Biomechanical Comparison of All-Suture Anchor Fixation and Interference Screw Technique for Subpectoral Biceps Tenodesis

Abstract

Purpose: To compare the biomechanical characteristics of the subpectoral Y-knot all-suture anchor fixation with those of the interference screw technique.

Methods: Sixteen fresh-frozen human cadaveric shoulders with a mean age of 67.6 ± 5.8 years (range, 52 to 74 years) were studied. The specimens were randomly grouped into 2 experimental biceps tenodesis groups (n = 8): Y-knot all-suture anchor or interference screw. The specimens were cyclically tested to failure by applying tensile forces parallel to the longitudinal axis of the humerus. A preload of 5 N was applied for 2 minutes prior to cyclic loading for 500 cycles from 5 to 70 N at 1 Hz; subsequently, a load-to-failure test at 1 mm/s was performed. The ultimate failure load, stiffness, displacement at cyclic and failure loading, and mode of failure were recorded.

Results: The all-suture anchor technique displayed values of ultimate failure load and stiffness comparable to that of the interference screw technique. The displacement at cyclic and failure loading of the all-suture anchor trials were significantly greater than the interference screw (P = .0002). The all-suture anchor specimens experienced anchor pullout and tendon tear equally during the trials, whereas the interference screw group experienced tendon tear in most of the cases and screw pullout in 2 trials.

Conclusions: The Y-knot all-suture anchor fixation provides equivalent ultimate failure load and stiffness when compared with the interference screw technique in tenodesis of the proximal biceps tendon from a subpectoral approach. However, the interference screw technique demonstrates significantly less displacement in response to cyclic and failure loading.

Clinical relevance: The all-suture anchor fixation is an alternative technique for subpectoral biceps tenodesis even at greater displacement when compared with the interference screw fixation during cyclic and failure loading.