Superior Primary Stability of a Knotless Double-Row Construct Compared to Mason-Allen Repair for Anatomical Refixation of Gluteal Tendons – Biomechanical Human Cadaver Study

Abstract

Abstract Background Hip abductor tendon tears are still an underrated diagnosis. This may lead to inefficient conservative therapy with only temporary pain relief and potential permanent disability. In clinical settings surgical treatments especially double-row repair techniques show good short-term results. However, sufficient biomechanical data are still lacking. Therefore, the aim of this study was to prove the superiority of knotless double-row (Hip Bridge) repair over still frequently used standard Mason-Allen technique in a cadaver study. Methods Gluteus minimus and medius were released in 12 fresh-frozen human cadaveric specimens and reattached to their footprints either with transosseous Mason-Allen (MA) or knotless double-row Hip Bridge (HB) technique. HB consisted of two proximal PEEK anchors, each preloaded with double-V shaped tapes, crossed, and distally fixated with two additional anchors. Femurs were fixated in a custom-made sample holder and gluteal muscles were clamped using a cryo-jaw. The construct underwent a cyclic loading test between 10 and 125 N for 150 cycles at 2.5 Hz (preload 10 N), followed by a pull-to-failure test. Failure mode and elongation were determined, the latter by a 3D optical measurement system. Statistical analysis was performed using a one-tailed t-test with a significance level set to p ≤0.05. Results HB resulted in significantly higher ultimate failure loads (339.1 ± 144.4 N) than MA (209.6 ± 62.1 N, p = 0.0381). HB failed ultimately only due to tendon failure, while MA showed different failure modes: tendon failure (1/6), bone cutting (4/6), and muscle rupture (1/6). During prior cyclic loading, the calculated final plastic elongation was 4.4 ± 0.5 mm for MA and 3.4 ± 1.4 mm for HB (p = 0.0731). During pull-to-failure testing, stiffness of 59.7 ± 12.5 N/mm and 66.8 ± 18.4 N/mm were observed for MA and HB (p = 0.247). Conclusion Hip Bridge technique provides a biomechanical stability superior to the standard Mason-Allen repair technique showing significantly higher ultimate failure loads and a trend of less elongation. A reason for this might be greater contact restoration of the anatomical footprint, a crucial advantage in the treatment of the typically weakened tendons and bones of elderly patients. Level of Evidence Laboratory study.