Fretting and Metal Release of Modular Neck Total Hip Arthroplasty

INTRODUCTION: In current total hip arthroplasty, modularity between the head-neck connection of the femoral stem is well established. More recently, implants with an additional modular connection between the neck and stem have become more popular. The ability to adjust the head centre relative to the stem axis intraoperatively, by connecting the neck in different positions, guarantees high versatility during surgery. The mechanical loading conditions of the neck-stem connection fundamentally differ from the well-established head-neck connection. Fretting caused by micro-motion between the modular components may lead to particle and ion release to the surrounding tissue. Titaniumcontaining particles may cause the release of cytokines that are associated with periprosthetic bone loss. Additionally, such particles may get trapped between the articulating surfaces of the artificial joint resulting in third-body wear. Modularity is often associated with corrosion effects and is seen as a weak link with a possible source of complications. The aim of this study was to analyse and compare the corrosion effects and to evaluate the particle and ion release of the modular neck hip implants currently used.