ABSTRACT
A computer graphics based sagittal plane model of the knee is developed for a prosthesis with fully unconstrained and congruous surfaces, which require retaining the cruciate and collateral ligaments of the knee. The aim of this study is to validate the model results with experimental observations, and to analyse the effects on joint mechanics of surgical malplacement of the implanted components. A single radius femur, a flat tibia and a congruous unconstrained meniscal bearing formed the model prosthesis components. The ligaments were modelled as arrays of elastic fibres which buckled when slack. The model muscles were represented by straight lines except where they wrapped around the bones. A bi-articulating model of the patello-femoral joint was used. A graphic interface was developed. The results show close agreement between the model calculations and the available experimental observations. The model can be used for quantitative and visual analysis of the effects of surgical errors in component placement.
