title: Radiographic, ultrasonographic, and anatomic assessment of femoral trochlea morphology in red foxes (Vulpes vulpes).
abstract: OBJECTIVE
  To compare repeatability and equivalency of measures of femoral trochlea depth and trochlear angle in red foxes (Vulpes vulpes) determined by use of radiography, ultrasonography, and digital photography of cadaver limbs.
  
  
  METHODS
  24 pelvic limbs from 12 red fox cadavers.
  
  
  METHODS
  Cranioproximal-craniodistal oblique (skyline) and lateromedial radiographic views of the stifle joint and ultrasonographic images at 5 locations along the femoral trochlea were used in the study. Spacing of the 5 locations was determined on the basis of patellar position with the stifle joint at various caudal angles ranging from 96° to maximal extension (approx 170°). Ultrasonographic measurements were compared with those obtained at matched locations on photographs of anatomic preparations. Trochlear depth was assessed with all 3 image formats, and trochlear angle (measured between the trochlear ridges and sulcus) was assessed on radiographs and ultrasonographic images. Patellar thickness was measured on radiographs. Values obtained were compared by means of ANOVA, modified Bland-Altman plots, and repeatability testing.
  
  
  RESULTS
  Depth measurement repeatability was considered good for all modalities. Small but significant differences between mean ultrasonographic trochlear depth and anatomic (photographic) measurements were found at 3 locations; 95% limits of agreement for paired anatomic and ultrasonographic measurements were wide. The ratio of trochlear depth to radiographic patellar thickness was approximately 30% for all modalities. Trochlear angle measurements were more variable than trochlear depth measurements, especially in the distal aspect of the trochlea.
  
  
  CONCLUSIONS
  Paired anatomic and ultrasonographic measurements did not appear equivalent in this study, possibly attributable to imprecise probe location, which could limit quantitative use of ultrasonography in assessing proximal trochlear depth in a clinical setting.
authors.affiliation: Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, 1870 Frederiksberg C, Denmark.
authors.forename: James E
authors.initials: JE
authors.lastname: Miles
authors.forename: Ulrik
authors.initials: U
authors.lastname: Westrup
authors.forename: Eiliv L
authors.initials: EL
authors.lastname: Svalastoga
authors.forename: Thomas
authors.initials: T
authors.lastname: Eriksen
mesh_terms: D000818:Animals; D002102:Cadaver; D005269:Femur / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005589:Foxes / Q000033:anatomy & histology*; D010329:Patella / Q000033:anatomy & histology / Q000000981:diagnostic imaging; D011859:Radiography; D013264:Stifle / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D014463:Ultrasonography