Adverse soft-tissue reactions around non-metal-on-metal total hip arthroplasty - a systematic review of the literature.

UNLABELLED Adverse local soft-tissue reactions have been associated with severe osteolysis and implant failure in metal-on-metal total hip arthroplasty (THA). Such a causal relationship has not often been associated with non metal-on-metal bearing surfaces. The purpose of this study was to assess the literature for cases of adverse soft-tissue reactions in non-metal-on-metal bearings in order to determine if a consistent histological diagnosis existed and if it was bearing-specific. METHODS A systematic review was performed in Medline and Embase databases, utilizing keyword searches to target reports of soft tissue complications following THA. Strict exclusion criteria were applied to retrieved studies in order to ensure that analyzed papers involved non-metal-on-metal bearing surfaces, had a final histological diagnosis, and had no previous history of periprosthetic infection or neoplastic process. Presenting symptoms, diagnostic work-up, histological diagnosis, and operative treatment were recorded for all reports retained for analysis. RESULTS Twenty-seven reports representing 31 cases of adverse soft-tissue reactions for non-metal-on-metal THAs met the criteria for analysis. In the majority of cases, patients presented with painful, limited motion in the affected hip, and radiological evidence of severe osteolysis. Histological examination often revealed a cystic mass, denoted by a granulomatous reaction comprised of histiocytes and giant cells, but few plasma cells. Revision of loose components was the most common successful therapeutic strategy utilized. CONCLUSION The present analysis revealed that similar adverse soft-tissue reactions have been described for both metal-on-polyethylene and ceramic bearing surfaces. When encountering such reactions in patients, a comprehensive diagnostic workup, including computed tomography (CT) scanning, lesion biopsy, and revision planning to alternate bearing surfaces should be considered.