Bone loss and reduced bone quality of the human femur after total hip arthroplasty under stress-shielding effects by titanium-based implant

The present work was aimed at clarifying the stress-shielding effect caused by hip-joint implantation into a femur by using a human cadaver with a cementless hip implant. In particular, bone quality was assessed from the standpoint of preferential c-axis orientation of biological apatite (BAp). Comparing the implanted side to the non-implanted side, a finite element analysis (FEA) indicated that artificial hip-joint implantation had a significant stress-shielding effect on the femur. The results also showed a marked decrease in the degree of preferential BAp orientation as well as bone loss in the medial-proximal femur. This is the first report showing a reduction in the degree of preferential BAp orientation due to a stress-shielding effect after artificial hip-joint implantation. Since preferential BAp orientation is an important index for determining bone mechanical function, these findings should be taken into account in future artificial hip-joint designs, especially those involving the stem component.