title: Clinical, radiological, histological and retrieval findings of Activ-L and Mobidisc total disc replacements: a study of two patients.
abstract: BACKGROUND
  This study evaluates the short-term clinical outcome, radiological, histological and device retrieval findings of two patients with second generation lumbar total disc replacement (TDR).
  
  
  METHODS
  The first patient had a single level L4-L5 Activ-L TDR, the second patient a L4-L5 Mobidisc and L5-S1 Activ-L TDR. The TDRs were implanted elsewhere and had implantation times between 1.3 and 2.8 years.
  
  
  RESULTS
  Plain radiographs and CT-scanning showed slight subsidence of the Activ-L TDR in both patients and facet joint degeneration. The patients underwent revision surgery because of recurrent back and leg pain. After removal of the TDR and posterolateral fusion, the pain improved. Histological examination revealed large ultrahigh molecular weight polyethylene (UHMWPE) particles and giant cells in the retrieved tissue surrounding the Mobidisc. The particles in the tissue samples of the Activ-L TDR were smaller and contained in macrophages. Retrieval analysis of the UHMWPE cores revealed evidence of minor adhesive and abrasive wear with signs of impingement in both TDR designs.
  
  
  CONCLUSIONS
  Although wear was unrelated to the reason for revision, this study demonstrates the presence of UHMWPE particles and inflammatory cells in second generation TDR. Long-term follow-up after TDR is indicated for monitoring wear and implant status.
authors.affiliation: Department of Orthopaedic Surgery, Maastricht University Medical Center, P.O. Box 5800, 6202 AZ, Maastricht, The Netherlands.
authors.forename: Shennah
authors.initials: S
authors.lastname: Austen
authors.forename: Ilona M
authors.initials: IM
authors.lastname: Punt
authors.forename: Jack P M
authors.initials: JP
authors.lastname: Cleutjens
authors.forename: Paul C
authors.initials: PC
authors.lastname: Willems
authors.forename: Steven M
authors.initials: SM
authors.lastname: Kurtz
authors.forename: Daniel W
authors.initials: DW
authors.lastname: MacDonald
authors.forename: Lodewijk W
authors.initials: LW
authors.lastname: van Rhijn
authors.forename: André
authors.initials: A
authors.lastname: van Ooij
mesh_terms: D005260:Female; D006801:Humans; D007403:Intervertebral Disc / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D055959:Intervertebral Disc Degeneration / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D017116:Low Back Pain / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011859:Radiography; D013123:Spinal Fusion; D059145:Total Disc Replacement / Q000379:methods*; D016896:Treatment Outcome