title: Polyethylene wear debris and long-term clinical failure of the Charité disc prosthesis: a study of 4 patients.
abstract: METHODS
  A clinical case series of 4 patients undergoing anterior lumbar revision due to failure of total disc replacement surgery.
  
  
  OBJECTIVE
  To assess the clinical significance of polyethylene wear debris in salvage surgery after initial total disc replacement, the pattern and the mechanisms of polyethylene wear in the retrieved cores, and the extent of polyethylene debris in the periprosthetic tissues obtained from 4 patients.
  
  
  BACKGROUND
  Previous in vitro wear tests have demonstrated low wear rates for lumbar artificial discs, suggesting that implant wear may not be a clinically relevant issue with total disc replacement. However, only long-term clinical investigations with analysis of retrieved implants and periprosthetic tissue can ultimately establish the significance of polyethylene wear debris for total disc arthroplasty.
  
  
  METHODS
  Starting in 2004, we began routinely performing salvage procedures in patients with failed total disc replacements. We report on the short-term outcomes of 4 patients at our institution who were revised with a Charité prosthesis (DePuy Spine, Raynham, MA). Wear analysis of the retrieved prosthesis and histologic examination of the periprosthetic tissue were also performed.
  
  
  RESULTS
  All of the retrieved polyethylene cores showed evidence of wear, but the extent and severity varied among the 4 patients. Wear and fracture of the core were associated with osteolysis of the underlying sacrum in 1 patient. Histologic examination of the periprosthetic tissues confirmed the presence of wear debris lying in inflammatory fibrous tissue. In 3 of the 4 patients, implant wear was associated with an unfavorable biomechanical environment (e.g., subsidence, migration, undersizing, and adjacent fusion). The mechanisms of wear included adhesive/abrasive wear of the central domed region of the polyethylene core, as well as chronic rim impingement, resulting in rim fatigue and fracture.
  
  
  CONCLUSIONS
  This study demonstrates the clinical significance of polyethylene wear debris and the potential for osteolysis with total disc replacements. The authors recommend that patients undergoing lumbar disc arthroplasty receive long-term follow-up to monitor the wear and functional status of their implants.
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Maastricht, Maastricht, The Netherlands. avoo@sort.azm.nl
authors.forename: André
authors.initials: A
authors.lastname: van Ooij
authors.forename: Steven M
authors.initials: SM
authors.lastname: Kurtz
authors.forename: Filip
authors.initials: F
authors.lastname: Stessels
authors.forename: Huub
authors.initials: H
authors.lastname: Noten
authors.forename: Lodewijk
authors.initials: L
authors.lastname: van Rhijn
mesh_terms: D000328:Adult; D001178:Arthroplasty; D015299:Discitis / Q000000981:diagnostic imaging / Q000209:etiology; D017586:Diskectomy; D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D020959:Polyethylene; D019736:Prostheses and Implants / Q000009:adverse effects; D011475:Prosthesis Failure; D012086:Reoperation; D014057:Tomography, X-Ray Computed; D017211:Treatment Failure; D016896:Treatment Outcome
chemical_list: D020959:Polyethylene