Flexor tendon ruptures in rheumatoid arthritis.

Flexor tendon ruptures in rheumatoid arthritis are caused by either attrition on bone spurs or by direct invasion of the tendon by hypertrophic tenosynovium. All attrition ruptures occur within the carpal canal and represent the most common cause of tendon rupture. Removal of the causative bone spur is imperative in the treatment of this condition. Ruptures due to invasive tenosynovitis also are frequently found within the carpal canal. These ruptures may be unanticipated, and may be discovered as an incidental finding during flexor tenosynovectomy. Ruptures due to invasive tenosynovitis within the digit carry an unfavorable prognosis. The prognosis for restoring flexion in the event of a flexor tendon rupture is determined by the location of the rupture, the etiology, the degree of articular involvement from the rheumatoid disease, and to a lesser extent, by the number of ruptured tendons. In general, isolated or double ruptures within the carpal canal due to attrition have a better prognosis than those caused by invasive tenosynovitis since the condition of the tendons is more favorable for reconstruction; however, as the number of ruptures increases, the prognosis in both conditions worsens. Rupture of both tendons within the digital sheath is quite difficult to treat, with ruptures in zone 2 carrying the worst prognosis for the restoration of flexion. The severity of the patient's rheumatoid arthritis and articular disease has a great effect on the outcome of the reconstructive surgery. Prevention of tendon ruptures by early tenosynovectomy and the removal of bone spurs should be the goal of the surgeon.