The mechanical effects of suture anchor insertion angle for rotator cuff repair

Twelve matched pairs of humerii were instrumented with suture anchor at 90°, 75°, 45°, and 30° relative to the cortical border at the junction of the greater tuberosity and articular surface. Two fixtures were inserted into each specimen at different angles and loaded to failure. Suture anchors failed at an average of 171, 219, 169, and 192 N with 90°, 75°, 45°, and 30° insertion angles, respectively. No statistical difference was detected between groups (P=.08). Although previous authors have prescribed angles ≤45° to improved pull-out strength, the current in vitro data does not support these recommendations.