Biomechanical Analysis of CT Scan-based Hip Prosthesis With an Optimal Hip Ball by Using Finite Element Analysis

Bone loss around the femoral stems during the insertion of a standard prosthesis is a major problem in hip arthroplasty. Moreover, long periods of use of the standard metallic prosthesis often lead to revision surgery because of disuse osteoporosis (stress shielding). The main factor behind this problem is the material-stiffness mismatch of the bone and implant, with the latter consisting of metals such as stainless steel, Co-Cr-Mo alloy, or Ti6Al4V alloy. Our study aimed to decrease the factor of geometric mismatch by designing and making customized hip prostheses from computed tomography scan data and finite element analysis. Therefore, the inner medullar cavity of the femur would match exactly with the prosthesis. Our results showed that the desired stress-strain values were close to the physiological level. We observed that the maximum Von Mises stresses for the bone and implant were 41.8 MPa and 197 MPa, respectively. An optimization analysis of the taper angle of the prosthesis hip ball for fixation with the stem has also been performed, in which the angle was found to be approximately 2 deg. The taper angle plays an important role in load transfer and safe levels of stress-strain using various ball materials.