Biomechanical comparisons of anterior cruciate ligament: reconstruction procedures with flexor tendon graft

An experimental study was conducted to compare the biomechanical characteristics of six currently available anterior cruciate ligament (ACL) reconstruction procedures with flexor digitorum profundus tendons. Forty porcine knees were divided into eight groups, of 5 knees each. In groups A, B, C, and D, the flexor tendon graft was fixed with sutures and an Endobutton, with 20-mm-wide polyester tapes and staples, with 10-mm-wide polyester tapes and an Endobutton, and with bone plugs and interference screws, respectively. In group E, the graft was fixed using a combined procedure of those in groups B and D. In group F, the graft was directly fixed with interference screws. In groups G and H, the bone-patellar tendon-bone graft was fixed with interference screws, and sutures, respectively. Each femur-graft-tibia complex specimen was tested with a tensile tester by anteriorly translating the tibia until failure. This study demonstrated that the biomechanical properties of the femur-graft-tibia complex reconstructed with the flexor tendon graft were significantly affected by synthetic fixation devices. Regarding the average maximal load of the groups with the flexor tendon graft, group B had the highest (893 N) and group C had the second highest (770 N). Groups E and A were in the third rank. Group F had the second lowest (312 N), and Group D had the lowest (230 N). The maximal load of group B was significantly greater (P < 0.01) than that of group G (656 N) with the bone-patellar tendon-bone grafts. As to clinical relevance, this study indicated that the flexor tendon graft can be an alternative substitute for the bone-patellar tendon-bone graft for ACL reconstruction, if we understand the biomechanical characteristics of each reconstruction procedure.