title: Normal values and variation of radiographic and CT infant lateral iliac wall angles in normal and dysplastic hips.
abstract: OBJECTIVE
  Indices from 3-D ultrasound may have a role in developmental dysplasia of the hip (DDH) assessment, but require a way to determine spatial orientation relative to body axes. The lateral iliac wall angle is a potentially suitable reference axis in 3-D ultrasound. We sought to quantify normal values and variations of the infant iliac wall angle on radiography, and compare with computed tomography (CT).
  
  
  METHODS
  Acetabular and lateral iliac angles were measured on frontal pelvic radiographs of 200 patients (400 hips, 183 with DDH) and coronal CT of 20 patients (40 hips) aged 0-12 months. Relationships among morphologic indices and demographics were assessed using linear regression, Welch's t-test, Pearson's correlation coefficient (r) and coefficients of variance (CoV). Reliability was assessed using intra-class correlation coefficients (ICC).
  
  
  RESULTS
  The radiographic iliac angle averaged 53.0° ± 7.7° (mean ± standard deviation; 95% CI, 38°-68°) in DDH vs. 56.2° ± 6.7° (95% CI, 43°-69°) in normal hips (p&lt;0.001), correlated weakly with age (r = 0.25), and showed no inter-sex differences (p = 0.79). Inter-reader and intra-reader reliability were ICC = 0.946 and 0.965. CT iliac angle had mean difference 5.8° ± 6.2° (p&lt;0.01), CoV = 10% and r = 0.68 vs. corresponding radiographs.
  
  
  CONCLUSIONS
  The radiographic infant lateral iliac wall angle has mean value 53-56° in dysplastic and normal hips with consistent range of variation approximately ±15°, was measured with high reliability, does not differ by sex, and is only slightly lower in the youngest infants. The iliac wall angle is an unbiased reference axis that may be suitable to establish general spatial orientation of 3-D hip ultrasound images.
authors: Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton - Canada.
authors: Vimarsha G
authors: VG
authors: Swami
authors: Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton - Canada.
authors: Lei
authors: L
authors: Liu
authors: Departmental of Biomedical Engineering, University of Alberta, Edmonton - Canada.
authors: Myles
authors: M
authors: Mabee
authors: Department of Radiology and Diagnostic Imaging, University of Alberta, Edmonton - Canada.|Departmental of Biomedical Engineering, University of Alberta, Edmonton - Canada.
authors: Jacob L
authors: JL
authors: Jaremko
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging; D016022:Case-Control Studies; D005260:Female; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging*; D006801:Humans; D007085:Ilium / Q000000981:diagnostic imaging*; D021621:Imaging, Three-Dimensional; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography