A comparative analysis on adaptation behavior and failure risk of femurs of different qualities under the effect of direct transfemoral fixations

Abstract

Osseointegrated transfemoral prostheses secure the direct attachment of prosthetic limbs. Despite the existence of relevant studies concerning these fixations, the effect of bone quality on their outcome has not been thoroughly investigated. In this study, the finite element (FE) analysis was linked to a bone remodeling algorithm to simulate the bone adaptation process. The 3D models of femurs with average shaft diameters of 24mm, 26mm, and 28mm were created based on computerized tomography (CT) scan images. Three initial densities representing high, moderate, and low-density femurs were also modeled based on the available data in the literature. Eventually, the effect of bone quality was evaluated in terms of bone adaptation and failure risk. The analysis revealed that the dissimilarities in bone quality considerably affect the bone mineral density (BMD) changes and stress distribution in the implantation area. The presence of transfemoral implants increased the interface failure risk at the distal zones for low-quality femurs while decreasing the failure risk at the proximal zones. It was also shown that the chance of fracture and interface failure is lower for dense femurs, and the remodeling process does not significantly affect their failure risk.