Round versus tape sutures with interference fit anchors perform similarly in cadaveric glenoid and greater tuberosity biomechanical testing

Abstract Purpose To determine whether suture shape (flat-tape vs. round-wire) influences biomechanical performance at the suture-anchor–bone interface in interference-fit anchors used for rotator cuff and glenoid labrum repair. Methods Four matched pairs of human cadaveric shoulders were used for the glenoid model, with six anchor sites per glenoid. Five matched pairs of cadaveric humeri were used for the rotator cuff model, with three anchor sites per humerus. Each model tested multiple suture-anchor constructs under cyclic loading followed by load-to-failure. Biomechanical outcomes included cyclic displacement, yield characteristics, ultimate failure strength, stiffness, and force at fixed displacements. A linear mixed-effects model was used to compare suture types, with suture type and anchor position as fixed effects and specimen as a random effect. Results In the glenoid/labrum model, there were no significant differences among suture types in cyclic displacement (cycles 1, 50, or 100; p = 0.376, 0.101, 0.109), displacement at yield ( p = 0.406), yield force ( p = 0.880), force at 1 mm ( p = 0.264) or 5 mm ( p = 0.085), or ultimate failure strength ( p = 0.204). Stiffness ( p = 0.050) and force at 2 mm displacement ( p = 0.033) differed at the overall model level, however, no significant pairwise differences were observed. In the humerus/rotator cuff model, displacement at cycle 50 ( p = 0.022) and cycle 100 ( p = 0.019) differed overall, although post hoc comparisons were not significant. Ultimate strength ( p = 0.037), yield force ( p = 0.012), and stiffness ( p = 0.005) differed among groups, with post hoc analysis showing greater ultimate strength, yield force, and stiffness for 2-mm FiberTape compared with 2-mm XbraidTT. No other pairwise comparisons were significant. Conclusion Suture shape did not meaningfully influence interference-fit fixation properties in the glenoid and humeral models evaluated in this study. Tape-type and round-type sutures demonstrated comparable biomechanical performance at the suture–anchor interface within the tested constructs. Level of evidence Controlled Laboratory Study.