Finite element comparison of three rotator cuff repair configurations across shoulder abduction angles: a static biomechanical study

Background Rotator cuff repair constructs may differ in the distribution of tendon and suture stresses under early postoperative loading. This finite element study compared three suture configurations across three modeled shoulder abduction angles. Methods A three-dimensional shoulder model was constructed using computed tomography data from one healthy male volunteer. Cross single-row, double-row, and double-locking-loop repair configurations were simulated at 0°, 45°, and 90° of abduction (nine deterministic models). The distal humerus was fixed and a 100 N static tensile load was applied to the free end of the supraspinatus tendon. Tendon, suture, cartilage, and humeral suture-tunnel stresses and construct displacements were evaluated. Results The double-locking-loop construct had the lowest modeled tendon and suture von Mises stresses and tendon displacements at all three angles. Its peak suture stresses were 1.2985, 1.6325, and 0.83125 MPa at 0°, 45°, and 90°, respectively: reductions of 54.4%–65.4% relative to cross single-row and 32.2%–51.4% relative to double-row repairs. Corresponding tendon displacements were 0.074922, 0.084226, and 0.054456 mm. Differences were descriptive outputs of deterministic simulations, not estimates of clinical efficacy. Conclusions Under the assumed geometry, linear-elastic material properties, bonded interfaces, and static loading, the double-locking-loop configuration yielded lower predicted local stresses and displacements than the other two configurations. These computational findings require verification and experimental validation and cannot establish improved tendon healing, reduced retears, or optimal rehabilitation positioning.