The goal of the study was to simultaneously obtain accurate kinematic and kinetic data from a total knee arthroplasty (TKA) during level walking, by coupling force plate data with the kinematics of TKA measured by a movable video-fluoroscopic system. Kinematic and kinetic information of a TKA is crucial for the improvement of implant designs and for the increased longevity of the implant components. Instrumented gait analysis, with skin mounted marker tracking and force plates, is a well-established method for the acquisition of kinematic and kinetic data of TKA in vivo and for non-invasive estimation of joint function. However, resultant moments at the knee joint are inaccurate with this method, due to skin movement artifacts. Video-fluoroscopy reduces these inaccuracies by means of the direct tracking of the implant components with X-ray. However this measuring technique carries disadvantages: it provides only kinematic data, and the image intensifier covers a limited field of view. This paper presents a newly developed measuring technique, which enables a more accurate resultant moments calculation for level walking than could be achieved by conventional instrumented gait analysis.