Biomechanical analysis of an anatomic anterior cruciate ligament reconstruction.

Abstract

The focus of most anterior cruciate ligament reconstructions has been on replacing the anteromedial bundle and not the posterolateral bundle. Anatomic two-bundle reconstruction restores knee kinematics more closely to normal than does single-bundle reconstruction. Controlled laboratory study. Ten cadaveric knees were subjected to external loading conditions: 1) a 134-N anterior tibial load and 2) a combined rotatory load of 5-N x m internal tibial torque and 10-N x m valgus torque. Resulting knee kinematics and in situ force in the anterior cruciate ligament or replacement graft were determined by using a robotic/universal force-moment sensor testing system for 1) intact, 2) anterior cruciate ligament deficient, 3) single-bundle reconstructed, and 4) anatomically reconstructed knees. Anterior tibial translation for the anatomic reconstruction was significantly closer to that of the intact knee than was the single-bundle reconstruction. The in situ force normalized to the intact anterior cruciate ligament for the anatomic reconstruction was 97% +/- 9%, whereas the single-bundle reconstruction was only 89% +/- 13%. With a combined rotatory load, the normalized in situ force for the single-bundle and anatomic reconstructions at 30 degrees of flexion was 66% +/- 40%and 91% +/- 35%, respectively. Anatomic reconstruction may produce a better biomechanical outcome, especially during rotatory loads. Results may lead to the use of a two-bundle technique.