title: Comparison of alternate references for femoral rotation in female patients undergoing total knee arthroplasty.
abstract: OBJECTIVE
  Accurate rotational alignment of the femoral component is of vital importance for successful total knee arthroplasty (TKA). Two anatomical references located on the anterior femur were recently introduced. To determine which is more reliable reference axis for the femoral component rotation in female patients receiving TKA, the trochlear anterior line was compared with the femoral anterior tangent line.
  
  
  METHODS
  Preoperative computed tomography in 76 patients receiving TKA for varus deformity was performed, and the images were reconstructed into three-dimensional models. The trochlear anterior line was defined as the line connecting the most anterior portion of the lateral and medial femoral condyles and the femoral anterior tangent line as the line parallel to distal anterior femoral surface. The two angles between these reference axes and the surgical transepicondylar axis (TEA) in three-dimensional images (trochlear anterior line/TEA, femoral anterior tangent line/TEA) were measured. The correlation between these two angles was computed. We investigated to see whether a significant difference in variance existed.
  
  
  RESULTS
  The trochlear anterior line was internally rotated by 6.1° ± 2.5° with respect to TEA, whereas the femoral anterior tangent line by 9.5° ± 3.8°. The trochlear anterior line was externally rotated by 3.4° ± 3.3° with respect to the femoral anterior tangent line. There was a significant correlation between the trochlear anterior line/TEA and the femoral anterior tangent line/TEA.
  
  
  CONCLUSIONS
  The variance of the trochlear anterior line/TEA was significantly smaller than that of the femoral anterior tangent line/TEA demonstrating a more consistent distribution. When conventional reference axes such as the posterior condylar axis or the anteroposterior axis are unclear or differ, surgeons can rely on these alternative references. When trochlear anterior line and femoral anterior tangent line contradicts, the former might be more reliable for the rotational alignment of the femoral component in female patients.
  
  
  METHODS
  Case series with no comparison group, Level IV.
authors.affiliation: Department of Orthopaedic Surgery, Ajou University of College of Medicine, 164, World Cup-ro, Yeongtong-gu, Suwon, 443-721, South Korea.
authors.forename: Hyung-Min
authors.initials: HM
authors.lastname: Ji
authors.affiliation: Department of Orthopaedic Surgery, Ajou University of College of Medicine, 164, World Cup-ro, Yeongtong-gu, Suwon, 443-721, South Korea.
authors.forename: Dong San
authors.initials: DS
authors.lastname: Jin
authors.affiliation: Department of Orthopaedic Surgery, Ajou University of College of Medicine, 164, World Cup-ro, Yeongtong-gu, Suwon, 443-721, South Korea.
authors.forename: Jun
authors.initials: J
authors.lastname: Han
authors.affiliation: Department of Orthopaedic Surgery, Ajou University of College of Medicine, 164, World Cup-ro, Yeongtong-gu, Suwon, 443-721, South Korea.
authors.forename: Ho-Sik
authors.initials: HS
authors.lastname: Choo
authors.affiliation: Department of Orthopaedic Surgery, Ajou University of College of Medicine, 164, World Cup-ro, Yeongtong-gu, Suwon, 443-721, South Korea. thrtkr@ajou.ac.kr.
authors.forename: Ye-Yeon
authors.initials: YY
authors.lastname: Won
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D017760:Bone Malalignment; D004838:Epiphyses / Q000601:surgery; D005260:Female; D005269:Femur / Q000502:physiology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D007719:Knee Joint / Q000601:surgery; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D012399:Rotation; D014057:Tomography, X-Ray Computed
keywords: Female; Femur; Humans; Knee joint; Knee replacement arthroplasty; Three-dimensional imaging; X-ray computed tomography