Risk of Impingement and Third-body Abrasion With 28-mm Metal-on-metal Bearings

Background Concerns have been raised about the sequelae of metal-on-metal (MoM) bearings in total hip arthroplasty (THA). However, retrieval studies, which offer the best insight into the clinically relevant mechanisms of MoM wear, have followed predictable trends to date such as indicting cobalt-chromium (CoCr) metallurgy, cup design, high conformity between the head and cup, “steep cups,” “microseparation,” and “edge wear.”