Abstract
Background: Transosseous-equivalent (TOE) rotator cuff repair has been theorized to be "self-reinforcing" against potentially destructive and increasing tendon loads. The goal of this study was to biomechanically verify and characterize the effect of increasing tendon load on frictional resistance over a repaired footprint for single-row (SR) and TOE repair techniques. Methods: In 10 fresh frozen human shoulders, TOE and SR supraspinatus tendon repairs were performed in each specimen. For all repairs, a pressure sensor was secured at the tendon-footprint interface. The supraspinatus tendon was loaded with 0, 20, 40, 60, and 80N at 0° and 30° abduction. Paired t tests and multivariate regression analyses were used for comparisons. Results: The SR repair had significant increases in footprint contact force, area, and pressure between each and all tendon-loading conditions (. P<.05). The TOE repair similarly demonstrated increases in footprint contact force with increasing tendon load (. P<.05). Comparing between repairs, TOE repair had more footprint contact force, area, pressure, and peak pressure at each load for both abduction angles (. P<.05). With increasing load, the TOE repair had a significantly higher progression (slope) of footprint force and pressure compared with the SR repair. Conclusions: Self-reinforcing capacity in rotator cuff repair has been biomechanically characterized and verified. The TOE repair, with tendon-bridging sutures fixed medially and spanning the footprint, provides disproportionately more progressive footprint frictional resistance with increasing tendon loads compared with the SR repair secured over isolated fixation points. This self-reinforcing effect could help sustain structural integrity and potentially improve healing biology. © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees.