Development of the novel simulator that reproduces physiological and active knee motion

Many kinds of knee simulators have been developed. There are several concerns about the current simulators. First, the simulators for wear testing are driven using knee kinematics and loading profile data obtained from a normal gait. However, knee kinematics and knee joint forces are "the outcome" caused by muscular forces and external loads applied to the knee joint. As for the simulators for the kinetics and kinematics measurement of total knee arthroplasty (TKA), the knee is flexed in a "passive way" by applying constant muscular tension forces. This being so, simulators should be driven by muscular forces and external loads, i.e. in an "active way". Second, the effects of hip joint motion are not taken into account. Thirdly, the external load for example, upper body weight is not applied in a physiological way. Finally, few simulators are capable of knee flexion greater than about 100°. To this end, we have developed a novel knee simulator that has the following advantages and innovative features. First, it is driven directly by muscles' tension forces, thereby generating active flexion. Secondly, a hip joint is incorporated and the lower limb motion is achieved in a synergistic way between the hip and knee joints. Thirdly, it is capable to make a complete deep knee flexion.