A biomechanical analysis of two biceps tenodesis fixation techniques

Purpose: To assess and compare the biomechanical properties and load-to-failure of 2 biceps tenodesis fixation techniques, interference screw fixation and double suture anchor fixation. Type of Study: Biomechanical study. Methods: Eleven fresh-frozen human cadaveric specimens were used in this study. A biceps tenodesis was performed using 1 of 2 techniques, interference screw fixation or double suture anchor fixation. A 7-mm interference screw was used in 5 cadaveric trials. A double suture anchor technique was performed in 6 cadaveric specimens. The tenodesis construct in each specimen was loaded to failure using a Servohydraulic materials test system (NITS Model 858; Bionix, MTS Corp, Minneapolis, MN). Each specimen was loaded at 5 mm/second with a preload of 5 N with the vector of pull distally in line with the long axis of the humerus. Each specimen was then loaded until failure of the repair occurred. Statistical analysis of the interference screw group compared with the suture anchor group was performed using a Student t test. Results: The mode of failure of the interference screw group was variable, but the suture anchor group consistently failed at the anchor or anchor eyelet. The average pullout strength of the suture anchor group was 135.5 +/- 37.8 N whereas the failure load in the interference group was 233.5 +/- 55.5 N. The interference group had a significantly greater resistance to pullout than the suture anchor group (P = .007). Conclusions: Based on these results, a biceps tenodesis using an interference screw will provide greater fixation strength than a biceps tenodesis performed with a double suture anchor technique. Clinical Relevance: The surgeon treating biceps tenodesis may wish to choose a fixation technique with higher initial strength (interference screw instead of double suture anchor) to lessen the chance of early failure, particularly if the patient begins early active elbow flexion.