Biomechanical evaluation of a laxity-minimizing suture for rotator cuff repair

Loss of approximation force can impair healing following rotator cuff repair. This study investigates the biomechanical properties of a high-strength, laxity-minimizing suture designed to enhance postrepair approximation force.

A comparative biomechanical model was employed to evaluate eight matched pairs of fresh-frozen ovine infraspinatus tendons. Tendons were repaired using either a laxity-minimizing suture (Dynacord group) or a reference suture (Permacord group) in a double-row configuration with bone anchors. Quasi-static and cyclic tensile loading were applied in a phosphate buffered saline bath at 37 °C to simulate physiological conditions. Tendon-bone displacement was quantified under different conditions using digital image correlation.

Following pretensioning at 25 N, relaxation forces at 2 hours were 7.68 N for Dynacord and 5.50 N Permacord, and 6.45 N vs. 3.58 N at 16 hours, respectively. A significant difference in approximation force was observed between groups (2.18 ± 0.67 N, P = .01). Under cyclic loading, all Dynacord-repaired tendons exhibited gap formation below the critical 3 mm threshold at loads up to 105 N, with two samples sustaining up to 155 N. In contrast, only seven Permacord samples withstood 105 N and only 1 reached 155 N. While Dynacord showed lower creep values under loaded and unloaded conditions, the difference did not reach statistical significance.

Dynacord suture could have superior approximation force retention compared to Permacord under low tensile forces. However, under cyclic loading conditions, Dynacord did not show statistically significant biomechanical advantages in this dynamic cadaveric model.