Imaging of Metal-on-Metal Hip Prostheses

Abstract

AJR:197, September 2011 metal THA and resurfacing failure are small acetabular or femoral head size, implant malposition, female sex, metal ion–mediated adverse inflammatory reactions, implant loosening, femoral neck fractures, and others [1]. In the Australian registry, loosening (presumably acetabular) is the most common cause of resurfacing and metal-on-metal THA failure [3]. Clinically, pain is the most common symptom of metal-on-metal THA and resurfacing failure. Adverse inflammatory reactions accompanying metal-on-metal hip prostheses are well documented. The biologic cascade leading to adverse inflammatory reactions as a result of metal-on-metal bearing metallic debris has not been completely elucidated. Adverse inflammatory reactions can present as microscopic foci of asymptomatic aseptic lymphocyte-dominated vasculitic lesions found at the time of metal-on-metal hip revision, asymptomatic or symptomatic cystic structures (i.e., pseudotumor) found on imaging of metal-on-metal hip prostheses, or aggressive cystic lesions causing bone and soft-tissue destruction around metal-on-metal hip prostheses [1]. The exact incidence of clinically significant adverse inflammatory reactions secondary to metal-on-metal hip prostheses has been reported to be as low as 0.1% [5] and as high as 4% [6].