title: Ultrasound-based computer navigation of the acetabular component: a feasibility study.
abstract: BACKGROUND
  This feasibility study investigated the accuracy of anterior pelvic reference plane (APP) registration and acetabular cup orientation in two cadavers with different BMIs.
  
  
  METHODS
  Five observers each registered the APP five times in the 2 cadavers (BMIs: 32 kg/m(2) and 25 kg/m(2)) using an ultrasound-based navigation system. By comparison against the CT-derived reference landmarks, the errors in determining the individual landmarks defining the APP, as well as the resulting errors in the orientation of the APP and the acetabular cup orientation were determined.
  
  
  RESULTS
  Across all measurements obtained with the ultrasound navigation system, the errors in rotation and version in determining the APP were 0.5° ± 1.0° and -0.4° ± 2.0°, respectively. The cup abduction and anteversion errors determined from all measurements of the five investigators for both cadavers together were -0.1° ± 1.0° and -0.4° ± 2.7°, respectively. The data further demonstrated a high reproducibility of the measurements for the resulting cup adduction and anteversion angle.
  
  
  CONCLUSIONS
  Our preliminary results confirm that ultrasound navigation is a highly accurate tool that allows a reproducible registration of the APP and thereby enables accurate and precise intraoperative determination of the acetabular cup orientation also in patients with increased BMI.
authors: Department of Orthopedics, Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, Germany. georgi.wassilew@charite.de
authors: Georgi I
authors: GI
authors: Wassilew
authors: Markus O
authors: MO
authors: Heller
authors: Olaf
authors: O
authors: Hasart
authors: Carsten
authors: C
authors: Perka
authors: Ingrid
authors: I
authors: Südhoff
authors: Viktor
authors: V
authors: Janz
authors: Georg N
authors: GN
authors: Duda
authors: Christian
authors: C
authors: König
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging*; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D015588:Observer Variation; D010384:Pelvic Bones / Q000000981:diagnostic imaging; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography