title: An evaluation of CT-scan to locate the femoral head centre and its implication for hip surgeons.
abstract: OBJECTIVE
  The aim of this preliminary study was to determine the accuracy of CT-scan to locate the femoral head centre.
  
  
  METHODS
  Eleven dried femurs were included for study. Three techniques were compared to determine femoral head centre (FHC) location: CT-scan, Motion Analysis and Faro-Arm. Markers were stuck on each femur to create a system of coordinates. Femurs lied on their posterior parts (bicondylar plane). Several points around the femoral head were palpated (Motion Analysis and Faro-Arm) or determined (Amira software for CT-scans). By a least-square regression method, the FHC location in 3D was defined for each technique.
  
  
  RESULTS
  The results of the FHC location determined by the CT-scan technique were compared with those measured by the faro-arm and the Motion Analysis techniques. The coordinates (X, Y, Z) of the FHC were compared between the three methods, and no statistical difference was found (p = 0.99). In a 3D plot, this gave a mean difference of 1.3 mm. The mean radius of the femoral head was of 22.5 mm (p = 0.6).
  
  
  CONCLUSIONS
  CT-scan is as accurate and reliable as gold-standard techniques (motion and faro-arm). Locating FHC before and after hip arthroplasty would allow hip surgeons to determine and compare 3D orientation of the upper-end of femur: offset, height and anteversion.
authors.affiliation: Faculté de Médecine Lyon-Sud Charles Mérieux, Laboratoire d'Anatomie, 165 Chemin du Petit Revoyet, BP 12, 69921, Oullins Cedex, France, anthony.viste@chu-lyon.fr.
authors.forename: Anthony
authors.initials: A
authors.lastname: Viste
authors.forename: Franck
authors.initials: F
authors.lastname: Trouillet
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Testa
authors.forename: Laurence
authors.initials: L
authors.lastname: Chèze
authors.forename: Romain
authors.initials: R
authors.lastname: Desmarchelier
authors.forename: Michel-Henri
authors.initials: MH
authors.lastname: Fessy
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D005270:Femur Head / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D006801:Humans; D014057:Tomography, X-Ray Computed / Q000379:methods