Morphological and functional analysis of the knee joint for implant design optimization

The aim of this thesis was to provide fundamental morphological and morpho-functional information and to develop an integrated computer-assisted image-based workflow for implant design optimization. For the morphological analysis of the native knee joint overall 59 geometrical features of the knee were identified, fully automatically extracted from a dataset of 831 knee geometries, and used for a comprehensive statistical analysis. Most of the features showed statistically significant gender-specific differences. Subsequently, the features were classified according to the direction of their measurement and normalized. However, large inter-individual variations remained after normalization, suggesting that patient-specific design solutions are required for an optimized implant design. The overall knee dimensions were used to calculate an adequate number of implant component sizes. The results indicated that there are more sizes necessary than currently offered by the market. Another major aspect was dedicated to the morpho-functional analysis. Parameterized functional surface models of the articulating surfaces were developed to allow systematic and repeatable shape variations of selected design parameters. Furthermore, we developed a patient-specific biomechanical in silico model of the lower extremity as well as an experimental in vitro knee testing rig to analyze the relation between design parameters and knee function. The feasibility of the morpho-functional analysis was demonstrated in the example of a patient-specific implant. The results of the kinematic analysis might have direct consequences on knee implant design optimization in terms of compatibility and sensitivity of design parameters.