Influence of Different Boundary Conditions in Finite Element Analysis on Pelvic Biomechanical Load Transmission.

OBJECTIVE: To observe the effects of boundary conditions and connect conditions on biomechanics predictions in finite element (FE) pelvic models.

METHODS: Three FE pelvic models were constructed to analyze the effect of boundary conditions and connect conditions in the hip joint: an intact pelvic model assumed contact of the hip joint on both sides (Model I); and a pelvic model assumed the hip joint connecting surfaces fused together with (Model II) or without proximal femurs (Model III). The model was validated by bone surface strains obtained from strain gauges in an in vitro pelvic experiment. Vertical load was applied to the pelvic specimen, and the same load was simulated in the FE model.

RESULTS: There was a strong correlation between the FE analysis results of Model I and the experimental results (R (2) = 0.979); meanwhile, the correlation coefficient and the linear regression function increased slightly with increasing load force. Comparing the three models, the stress values in the point near the pubic symphysis in Model III were 48.52 and 39.1% lower, respectively, in comparison with Models I and II. Furthermore, the stress values on the dome region of the acetabulum in Models II and III were 103.61 and 390.53% less than those of Model I. Besides, the posterior acetabular wall stress values of Model II were 197.15 and 305.17% higher than those of Models I and III, respectively.

CONCLUSIONS: These findings suggest that the effect of the connect condition in the hip joint should not be neglected, especially in studies related to clinical applications.