Minimum 10-year follow-up of micro-arc oxidation coating on a cementless grit-blasted tapered-wedge stem of total hip arthroplasty: a multicentre study

Background: Recently, a femoral stem treated with grit-blasting and micro-arc oxidation (MAO) coating has commercialised but medium-term follow-up studies are lacking. The aim of this study was to report the outcome of a grit-blasted and MAO-coated femoral component designed as a straight, double-wedged, tapered stem with a rectangular cross-section with minimum 10 years follow-up. Methods: Between March 2006 and December 2008, 309 primary total hip arthroplasties using a grit-blasted and MAO-coated femoral component were performed by 3 experienced hip surgeons in 3 hospitals. At minimum 10 years after index THA, 299 hips were living, 10 hips were deceased, and 65 hips were lost to follow-up or had a follow-up period <10 years. Finally, 234 hips were enrolled in this study. Results: Mean duration of clinical follow-up was 129.6 months. The mean Harris Hip Score was improved from 46.9 to 88.4 at the final follow-up. 4 hips were revised for 2 aseptic femoral loosening, 1 aseptic acetabular cup loosening and 1 late infection. 3 hips were revised for a periprosthetic femoral fracture requiring a femoral component revision. The average time to revision was 51.6 (range 0-148) months. Kaplan-Meier survivorship analysis with an end point of revision for any reason demonstrated a survival rate of 97.4% at 10 years. Survival was 98.7% with revision for aseptic loosening as the endpoint. Conclusions: The outcomes of a cementless grit-blasted and MAO-coated tapered-wedge stem of THA were excellent to satisfactory after a follow-up of at least 10 years.