Joint kinematics following total knee replacement (TKR) is important as it affects joint loading, joint functionality, implant wear and ultimately patient comfort and satisfaction. It is believed that restoring the natural motion of the joint (such as the screw-home mechanism) with a medial pivot knee implant will improve clinical outcomes. Daily activities such as stair climbing and stair descent are among the most difficult tasks for these patients. This study analysed dynamic knee joint motion after implantation of a medial pivot knee implant using fluoroscopy during stair ascent and descent activity. Ethics approval was granted by Macquarie University to undertake fluoroscopic testing. Four patients who had undergone a TKR were asked to participate in the study. All patients were operated by a single surgeon (JS) and were implanted with a medial pivot knee prosthesis (Sphere, Medacta International). Participants were tested at the 12 month post-operative time- point. Participants were asked to step up or down a short stair-case at a comfortable self-selected speed. Fluroscopic images were taken using a flat panel Artis Zeego (Siemens Healthcare GmbH, Erlangen) angiography system during the dynamic activity. Images were processed using Joint Track Auto (Banks, University of Florida), whereby the specific femoral and tibial component CAD files were superimposed onto the fluoroscopic images, ensuring an optimised match to the outlined components. Joint kinematics were calculated using custom written code in Matlab 2017a.Introduction
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