J Orthop Res. 2000 Jan;18(1):109-15.

Christina R. Allen, Eric K. Wong, Glen A. Livesay, Masatake Sakane, Freddie H. Fu, and Savio L-Y. Woo


The incidence of mediscal tears in the chronically anterior cruciate ligament-deficient knee is increased, particuarly in the medial meniscus because it performs an important function in limiting knee motion. We evaluated the role of the medial meniscus in stabilizing the anterior cruciate ligament-deficient knee and hypothesized that the resultant force in the meniscus is significantly evaluated in the anterior cruciate ligament-deficient knee. To test this hypothesis, we employed a robotic/universal force-moment sensor testing system to determine the increase in the resultant force in the human medial meniscus in response to an anterior load following transection of the anterior cruicate ligament. We also measured changes in the kinematics of the knee in multiple degrees of freedom following medial meniscectomy in the anterior cruciate ligament-deficient knee. In response to a 134-N anterior tibial load, the resultant force in the medial meniscus of the anterior ligament-deficient knee increased signifiacntly compared with that in the meniscus of the intact knee; it increased by a minimum of 10.1 N (52%) at full knee extension to a maximum 0f 50.2 N (19.7%) at 60° of flexion. Medial meniscectomy in the anterior cruciate ligament-deficient knee also caused a significant increase in anterior tibial translation in response to the anterior tibial load, ranging from an increase of 2.2 mm at full knee extension to 5.8 mm at 60° of flexion. Conversely, coupled internal tibial rotation in response to the load decreased significantly, ranging from a decrease of 2.5° at 15° of knee flexion to 4.7° at 60° of flexion. Our data confirm the hypothesis that the resultant force in the medial meniscus is significantly greater in the anterior cruciate ligament-deficient knee than in the intact knee when the knee is subjected to anterior tibial loads. This indicates that the demand on the medial meniscus in resisting anterior tibial loads is increased in the anterior cruciate ligament-deficient knee compared with in the intact knee, suggesting a mechanism for the increased incidence of medial meniscal tears observed in chronically anterior cruciate ligament-deficient patients. The large changes in kinematics due toi medial meniscectomy in the anterior cruciate ligament-deficient knee confirm the important role of the medial meniscus in controlling knee stability. These findings suggest that the reduction of resultant force in the meniscus may be a further motive for reconstructing the anterior cruicate ligament, with the goal of preserving meniscal integrity.