title: Periprosthetic pathology in 'at risk' ceramic-on-polyethylene total hip arthroplasty: a clinical study using MARS-MRI in 50 patients.
abstract: OBJECTIVE
  Recent studies of metal-on-metal (MoM) total hip arthroplasty (THA) using metal-artefact-reducing-sequence software for magnetic resonance Imaging (MARS-MRI) have revealed remarkable soft tissue pathology around the hip, usually referred to as pseudotumours. Case reports describe identical pathology in non-MoM THA, but descriptive overviews of MRI abnormalities in patients with non-MoM prosthesis are scarce.
  
  
  METHODS
  A clinical study in a cohort of 50 ceramic-on-polyethylene (CoP) THA selected for high risk of peri-prosthetic pathology including 2 subgroups: (i) 40 patients with a high polyethylene (PE) wear rate (&gt;0.2 mm per year) and 5-12 years follow-up; (ii) 10 patients with a 2 to 5 years follow-up and a documented history of persistent complaints. All patients were clinically evaluated, MARS-MRIs were completed and chrome and cobalt serum samples were taken.
  
  
  RESULTS
  17 scans were normal (34%). Periprosthetic fluid collections were seen as a bursae iliopsoas (n = 12, 24%), in the trochanter bursae (n = 4, 8%) and in the surgical tract (n = 9, 18%). 1 case demonstrated a cyst on MARS-MRI resembling a pseudotumour as seen with MoM THA (2%). Intraosseous acetabular cysts were seen in 12 cases (24%), intraosseous trochanteric cysts in 10 cases (20%).
  
  
  CONCLUSIONS
  Soft tissue abnormalities after non-MoM THA are common in selected patients and can be clearly visualised with MARS-MRI. Pseudotumours as seen on MARS-MRI do occur in non-MoM hip arthroplasty but with low prevalence.
authors.affiliation: Department of Orthopaedic Surgery, St. Anna Hospital, Geldrop - The Netherlands.
authors.forename: Dirk H
authors.initials: DH
authors.lastname: Das
authors.affiliation: Department of Orthopaedic Surgery, St. Anna Hospital, Geldrop - The Netherlands.
authors.forename: Walter
authors.initials: W
authors.lastname: van der Weegen
authors.affiliation: Department of Orthopaedic Surgery, St. Anna Hospital, Geldrop - The Netherlands.
authors.forename: Jorgen A
authors.initials: JA
authors.lastname: Wullems
authors.affiliation: Department of Radiology, St. Anna Hospital, Geldrop - The Netherlands.
authors.forename: Koen
authors.initials: K
authors.lastname: Brakel
authors.affiliation: Department of Orthopaedic Surgery, St. Anna Hospital, Geldrop - The Netherlands.
authors.forename: Thea
authors.initials: T
authors.lastname: Sijbesma
authors.affiliation: Department of Orthopaedic Surgery, Leiden University Medical Centre, Leiden - The Netherlands.
authors.forename: Rob G
authors.initials: RG
authors.lastname: Nelissen
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000379:methods; D002516:Ceramics; D003430:Cross-Sectional Studies; D005260:Female; D005500:Follow-Up Studies; D006104:Granuloma, Plasma Cell / Q000000981:diagnostic imaging / Q000473:pathology*; D006622:Hip Prosthesis; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D020959:Polyethylene; D011183:Postoperative Complications / Q000000981:diagnostic imaging / Q000473:pathology; D011474:Prosthesis Design / Q000009:adverse effects / Q000379:methods*; D011475:Prosthesis Failure; D012086:Reoperation / Q000379:methods; D018570:Risk Assessment; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D020959:Polyethylene