Cyclic loading of rotator cuff repairs: A comparison of bioabsorbable tacks with metal suture anchors and transosseous sutures

Purpose: The purposes of the study were (1) to compare rotator cuff repair strengths after cyclic loading of 2 bioabsorbable nonsuture-based tack-type anchors, transosseous sutures, and a metal suture-based anchor, and (2) to correlate bone mineral density with mode of failure and cycles to failure. We hypothesized that specimens with a lower bone density would fail throug h bone at a lower number of cycles independent of the method of cuff fixati on. Type of Study: Ex vivo biomechanical study. Methods: Standardized full- thickness rotator cuff defects were created in 30 fresh-frozen cadaveric sh oulders that were randomized to 1 of 4 repair groups: transosseous sutures; Mitek Super suture anchors (Mitek Surgical Products, Westwood, MA); smooth bioabsorbable 8-mm Suretacs (Acufex, Smith & Nephew Endoscopy, Mansfield, MA); or spiked bioabsorbable 8-mm Suretacs (Acufex). All repairs were cycli cally loaded from IO to 180 N; the numbers of cycles to 50% (gap, 5 mm) and 100% (gap, 10 mm) failure were recorded. Results: In comparing the repair groups, we found only I significant difference: the number of cycles to 100 % failure was significantly higher (P < .05) for the smooth bioabsorbable t ack than for the transosseous suture group. There were no statistically sig nificant (P <less than or equal to> .05) differences in bone mineral densit ies with regard to each specimen's mode of failure. Conclusions: Our result s suggested that immediate postoperative fixation provided by bioabsorbable tacks was similar to that provided by Mitek anchors and more stable than t hat provided by transosseous sutures. Therefore, the immediate postoperativ e biomechanical strength of bioabsorbable tacks seems comparatively adequat e for fixation of selected small rotator cuff tears. However, additional ev aluation in an animal model to examine degradation characteristics and sust ained strength of repair is recommended before clinical use.