Bone Quality Positively Correlates With Biomechanical Strength of All-Suture Anchors Utilized in Biceps Tenodesis

Background: All-suture anchors (ASAs) are increasingly used in biceps tenodesis (BT), and their fixation strength may vary with cortical bone and surgical position. Defining the influence of bone mineral density (BMD) on ASA pullout strength and failure mode across the high bicipital groove (HG), low bicipital groove suprapectoral position (SUP), and subpectoral (SUB) positions may allow for optimal anchor placement. Hypothesis: ASA biomechanical characteristics at each region of the bicipital groove would improve with increasing regional BMD. Study Design: Controlled laboratory study. Methods: ASAs measuring 2.6 mm were inserted into the HG, SUP, and SUB positions of the bicipital groove 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: Mean load to failure of ASAs placed in the HG, SUP, and SUB positions were 370.7 ± 111.2 N (95% CI, 300.0-441.3 N), 600.5 ± 120.8 N (95% CI, 523.8-677.3 N), and 668.1 ± 117.2 N (95% CI, 593.6-742.5 N), respectively. Mean load to failure of ASAs placed in the SUP and SUB positions was significantly greater than in the HG position ( P < .01). There was no significant difference in mean pullout force between the SUP and SUB positions. The most common mode of failure was anchor pullout in the HG (100%) and suture breakage in the SUP (58%) and SUB (75%) positions. Mean BMD and cortical BMD were significantly greater in the SUP and SUB positions compared to the HG position ( P < .05). Pullout force measured throughout the bicipital groove was significantly correlated to cortex mean bone density, cortex volume, mean BMD, and bone volume ( P < .01). Conclusion: ASA pullout strength was correlated with local cortical BMD. ASA fixation strength and BMD were robust in all tested regions of the bicipital groove but were greatest in the SUP and SUB positions. Clinical Relevance: ASAs can effectively be placed throughout the bicipital groove. ASAs in all 3 tested positions can withstand not only the force reportedly placed on the anchor by the native biceps but also the force previously reported to cause failure at the suture-biceps tendon interface. These biomechanical findings add to the growing clinical and basic science evidence supporting the use of ASA for BT.