Anatomical-based design of customized osseointegrated prosthetic components for individuals with transfemoral amputation

Osseointegrated prostheses offer a promising alternative to socket prostheses for transfemoral amputation. Success depends on factors like primary stability and efficient load transfer at the bone-prosthesis interface. Customized devices could address this issue by maximizing the fit-and-fill. To date, however, transfemoral prostheses lack customized solutions, with current options limited in size and adaptability to anatomical variations. The main aim of PhD project was to design a patient-specific transfemoral prosthesis by (i) adapting to a broader range of femoral canal anatomies and (ii) enhancing the fit-and-fill between bone and implant. In the first part of the project, a Statistical Shape Modelling (SSM) was adopted to evaluate the variability of the femoral medullary canal, also assessing variations depending on different resection levels. Results showed how the main modes of variation corresponded to geometric parameters such as length, radius of curvature, ellipticity, mean diameter, and conicity. Based on these variations, a customized prosthesis concept was designed, named “OsteoCustom”. The performance in terms of cortical bone preservation and stem-bone contact area was compared to a similar commercial stem. The ‘OsteoCustom’ stem, tailored to these subject-specific parameters, achieved improved fit-and-fill, removing 33%-42% less cortical bone based on resection level and increasing contact area by 20% at more distal levels. After completing the morphological evaluation, other issues were addressed. A pre-clinical analysis was then performed to evaluate better results in terms of primary stability, which confirmed OsteoCustom superior performance compared to a commercial design, also in accommodating anatomies currently ineligible under existing guidelines. Furthermore, a gait assessment was conducted to assess the feasibility of using wearable devices for rehabilitation purposes, which indicated promising applications. The project aimed to advance prosthetic solutions for transfemoral individuals.