title: The Prevalence of Positive Findings on Metal Artifact Reduction Sequence Magnetic Resonance Imaging in Metal-on-Metal Total Hip Arthroplasty.
abstract: We sought to assess the prevalence of soft tissue changes seen on magnetic resonance imaging (MRI) after metal-on-metal (MOM) total hip arthroplasty (THA) and determine if the presence of pseudotumors was associated with metal ion levels, acetabular cup position, outcomes scores, and femoral head size.
  
  
  
  After receiving an institutional review board exemption for secondary data analysis, we performed a cross-sectional study identifying 55 patients (55 hips) that underwent primary THA with a MOM articulation and had subsequent MRI imaging between February 2013 and February 2014 at a single academic medical center.
  
  
  
  Twenty-four patients (44%) had no evidence of pseudotumors, 27 (49%) had type I pseudotumors, and 4 (7%) were classified as having type II pseudotumors. The presence and severity of pseudotumors were associated with higher serum chromium levels (P = .043). Neither acetabular inclination nor acetabular version was associated with the presence of pseudotumors, the severity of pseudotumors, or elevated serum metal ion levels (all P > .05). Increased metal ion levels were associated with lower Harris Hip Score and higher Harris Hip Score pain subscores (all P < .05).
  
  
  
  In conclusion, pseudotumors on metal artifact reduction sequencing MRI may be present in both symptomatic and asymptomatic MOM THAs. Surgeons should therefore exercise caution in placing too much emphasis on isolated studies such as cross-sectional imaging. Instead, a structured approach to evaluation of MOM arthroplasty should be followed.
authors.affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, Utah.
authors.forename: Kevin
authors.initials: K
authors.lastname: Lindgren
authors.affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, Utah.
authors.forename: Mike B
authors.initials: MB
authors.lastname: Anderson
authors.affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, Utah.
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Peters
authors.affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, Utah.
authors.forename: Christopher E
authors.initials: CE
authors.lastname: Pelt
authors.affiliation: Department of Orthopaedics, University of Utah, Salt Lake City, Utah.
authors.forename: Jeremy M
authors.initials: JM
authors.lastname: Gililland
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods; D016477:Artifacts; D003430:Cross-Sectional Studies; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging; D006622:Hip Prosthesis; D006801:Humans; D007249:Inflammation / Q000097:blood / Q000000981:diagnostic imaging* / Q000209:etiology; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D061825:Metal-on-Metal Joint Prostheses; D008670:Metals / Q000097:blood; D008875:Middle Aged; D009929:Organ Size; D015995:Prevalence; D011474:Prosthesis Design; D012042:Registries; D016896:Treatment Outcome
chemical_list: D008670:Metals
keywords: MARS MRI; metal on metal; pseudotumors; total hip arthroplasty