title: Coronal alignment is a predictor of the rotational geometry of the distal femur in the osteo-arthritic knee.
abstract: OBJECTIVE
  There is a lot of inter-individual variation in the rotational anatomy of the distal femur. This study was set up to define the rotational anatomy of the distal femur in the osteo-arthritic knee and to investigate its relationship with the overall coronal alignment and gender.
  
  
  METHODS
  CT-scans of 231 patients with end-stage knee osteo-arthritis prior to TKA surgery were obtained. This represents the biggest series published on rational geometry of the distal femur in literature so far.
  
  
  RESULTS
  The posterior condylar line (PCL) was on average 1.6° (SD 1.9) internally rotated relative to the surgical transepicondylar axis (sTEA). The perpendicular to trochlear anteroposterior axis (⊥TRAx) was on average 4.8° (SD 3.3°) externally rotated relative to the sTEA. The relationship between the PCL and the sTEA was statistically different in the different coronal alignment groups (p < 0.001): 1.0° (SD 1.8°) in varus knees, 2.1° (SD 1.8°) in neutral knees and 2.6° (SD 1.8°) in valgus knees. The same was true for the ⊥TRAx in these 3 groups (p < 0.02).There was a clear linear relationship between the overall coronal alignment and the rotational geometry of the distal femur. For every 1° in coronal alignment increment from varus to valgus, there is a 0.1° increment in posterior condylar angle (PCL vs sTEA).
  
  
  CONCLUSIONS
  The PCL was on average 1.6° internally rotated relative to the sTEA in the osteo-arthritic knee. The relationship between the PCL and the sTEA was statistically different in the different coronal alignment groups.
  
  
  METHODS
  III.
authors.affiliation: Department of Orthopaedic Surgery, University Hospital Leuven, Pellenberg, Belgium, luyckx.thomas@gmail.com.
authors.forename: T
authors.initials: T
authors.lastname: Luyckx
authors.forename: F
authors.initials: F
authors.lastname: Zambianchi
authors.forename: F
authors.initials: F
authors.lastname: Catani
authors.forename: J
authors.initials: J
authors.lastname: Bellemans
authors.forename: J
authors.initials: J
authors.lastname: Victor
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D060750:Bone Anteversion / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D060751:Bone Retroversion / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D020370:Osteoarthritis, Knee / Q000150:complications / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D012189:Retrospective Studies; D012399:Rotation; D012737:Sex Factors; D014057:Tomography, X-Ray Computed