title: Assessment of bone mineral density of the femoral head in dogs with early osteoarthritis.
abstract: OBJECTIVE
  To compare the bone mineral density (BMD) of the proximal portion of the femur in dogs with and without early osteoarthritis secondary to hip dysplasia.
  
  
  METHODS
  24 dogs (3 Greyhounds, 6 Labrador-Greyhound crossbreeds, and 15 Labrador Retrievers).
  
  
  METHODS
  Computed tomography (CT) of the pelvis, including a bone-density phantom, was performed for each dog. Centrally located transverse CT slices and a computer workstation were used to identify 16 regions of interest (ROIs) in the proximal portion of the femur. For each ROI, the mean Hounsfield unit value was recorded; by use of the bone-density phantom and linear regression analysis, those values were converted to equivalent BMD (eBMD). Mean eBMD values for the subchondral and nonsubchondral ROIs in dogs with and without osteoarthritis (determined at necropsy) were compared. A mixed-model ANOVA and post hoc linear contrasts were used to evaluate the effects of osteoarthritis, breed, and sex on the BMD value.
  
  
  RESULTS
  At necropsy, osteoarthritis was detected in 14 hip joints in 9 dogs; all lesions included early cartilage fibrillation. After adjusting for breed and sex, eBMD in subchondral ROIs 8 and 12 (adjacent to the fovea) were 8% and 6% higher, respectively, in osteoarthritis-affected dogs, compared with unaffected dogs; in the nonsubchondral ROIs, eBMD was 10% higher in osteoarthritis-affected dogs.
  
  
  CONCLUSIONS
  Compared with findings in unaffected dogs, increased eBMD in hip joints of dogs with early osteoarthritis supports a strong relationship between the subchondral and epiphyseal regions and articular cartilage in the pathogenesis and progression of osteoarthritis.
authors.affiliation: Department of Clinical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Heather J
authors.initials: HJ
authors.lastname: Chalmers
authors.forename: Nathan L
authors.initials: NL
authors.lastname: Dykes
authors.forename: George
authors.initials: G
authors.lastname: Lust
authors.forename: James P
authors.initials: JP
authors.lastname: Farese
authors.forename: Nancy I
authors.initials: NI
authors.lastname: Burton-Wurster
authors.forename: Alma J
authors.initials: AJ
authors.lastname: Williams
authors.forename: Rory J
authors.initials: RJ
authors.lastname: Todhunter
mesh_terms: D000818:Animals; D015519:Bone Density / Q000502:physiology*; D002358:Cartilage, Articular; D004283:Dog Diseases / Q000503:physiopathology*; D004285:Dogs; D005260:Female; D005270:Femur Head / Q000033:anatomy & histology / Q000503:physiopathology*; D008297:Male; D010003:Osteoarthritis / Q000503:physiopathology / Q000662:veterinary*; D014057:Tomography, X-Ray Computed / Q000662:veterinary