All Suture Biceps Tenodesis Has Greater Biomechanical Strength Than Metal Button Fixation

Abstract

Purpose: To evaluate the maximal load to failure, cyclic displacement, stiffness, and modes of failure of onlay subpectoral biceps tenodesis with an intramedullary unicortical metal button (MB) versus an inlay, all-suture Caspari-Weber (CW) technique. Methods: Sixteen matched paired human cadaveric proximal humeri were randomly allocated for subpectoral BT with either CW or MB using a high-strength suture (N = 16; 8 male, 8 female, mean age = 82.5 years, range 62-99 years). Specimens were tested on a servohydraulic mechanical testing apparatus under cyclic load for 1,000 cycles and then loaded to failure. Maximal load to failure, displacement, construct stiffness, and mode of failure were compared. Results: There was no significant difference between groups when comparing construct stiffness, creep displacement, or displacement at ultimate load. The maximal load to failure for the CW technique was greater than the unicortical MB (588.36 ± 149.06 N vs 375.83 ± 131.4 N, P = .014). Conclusions: In this study, the all-suture CW biceps tenodesis technique had a greater maximal load to failure than the onlay unicortical MB technique while having similar construct displacement and stiffness. The CW subpectoral biceps tenodesis may offer a lower cost alternative with a mechanically robust fixation when performing an open subpectoral biceps tenodesis. Clinical Relevance: This cadaveric biomechanical study can help guide surgeons when selecting a fixation technique for biceps tenodesis.