Elevated-rim liner positioning in total hip arthroplasty: a compromise between dislocation biomechanics and range of...

Dislocation remains a common complication after total hip arthroplasty (THA). Elevated-rim liners may enhance stability, but their effectiveness depends on rim orientation and cup position. This study aimed to develop a capsule-informed framework integrating dislocation biomechanics and impingement-free range of motion (IFROM) to optimize elevated-rim liner positioning. A fiber-reinforced finite element (FE) model of the hip capsule was developed and calibrated using cadaveric data. A THA model was used to quantify IFROM across combinations of liner orientation and cup position, defining impingement-free safe zones (IFSZs). Liner edge contact pressure, plastic strain, and resistive moments were evaluated under three representative dislocation maneuvers. The framework accurately reproduced capsular mechanical behavior and identified IFSZs. Hyperextension produced the most severe edge loading. Posteroinferior rim orientation reduced edge loading and increased resistive moments, particularly for posterior dislocation. A clear trade-off existed between maximizing resistive moment and preserving IFROM. Liner positioning cannot rely solely on geometric parameters. A multi-objective strategy balancing IFROM and resistive moments while maintaining safe edge loading is required. The proposed framework provides a quantitative tool for patient-specific planning to reduce mechanical failure and improve joint stability after THA.