Three-dimensional Finite Element Analysis of Acetabular Prosthesis in an Adult Patient with Total Hip Arthroplasty for High Dislocation

Objective To observe stress distributions around the acetabular prosthesis and the bones of a patient who underwent total hip arthroplasty (THA). Methods Finite element analysis (FEA) was performed with an osteoarthritis patient who underwent THA for her secondary hip high dislocations:Scenario A——deepened acetabulum at the true acetabulum with a small 44 mm cup; Scenario B——structural bone graft at lateral acetabular with a 48 mm cup; Scenario C——place tantalum metal acetabular reconstruction at the lateral acetabular with a 48 mm cup; Scenario D——the normal side of the hip. According to the Wasielewski methods, acetabular was divided into four zones, in the same way on the lining surface. Ten points were taken in each zone for measuring the Von Mises stress values. Results Scenario A generated significantly greater stress values in the bones in zone one than the other three scenarios. Significantly greater stress was also found in the inner surface of polyethylene over all of the four zones under scenario A compared with those of the scenario B and C, especially in zone one and two. The cup initial micro-mobility for scenario A was 49.18 μm, 19 times of that of scenario B and 8 times of that of scenario C. Conclusion ① Deepened acetabulum with small cup can cause stress concentration in the acetabular bones and liner, leading to large cup initial micro-mobility. ② Acetabular lateral structural bone grafting and placement of tantalum metal reconstruction have better biomechanical properties, which can enable the use of bigger cups.