Novel osseointegration implant optimization

Osseointegrated prosthesis is an effective treatment of femur amputation that resolves many of the socket prosthesis-related issues such as skin infections and low remnant bone quality. However, the stress shielding and stability of the implant are two major concerns, which jeopardize the success of long-term fixation to the residual femur. In the design aspect, finite element analysis is commonly used to evaluate the stress distribution on the residual femur and implant stability. This paper demonstrates a paradigm of simulation setup for a novel osseointegrated implant, which is customizable based on the patient’s bone quality, under two static normal walking loading conditions. A parametric optimization scheme was established to obtain the optimal structure for the novel implant, which aimed to maintain sufficient stress levels on the femur to reduce the effect of stress shielding on bone mineral density. This paper presents the optimal implant shape for a residual femur length which is the most common osteotomy level of 250mm above the knee. The result demonstrates that the residual femur with the optimal implant shared similar stress distribution with the intact femur. Even though the average stress level is lower compared to the result of the intact femur under a certain length of the intramedullary stem, the optimization result reveals the potential of the novel design to minimise the risk of stress shielding. Moreover, a clear relationship between the average stress on the interest area and the length of the intramedullary stem is identified in this paper. The findings demonstrate the potential of the novel osseointegrated implant on maintaining bone mineral density and ensuring long-term stability.