The Relationship Between Bone Quality and Biomechanical Strength of All-Suture Anchors Utilized in Rotator Cuff Repairs.

Background: All-suture anchors (ASAs) are increasingly used in arthroscopic rotator cuff repair and rely on cortical bone for strength. No study has compared ASA pullout strength in relation to bone mineral density (BMD) in the different quadrants of the supraspinatus footprint on the greater tuberosity (GT). Hypothesis: ASA biomechanical characteristics at each quadrant would improve with increasing regional BMD. Study Design: Controlled laboratory study. Methods: Four 2.6-mm ASAs were inserted into the anteromedial, posteromedial, anterolateral, and posterolateral quadrants of the GT supraspinatus footprint of 12 cadaveric specimens. Local measures of bone quality around each anchor were evaluated using micro-computed tomography. Afterward, each ASA was biomechanically loaded to failure to determine the ultimate pullout strength and mode of failure. Repeated measures correlations were calculated to determine the relationship between measures of bone quality and pullout strength. Results: The mean load to failure of ASA placed in the posterolateral GT was significantly greater than all 3 of the other quadrants (P < .01). There was no significant difference in mean pullout force in the posteromedial, anterolateral, and anteromedial quadrants. Cortical BMD and mean BMD were also significantly greater in the posterolateral corner (P < .05). The pullout force measured across all quadrants was significantly correlated with cortex mean bone density, cortex volume, mean bone mineral density, and bone volume (P < .01). Conclusion: ASA pullout strength is correlated with local cortical BMD. ASA fixation strength and BMD were robust in all quadrants on the GT, and were greatest in the posterolateral GT. Clinical Relevance: This finding expands the available geography for ASA placement by demonstrating that the lateral GT has adequate BMD to support ASAs.