Comparison of stress shielding among different cement fixation modes of femoral stem in total hip arthroplasty - A three-dimensional finite element analysis

Local bone loss after cementless and cemented implantation of prostheses remains an unsolved problem during the long-term application of total hip replacement. Stress shielding is considered to be one of several important factors that result in local bone loss after prosthesis implantation. This study was designed to investigate the roles of bone cement in different fixation configurations on initial stress shielding using a three-dimensional finite element analysis. Synthetic femora were used to create four finite element models including intact, and femora after implantation of C-fit stem with three different configurations of cement fixation: cementless, proximally-cemented and fully-cemented fixations. Under a 1,000-N vertical loading, the proximal strain distributions of the four models were analyzed and compared. The results revealed that, regardless of cement fixation configurations, stress shielding was found at the proximal femur following the insertion of stem. Less stress shielding was found for femur with fully-cemented fixation, whereas the most obvious stress shielding was found in the femur with cementless fixation. The introduction of bone cement was considered to produce more uniform transmission of external force, which led to the reduction of stress shielding.