Homogeneous material models can overestimate stresses in high tibial osteotomy: A finite element analysis

Although widely used numerical models can assess the stability of lateral hinges in high tibial osteotomy (HTO) and may provide acceptable results in comparative studies, accurate stress prediction may not be possible due to simplified homogeneous models of the bone. The present study aimed to investigate the effect of a heterogeneous versus four homogeneous models on the results of stress and force. Each of the four homogenized FE models utilized the same elastic modulus of 16,700 MPa for the cortical while employing a single elastic modulus varying from 155 to 5000 MPa for the cancellous. In heterogeneous model, the modulus of each element was assigned using the bone density. It was found that stresses at the hinge in homogeneous models were higher than those in the heterogeneous model. The maximum principal stress (MPS) was 437 MPa for the heterogeneous model while that was 2179, 2351, 2581, and 2637 MPa for the homogeneous models with the elastic moduli of 155, 500, 2130, and 5000 MPa, respectively. Also, the opening force was 150 N for the heterogeneous model significantly lower than 649-1534 N range predicted for the homogeneous models. The use of a homogeneous model in the FE analysis of HTO overestimated the stresses and force. Thus, in addition to casting doubt on the use of a single modulus in the numerical analysis of HTO, Future HTO studies can use our results as a benchmark for comparison purposes and highlight the use of patient-specific bone density - elastic modulus relation in simulation.