Finite element analysis of biomechanical behavior of fractured tibia applied by composite bone plates

Abstract

In this research, finite element analysis was used for estimate the rate of bone healing at fracture site applied by composite bone plates. Interfragmentary strain theory was used for this analysis. Referring to the previous research, the callus generated and developed at the fracture site had different material properties according to the interfragmentary strain during healing period. Therefore, the callus was modeled to have different material properties according to the interfragmentary strains. In order to impose the actual condition on the finite element model, contact conditions between the tibia and the bone plate and time-varying loading conditions were considered. Commercial finite element code (ABAQUS v6.9) was used for the analysis. And a user subroutine was developed by PYTHON code to impose different material properties on each callus element for the iterative calculations during healing period. On the other hand, the preliminary study [7] having used averaged callus properties had a limitation for predicting the exact callus generation and its development at each callus element. It is expected that this research result is able to explain the actual behaviour of callus development more precisely than the previous result because the newly developed method dealt with different material properties for each callus element. From the analysis results it was found that the flexible composite bone plate generated relatively high strain distributions relative to the previously calculated results which used average callus properties. This result concluded that the composite bone plate with slightly higher modulus than previously determined modulus (18GPa) is needed for better healing bone fractures.