title: Gadolinium-enhanced MR imaging of pediatric patients after reduction of dysplastic hips: assessment of femoral head position, factors impeding reduction, and femoral head ischemia.
abstract: OBJECTIVE
  We describe gadolinium-enhanced MR imaging of position and vascular enhancement of the femoral head in pediatric patients who have undergone reduction of hip dislocation.
  
  
  METHODS
  Within 24 hr of hip reduction and spica casting, we performed 25 gadolinium-enhanced MR studies in 18 infants and young children (15 girls, three boys) with 23 dysplastic hips. All but two patients underwent closed reductions. We evaluated intraoperative arthrograms for obstacles to reduction and subsequent radiographs for avascular necrosis.
  
  
  RESULTS
  MR images showed that all femoral heads were in their respective acetabula, but several structures interfered with concentric reduction. Obstacles to reduction included a pulvinar (n = 16), infolding of the capsule (n = 9), interposition of the labrum (n = 2), and a hypertrophied ligamentum teres and transverse ligament (n = 2). All 50 femoral heads showed enhancement: 35 normally, 10 homogeneously but less than on the contralateral femoral head or the ipsilateral greater trochanter, and five with areas of focally decreased enhancement. Hips that showed decreased enhancement had undergone greater degrees of abduction (r = .38, p < .01).
  
  
  CONCLUSIONS
  Gadolinium-enhanced MR imaging can reveal abnormalities of hip position and proximal femoral epiphyseal and physeal vascularity that can occur after hip reduction. Abnormalities of enhancement were more frequent in patients who had greater femoral abduction. The effect of decreased epiphyseal vascular enhancement is still uncertain.
authors.affiliation: Department of Radiology, Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
authors.forename: D
authors.initials: D
authors.lastname: Jaramillo
authors.forename: O
authors.initials: O
authors.lastname: Villegas-Medina
authors.forename: T
authors.initials: T
authors.lastname: Laor
authors.forename: F
authors.initials: F
authors.lastname: Shapiro
authors.forename: M B
authors.initials: MB
authors.lastname: Millis
mesh_terms: D001175:Arthrography; D005260:Female; D005270:Femur Head / Q000033:anatomy & histology*; D005271:Femur Head Necrosis / Q000175:diagnosis*; D005500:Follow-Up Studies; D005682:Gadolinium; D006618:Hip Dislocation, Congenital / Q000175:diagnosis* / Q000601:surgery*; D006801:Humans; D007089:Image Enhancement; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D016343:Monitoring, Intraoperative; D011183:Postoperative Complications / Q000175:diagnosis
chemical_list: D005682:Gadolinium