title: [Comparison of total hip replacements cup orientation and position. Navigation vs. conventional manual implantation of hip prostheses].
abstract: BACKGROUND
  Aim of this in-vitro study was to compare the hip cup placement for total hip replacement when using different navigation systems compared with the traditional, non-navigated technique.
  
  
  METHODS
  Five different navigation systems were used: the CT-less systems Navitrack, Orthopilot and Surgetics Station, as well as the CT-based Navitrack and VectorVision. Three different surgeons carried out five cup implantations using all navigation systems and the manual approach on a surgery dummy. Cup orientation (inclination and anteversion) and the cup position (achieved cup center) were determined with a coordinate measuring machine.
  
  
  RESULTS
  In the manual group the variability of the cup orientation was higher in comparison and hardly influenced by the surgeon. Navigation was identified as a significant factor for smaller deviations from planned inclination and anteversion angles (p<0,001 for both). Cup position was not affected by surgeon in the manual group (p=0,966). Compared with manual technique, the cup misplacement vector was significantly smaller in the CT-Navitrack group (p<0,001) but higher in the Navitrack (CT-less) and VectorVision group (p<0,001).
  
  
  CONCLUSIONS
  The use of computer navigation will help the surgeon to orientate the acetabular component more accurately but not necessarily with regard to cup positioning.
authors.affiliation: Department of Orthopedic Surgery, Rush University Medical Center, Chicago, IL 60612, USA. matthias_honl@rush.edu
authors.forename: M
authors.initials: M
authors.lastname: Honl
authors.forename: K
authors.initials: K
authors.lastname: Schwieger
authors.forename: C H
authors.initials: CH
authors.lastname: Gauck
authors.forename: F
authors.initials: F
authors.lastname: Lampe
authors.forename: M M
authors.initials: MM
authors.lastname: Morlock
authors.forename: M A
authors.initials: MA
authors.lastname: Wimmer
authors.forename: E
authors.initials: E
authors.lastname: Hille
mesh_terms: D000077:Acetabulum / Q000473:pathology / Q000601:surgery; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D012371:Robotics / Q000295:instrumentation* / Q000379:methods; D025321:Surgery, Computer-Assisted / Q000295:instrumentation* / Q000379:methods; D016896:Treatment Outcome