Biomechanical analysis of single-row anchor, double-row anchor, and single-row knotless tape repair techniques for complete subscapularis tears

Background Repair techniques for complete subscapularis (SSC) tendon tears have not been evaluated and compared in detail. The purpose of this study was to evaluate the biomechanical performance of different repair techniques for complete SSC tendon tears. Purpose To evaluate the biomechanical performance of different repair techniques for complete SSC tendon tears. Methods In a total of eighteen fresh-frozen shoulders with an intact rotator cuff, complete SSC tendon tears were created. Six shoulders matched by age and gender were allocated to each of the three repair technique groups: (1) knotted mattress single-row repair (group SR), (2) knotted mattress double-row repair (group DR), and (3) knotless tape single-row repair (group SRT). The quality of reconstruction was evaluated by measuring the SSC tendon footprint coverage (% of pre-operative footprint), repair stiffness (N/mm), cyclic displacement (mm), and the ultimate load to failure (N). Results DR repair showed a significantly higher relative repair area compared to SR repair techniques (DR = 73.6% vs. SR=45.6%, P = .009 vs. SRT=49.4%, P = .006). Stiffness and cyclic displacement were comparable among all three groups ( P = .292; P = .215). Ultimate failure load was greatest in the DR group at 305 N ±12 and showed a trend toward higher ultimate failure load compared to the SRT group (170 N ±42; P = .061). There was no significant difference between DR and SR groups (246 N ±71.4; P = .883). Conclusion DR repair technique for complete SSC tendon tears achieves a significantly greater footprint coverage and the highest load to ultimate failure of the repair compared to SR repair techniques.