title: Head-shaft angle measurement in children with cerebral palsy.
abstract: BACKGROUND
  It has been observed in children with cerebral palsy (CP) that the femoral head rests in a valgus position as compared to the proximal neck and/or shaft. The purpose of this study was to compare the head-shaft angle (HSA) as a measure of femoral head valgus in children with CP (group 1) with a subset of children with CP who have more significant hip subluxation (group 2, as demonstrated by the need for surgery to correct the deformity), with age-matched (group 3) and historical controls.
  
  
  METHODS
  There were a total of 39 patients (70 hips), 15 patients in group 1, 10 in group 2, and 14 in group 3. The HSA was measured as described by Southwick (Southwick WO. Osteotomy of the lesser trochanter for slipped capital femoral epiphysis. J Bone Joint Surg Am. 1967;49A:803-835). Interrater and intrarater reliabilities and the variation of these measures with rotation were assessed.
  
  
  RESULTS
  The mean HSA in group 1 was 160.8 degrees; group 2, 170.3 degrees; group 3, 152.5 degrees; and historical control, 146.7 degrees. The difference was statistically significant between groups 1 and 2 and between both CP groups and the control groups. Intrarater and interrater reliabilities were found to be low, and variation with rotation was found to be minimal.
  
  
  CONCLUSIONS
  This study demonstrates that HSA is greater in children with CP than in typically developing children and that this is more pronounced in children with CP who are at risk for eventual subluxation. Evaluation of the HSA may be prudent in children with CP.
authors.affiliation: Department of Orthopaedic Surgery & Rehabilitation, University of Wisconsin Hospitals and Clinics, Madison, WI, USA.
authors.forename: Abtin
authors.initials: A
authors.lastname: Foroohar
authors.forename: James J
authors.initials: JJ
authors.lastname: McCarthy
authors.forename: David
authors.initials: D
authors.lastname: Yucha
authors.forename: Sylvan
authors.initials: S
authors.lastname: Clarke
authors.forename: Jennifer
authors.initials: J
authors.lastname: Brey
mesh_terms: D002547:Cerebral Palsy / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002648:Child; D004839:Epiphyses, Slipped / Q000000981:diagnostic imaging / Q000209:etiology*; D005260:Female; D005270:Femur Head / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006617:Hip Dislocation / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D006801:Humans; D008297:Male; D015588:Observer Variation; D010027:Osteotomy / Q000379:methods; D011859:Radiography; D012189:Retrospective Studies; D012399:Rotation