The biomechanical evaluation of four fixation techniques for proximal biceps tenodesis

Purpose: The purpose of this study was to compare the cyclic displacement and ultimate failure strength of 4 proximal biceps tendon tenodesis fixation methods: the open subpectoral bone tunnel (SBT) biceps tenodesis, the arthroscopic suture anchor (SA) tenodesis, the open subpectoral interference screw (SIS) fixation technique, and the arthroscopic interference screw (AIS) technique. Type of Study: Biomechanical experimental control. Methods: Twenty fresh-frozen cadaver shoulders were dissected free of soft tissues, leaving the proximal humerus and the proximal biceps tendon as a free graft. Specimens were randomized to I of 4 groups with 5 total specimens in each group. A proximal biceps tenodesis was performed according to the techniques listed above. The specimens were mounted for an axial pull of the biceps tendon on a servohydraulic materials testing system with a 100-N load cycled at 1 Hz for 5,000 cycles, followed by an axial load to failure test. Cyclic displacement, ultimate load to failure, and site of failure were recorded for each specimen. Results: The mean cyclic displacement recorded for each experimental group was as follows: SBT group, 9.39 +/- 2.82 mm; AIS group, 5.26 +/- 2.60 mm; SIS group, 1.53 +/- 0.60 mm; and SA group, 3.87 +/- 2.11 mm. The mean ultimate failure loads after 5,000 cycles were as follows: SBT group, 242.4 +/- 51.33 N; AIS group, 237.6 +/- 27.58 N; SIS group, 252.4 +/- 68.63 N; and SA group, 164.8 +/- 37.47 N. Each specimen failed at the tenodesis site. Conclusions: The SBT group showed statistically significant greater displacement than the other tenodesis methods. There were no statistically significant differences in ultimate failure strength between any of the biceps tenodesis methods tested. Clinical Relevance: The data serve as a guide to the surgeon performing a proximal biceps tenodesis in choosing a fixation method.