Introduction of Maximum Stress Parameter for the Evaluation of Stress Shielding Around Orthopedic Screws in the Presence of Bone Remodeling Process

Abstract

The current study introduces a novel parameter called maximum stress parameter (MSP) which supersedes the conventional parameter known as stress transfer parameter (STP). It also incorporates the bone remodeling algorithm into the finite element analysis. The results from MSP can be approved by those of STP; however, MSP is preferable due to its benefits, which is discussed in this study. The current study simulates a 48 months healing process and investigates the effect of screw parameters using a two-dimensional finite element model in the presence of bone remodeling process. Lower MSP values demonstrate a more homogeneous stress distribution between the screw and bone, which results in less stress shielding. However, the reciprocal of MSP, shown as RMSP is defined in order to enable the comparison between MSP and STP. The results of current study demonstrate that increasing the number of threads and outer diameter, and decreasing pitch and Young's modulus of screw improve the performance of screw and reduce the possibility of screw loosening. The results also show that MSP is a promising parameter, which can supersede STP in future studies, and increase the reliability of results.

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