title: Intra- and extra-articular planes of reference for use in total hip arthroplasty: a preliminary study.
abstract: OBJECTIVE
  Acetabular component malalignment in total hip arthroplasty can lead to potential complications such as dislocation, component impingement and excessive wear. Computer-assisted orthopaedic surgery systems generally use the anterior pelvic plane (APP). Our aim was to investigate the reliability of anatomical landmarks accessible during surgery and to define new potential planes of reference.
  
  
  METHODS
  Three types of palpations were performed: virtual, on dry bones and on two cadaveric specimens. Four landmarks were selected, the reproducibility of their positioning ranging from 0.9 to 2.3 mm. We then defined five planes and tested them during palpations on two cadaveric specimens.
  
  
  RESULTS
  Two planes produced a mean orientation error of 5.0° [standard deviation (SD 3.3°)] and 5.6° (SD 2.7°).
  
  
  CONCLUSIONS
  Even if further studies are needed to test the reliability of such planes on a larger scale in vivo during surgery, these results demonstrated the feasibility of defining a new plane of reference as an alternative to the APP.
authors.affiliation: LBM, Arts et Metiers ParisTech, 151 bd de l'Hôpital, 75013, Paris, France. jerome.hausselle@gmail.com
authors.forename: Jerome
authors.initials: J
authors.lastname: Hausselle
authors.forename: Pierre Etienne
authors.initials: PE
authors.lastname: Moreau
authors.forename: Loic
authors.initials: L
authors.lastname: Wessely
authors.forename: Emmanuel
authors.initials: E
authors.lastname: de Thomasson
authors.forename: Ayman
authors.initials: A
authors.lastname: Assi
authors.forename: Sebastien
authors.initials: S
authors.lastname: Parratte
authors.forename: Jerome
authors.initials: J
authors.lastname: Essig
authors.forename: Wafa
authors.initials: W
authors.lastname: Skalli
mesh_terms: D000077:Acetabulum / Q000033:anatomy & histology* / Q000601:surgery; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D017760:Bone Malalignment / Q000517:prevention & control; D002102:Cadaver; D005260:Female; D006621:Hip Joint / Q000033:anatomy & histology* / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D012015:Reference Standards; D015203:Reproducibility of Results; D025321:Surgery, Computer-Assisted / Q000379:methods*