title: Metal-on-metal total hip arthroplasty: do symptoms correlate with MR imaging findings?
abstract: OBJECTIVE
  To determine the prevalence of magnetic resonance (MR) imaging abnormalities after metal-on-metal total hip arthroplasty and to determine whether presence of symptoms correlates with findings at MR imaging.
  
  
  METHODS
  This HIPAA-compliant study was approved by the institutional review board, and informed consent was waived. MR imaging was performed with conventional sequences and a 1.5-T clinical imager in 192 hips (174 patients) evaluated during a 15-month period. Two observers retrospectively reviewed the images for the presence and size of pseudotumor, communication with the pseudocapsule, wall thickness, synovial hypertrophy, compartmentalization, solid components, foci of wall susceptibility, osteolysis, bone marrow edema, abductor muscle or tendon abnormality, and Anderson MR grade (normal, infection, or varying severity of metal-on-metal disease). These findings were compared between asymptomatic and symptomatic patients by using the Fisher exact test or the Wilcoxon-Mann-Whitney test, as appropriate.
  
  
  RESULTS
  Prevalence of pseudotumors per patient and per hip was 69% (120 of 174 patients, 132 of 192 hips). Bone marrow edema (present in six asymptomatic patients and 19 patients with pain, P < .01) and tendon tearing (present in five asymptomatic patients and 13 patients with pain, P < .05) were predictors of pain. Presence of symptoms was not correlated with presence (P = .4151) or size of pseudotumors. Anderson MR grade binarized into normal versus abnormal showed moderate agreement between readers (κ = 0.439) but was also not correlated with symptoms (P = .6648).
  
  
  CONCLUSIONS
  The presence of bone marrow edema and abductor tendon tears but not the presence or size of pseudotumor was associated with patient pain.
authors.affiliation: Department of Radiology, Veterans Affairs San Diego Healthcare System, 3350 La Jolla Village Dr, MC 114, San Diego, CA 92161, USA. ericchangmd@gmail.com
authors.forename: Eric Y
authors.initials: EY
authors.lastname: Chang
authors.forename: James L
authors.initials: JL
authors.lastname: McAnally
authors.forename: James R
authors.initials: JR
authors.lastname: Van Horne
authors.forename: Sheronda
authors.initials: S
authors.lastname: Statum
authors.forename: Tanya
authors.initials: T
authors.lastname: Wolfson
authors.forename: Anthony
authors.initials: A
authors.lastname: Gamst
authors.forename: Christine B
authors.initials: CB
authors.lastname: Chung
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D004185:Disability Evaluation; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008670:Metals; D008875:Middle Aged; D010149:Postoperative Pain / Q000175:diagnosis / Q000453:epidemiology; D011183:Postoperative Complications / Q000175:diagnosis* / Q000453:epidemiology; D015995:Prevalence; D011475:Prosthesis Failure; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
chemical_list: D008670:Metals