath Dorsal to the wrist joint, the deep fascia thickens to form an extensor support band approximately 75 px wide, which functions as a glide for the extensor tendon traveling in the sheath canal. The vertical sheaths running from the palmar surface of the extensor support band to the dorsal surface of the radial ulna form a total of six extensor sheaths, which are named numerically. The tendon in each sheath canal is surrounded by a synovial membrane that begins at the proximal end of the proximal edge of the extensor support band and extends to the level of the metacarpal base, whereas the distal tendon is covered by peritendinous, not synovial, tissue. On the palmar side of the carpal joint, the flexor tendons of the thumb and fingers and the median nerve pass from the transverse carpal ligament (flexor support band), which covers the palmar side of the carpal bone and attaches to the mostly angular and navicular bones on the radial side and to the hook bone hook and bean bone on the ulnar side, forming the top of the carpal tunnel. Before the flexor tendon enters the carpal tunnel, it is wrapped by a common tendon synovial membrane. Dorsal (extensor) synovitis of the wrist joint Dorsal synovitis of the wrist joint presents as swelling of the dorsal aspect of the wrist joint. The swelling can be mild or extensive and can involve one, several or all of the extensor tendons. Because the skin on the dorsal aspect of the wrist joint and the back of the hand is thin and easily pushed, the clinical manifestations of tendon synovial hyperplasia and dorsal synovitis are very obvious, and its may be the first symptom of rheumatoid arthritis. Solitary synovitis is painless and the patient usually ignores the swelling. It is not until the tendon is ruptured and active extension is lost that the patient becomes aware of his or her disease. Early in the disease, the synovial tissue is thin and extends along the tendon sheath. As the disease progresses, the synovial tissue thickens and becomes tough, similar to the synovial tissue within the joints of progressive rheumatoid arthritis. Sometimes, fibrinous “rice grain bodies” fill the tendon sheaths of tendons, and the hyperplastic synovial membrane adheres to the surface of the tendon and gradually invades the tendon, resulting in weakened tendon strength and tendon rupture. Sometimes rheumatoid nodules can be found in the tendon. Early synovitis of the dorsal wrist may resolve spontaneously or with the use of medication. However, progression of the disease and synovial hyperplasia make it difficult to be relieved by the above treatment methods alone. Therefore, early dorsal carpal synovectomy is recommended (if the condition does not improve significantly after 4-6 months of regular, formal conservative treatment). After dorsal carpal synovectomy, spontaneous rupture of the tendon in the extensor sheath canal is rare, despite the poor quality of the tendon due to synovitis involvement (there is evidence of wear and tear of the tendon). Complications Complications of dorsal carpal synovectomy are uncommon; the most serious complication is skin necrosis. After skin necrosis, the extensor tendon is exposed and there is a great risk of rupture and scar formation. In patients with rheumatoid arthritis (especially those taking glucocorticoids), postoperative subcutaneous hematoma formation under the dorsal flap is the most important cause of delayed wound healing, and intraoperative care should be taken to prevent hematoma formation with tension-free skin sutures, routine placement of drainage, and, if necessary, open distal and proximal openings of the wound to prevent hematoma formation. Sutures are placed under the skin to cover the extensor tendon, and sometimes when the skin is broken, an extensor support band can also be placed over the extensor tendon to protect it. Do not remove the sutures prematurely, and if there is skin breakdown, the wound can be expanded and the skin covered. Wear a brace to immobilize the metacarpophalangeal joint in the extended position until the wound heals in 2-3 weeks. Sometimes, postoperative tendon adhesions can lead to metacarpophalangeal joint extensor tendon laxity or limited active finger flexion. Hand rehabilitation is adjusted as needed, with emphasis on flexion and extension activities. If the patient is in pain or weak flexion prevents flexion, passive flexion is assisted and a powered flexion brace is used, or if there is significant extensor tendon laxity, a powered extension traction brace is used. Reduced range of motion after dorsal wrist synovectomy is most often seen in patients with poor intraoperative tendon quality, polyarticular involvement, and low pain thresholds. Tendon release is rarely needed after dorsal carpal synovectomy, but if functional limitations are still evident 6 months after surgery, tendon release should be considered.