Transosseous all-suture anchor fixation for bony Bankart lesions: a biomechanical study

Background: The use of all-suture anchors (ASA) for treating bony Bankart lesions remains challenging because of the limited availability of cortical bone for secure fixation. In this study, the mechanical properties of transosseous ASA fixation, wherein the anchor is placed through the far cortex, were compared with those of metallic suture anchors and standard ASA fixation. Methods: For this controlled experimental study, 24 suture anchors were inserted into 12 synthetic scapulae with simulated bony Bankart lesions, with two anchors placed in each scapula. The scapulae were randomly assigned to Group A (two 2.7-mm metallic anchors), Group B (two 1.3-mm ASAs secured through standard fixation), or Group C (two 1.3-mm ASAs secured transosseously). For biomechanical analysis, a 5 N preload was applied for 2 min, followed by cyclic loading from 5 to 25 N at 1 Hz for 100 cycles. In addition, a load-to-failure test was conducted at a rate of 60 mm/min. Displacement, stiffness, ultimate failure load, and failure mode were recorded. Results: There were no significant differences and low correlations in biomechanical properties between the two anchors placed in each scapula. Nor significant intergroup differences were noted in cyclic displacement or linear stiffness. Group C exhibited a significantly higher (P < 0.001) ultimate failure load (176.8 ± 32.7 N) than did with Group A (104.4 ± 17.5 N) and Group B (83.0 ± 10.8 N). All failures resulted from anchor pullout, except for two cases in Group C, where deformed suture balls were observed without pullout. Conclusion: Compared with metallic suture anchors and standard ASA fixation, transosseous ASA fixation significantly improved the maximum failure load in a bony Bankart lesion model, without increasing cyclic displacement. Level of evidence: Basic Science Study; Biomechanics.