title: The utility of repeat ultrasound imaging in the follow-up of metal-on-metal hip arthroplasty patients.
abstract: BACKGROUND
  We assessed changes in metal-on-metal hip arthroplasties (MoMHAs) after repeat ultrasound examination.
  
  
  METHODS
  This retrospective, single-centre cohort study involved all patients undergoing two ultrasound examinations of the same MoMHA. Between 2010 and 2014, 96 ultrasound examinations were performed in 48 MoMHAs (mean time between scans = 1.1 years). A radiologist assigned each scan to one of four grades and measured volumes of any solid/cystic masses. Changes in grade and lesion volume between scans were analysed.
  
  
  RESULTS
  Change in grade between scans was significant (p=0.012); 27% (n=13) of MoMHAs increased in grade, 67% (n=32) had no grade change, and 6% (n=3) decreased in grade. The mean increase in lesion volume was 24.2cm(3) by the second scan, and was significant (p=0.023). Evidence of progression in findings was observed in 54% (26/48) of MoMHAs. Of patients with normal scans initially, 44% (8/18) developed abnormalities. No factors (including blood metal ion concentrations and cup position) were associated significantly with progression of ultrasound findings.
  
  
  CONCLUSIONS
  Repeat ultrasound in MoMHA patients demonstrated that findings frequently progress in the short-term. Therefore, regular surveillance of MoMHA patients is important, with ultrasound representing an effective investigation for identifying the development and progression of lesions.
authors.affiliation: The Royal Orthopaedic Hospital , Birmingham, UK.
authors.forename: G S
authors.initials: GS
authors.lastname: Matharu
authors.affiliation: The Royal Orthopaedic Hospital , Birmingham, UK.
authors.forename: S
authors.initials: S
authors.lastname: Janardhan
authors.affiliation: The Royal Orthopaedic Hospital , Birmingham, UK.
authors.forename: L
authors.initials: L
authors.lastname: Brash
authors.affiliation: The Royal Orthopaedic Hospital , Birmingham, UK.
authors.forename: P B
authors.initials: PB
authors.lastname: Pynsent
authors.affiliation: The Royal Orthopaedic Hospital , Birmingham, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Dunlop
authors.affiliation: The Royal Orthopaedic Hospital , Birmingham, UK.
authors.forename: S L J
authors.initials: SL
authors.lastname: James
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D019544:Equipment Failure Analysis / Q000379:methods*; D005260:Female; D006615:Hip / Q000000981:diagnostic imaging* / Q000601:surgery; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011475:Prosthesis Failure; D012189:Retrospective Studies; D014463:Ultrasonography
keywords: Adverse reaction to metal debris; follow-up; hip arthroplasty; metal-on-metal; ultrasound