title: [Three-dimensional ultrasonography and intraoperative navigation:a new application of ultrasonograms in osteotomy of the proximal femur].
abstract: OBJECTIVE
  As precise operative control is difficult to achieve, the accuracy of femoral osteotomies can only be estimated. Therefore, a computer-assisted ultrasound navigation system was developed in order to apply an on-line control for femoral osteotomies.
  
  
  METHODS
  Three ultrasound emitters were fixed on a triangle. The exact position of triangles could be determined by measuring the time the ultrasound beam takes to reach microphones positioned in a frame. With a reference triangle fixed distally to the osteotomy and a second triangle fixed on the surgical chisel the exact correction angle can be determined three-dimensionally.
  
  
  RESULTS
  A high degree of accuracy was found in both laboratory trials and in simulation trials using pig femurs. The deviation of measured values compared to a laser beam control was less than 0.5 degrees.
  
  
  CONCLUSIONS
  The system was introduced into our operating theatre as an optimised control device that can provide excellent support to the surgical procedure.
authors.affiliation: Orthopädische Universitätsklinik Bonn.
authors.forename: T
authors.initials: T
authors.lastname: Wallny
authors.forename: J
authors.initials: J
authors.lastname: Klose
authors.forename: G
authors.initials: G
authors.lastname: Steffny
authors.forename: D
authors.initials: D
authors.lastname: Schulze Bertelsbeck
authors.forename: L
authors.initials: L
authors.lastname: Perlick
authors.forename: G
authors.initials: G
authors.lastname: Schumpe
mesh_terms: D000818:Animals; D005269:Femur / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D016343:Monitoring, Intraoperative / Q000295:instrumentation / Q000379:methods*; D010027:Osteotomy; D015203:Reproducibility of Results; D013552:Swine; D014463:Ultrasonography / Q000295:instrumentation* / Q000379:methods*