Kinematics of the LCS Mobile Bearing Total Knee Arthroplasty

Abstract

The determination of three-dimensional femoral-tibial kinematics dramatically improved with the introduction of in vivo weight bearing fluoroscopic studies. It is now believed that these techniques are highly accurate and reproducible as compared to earlier non-fluoroscopic methods. From literature review, those older techniques included in vitro cadaver studies, in vivo non-weight bearing radiographic studies, gait analysis, goniometric studies, and photogrammetry (RSA). In vitro cadaver studies measured the passive effects of the primary and secondary ligament constraints but were unable to add the physiologic muscle forces or the dynamic loading of actual human weight bearing. The disadvantage of gait studies and goniometric fixtures was the significant error introduced by non-stationary soft tissues which has been shown to be substantial. Roentgenographic stereo-photogrammetry (RSA) can be stated as highly precise with accuracy of 0.03 mm but the method must be considered non-weight bearing as subjects are not able to walk, stair climb, deep knee bend, etc.