Biomechanical Analysis of Damage Formation in Total Hip Arthroplasty under Falling Conditions

Abstract

Computational finite element models of femoral bones, bone X and Y, with different bone quality were constructed using CT-images of two elderly female patients. Then, three different stem models of total hip arthroplasty (THA) were implanted into the femoral models. Nonlinear finite element analysis was performed under four different falling conditions in order to assess the effects of bone quality and stem design on the fracture mechanisms of femoral bone. It was found that the stem geometry had some effects on the cumulative number of element failures in the internal region of bone X (greater bone quality) along with the changes in the falling condition, while such effects were very small in bone Y models with lower bone quality. By analyzing the damage formation in the external bone regions, it was found that the fracture formation drew a parallel view to type A_G of Vancouver fracture classification which occurred in all of the THA models. It was also found that the internal damage distribution of the THA models of bone X had a pattern of concentrated damages at zone 1 and zone 7 of the Gruen zone system and the pattern was consistent in all stem designs and falling conditions. On the contrary, in the THA models of bone Y, the damaged distributions were scattered throughout the bone-stem interfaces.