title: Ultrasound findings in asymptomatic patients with modular metal on metal total hip arthroplasty.
abstract: OBJECTIVE
  The use of metal-on-metal and modular total hip arthroplasty is associated with potentially serious local and systemic complications. The primary aim of this study was to identify the prevalence of a pseudotumor in asymptomatic patients with a particular metal-on-metal hip prosthesis after a minimum follow-up of 5 years using ultrasound evaluation. A secondary purpose was to identify associations between the presence of pseudotumor and serum metal ion levels following implantation.
  
  
  METHODS
  We prospectively evaluated data collected from 36 asymptomatic patients who underwent implantation of a Profemur Z metal-on-metal total hip arthroplasty from January 2004 to January 2010. Serum metal ion levels were collected in 2012 and 2015. Hip ultrasounds were performed in 2015.
  
  
  RESULTS
  Pseudotumors were found in 7/36 patients (19.4%). The average pseudotumor size measured 38.2 cm3(range 7.35 cm3-130.81 cm3). Elevated metal ion levels were found in all patients at all time points. No statistical correlation was found between the presence of pseudotumor and patient age, age of the implant, component design, and any of the serum metal ion levels or ratios.
  
  
  CONCLUSIONS
  One in every five asymptomatic patients with metal-on-metal implants was found to have a periarticular pseudotumor. There was no dose-dependent relationship found between elevated serum metal ion levels and the development of a pseudotumor. Our findings suggest that in patients with known elevated metal ion levels, continued monitoring of ion levels may not be a reliable predictor of pseudotumor formation, and ultrasound surveillance can and should be routinely used to document the presence and progression of pseudotumor.
authors.affiliation: Department of Orthopaedic Surgery, Henry Ford Hospital, 2799 West Grand Boulevard, CFP-6, Detroit, MI, 48202, USA. nick@gafrisch.com.
authors.forename: Nicholas B
authors.initials: NB
authors.lastname: Frisch
authors.affiliation: Department of Orthopaedic Surgery, Henry Ford Hospital, 2799 West Grand Boulevard, CFP-6, Detroit, MI, 48202, USA.
authors.forename: Nolan M
authors.initials: NM
authors.lastname: Wessell
authors.affiliation: Department of Orthopaedic Surgery, Henry Ford Hospital, 2799 West Grand Boulevard, CFP-6, Detroit, MI, 48202, USA.
authors.forename: Kevin
authors.initials: K
authors.lastname: Taliaferro
authors.affiliation: Department of Radiology, Henry Ford Hospital, 2799 W. Grand Blvd, Detroit, MI, 48202, USA.
authors.forename: Marnix
authors.initials: M
authors.lastname: Van Holsbeeck
authors.affiliation: Department of Orthopaedic Surgery, Henry Ford Hospital, 2799 West Grand Boulevard, CFP-6, Detroit, MI, 48202, USA.
authors.forename: Craig D
authors.initials: CD
authors.lastname: Silverton
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006104:Granuloma, Plasma Cell / Q000097:blood / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000601:surgery; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008670:Metals / Q000097:blood*; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D014463:Ultrasonography / Q000379:methods*
chemical_list: D008670:Metals
keywords: Metal-on-metal; Profemur Z; Pseudotumor; Total hip arthroplasty; Ultrasound