Differences of the function between the anteromedial bundle and posterolateral bundle of the anterior cruciate ligament

Objective To study the role of the anteromedial bundle(AMB) and posterolateral bundle(PLB) of the anterior cruciate ligament(ACL) in maintaining knee joint stability.Methods In this study,12 fresh-frozen human cadaveric knees were tested under two kinds of external loading conditions including a 100N anterior tibial load with the knee at 0°,15°,30°,60°and 90°of flexion;and a 5Nm pronation load with the knee at 0°,15°and 30°of flexion.The two bunches of ligament were pulled tight that led the strain gauge to deformation,and changed output voltage value.Results In response to a 100N anterior tibial load,the situ force in the AMB was significantly greater at 60°and 90°than at full extension and 15°of flexion(P 0.05);the situ force in the PLB was significantly greater at full extension and 15°than at 30°,60° and 90°of flexion(P 0.05);the situ force in the PLB was significantly greater than the AMB at full extension and 15°;the situ force in the AMB was significantly greater than the PLB at 30°,60° and 90°.In response to a 5Nm interned tibial torques load,the situ force in the AMB was significantly greater than the PLB at 15° and 30° of flexion(P 0.05);no statistical difference occurred between AMB and PLB at full extension(P 0.05).Conclusion Though the AMB plays an important role in the ACL,the role of PLB should not be ignored in maintaining anterior and internal rotational stability at low flexion angles.