Analysis of Loosening Phenomenon in Artificial Hip Joint Application Related to Design Parameters

인공고관절의 설계인자들이 해리현상에 미치는 영향에 대한 해석

The human's biomechanical structure keeps an optimal state by adapting the original biomechanical structure according to a change in the physical environment. This phenomenon is believed to be the main cause of loosening of the total hip replacement which is used widely in these days. In this study the bone density change due to artificial hip joint, which is generally believed as bone-remodeling, was investigated by the finite element method. For this, 2-D FEM models with 4 nodal point elements were constructed for intact and implanted cases. The density was calculated by comparing the relative amounts of effective stress for these two cases. In this way, calculated new density values were used in the next step as input values and this procedure repeated until convergence was obtained. Severe density change was detected at the femoral cortex of the proximal-medial side as expected. Moreover, following surprising result was found from this analysis. Titanium alloy prosthesis showed less density change compared to stainless steel prosthesis at earlier stage, however, almost same amount of the density change was detected at final stage. It was also found that other design parameters could not significantly affect its density change.