title: Predicting proximal femur rotation by morphological analyses using translucent 3-dimensional computed tomography.
abstract: BACKGROUND
  Predicting rotation of proximal femur in femur fracture surgeries is important to prevent malrotation.
  
  
  OBJECTIVE
  We aimed to prevent malrotation by developing a simple guideline that enables the prediction of proximal femur rotation using translucent 3-dimensional computed tomography (3D CT).
  
  
  METHODS
  Retrospective.
  
  
  METHODS
  One tertiary general hospital in the Republic of Korea.
  
  
  METHODS
  Thirty-six subjects who underwent CT angiographies for vascular evaluation.
  
  
  METHODS
  Translucent 3D CT images were created from the CT data.
  
  
  METHODS
  Morphologic ratios of the great trochanter (GT) and lesser trochanter (LT) with the hip center as a basic point were measured at neutral position and at 5°, 10°, 15°, 20°, 25°, and 30° of internal rotation (IR) and external rotation (ER). The rotation angles at which the GT ratio becomes 0.5 and 0.33 and the rotation angles at which the LT ratio becomes 0.0 and 1.0 were determined to serve as guide angles.
  
  
  RESULTS
  Both the proportion of GT and LT compared with proximal femur with hip center as a reference (GT and LT ratio) gradually increased in the shift from IR to ER. At a neutral position, the GT and LT ratios were approximately 0.4 and 0.5, respectively. At 10°-15° of ER, the approximate GT and LT ratios were 0.5 and 1.0, respectively. At 30° of ER, the GT ratio exceeded 0.6, and the LT ratio exceeded 1.0. Between 10° and 15° of IR, the GT ratio decreased to approximately 0.33 and the LT ratio decreased to 0.0, which indicated that the LT was invisible.
  
  
  CONCLUSIONS
  We suggested practical values which might be useful as a reference in the operating room practically and hope that our findings would be helpful to prevent malrotation while performing proximal femur or femur shaft surgeries.
authors.affiliation: Department of Orthopaedic Surgery, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, Korea.
authors.forename: Chang Dong
authors.initials: CD
authors.lastname: Han
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.forename: Kyu Hyun
authors.initials: KH
authors.lastname: Yang
authors.forename: Ick Hwan
authors.initials: IH
authors.lastname: Yang
authors.forename: Woo Suk
authors.initials: WS
authors.lastname: Lee
authors.forename: Yoo Jung
authors.initials: YJ
authors.lastname: Park
authors.forename: Kwan Kyu
authors.initials: KK
authors.lastname: Park
mesh_terms: D000368:Aged; D005260:Female; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006621:Hip Joint / Q000033:anatomy & histology* / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016059:Range of Motion, Articular; D012189:Retrospective Studies; D012399:Rotation; D014057:Tomography, X-Ray Computed / Q000379:methods*