title: Update on the etiology of revision TKA -- Evident trends in a retrospective survey of 1449 cases.
abstract: BACKGROUND
  A working and complete knowledge of the different causes of dysfunction and pain after TKA is essential for the ability to correctly determine the cause of failure and to address this problem specifically. The purpose of this study was to update the etiology of implant failure. New diagnosis and current trends should be displayed.
  
  
  METHODS
  All TKA revisions performed in our institution between 2001 and 2010 were reviewed retrospectively. Patient demographics and the precise indication for the surgery were documented. Descriptive statistical analyses and association analyses of both the diagnosis and patient demographics were performed.
  
  
  RESULTS
  Within our collective of 1449 revision TKA a total of 40 different pathologies leading to revision surgery were identified and categorized. Overall 68.5% of the revisions were categorized aseptic, 31.5% as septic implant failure. Some recently debated diagnoses like low-grade-infection showed a high increase in incidence whereas classic failure mechanisms like polyethylene wear showed a decrease over the time.
  
  
  CONCLUSIONS
  We believe that this study successfully updates the current knowledge of different failure mechanisms in revision TKA, which have to be considered on dysfunction or pain after surgery. We were able to evaluate the clinical relevance of each pathology and could shift from implant related problems like wear to more surgical problems like instability and or malalignment over the last years. With a higher alertness to chronic low-grade-infections the incidence of infection is even increasing.
  
  
  METHODS
  Level II, economic and decision analysis.
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 3, 30625 Hannover, Germany. Electronic address: tilman.calliess@ddh-gruppe.de.
authors.forename: Tilman
authors.initials: T
authors.lastname: Calliess
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 3, 30625 Hannover, Germany. Electronic address: max.ettinger@ddh-gruppe.de.
authors.forename: Max
authors.initials: M
authors.lastname: Ettinger
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 3, 30625 Hannover, Germany. Electronic address: natalie.huelsmann@gmx.de.
authors.forename: Natalie
authors.initials: N
authors.lastname: Hülsmann
authors.affiliation: Orthopädische Praxis und Gelenk-Klinik, Alte Bundesstrasse 58, 79194 Gundelfingen, Germany. Electronic address: svenostermeier@googlemail.com.
authors.forename: Sven
authors.initials: S
authors.lastname: Ostermeier
authors.affiliation: Department of Orthopaedic Surgery, Hannover Medical School, Anna-von-Borries-Str. 3, 30625 Hannover, Germany. Electronic address: henning.windhagen@ddh-gruppe.de.
authors.forename: Henning
authors.initials: H
authors.lastname: Windhagen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000453:epidemiology / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D011795:Surveys and Questionnaires; D013997:Time Factors
keywords: Failure mechanisms; Knee; Knee arthroplasty