Model-based wear measurements in total knee arthroplasty : development and validation of novel radiographic techniques

The primary aim of this work was to develop novel model-based mJSW measurement methods using a 3D reconstruction and compare the accuracy and precision of these methods to conventional mJSW measurement. This thesis contributed to the development, validation and clinical application of model-based mJSW measurements for the natural knee and for total knee prostheses. The majority of this work focusses on measuring linear wear of the total knee protheses by estimating the remaining insert thickness with the mJSW. Both in vivo and in vitro research shows that the application of model-based techniques can give a large improvement in measurement accuracy and precision. This applies for measurements based on both Röntgen Stereogrammetric Analysis (RSA) and standard radiographs. Secondary, this work investigated volumetric wear measurement and the effect of patient positioning on the measurement outcome. In conclusion, this work presents convincing evidence that the mJSW measurement accuracy and precision is improved using model-based measurement techniques in RSA images as well as in standard AP radiographs. The next steps towards clinical application are to improve the measurement software and to conduct further research on the influence of knee flexion and implant design on the reliability of mJSW as surrogate for the insert thickness.