Simulation of the biodegradable behavior of composite bone plate under human body environment

The Young's modulus degradation of a biodegradable composite based on the exposure time to phosphate-buffered saline (PBS) solution was simulated by estimating the material's effective diffusion coefficient. The relationship between PBS uptake rate and material removal was investigated by comparing the finite element analysis and experimental results, and a criterion for the material removal of finite elements was proposed for an accurate material degradation simulation. The diffusion coefficient was calibrated to determine the best fit for the PBS uptake rate based on exposure time. The degradation behavior of a bone plate made of a fully biodegradable composite was analyzed using a calibrated diffusion coefficient; it was found that the screw hole parts were severely damaged owing to PBS uptake, which induced premature structural failure. To address this drawback, a hybrid bone plate composed of a nondegradable composite and a Mg wire/Polylactic acid (PLA) composite was introduced; its serviceability was verified using finite element analysis.