title: "Asymptomatic" pseudotumors after metal-on-metal hip resurfacing arthroplasty: prevalence and metal ion study.
abstract: Symptomatic abnormal periprosthetic soft-tissue reactions ("pseudotumors") have been reported after metal-on-metal hip resurfacing arthroplasty (MoMHRA). The aims of this study were (1) to determine the prevalence of asymptomatic pseudotumors after MoMHRA and (2) to measure metal ion levels in these patients. A total of 201 hips in 158 patients were evaluated at a mean follow-up of 61 months (range, 36-88) using ultrasound/magnetic resonance imaging and serum/hip aspirate cobalt and chromium measurements. Pseudotumors found in 7 patients (4%) were associated with significantly higher cobalt and chromium levels and inferior functional scores. Elevated levels of cobalt and chromium ions suggest that pseudotumors are associated with increased wear generated from metal-on-metal articulations. Clinicians need to be aware of pseudotumors as a differential diagnosis during clinical evaluation of MoMHRA patients, and further imaging such as ultrasound or magnetic resonance imaging is recommended to confirm the diagnosis.
authors.affiliation: Department of Orthopaedic Surgery, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts 02116, USA.
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Kwon
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Ostlere
authors.forename: Peter
authors.initials: P
authors.lastname: McLardy-Smith
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Athanasou
authors.forename: Harinderjit S
authors.initials: HS
authors.lastname: Gill
authors.forename: David W
authors.initials: DW
authors.lastname: Murray
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002857:Chromium / Q000009:adverse effects / Q000097:blood; D003035:Cobalt / Q000009:adverse effects / Q000097:blood; D005260:Female; D006104:Granuloma, Plasma Cell / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008670:Metals / Q000009:adverse effects* / Q000097:blood; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery; D015995:Prevalence; D012189:Retrospective Studies; D017695:Soft Tissue Injuries / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D014463:Ultrasonography
chemical_list: D008670:Metals; D002857:Chromium; D003035:Cobalt