Tensile strength of flexor tendon repairs in a dynamic cadaver model

Twenty-six fresh-frozen cadaver hands (78 tendons) underwent sharp zone II profundus tendon transection and repair with Bunnell, Kessler, Kessler with circumferential epitenon, or epitenon-alone sutures. Suture assignment was randomized, and core sutures were placed either palmarly or dorsally (also randomized) within the flexor tendon. Ten trials of each suture type and placement were performed. Flexion of the repaired digit at a constant excursion rate was performed up to tendon rupture. In all cases, dorsally placed sutures provided significantly more tensile strength than palmarly placed sutures. In light of the previous evidence that tendon viability is dependent on diffusion and not dependent on the vascular supply, we believe that a dorsally placed core suture and circumferential epitenon repair for zone II profundus repairs should be considered because of their increased strength. All future testing of tendon repairs should be performed in an anatomic "curvilinear" model because it simulates the specific biomechanical conditions that are unique to the flexing digit.