Evaluating Functionally Graded Material Designed for Bone Fixation Plates via Finite Element Methods

Background: The use of traditional metallic bone fixation devices, such as stainless steel and titanium, often leads to complications, including stress shielding, allergic reactions, and imaging interference. This necessitates the exploration of alternative materials with better biomechanical compatibility and reduced adverse effects.

Objective: This research aims to evaluate the efficacy of functionally graded, chopped, carbon-fiber-reinforced polyether ether ketone (CCF/PEEK) composites as bone fixation plates, particularly focusing on their ability to minimize stress-shielding effects while enhancing biocompatibility and healing performance during the bone healing process.

Methods: Finite element analysis (FEA) was employed to examine the effects of stress shielding in bone plates composed of CCF/PEEK composites with various gradient distributions under both static and instantaneous dynamic loading conditions. The FGM bone plate models were developed using ABAQUS software along with user subroutines USDFLD and VUSDFLD, with each FGM plate maintaining an equivalent overall elastic modulus but featuring distinct gradient distributions.

Results: The results revealed that all FGM bone plates exhibited lower stress-shielding effects compared to metal bone plates. Compared with ST316L, the average stresses provided by the FGM3 plate with an elastic modulus gradually increased from the center to both sides are 8.67 %, 10.89 %, and 10.92 % higher in the healing stages of 1 %, 50 %, and 75 %, respectively. At the same time, the ranges of the stress for the FGM3 plate are the lowest (1 % healing stage) and second lowest (50 % and 75 % healing stages) out of all types of plate materials.

Conclusion: The study indicates that CCF/PEEK composites, particularly the FGM3 plate, which has an elastic modulus gradually increased from the center to both sides, can provide maximum stress stimulation and the most uniform stress distribution within the fractured area.