Optimized design for a novel acetabular component with three wings. A study of finite element analysis.

BACKGROUND: A novel acetabular component with three wings has earlier been explored for reconstructing extensive acetabular bone defects in hip revision arthroplasty with a satisfying clinical result. However, the periacetabular stress patterns and mechanisms by which the acetabular cup obtains initial stability are not clear.

PURPOSES: The purpose of this study was to evaluate the stress patterns of the novel cup using finite element method and possible effects of joint loading postoperatively, and to analyze its optimized design for the structural parameters of the cup.

METHODS: Three-dimensional finite-element (FE) models of the cup with three wings and the hemispherical cup were created to calculate the stress patterns during a normal gait cycle using FE formulations. The stresses of these acetabular components were analyzed and compared.

RESULTS: FE analysis demonstrated that the cup with three wings and the hemispherical cup had the same trend for stress and strain. The stress of the wings increased gradually from rim to root. Its peak stress was significantly lower than the yield force of the Co-Cr-Mo alloy at the joint between the wing and the shell. The graft portion near the acetabular component was subjected to higher stress conditions. The contact stresses were found to be decreased with a reduced abduction angle of wings and not affected by changed eversion angle of wings. The cup with wings of abduction angle of 15° had lower stresses compared with other cups.

CONCLUSIONS: The cup with wings is a reliable option for the reconstruction of the acetabulum with extensive bone socket defects. The reduced abduction angle of wings helps to decrease the stress of the cup with wings. However, removing the eversion angle of wings may be the most prudent choice to avoid the introduction of adverse variables, which may contribute to the loosening of the acetabular component. FE analysis is a useful tool with which to address these issues.