title: Multiplanar CT assessment of femoral head displacement in slipped capital femoral epiphysis.
abstract: BACKGROUND
  With recent changing approaches to the management of slipped capital femoral epiphysis (SCFE), the accurate radiographic assessment of maximum extent of displacement is crucial for planning surgical treatment.
  
  
  OBJECTIVE
  To determine what plane best represents the maximum SCFE displacement as quantified by the head-neck angle difference (HNAD), whether HNAD can quantitatively differentiate the SCFE cohort from the normal cohort, based on CT, and how Southwick slip angle (SSA) compares to HNAD.
  
  
  METHODS
  We reviewed 19 children with SCFE (23 affected hips) with preoperative CT scans and 27 age- and sex-matched children undergoing abdominal CT for non-orthopedic problems. Head-neck angle (HNA), the angle between the femoral epiphysis and the neck axis, was measured in three planes on each hip and the HNAD (affected - unaffected hip) was determined. SSA was measured on radiographs.
  
  
  RESULTS
  The coronal HNAD (mean 8.7°) was less than both the axial-oblique (mean 30.7°) and sagittal (mean 37.4°) HNADs, which were also greater than the HNADs of the normal cohort. Grouping HNAD measurements by SSA severity classification did not consistently distinguish between SCFE severity levels.
  
  
  CONCLUSIONS
  Axial-oblique and sagittal planes best represent the maximum SCFE displacement while biplanar radiograph may underestimate the extent of the displacement, thereby potentially altering the management between in situ pinning and capital realignment.
authors.affiliation: Department of Orthopedics, Rady Children's Hospital and Health Center, San Diego, CA, USA.
authors.forename: Shafagh
authors.initials: S
authors.lastname: Monazzam
authors.forename: Jerry R
authors.initials: JR
authors.lastname: Dwek
authors.forename: Harish S
authors.initials: HS
authors.lastname: Hosalkar
mesh_terms: D000293:Adolescent; D000465:Algorithms; D059925:Anatomic Landmarks / Q000000981:diagnostic imaging*; D002648:Child; D005260:Female; D005270:Femur Head / Q000002:abnormalities* / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D056888:Patient Positioning / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D060048:Slipped Capital Femoral Epiphyses / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed / Q000379:methods*