title: [Endoprosthesis failure in the ankle joint : Histopathological diagnostics and classification].
abstract: BACKGROUND
  Endoprostheses of the ankle joint show higher revision rates of 3.29 revisions per 100 component years. The aims of this study were the application and modification of the consensus classification of the synovia-like interface membrane (SLIM) for periprosthetic failure of the ankle joint, the etiological clarification of periprosthetic pseudocysts and a detailed measurement of proliferative activity (Ki67) in the region of osteolysis.
  
  
  METHODS
  Tissue samples from 159 patients were examined according to the criteria of the standardized consensus classification. Of these, 117 cases were derived from periprosthetic membranes of the ankle. The control group included 42 tissue specimens from the hip and knee joints. Particle identification and characterization were carried out using the particle algorithm. An immunohistochemical examination with Ki67 proliferation was performed in all cases of ankle pseudocysts and 19 control cases.
  
  
  RESULTS
  The consensus classification of SLIM is transferrable to endoprosthetic failure of the ankle joint. Periprosthetic pseudocysts with the histopathological characteristics of the appropriate SLIM subtype were detectable in 39 cases of ankle joint endoprostheses (33.3%). The mean value of the Ki67 index was 14% and showed an increased proliferation rate in periprosthetic pseudocysts of the ankle (p-value 0.02037).
  
  
  CONCLUSIONS
  In periprosthetic pseudocysts an above average higher detection rate of type 1 SLIM induced by abrasion (51.3%) with an increased Ki67 proliferation fraction (p-value 0.02037) was found, which can be interpreted as local destructive intraosseus synovialitis. This can be the reason for formation of pseudocystic osteolysis caused by high mechanical stress in ankle endoprostheses. A simplified diagnostic classification scoring system of dysfunctional endoprostheses of the ankle is proposed for collation of periprosthetic pseudocysts, ossifications and the Ki67 proliferation fraction.
authors.affiliation: Zentrum für Histologie, Zytologie und molekulare Diagnostik, Max-Planck-Straße 5, 54296, Trier, Deutschland. s.mueller@patho-trier.de.
authors.forename: S
authors.initials: S
authors.lastname: Müller
authors.affiliation: Schön-Klinik München-Harlaching, München, Deutschland.
authors.forename: M
authors.initials: M
authors.lastname: Walther
authors.affiliation: Schön-Klinik München-Harlaching, München, Deutschland.
authors.forename: A
authors.initials: A
authors.lastname: Röser
authors.affiliation: Zentrum für Histologie, Zytologie und molekulare Diagnostik, Max-Planck-Straße 5, 54296, Trier, Deutschland.
authors.forename: V
authors.initials: V
authors.lastname: Krenn
mesh_terms: D000843:Ankle Joint / Q000473:pathology* / Q000601:surgery*; D058737:Arthroplasty, Replacement, Ankle / Q000009:adverse effects* / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010014:Osteolysis / Q000209:etiology* / Q000473:pathology*; D011475:Prosthesis Failure / Q000009:adverse effects*; D016896:Treatment Outcome
keywords: Ki67 proliferation; Periprosthetic pseudocysts; Prosthesis failure; Synovia-like interface membran; Total ankle replacement