The effect of different quadriceps loading patterns on tibiofemoral joint kinematics and patellofemoral contact pressure during simulated partial weight-bearing knee flexion.

Purpose: The purpose of this in vitro study was to investigate the influence of different quadriceps loading patterns on tibiofemoral joint kinematics and patellofemoral pressure.

Methods: A dynamic muscle-loaded knee squat was simulated on eight knee specimens with an upright knee simulator while measuring tibiofemoral joint kinematics and patellofemoral pressure distribution. The quadriceps muscle was attached to three actuators simulating the three main extensor muscles, and five different quadriceps loading patterns were tested.

The anterior cruciate ligament provides resistance to externally applied anterior tibial force but not to internal rotational torque during simulated weight-bearing flexion.

Purpose: We investigated knee kinematics during simulated weight-bearing flexion and determined the effect of 3 different parameters of external tibial loading on the kinematics of the anterior cruciate ligament (ACL)-intact and ACL-deficient knee.

Methods: Ten human knee specimens were mounted on a dynamic knee simulator, and weight-bearing muscle-loaded knee flexions were simulated while a robotic/universal force sensor system was used to provide external tibial loads during the motion. Three different loading conditions were simulated: partial body weight only, an additional 50 N of anterior tibial force (ATD), or an additional 5 Nm of internal rotational tibial torque (IRT).

Simulation of force loaded knee movement in a newly developed in vitro knee simulator.

Simulating knee movement under physiological muscle loading is a prerequisite in order to improve surgical treatment and rehabilitation techniques. An apparatus is presented which can simulate five knee muscles to control a definite amount of body weight using the ankle force as the target value for the control mechanism. The influence of different amounts of simulated ankle forces upon the knee movement was investigated.