Biomechanical Evaluation of Whipstitch Reinforcement in Cadaveric Semitendinosus Grafts

Background: One challenge surgeons face when using certain suture knot techniques is where the forces concentrate along the central axis of the tissue, making the suture knot prone to failure due to suture pull-through and tissue shredding. New reinforcement techniques have been developed (suture tape augmentation) and are becoming popular to minimize tissue damage. Purpose: To assess biomechanical performance of whipstitch reinforcement techniques (locking stitch method or additional suture material) in human cadaveric semitendinosus tendons (STs). Study Design: Controlled laboratory study. Methods: A total of 42 STs were harvested and divided into 6 groups consisting of a standard whipstitch and varying reinforcement techniques based on stitch pattern (whipstitch [WS], whipstitch through tag [WT], locking whipstitch [WL], or locking whipstitch through tag [WLT]), and products from varying manufacturer samples were preconditioned and then loaded from 50 to 200 N at 1 Hz for 500 cycles, followed by load to failure. Elongation, stiffness, ultimate load, and failure mode were compared across groups. Results: No significant differences were observed between whipstitch groups WS 1 and WS 2 . Addition of suture material for reinforcement (WT 2 ) significantly improved biomechanical performance across all metrics compared with WS 2 . Reinforcement using a new locking whipstitch method (WL) resulted in significant increase in ultimate load compared with WS 1 . All reinforcement groups (WL, WT 1 , WT 2 , and WLT) achieved a similar level of biomechanical performance, with no significant differences across any metric. Addition of a second reinforcement (WLT) did not significantly enhance biomechanics beyond those achieved with a single reinforcement (WL). The failure mode for no-reinforcement groups was tissue pull-through, while reinforcement groups utilizing either material or locking method failed from suture breakage. Conclusion: Whipstitch alone offers limited biomechanical security, but reinforcement with either a locking method or additional suture material significantly enhances biomechanical performance. Clinical Relevance: Reinforcement may help limit tissue damage. The locking whipstitch method offers a promising alternative to reinforce a stitch with relatively less suture material.