Quadruple Semitendinosus Graft Construct With Double Cortical Suspensory Fixation for Anterior Cruciate Ligament Reconstruction: A Biomechanical Study

The purpose of this study was to evaluate the biomechanical properties of a graft construct with quadrupled Semitendinosus and two cortical buttons with adjustable loops concerning elongation, stiffness and resistance. A total of 15 fresh human cadaveric semitendinosus tendons were quadrupled over the two adjustable loops and stitched at the tibial tip with a cerclage type suture. They underwent pre-tensioning at 300 N for 2 minutes followed by cyclic loading (1000 cycles between 50–250 N) and finally a load-to-failure test. Statistical analysis was performed using SPSS Statistics software and groups were compared using a paired t-test, with a significance level set at α = 0.05. Graft construct elongation after pre-tensioning at 300 N was 12.8 mm (9.3 mm–16.5 mm) and mean cyclic elongation 0.4 mm (0.2 mm–0.9 mm), considered significant (p < 0,001). The resistance and stiffness values were respectively 849.46 N (649.30 N-1027.90 N) and 221.49 N (178,30 N – 276.10 N). Quadruple ST graft construct using two cortical buttons and adjustable loops showed a high stiffness and resistance with a very low elongation after cycling.