title: Conversion of a unicompartmental knee arthroplasty to a total knee arthroplasty: can we achieve a primary result?
abstract: OBJECTIVE
  Unicompartmental knee arthroplasty (UKA) is a potential treatment for isolated bone on bone osteoarthritis when limited to a single compartment. The risk for revision of UKA is three times higher than for total knee arthroplasty (TKA). The aim of this review was to discuss the different revision options after UKA failure.
  
  
  METHODS
  A search was performed for English language articles published between 2006 and 2016. After reviewing titles and abstracts, 105 papers were selected for further analysis. Of these, 39 papers were deemed to contain clinically relevant data to be included in this review.
  
  
  RESULTS
  The most common reasons for failure are liner dislocation, aseptic loosening, disease progression of another compartment and unexplained pain. UKA can be revised to or with another UKA if the failure mode allows reconstruction of the joint with UKA components. In case of disease progression another UKA can be added, either at the patellofemoral joint or at the remaining tibiofemoral joint. Often the accompanying damage to the knee joint doesn't allow these two former techniques resulting in a primary TKA. In a third of cases, revision TKA components are necessary. This is usually on the tibial side where augments and stems might be required.
  
  
  CONCLUSIONS
  In case of failure of UKA, several less invasive revision techniques remain available to obtain primary results. Revision in a late stage of failure or because of surgical mistakes might ask for the use of revision components limiting the clinical outcome for the patients. Cite this article: Bone Joint J 2017;99-B(1 Supple A):65-9.
authors.affiliation: University Hospital Saint Luc-UCL, Department of Orthopaedic surgery, Av. Hippocrate 10, 1200 Brussels, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Thienpont
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D006801:Humans; D007720:Knee Prosthesis; D020370:Osteoarthritis, Knee / Q000601:surgery; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation / Q000379:methods*
keywords: Failure; Revision; Total knee arthroplasty; Unicompartmental knee arthroplasty