Design of a Biofidelic Talus Implant Using Topology Optimization

Abstract

The talus bone, a pivotal component in the ankle joint, plays a significant role in load transmission and motion facilitation. As with other bones, and due to its fragile vascular nature, it is especially susceptible to fracture which typically requires surgical intervention. For more extreme fractures, among the most common treatments are total talar replacements. Currently, they are custom made for each individual patient, resulting in increased financial costs and time until surgical implantation. To circumvent these drawbacks, generic talar prostheses were proposed. The primary issue is the lack of studies in literature on the optimization of generic talar prostheses. Therefore, this thesis research aims to design a biofidelic generic talus implant using topology optimization that is intended to tackle the drawbacks of custom talus implants, rendering its use more cost-effective and feasible in clinical situations, resulting in reduced complications for the patient pre- and post-operatively. This is done through establishing the loading and boundary conditions for three postures: dorsiflexion, neutral standing, and plantarflexion. Following that, the optimization for the generic implant is setup and carried out. The optimized geometry is then extracted and setup for the finite element evaluation of its stresses, to ensure its safety, and its contact characteristics, to explore its behavior on adjacent bone cartilages. The resulting optimized implant's mass is reduced by approximately 66.6%. Its stresses do not exceed 70 MPa, and has a safety factor of 15.7. Based on the aforementioned, the implant's safety against static loading in the defined three postures is ensured. Moreover, based on the contact characteristics, no improvement was shown as compared to its non-optimized, solid counterpart. Nevertheless, as intended, material, cost, and time reductions are expected, especially considering that the implant should be mass-produced.

Date of Award	Jun 2022
Original language	American English