Advances in Specialist Hip Surgery

Abstract

In past two decades, the use of metal-on-metal (MoM) bearings in total hip arthroplasty (THA) has gained popularity due to the lower wear rates and attractive tribological profile. Large-head MoM THAs have an advantage of improved stability. However, they exhibited high acetabular loosening rates and adverse reactions to metal debris (ARMD) with early implant failures. Second-generation MoM THA with a small-diameter head is recognized to have lower frictional torque, better metallurgy, and greater control over dimensional clearance. This bearing has generally been associated with a reduced incidence of polyethylene particle-induced osteolysis. However, recent reports have raised concerns regarding elevated serum metal ion levels and ARMD in small-head MoM THA on long-term follow-up. This review discusses the clinical performance of MoM THAs according to femoral head size with literature review of the history and tribological characteristics of MoM bearings, wear and corrosion, metal ion levels, and ARMD. © Springer Nature Switzerland AG 2021.