Braided Hamstring Tendons for Reconstruction of the Anterior Cruciate Ligament: A Biomechanical Analysis

Abstract

Background: In an effort to improve the strength and stiffness of anterior cruciate ligament grafts, several authors have advocated alterations of graft structure and orientation, including braiding the tendons in hamstring tendon grafts. Hypothesis: Braiding hamstring tendons does not increase graft strength and stiffness. Study Design: Controlled laboratory study. Methods: Sixteen hamstring tendon and 21 bone-patellar tendon-bone grafts were harvested from 12 cadavers and divided into three groups: 1) braided four-strand hamstring tendon, 2) unbraided four-strand hamstring tendon, and 3) bone-patellar tendon-bone. All grafts were placed under a 50-N preload on a servohydraulic testing device and were tensioned to failure. Results: The strength and stiffness of the tested specimens averaged 427 ± 36 N and 76 ± 10 N/mm, respectively, for braided specimens, 532 ± 44 N and 139 ± 18 N/mm for unbraided specimens, and 574 ± 46 N and 158 ± 15 N/mm for patellar tendon specimens. There was a 20% decrement in hamstring tendon graft tensile strength and a 45% decrease in stiffness after braiding because of the suboptimal multidirectional orientation of individual tendons within the braided grafts. Conclusions: In vitro braided hamstring tendon grafts demonstrated mechanically inferior strength and stiffness characteristics compared with unbraided hamstring tendon grafts and patellar tendon grafts. Clinical Relevance: Braiding of hamstring tendon grafts provides no mechanical advantage in anterior cruciate ligament reconstruction.