Diagnosis of adverse local tissue reactions following metal-on-metal hip arthroplasty.

Metal-on-metal (MOM) bearing surfaces in hip arthroplasty have distinct advantages that led to the increase in popularity in North America in the early 2000s. However, with their increased use, concerns such as local cytotoxicity and hypersensitivity reactions leading to soft tissue damage and cystic mass formation (known collectively as adverse local tissue reactions (ALTR)) became apparent. The clinical presentation of ALTR is highly variable. The diagnosis of ALTR in MOM articulations in hip arthroplasty can be challenging and a combination of clinical presentation, physical examination, implant track record, component positioning, serum metal ion levels, cross-sectional imaging, histopathologic analysis, and consideration of alternative diagnoses are essential.