The effect of weight-bearing status on kinematics and cruciate ligament force in normal knees

Evaluating WB status during normal knee flexion activities is important for optimizing surgical procedures and postoperative rehabilitation. This study aimed to clarify the effects of weight-bearing (WB) on in vivo knee kinematics and cruciate ligament forces in normal knees. Fluoroscopic imaging in the sagittal plane was used while volunteers performed squatting and active-assisted knee flexion. Tibiofemoral kinematics were measured using a two-dimensional/three-dimensional registration technique. Forces in the anterior cruciate ligament (anteromedial/posterolateral; aACL/pACL) and the posterior cruciate ligament (anterolateral/posteromedial; aPCL/pPCL) were analyzed. Anteroposterior translation (APT) of low contact points (LCPs) in WB and non-weight-bearing (NWB) conditions showed no anterior translation from extension to mid-flexion. The medial APT of LCPs in the NWB was more posterior than in WB. Medial stabilized articular surface and/or a surgical technique may help restore native knee kinematics across WB conditions.