Biomechanical rationale and testing on femoral prosthetic component for amputees

Osseointegrated transfemoral prostheses, like other uncemented prostheses, experience the risk of aseptic loosening and post-operative periprosthetic fractures with an incidence between 3% and 30%. Implant stability of a prosthetic device is crucial for a pre-clinical evaluation of uncemented prostheses. However, the methods to experimentally investigate the primary stability and load transfer are far from consolidated. Moreover, osseointegrated prostheses are manufactured in a limited number of sizes and several patients do not meet the strict eligibility criteria of commercial osseointegrated prostheses. To mitigate these problems, I contributed to the development of a new concept of osseointegrated transfemoral prosthesis (OsteoCustom). The aim of this PhD project was to assess preclinically the different issues of a customized osseointegrated stem. This included investigating the biomechanical rationale for the characterization of osseointegrated transfemoral stems, performing a pre-clinical biomechanical tests to evaluate the mechanical stability of the OsteoCustom stem with the bone, and developing a framework for testing the endurance properties of the stem itself. A method to quantify the primary stability and the load transfer of osseointegrated transfemoral prosthesis was successfully developed. The method highlighted the potential benefits of the OsteoCustom prosthesis in terms of primary stability and load transfer. Moreover, a framework for the assessment of the endurance properties of a discrete customized transfemoral osseointegrated stem was developed and validated. In conclusion, this PhD project has developed and defined a set of methodologies for the pre-clinical evaluation of an osseointegrated transfemoral stem. Moreover, given the problems of a commercial osseointegrated stem, it has been developed and evaluated preclinically the performance of the OsteoCustom stem with in vitro and in silico models. The potential benefits of the OsteoCustom stem were shown in this project. Further pre-clinical analyses will be necessary to understand the real applicability of this prosthesis in the clinic.