title: Measuring physiological and pathological femoral anteversion using a biplanar low-dose X-ray system: validity, reliability, and discriminative ability in cerebral palsy.
abstract: OBJECTIVE
  The aims of this study were to evaluate the concurrent validity and reliability of a low-dose biplanar X-ray system (Ld-BPR) for the measurement of femoral anteversion (FA) by comparing Ld-BPR-based three-dimensional measures with CT-scan-based measures and to assess the discriminative ability of this method in children with cerebral palsy.
  
  
  METHODS
  Fifty dry femora were scanned using both a CT scan and the Ld-BPR system. Ten femora were artificially modified to mimic a range of anteversion from -30° to +60° and scanned by both modalities. FA was quantified using the images from both modalities and statistically compared for concurrent validity. Intra- and inter-observer reliability of the Ld-BPR system was also determined. Further, Ld-BPR data from 16 hemiplegic and 22 diplegic children were analyzed for its discriminative ability.
  
  
  RESULTS
  The concurrent validity between the Ld-BPR and CT-scan measures was excellent (R (2) = 0.83-0.84) and no significant differences were found. The intra- and inter-trial reliability were excellent (ICCs = 0.98 and 0.97) with limits of agreement of (-2.28°; +2.65°) and (-2.76°; +3.38°) respectively. Further, no significant effects of angle or method were found in the sample of modified femora. Ld-BPR measures for FA were significantly different between healthy and impaired femora.
  
  
  CONCLUSIONS
  The excellent concurrent validity with the CT scan modality, the excellent reliability, and the ability to discriminate pathological conditions evaluated by this study make this radiological method suitable for a validated use across hospitals and research institutes.
authors.affiliation: Laboratoire de Traitement de l'Information Médicale, INSERM U1101, Batiment 1, Premier etage, CHRU Morvan - 2 Ave. Foch, Brest, France, 29609.|CHRU de Brest, Hôpital Morvan, Service de chirurgie pédiatrique, Brest, France.
authors.forename: Matthias
authors.initials: M
authors.lastname: Thépaut
authors.affiliation: Laboratoire de Traitement de l'Information Médicale, INSERM U1101, Batiment 1, Premier etage, CHRU Morvan - 2 Ave. Foch, Brest, France, 29609.|CHRU de Brest, Hôpital Morvan, Service de Médecine Physique et de Réadaptation, Brest, France.|Université de Bretagne Occidentale, Brest, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Brochard
authors.affiliation: Laboratoire de Traitement de l'Information Médicale, INSERM U1101, Batiment 1, Premier etage, CHRU Morvan - 2 Ave. Foch, Brest, France, 29609.
authors.forename: Julien
authors.initials: J
authors.lastname: Leboucher
authors.affiliation: Laboratoire de Traitement de l'Information Médicale, INSERM U1101, Batiment 1, Premier etage, CHRU Morvan - 2 Ave. Foch, Brest, France, 29609.|CHRU de Brest, Hôpital Morvan, Service de Médecine Physique et de Réadaptation, Brest, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Lempereur
authors.affiliation: Laboratoire de Traitement de l'Information Médicale, INSERM U1101, Batiment 1, Premier etage, CHRU Morvan - 2 Ave. Foch, Brest, France, 29609.|CHRU de Brest, La Cavale Blanche, Service d'Orthopédie-Traumatologie, Brest, France.|Université de Bretagne Occidentale, Brest, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Stindel
authors.affiliation: CHRU de Brest, Service de radiologie, Brest, France.
authors.forename: Valentin
authors.initials: V
authors.lastname: Tissot
authors.affiliation: Laboratoire de Traitement de l'Information Médicale, INSERM U1101, Batiment 1, Premier etage, CHRU Morvan - 2 Ave. Foch, Brest, France, 29609. bhushan.borotikar@telecom-bretagne.eu.|Institut Mines-Telecom, Telecom Bretagne, Brest, France. bhushan.borotikar@telecom-bretagne.eu.
authors.forename: Bhushan S
authors.initials: BS
authors.lastname: Borotikar
mesh_terms: D000293:Adolescent; D002547:Cerebral Palsy / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D005269:Femur / Q000000981:diagnostic imaging*; D006801:Humans; D021621:Imaging, Three-Dimensional; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed
keywords: Biplanar X-rays; Computed tomography; Discriminative ability; EOS; Reliability; Validity