Biomechanical comparisons of three posterior cruciate ligament reconstruction procedures with load-controlled and displacement-controlled cyclic tests.

Abstract

Biomechanical behaviors of posterior cruciate ligament reconstructions under cyclic loading have not been sufficiently clarified. Biomechanical behaviors of the reconstruction that involves use of flexor tendons and an Endobutton are significantly different under cyclic loading from behaviors of the two standard reconstructions in which bone-patellar tendon-bone graft is used. Controlled laboratory study. In a porcine model, the tendon/Endobutton reconstruction, the tendon-bone/interference screw reconstruction, and the tendon-bone/tibial-inlay reconstruction were biomechanically compared by using two cyclic tests. In each group of 15 specimens, 5 knees underwent tensile testing without cyclic loading, and the remaining 10 underwent the same tensile test after 5000 cycles of load-controlled or displacement-controlled loading. At the 5000th cycle, the peak displacement or the peak load was affected by each type of cyclic loading to a significantly greater degree in the knees with the tendon/Endobutton procedure than in the knees reconstructed with the other two procedures. Plastic deformation occurred more easily during cyclic loading in the knees with the tendon/Endobutton reconstruction than in the knees with the tendon-bone reconstructions. When the tendon/Endobutton reconstruction is used, a longer period of postoperative immobilization is necessary.