title: Low reproducibility of the intra-operative measurement of the transepicondylar axis during total knee replacement.
abstract: BACKGROUND
  The transepicondylar axis is often used for positioning of the femoral component in knee replacement.
  
  
  METHODS
  We studied the reproducibility of the intra-operative palpation of the transepicondylar axis for rotational alignment of the femoral component in 20 total knee replacement (TKR) implantations with a non-image-based navigation system. 2 surgeons defined the transepicondylar axis 3 times each without changing the reference plane.
  
  
  RESULTS
  The angle between the reference plane and the transepicondylar axis was measured by the navigation system. The mean intra-observer ranges of variation were 5 degrees and 6 degrees for both surgeons, with a maximum of 15 degrees. The mean inter-observer range of variation was 9 degrees, with a maximum of 15 degrees. Variations occurred in either internal or external rotation. Intra-observer agreement was considered good for one surgeon and poor for the other. There was no agreement between the two observers.
  
  
  CONCLUSIONS
  To define the rotational alignment of the femoral component of a TKR according to the intra-operative palpation of the transepicondylar axis may not be as reproducible as expected. However, the exact effect of this variability on the outcome after TKR should be studied.
authors.affiliation: Centre de Traumatologie et d'Orthopédie, 10 avenue Baumann, FR-67400 Illkirch, France. jean-yves.jenny@evc.net
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Jenny
authors.forename: Cyril
authors.initials: C
authors.lastname: Boeri
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000033:anatomy & histology*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D020370:Osteoarthritis, Knee / Q000601:surgery*; D010173:Palpation / Q000379:methods*; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted