title: Conversion from knee arthrodesis to arthroplasty: systematic review.
abstract: Arthrodesis (AD) of the knee reduces pain and provides stability, but has severe functional and social limitations. There has been ample discussion on the value of a conversion of an AD to a total knee arthroplasty (TKA). The aim of this study was to perform a review and meta-analysis of the current literature on conversion of an AD to TKA and assess clinical outcome, complication rate, surgical technique and overall patient-related outcome measures.
  
  
  
  PubMed, Embase, Web of Science, Cochrane, CENTRAL, CINAHL, Academic Search Premier, ScienceDirect and searching by hand for papers on conversion of AD of the knee to TKA. Two reviewers independently reviewed all titles and abstracts, and extracted the available data. Study eligibility criteria were: conversion of knee AD to TKA, five cases or more and non-oncology patients. Data consisted of study characteristics, patient demographics, clinical outcome and complications. Additionally, details on surgical technique were reviewed.
  
  
  
  Of the 866 unique references identified, six papers were included for further analyses, comprising a total of 123 knees with conversion of AD of the knee to TKA. Mean gain of knee flexion was 80 degrees and the mean HSS score improved with 20 points. A complicated postoperative course was found in 65 % of all cases. The most frequent complication was skin necrosis (25 %), followed by arthrofibrosis (13 %), infection (11 %) and revision (11 %). Major complications such as refusion, amputation and death occurred in less than 5 % of all cases.
  
  
  
  The majority of the papers consisted of small case series of moderate methodological quality, resulting in 123 included knees. Further series are necessary to draw definitive conclusions.
  
  
  
  This is the first systematic review and meta-analysis on conversion of a knee arthrodesis to TKA. Good clinical results can be expected after conversion, albeit at a high risk of postoperative complications.
authors.affiliation: Department of Orthopaedic Surgery, Leiden University Medical Centre, Albinusdreef 2, PO Box 9600, 2300 RC, Leiden, Netherlands. wakernkamp@gmail.com.
authors.forename: Willem Alexander
authors.initials: WA
authors.lastname: Kernkamp
authors.affiliation: Department of Orthopaedic Surgery, Leiden University Medical Centre, Albinusdreef 2, PO Box 9600, 2300 RC, Leiden, Netherlands.
authors.forename: Wiebe Christiaan
authors.initials: WC
authors.lastname: Verra
authors.affiliation: Department of Orthopaedic Surgery, Leiden University Medical Centre, Albinusdreef 2, PO Box 9600, 2300 RC, Leiden, Netherlands.
authors.forename: Bart Godefridus
authors.initials: BG
authors.lastname: Pijls
authors.affiliation: Walaeus Library, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Jan Wilhelmus
authors.initials: JW
authors.lastname: Schoones
authors.affiliation: Department of Orthopaedic Surgery, Leiden University Medical Centre, Albinusdreef 2, PO Box 9600, 2300 RC, Leiden, Netherlands.
authors.forename: Henrica Maria Jannetta
authors.initials: HM
authors.lastname: van der Linden
authors.affiliation: Department of Orthopaedic Surgery, Leiden University Medical Centre, Albinusdreef 2, PO Box 9600, 2300 RC, Leiden, Netherlands.
authors.forename: Rob Gerardus Henricus Hubertus
authors.initials: RG
authors.lastname: Nelissen
mesh_terms: D001174:Arthrodesis; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D006801:Humans; D007592:Joint Diseases / Q000601:surgery*; D007719:Knee Joint / Q000601:surgery*; D020127:Recovery of Function; D012086:Reoperation
keywords: Arthrodesis; Clinical outcome; Joint fusion; Systematic review; Total knee arthroplasty