Three-dimensional Finite Element Analysis of Stress in Femur after Total Hip Replacement and Its Correlation with Bone Mineral Density

Objective To investigate the stress in femur after total hip replacement using three dimensional finite element analysis,and to explore the correlation between the stress and bone mineral density.Methods Twenty patients who underwent total hip replacement in the second affiliated hospital of Nanchang university between 2008 and 2009 were selected in this study.Three-dimensional finite element analysis of stress in the femur was carried out at 1,3,6,12,24 and 36 months after operation.At the same time,bone mineral density was measured by dual-energy X-ray absorptiometry.Periprosthetic regions of interest(ROI) were defined according to Gruen(ROI 1-7).All statistical analyses were performed using t-test(SPSS 15).Results The level of stress shielding was highest in ROI 7 and lowest in ROI 3.The level of stress shielding at 1,2 and 3 years post-operation significantly decreased compared with the shielding at 1,3 and 6 months post-operation(P0.05).Bone mineral density showed a significant decrease at 3-month post-operation,and the most obvious decrease was found in ROI 7(P0.01).No further reduction of bone mineral density occurred at 1,2 and 3 years post-operation.Conclusion Bone mineral density is correlated with stress shielding and postoperative time in femur after total hip replacement.