title: Radiographic evaluation of BFX acetabular component position in dogs.
abstract: OBJECTIVE
  To assess the reliability of radiographic measurement of angle of lateral opening (ALO) and angle of version of BFX acetabular cups.
  
  
  METHODS
  In vitro radiographic study.
  
  
  METHODS
  BFX cups (24, 28, and 32 mm).
  
  
  METHODS
  Total hip replacement constructs (cups, 17 mm femoral head and a #7 CFX stem) were mounted on an inclinometer. Ventrodorsal radiographs were obtained with ALO varying between 21° and 70° and inclination set at 0°, 10°, 20°, and 30°. Radiographs were randomized using a random sequence generator. Three observers blinded to the radiograph order assessed ALO using 3 methods: (1) an ellipse method based on trigonometry; (2) using a measurement from the center of the femoral head to the truncated surface of the cup; (3) by visual estimation using a reference chart. Version was measured by assessing the ventral edge of the truncated surface.
  
  
  RESULTS
  ALO methods 2 and 3 were accurate and precise to within 10° and were significantly more accurate and precise than method 1 (P < .001). All methods were significantly less accurate with increasing inclination. Version measurement was accurate and precise to within 7° with 0-20° of inclination, but significantly less accurate with 30° of inclination.
  
  
  CONCLUSIONS
  Methods 2 and 3, but not method 1, were sufficiently accurate and precise to be clinically useful. Version measurement was clinically useful when inclination was ≤ 20°.
authors.affiliation: Willows Referral Service, Solihull, UK Royal Veterinary College, North Mymms, UK. arenvc@btconnect.com
authors.forename: Alasdair
authors.initials: A
authors.lastname: Renwick
authors.forename: Toby
authors.initials: T
authors.lastname: Gemmill
authors.forename: Jonathan
authors.initials: J
authors.lastname: Pink
authors.forename: David
authors.initials: D
authors.lastname: Brodbelt
authors.forename: Malcolm
authors.initials: M
authors.lastname: McKee
mesh_terms: D000077:Acetabulum / Q000000981:diagnostic imaging*; D000818:Animals; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D004285:Dogs / Q000601:surgery*; D005270:Femur Head / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis / Q000662:veterinary*; D066298:In Vitro Techniques; D011859:Radiography; D015203:Reproducibility of Results