Cyclic and Load to Failure Properties of All-Suture Anchors in Synthetic Acetabular and Glenoid Cancellous Bone

Abstract

To evaluate the cyclic displacement, maximum load to failure, and failure mode of multiple all-suture anchors (ASAs) in 2 different densities of sawbones cancellous bone substitute. Anchors tested included the Suturefix Ultra 1.7mm, JuggerKnot 1.45mm (No. 1 and No. 2 MaxBraid) and 2.9mm, Y-Knot Flex 1.3mm and 1.8mm, Iconix 1, 2, 25, and 3, Q-Fix 1.8mm, and Bioraptor 2.3 PK. The Bioraptor served as a non-all-suture-based control. Seven to eleven anchors were tested in both 20 and 30 pounds per cubic foot (pcf) test blocks that were chosen to simulate glenoid and acetabular cancellous bone, respectively. After a 40N deployment force, anchors were cyclically loaded at 0.5Hz from 10 to 50N and then 10 to 100N for 200 cycles each. Surviving specimens were pulled to failure at 10mm/s. Displacement, stiffness, maximum load, and failure mode were recorded. Welch t-tests and Welch analysis of variance with Games-Howell post hoc tests were used for statistical analysis. In higher density blocks, 11 of 12 anchors had significantly (P < .05) higher maximum loads to failure, and 8 anchors showed significantly lower post-cyclic displacement. The Q-Fix 1.8 displayed the lowest post-cyclic displacement in both densities (0.1 ± 0.2mm, mean ± standard deviation, in both densities). All other groups exhibited at least 2.8mm and 0.6mm post-cyclic displacement in 20 and 30 pcf, respectively. The Bioraptor did not survive cyclic testing in 20 pcf and had 0.6 ± 0.3mm post-cyclic displacement in 30 pcf. ASAs show better fixation in higher density synthetic bone. The cyclic displacement and maximum load of ASAs vary widely depending on anchor design and bone density. Most anchors fail by suture anchor pullout. In general, the Bioraptor 2.3 PK outperformed ASAs in higher density test blocks with mixed results in lower density test blocks. ASAs show mixed results compared with a traditional suture anchor. They perform better in higher density bone substitute.