Biomechanical Analysis of Effect of Inclination Angle on Stress Distribution in the Acetabulum and Acetabularcup after Total Hip Arthroplasty

Total Hip Arthroplasty (THA) is one of the most successful orthopedic surgeries, which is advised by the specialist in cases which osteoarthritis worsens in the hip joint. In the long run, functionality of THA may be subject to problems such as wear, loosening, and displacement. Structural and mechanical mismatches of artificial joint with the patient's natural joint after THA leads to the changes stress distribution pattern on the bones in a way that the majority of the load is on the artificial joint and a small percentage is implemented on the patient’s bone; in the long run, it reduces bone density and leads to loosening and displacement. One of the most important factors determining the stress distribution in the bone and prosthesis is the acetabularcup inclination in the acetabulum socket. In this study, a 24-year-old patient, who had been injured in the hip joint, is studied and the effect of the inclination angle on stress distribution in the acetabulum and acetabularcup is assessed. First, a 3D model of the patient’s bone is obtained, using CT-scan imaging and its mechanical properties are found. Gait analysis is carried out on the patient and the movement pattern and muscle forces in a gait cycle are found, using OpenSim software. The hip prosthesis is designed and the mechanical analysis of the joint is carried out, using ABAQUS finite element software, and the appropriate inclination angle for the acetabularcup for this patient is derived. The results show that the acetabularcup implantation in 45 degrees of inclination leads to better prosthesis functionality and a longer life.