title: Medial Calcar Erosion Is Associated With Synovial Thickness in Patients With ASR XL Total Hip Arthroplasty.
abstract: Medial calcar erosion is considered a late finding in patients with severe adverse local tissue reactions (ALTRs) after total hip arthroplasty (THA) with dual modular neck stems. Although calcar erosion has been associated with dual modular neck stems, one would expect similar findings in standard stems owing to analogous corrosion at the taper junction. The aim of this study was to evaluate whether medial calcar erosion is also associated with ALTR in patients with standard stems in metal-on-metal (MoM) THA.
  
  
  
  A total of 96 patients (108 hips) with MoM THA had radiographs and a magnetic resonance imaging of the hip performed at a mean time of 5.7 years after surgery. Calcar erosion was assessed from radiographs. ALTR Anderson grade, diameter, volume, and synovial thickness were assessed from magnetic resonance imaging.
  
  
  
  Calcar erosion was present in 54 hips (50%) and was associated with ALTR synovial thickness but not with Anderson grade, diameter, or volume. Most of the hips with calcar erosion (n = 45) had an ALTR (positive predictive value 0.83, 95% confidence interval 0.70-0.92). The relative risk of having a synovial thickness > 3 mm increased by a factor of 3.0 (95% confidence interval 1.3-6.5) if calcar erosion was observed.
  
  
  
  Subtle erosions of the medial calcar after MoM THA may be an early indicator of an adverse reaction to wear particles warranting cross-sectional imaging. Synovial thickness may also be more relevant than absolute size in the classification of ALTR severity and collateral tissue damage.
authors.affiliation: Harris Orthopaedic Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, Massachusetts; Department of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts.
authors.forename: Rami
authors.initials: R
authors.lastname: Madanat
authors.affiliation: Harris Orthopaedic Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, Massachusetts; Department of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts.
authors.forename: Ola
authors.initials: O
authors.lastname: Rolfson
authors.affiliation: Harris Orthopaedic Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Gabrielle S
authors.initials: GS
authors.lastname: Donahue
authors.affiliation: Harris Orthopaedic Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, Massachusetts.
authors.forename: Daniel K
authors.initials: DK
authors.lastname: Hussey
authors.affiliation: Department of Radiology and Imaging, Hospital for Special Surgery, New York, New York.
authors.forename: Hollis G
authors.initials: HG
authors.lastname: Potter
authors.affiliation: Department of Orthopaedic Surgery, Sportsmed.SA, Stepney, South Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Wallace
authors.affiliation: Harris Orthopaedic Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, Massachusetts; Department of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts.
authors.forename: Orhun K
authors.initials: OK
authors.lastname: Muratoglu
authors.affiliation: Harris Orthopaedic Laboratory, Department of Orthopaedic Surgery, Massachusetts General Hospital, Boston, Massachusetts; Department of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts.
authors.forename: Henrik
authors.initials: H
authors.lastname: Malchau
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D003343:Corrosion; D005260:Female; D005549:Foreign-Body Reaction / Q000209:etiology; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008670:Metals; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging* / Q000209:etiology; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D012086:Reoperation; D012307:Risk Factors; D013583:Synovial Membrane / Q000000981:diagnostic imaging*
chemical_list: D008670:Metals
keywords: adverse local tissue reaction; calcar erosion; hip arthroplasty; metal-on-metal; synovial thickness