he incidence of flexor tendon injury is 33 injuries per 100,000 person-years. 1,2 Advancements in flexor tendon repair, including wide-awake surgery, have led to improved outcomes. 3 In studies using multiple strand repairs and active range of motion, excellent results (defined as total active range of motion more than 150 degrees 4 ) have been noted in up to 86 percent of cases. 5,6 Despite this, reoperation still occurs. In a retrospective review of 5229 patients undergoing primary flexor tendon repair, there was a 6 percent reoperation rate, with 58 percent of these patients requiring tenolysis alone, 38 percent requiring rerepair alone, and 4 percent requiring both. 7 In such cases, the surgeon must have an understanding of the available reconstructive options for the treatment of patients with neglected, failed, or scarred tendon repairs. This article will review the indications and management options for failed flexor tendon surgery.
THE MECHANICAL IMPACT OF FAILED FLEXOR TENDON REPAIRComplications following flexor tendon repairs include decreased range of motion, tendon bowstringing, quadriga, and lumbrical-plus deformity. 8-10 Compared to patients with primary flexor tendon repair, who have a mean QuickDASH score of 19.3, patients who require two-stage tendon reconstruction have a mean QuickDASH score of 34.4, emphasizing the importance of successful primary repair. 11 Flexor tendon pulley injury and tendon bowstringing can contribute to poor results. The pulley system consists of several fibro-osseous tunnels that run from the metacarpal head to the distal interphalangeal joint. These tunnels hold the tendons close to the joint's axis, allowing maximal motion for small amounts of tendon excursion. Biomechanical cadaver studies show an 8.5 percent increase in tendon excursion with loss of the A2 pulley, a 9.9 percent increase with loss of the A4 pulley, and a 33.7 percent increase with loss of both A2 and A4. 12 The loss of both pulleys leads to a 107 percent increase in the work of flexion. 12 This can lead to loss of motion and joint contracture. Pulley damage can be avoided by accessing and performing the tendon repair through the cruciate pulleys. Recent reports have shown that