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

Introduction 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 post-repair approximation force. Materials and Methods 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 (PBS) bath at 37°C to simulate physiological conditions. Tendon-bone displacement was quantified under different conditions using Digital image correlation (DIC) . Results Following pre-tensioning at 25N, relaxation forces at 2 hours were 7.68N for Dynacord and 5.50N Permacord, and 6.45N versus 3.58N at 16 hours, respectively. A significant difference in approximation force was observed between groups (2.18 ± 0.67N, P=0.01). 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 one reached 155 N. While Dynacord showed lower creep values under loaded and unloaded conditions, the difference did not reach statistical significance. Conclusion 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.