Can a Two Simple Stitches Method Provide Secure Fixation Strength in Biceps Tenodesis?: Biomechanical Evaluation of Various Suture Techniques

BACKGROUND: The purpose of this study was to compare the initial fixation strength between four different suture methods for the long head of the biceps. METHODS: Forty-eight fresh frozen porcine flexor hallucis longus tendons (mean width at suture site, 8.5 ± 0.9 mm) and phalanx bones were randomly assigned to one of the four arthroscopic biceps tenodesis techniques: simple stitch (SS), mattress suture (MS), lasso-loop (LL), and two simple stitches (2SS). A biceps tenodesis was performed according to the four techniques using all-suture type suture anchors (1.9-mm SUTUREFIX anchor with No. 1 ULTRABRAID sutures). Biomechanical evaluations were performed to test load to failure (N), stiffness (N/mm), stress (N/m(2)), and mode of failure. RESULTS: As for the SS, MS, LL, and 2SS, the mean load to failure was 50.9 ± 14.61 N, 82.3 ± 24.8 N, 116.2 ± 26.7 N, and 130.8 ± 22.5 N (p < 0.001), respectively; mean stiffness was 6.1 ± 1.3 N/mm, 6.7 ± 2.6 N/mm, 7.8 ± 1.4 N/mm, and 8.1 ± 4.2 N/mm, respectively (p = 0.258); and mean stress was 0.7 ± 0.3 N/m(2), 1.4 ± 0.8 N/m(2), 2.9 ± 0.7 N/m(2), and 2.7 ± 0.8 N/m(2), respectively (p < 0.001). All the failures happened by the suture cutting through the tendon along its longitudinal fibers. CONCLUSIONS: Neither the SS nor the MS method was enough to securely fix the biceps tendon with a significantly lower mechanical strength; however, the 2SS method showed similar initial fixation strength as the LL technique.