In Silico Evaluation of the Primary Stability of Acetabular Revision Cups: Standard Versus Locking Screws

Abstract

Given the increasing complexity of revision total hip arthroplasty, ensuring optimal stability of acetabular revision cups (ARCs) is crucial, especially in cases of bone stock loss. In this study, the primary stability of ARCs was investigated by modeling various configurations of screw placements, including all standard, all locking, and mixed setups, under different load scenarios. Finite element (FE) models were implemented to evaluate the stress distribution and micromotions at the bone–prosthesis interface, simulating three primary load cases: “walking,” “stairs-down,” and “stand-up.” The results indicated that the stairs-down load case generated the highest von Mises stresses and sliding distances, marking it as the most critical load scenario. Configurations using all standard screws showed higher peak stresses and reduced stable areas, compared to those utilizing locking screws. While the locking screws provided a stiffer connection, the mixed screw configuration offered a balanced performance by combining the compression benefits of standard screws with the rigid fixation of locking screws. Configurations with a single standard screw complemented by locking screws showed enhanced stability, suggesting this combination could be advantageous in clinical applications. This study underscores the importance of screw type and placement in ensuring the primary stability of ARCs. Locking screws are recommended for use when feasible. For ARCs allowing both screw types, a mixed configuration starting with a standard compression screw followed by locking screws appears optimal. Future research should further explore various combinations of screw geometries and lengths to refine these findings and enhance surgical outcomes in acetabular revisions.