Adverse local tissue reaction associated with a modular hip hemiarthroplasty

Background: The local and systemic effects of wear debris and corrosion products remain a concern in arthroplasty and reaction to corrosion or wear products from modular junctions has been reported in primary and revision total joint arthroplasties. These effects have not been reported previously for unipolar hemiarthroplasties where there is no prosthetic bearing surface to contribute to the phenomenon. This may have implications for clinical surveillance and implant design. Case Description: We report the case of a 72-year-old man who had symptomatic pseudotumor formation, confirmed by pathologic examination of the excised pseudotumor, with a large-head modular hip hemiarthroplasty. Metallosis and corrosion of the modular head/neck taper junction were noted at the time of revision surgery. Literature Review: To our knowledge, this is the first report of pseudotumor formation where the corrosion or wear products arose from the modular junction of the implant with no bearing couple present to contribute wear debris that may influence the formation of the pseudotumor. Purposes and Clinical Relevance: Adverse tissue reactions to wear debris generated at prosthetic articulating surfaces and corrosion and wear products from nonarticulating prosthetic junctions have been reported. The problem has been reported to be higher in metal-on-metal bearing couples and in large-diameter hip arthroplasties. Mixed-alloy junctions appear to be more susceptible to corrosion. We believe that corrosion should be considered a possible diagnostic entity when investigating persistent symptoms after hemiarthroplasty and may be avoided with the use of monoblock components.