Suture strength and angle of load application in a suture anchor eyelet

Purpose: To assess the effect of suture material, anchor orientation, and anchor eyelet design on the static loading properties of suture anchors. Type of Study: Biomechanical bench study. Methods: Two metallic suture anchors, Mitek GII (Mitek, Westwood, MA) and Corkscrew (Arthrex, Naples, FL) and a bioabsorbable anchor (Biocorkscrew; Arthrex) were tested with single strand of No. 2 Ethibond (Ethicon, Norderstedt, Germany) or No. 2 FiberWire (Arthrex) suture. Suture pull angle was varied through 0 degrees, 45 degrees, and 90 degrees with the anchor rotation angle in either a sagittal or coronal plane. Constructs were tested to failure using an MTS 858 Bionix testing machine (Material Testing b Systems, Eden Prairie, MN). Peak loads, stiffness, energy to peak load, and failure modes were determined for all samples. Results: FiberWire showed superior static mechanical properties when compared with single-strand Ethibond over all testing conditions (P < .05). Suture pull angle had a significant effect on load to failure with both metallic anchors but not on the bioabsorbable anchor (1 < .05). Conclusions: Suture pull angle and anchor rotation angle play an important role in the failure load of suture when placed in an eyelet. The polyaxial nature of the Biocorkscrew eyelet allows for increased degrees of freedom but introduces failure of the suture eyelet as a new failure mode. Clinical Relevance: The loading direction and placement of the suture anchor plays a role in the performance of the suture anchor-suture complex.