Risk factors for mid-term revision surgery in patients with articular surface replacement total hip arthroplasty.

INTRODUCTION: This study assessed the associations between gender and implant survival, as well as adverse local tissue reaction (ALTR), in patients with articular surface replacement (ASR) XL total hip arthroplasty (THA). Secondly, we sought to report the differences between genders in metal ion levels and patient reported outcome measures (PROMs) in these patients.

METHODS: 563 unilateral ASR XL THA patients were enrolled in a multicentre follow-up study at a mean of 6.4 years after index surgery. All patients had blood metal ion levels and PROMs obtained annually, and a valid anteroposterior pelvis radiograph. A sub-set of patients from a single centre had annual MRI performed and were analysed for the presence of moderate-to-severe ALTR.

RESULTS: 60 hips (11%) were revised during the study period. The only variables found to be associated with revision surgery in patients with unilateral THA were VAS pain (hazard ratio [HR], 1.35; p<0.001) and elevated cobalt metal ion levels (HR, 1.05; p<0.001). No variables assessed were found to be associated with prevalence of ALTR. Chromium concentrations were greater in female patients than males, while cobalt levels were similar between genders. Males reported higher HHS, EQ-5D and UCLA scores than females.

CONCLUSIONS: Both males and females with metal-on-metal THA implants should be followed with equal vigilance as gender does not appear to be associated with poor outcomes, such as revision surgery and presence of ALTR.