Design of a biodegradable plate for femoral shaft fracture fixation

Abstract

Biodegradable materials have been generating increasing bit of interest in biomedical applications and associated research. The evolution of implants made up of such materials (Mg-alloys, etc.) has the potential to be a game changer in fracture surgeries. These implants are essentially made up of a plate and a number of screws. In orthopaedic applications, they offer the biggest advantage of complete degradation after successfully supporting the fractured bone for the desired period. They may provide some nutrients that accelerate the healing process while simultaneously ensuring adequate mechanical stability. This article essentially focuses on design of a biodegradable implant plate for femoral shaft fracture, taking into consideration the dimensional accuracy of the plate, uniform biodegradation rate and adequate mechanical stability of the plate across the entire process span. The design of a biodegradable implant plate and associated specified screws that support the plate, fitted over two segments for fixation of femoral shaft fracture, has been made on the basis of femur's standard dimensions, optimized plate dimensions and uniform biodegradation rate. A confirmation regarding the safe design of the implant plate is obtained through computational structural analysis. The implant plate design turns out to be safe at specific optimized dimensions for a human being weighing 80 Kg, at corresponding loading and boundary conditions. For average monthly degradation of the plate across a period of six months, the factor of safety comes out to be more than unity. The implant plate eventually goes through complete degradation 3-6 months after the completion of the healing process and this is where the plate thickness plays a significant role.

Keywords: Biodegradable materials; Implant plate: Femoral shaft fracture; Topological optimization.