Interference screw fixation of doubled flexor tendon graft in anterior cruciate ligament reconstruction - biomechanical evaluation with cyclic elongation

Objective. To biomechanically evaluate interference screw fixation of the d oubled flexor tendon graft in anterior cruciate ligament reconstruction usi ng cyclic elongation. Design. Biomechanical properties of the interference screw fixation of the flexor tendons were compared with those of three standard fixation techniqu es which had been commonly performed in anterior cruciate ligament reconstr uction. Background. The interference screw fixation of the flexor tendon graft has attracted notice because of various possible advantages. Methods. Forty fresh frozen porcine hind limbs were divided into four group s of ten knees each. Anterior cruciate ligament reconstruction was carried out in each group using one of four different procedures. For each group, f ive femur-graft-tibia complexes underwent submaximal cyclic elongation of 5 000 cycles after initial tension of 80 N was applied. Then, tensile testing was performed in the same manner for the complex with a tensile tester. Th e remaining five complexes were examined in the same tensile test without a pplying any cyclic elongation. Results. The initial tension was more rapidly relaxed by cyclic elongation in the flexor tendon graft fixed with interference screws than in the bone- patellar tendon-bone graft fixed with two standard techniques. After cyclic elongation, while the ultimate failure load of the former was significantl y lower than the latter, the linear stiffness of the former was significant ly higher than the flexor tendon graft fixed with sutures. Conclusion. The present study has clarified that the advantage of the inter ference fixation for the doubled flexor tendon graft is the high linear sti ffness of the FGT complex, and the disadvantage of this screw is the low ul timate failure load of the FGT complex.