A Comparison of Structural and Mechanical Properties of Tubularized and Native Semitendinosus Graft

Abstract

Background: The semitendinosus tendon has a broad and thin length of aponeurosis. Tubularizing this portion of the graft converts it into a cylindrical structure, which may have implications for graft fixation. Hypothesis: A tubularized semitendinosus tendon will demonstrate a higher tensile load to failure and increased stiffness compared with its native form. Study Design: Controlled laboratory study. Methods: Twenty cadaveric paired semitendinosus specimens were used. Ten served as the control group; the other 10 underwent tubularization along the length of the aponeurosis. All testing was performed on the MTS 858 Mini Bionix II. Outcome measures included cross-sectional area, stress, stiffness, and peak load to failure. Results: The nontubularized tendons had a higher peak tensile load to failure (mean 1112.6 ± 345.0 N) than the tubularized tendons (mean 711.4 ± 228.7 N, P = .007). The nontubularized specimens also had a higher stiffness (213.0 ± 37.2 N) than the tabularized group (144.9 ± 44.8 N, P = .002). Conclusion: Tubularization of the semitendinosus graft weakens its structural and mechanical properties. Clinical Relevance: On the basis of the results of this study, we do not tubularize the semitendinosus graft in ACL reconstruction because of weakened structural and mechanical properties.