The effect of bush material property on the metal-polymer contact stress in knee megaprosthesis – An in silico study

Abstract

The long bone loss management using segmental resection for the fixation between femur and tibia is called modular megaprostheses. Despite the huge development of design and materials of biomedical implants, the design issue of megaprostheses are still highly challenging. The wear and formation of wear debris of the polymer bush in the megaprosthesis is one of the significant problems faced. The objective of the study is to compare between PEEK, UHMWPE and their composites as the bush material and to find their suitability in order to reduce the polymer-metal contact stress. A three- dimensional model of the bone assembly is extracted from the Computerized Tomography (CT) scan for both femur and tibia using image processing software, Mimics. A 3D model of custom-made knee prosthesis is also developed. Both the 3D models were assembled and analyzed by giving boundary conditions with reference to the clinical conditions. The finite element analysis employed on the assembled prosthesis clearly shows the stress distribution and deformation in different parts and components of the megaprosthesis as well as adjacent femur and tibia. It is seen that the stress generated in the polymer-metal interfaces, which is one of the chief reasons behind the bush wear, could be varied by using varied bush materials.