Stem Migration and Fretting Corrosion of the Antirotation Pin in the K2/Apex Hip System

95 patients undergoing hip surgery were randomized to undergo the surgery using either a K2 stem or an Apex System stem. This study was terminated early due to the withdrawal of the stems from the market. This study provided a comparison of clinical outcomes, bone mineral density, stem stability (RSA), and additionally documented factors that may have contributed to the need for revision surgery. The findings of this study demonstrated that clinical outcomes improved significantly from baseline in both groups and that Oxford Hip Scores, Harris Hip scores, and bone density changes were comparable between groups. While subsidence and retroversion were similar between groups, potentially concerning subsidence and retroversion were identified in both groups. Evidence suggestive of aseptic lymphocyte-dominated vasculitis-associated lesions was observed in revision cases, and fretting corrosion of the antirotation pin and trunnion were noted as well.