Clinical outcomes of zone II flexor tendon repair depending on mechanism of injury

Purpose: To determine whether mechanism of injury affects outcomes of Zone II flexor tendon repairs. Methods: We retrospectively analyzed patients who underwent Zone II flexor tendon repair between 2001 and 2010 with a minimum of 12-month follow-up. Exclusion criteria included fingers with fracture, pulley reconstruction, or flexor tendon bowstringing. The saw group injuries were from saws or from tearing mechanisms; the sharp group had clean transection injuries from knives or glass. At final evaluation, primary outcomes were total passive motion (TPM) and total active motion (TAM) at the proximal interphalangeal and distal interphalangeal joints. Secondary comparisons included strength, Disabilities of the Shoulder, Arm, and Hand (DASH) score, percentage of postoperative tendon rupture, and percentage of patients requiring secondary surgery. The saw group had 13 patients with 17 fingers studied. The sharp group had 21 patients with 24 fingers studied. All patients had primary flexor digitorum profundus repairs in Zone II. Operative records review confirmed for all but 1 patient that flexor digitorum profundus injuries were repaired with a minimum of a 4-strand core suture technique. In the saw group, 9 of 14 fingers with a 50% or greater laceration of flexor digitorum superficialis were repaired; in the sharp group, 15 of 18 such flexor digitorum superficialis injuries were repaired. Average follow-up was 4 years (range, 1-9 y). Results: The saw group had significantly less TAM and TPM compared with the sharp group. There was no significant difference in DASH scores, strength measurements, or tendon rupture rates. The rate of secondary surgery was significantly higher in the saw group. Conclusions: Tearing types of injury, such as those caused by saws, led to poorer outcomes for Zone II flexor tendon injuries compared with sharp injuries at an average follow-up of 4 years. Our results can be useful when discussing expected outcomes. Mechanism of injury in Zone II flexor tendon lacerations may eventually help define optimal treatment. Type of study/level of evidence: Therapeutic III.