Knee replacement surgery has made a huge evolution during the past decades. For further improvements of knee arthroplasty, dynamic knee simulators are used for fully instrumented ex-vivo tests. This paper provides a closer look at the validation of the rig. Therefore, a hinge model is constructed, resulting in an unambiguous evaluating method. The actual position of the ankle and the reaction forces at the ankle are measured and compared with the simulations. The results indicate an excellent agreement between the outcome of the numerical simulations and the measured values. The kinematics and kinetics of the rig are accordingly considered as validated. In the future, the behaviour of a more realistic knee representation will be evaluated.