title: A comparison of conventional guidewire alignment jigs with imageless computer navigation in hip resurfacing arthroplasty.
abstract: BACKGROUND
  Correct positioning of the initial femoral guidewire is vital in order to prepare the femoral head properly for hip resurfacing. The purpose of the present investigation was to determine the accuracy and precision of the placement of the initial femoral guidewire with use of conventional alignment jigs and to compare the results with those of imageless computer navigation.
  
  
  METHODS
  Five commercially available jigs (two lateral pin jigs, two neck centering jigs, and one head planing jig) were obtained. Four surgeons used each jig and navigation three times to insert a guidewire in 10 degrees of relative valgus and neutral version into individual synthetic femora. A single surgeon then used each jig three times to align the initial guidewire in 10 degrees of relative valgus and neutral version in each of ten human cadaver femora. Radiographs of the synthetic and human femora were made to assess and compare guidewire inclination and version between conventional instrumentation and navigation.
  
  
  RESULTS
  Navigation provided ranges of error in the coronal guidewire alignment of up to eight times less than the conventional jigs, but both methods provided similar ranges of error for version. In both arms of the study, there were significant differences in coronal alignment accuracy between the two neck centering jigs. Next to navigation, one lateral pin jig provided the most accurate coronal placement of the initial guidewire whereas one neck centering jig provided the most precise coronal placement of the guidewire. Navigation was similar to conventional jigs in terms of the accuracy and precision of guidewire version.
  
  
  CONCLUSIONS
  In hip resurfacing arthroplasty, the choice of a femoral alignment device may influence the accuracy and precision of guidewire insertion, ultimately impacting femoral component placement. Imageless computer navigation can facilitate accurate and precise coronal alignment of the initial femoral guidewire, superior to that of conventional instrumentation.
  
  
  CONCLUSIONS
  The results of this study may aid surgeons in the selection of alignment instruments for placement of the initial femoral guidewire during hip resurfacing.
authors.affiliation: Martin Orthopaedic Biomechanics Laboratory, Institute of Biomaterials and Biomedical Engineering, St. Michael's Hospital, University of Toronto, 5-066 Shuter Wing, 30 Bond Street, Toronto, ON M5B 1W8, Canada. olsenmi@smh.toronto.on.ca
authors.forename: Michael
authors.initials: M
authors.lastname: Olsen
authors.forename: Mark
authors.initials: M
authors.lastname: Chiu
authors.forename: Patrick
authors.initials: P
authors.lastname: Gamble
authors.forename: Richard A
authors.initials: RA
authors.lastname: Boyle
authors.forename: Nezar
authors.initials: N
authors.lastname: Tumia
authors.forename: Emil H
authors.initials: EH
authors.lastname: Schemitsch
mesh_terms: D000704:Analysis of Variance; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation*; D002102:Cadaver; D005270:Femur Head / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D011859:Radiography; D018709:Statistics, Nonparametric; D025321:Surgery, Computer-Assisted / Q000379:methods*