Biomechanical Comparison of Arthroscopic Single- and Double-Point Repair Techniques for Acute Bony Bankart Lesions

OBJECTIVES: Single-point and double-point arthroscopic reconstruction techniques for acute osseous Bankart lesions have been described in the literature. We hypothesized that the double-point fixation technique (bony Bankart bridge) would provide superior fracture reduction and stability at time zero compared to the single-point technique in a cadaveric bony Bankart model. METHODS: Testing was performed on 14 matched glenoid pairs with simulated bony Bankart fractures; the defect width was 25% of the glenoid diameter and the fracture was perpendicular to the 3 o’clock position. Additionally, a labral avulsion was created and extended from the 6 to the 12 o’clock position. All labral avulsions were then repaired above and below the bony Bankart with suture anchors. Half of the bony Bankart fractures were repaired with a double-point technique, while the contralateral glenoid was repaired with a single-point technique (Fig 1). Following the repairs, distance between the intra-articular surfaces of the fragment and glenoid were measured for an unloaded condition and with 10 N of tension applied to the fragment, to quantify fracture displacement. To determine the biomechanical stability of the repairs, specimens were secured in a tensile testing machine and aligned so that the load vector was 30° medial to the superior-inferior plane. The repair constructs were preconditioned with sinusoidal cyclic loading between 5 N to 25 N for 10 cycles and then pulled to failure at a rate of 5 mm/min. Load (N) at 1 mm and 2 mm of fracture displacement were determined. Non-parametric statistics were used (MWU). RESULTS: The bony Bankart defect length measured more than half of the maximum antero-posterior diameter of the inferior glenoid in all specimens. Loads at 1 mm and 2 mm of fracture displacement, and fracture reduction are reported in Table 1. The double-point technique required significantly higher forces to achieve fracture displacements of 1 mm (mean: 60.6 N, range: 39.0 N to 93.3 N; p = 0.001) and 2 mm (mean: 94.4 N, range: 43.4 N to 151.2 N; p = 0.004) (Fig 1) than the single-point technique (1 mm displacement mean: 30.2 N, range: 14.0 N to 54.1 N; 2 mm displacement mean: 63.7, range: 26.6 to 118.8). Fracture displacement was significant lower after double-point repair for both the unloaded condition (mean: 1.1 mm, range: 0.3 to 2.4 mm; p = 0.005) (Fig 1) and in response to a 10 N anterior force applied to the defect (mean: 1.6 mm, range: 0.5 to 2.7 mm; p = 0.001) compared to single-point repair (unloaded mean: 2.1 mm, range: 1.3 to 3.4 mm; loaded mean: 3.4, range: 1.9 to 4.7 mm). CONCLUSION: The double-point fixation technique (bony Bankart bridge) for clinically relevant sized, acute osseous Bankart lesions resulted in lower fracture displacement and superior stability at time zero in comparison to the single-point technique and was the preferred biomechanical technique in this model of bony Bankart fractures. This information may influence the surgical technique used to treat large osseous Bankart fractures and the postoperative rehabilitation protocols implemented when such repair techniques are used.