Double-band reconstruction of the ACL using a synthetic implant: a cadaveric study of knee laxity.

In this study, the anterior laxity and internal rotation of five cadaveric knee joints were compared when the anterior cruciate ligament (ACL) was intact, after its reconstruction with the anteromedial band (AMB) only, then after its reconstruction with the double band, with the posterolateral band (PLB) tensioned first at 20 degrees and then at 90 degrees, and finally with the ACL resected. The tests were performed using a mechanical apparatus that allowed the joint 6 degrees of freedom and also the application of external loads and torques on the tibia. The loads used were 50, 90, and 130 N for the anterior laxity test, and a torque of 2, 3, and 4 Nm in the internal rotation test. In all cases, laxity with double-band reconstruction was closer to the natural value than when it was constructed with the AMB only. In some cases, double-band reconstruction imposed a higher constraint on the joint than did the natural ACL. Measurement of the residual tension on the PLB after its final anchoring was also performed during passive flexion. This test revealed a high tension on this band with the knee in hyperextension, followed by a decrease in value through to 45 degrees and a slight increase at 90 degrees, thus following a similar trend to that of the natural PLB.