title: Subchondral bone micro-architectural alterations in osteoarthritis: a synchrotron micro-computed tomography study.
abstract: OBJECTIVE
  We evaluated the three-dimensional (3D) micro-architecture of subchondral trabecular (Tb) bone in osteoarthritis (OA). Due to high signal-to-noise ratio and high resolution, micro-computed tomography (micro-CT) by synchrotron radiation is considered as the gold standard for bone micro-architecture imaging.
  
  
  METHODS
  Subchondral bone were extracted from femoral heads in OA cases in areas without cartilage (OAc-; n=6) and in adjacent areas with cartilage (OAc+; n=6) and compared to eight subchondral bone cores from osteoporosis cases (OP). The voxel size of images was 10.13 microm. We measured the bone volume fraction (BV/TV) and morphological parameters: Tb thickness (TbTh), Tb spacing (TbSp), Tb number (TbN), and bone surface/bone volume (BS/BV). The degree of anisotropy (DA), the connectivity by the Euler number and the degree of mineralization (DM) were equally assessed.
  
  
  RESULTS
  BV/TV and morphological parameters showed significant differences between OAc- and OP samples (P<0.01 except TbTh: P<0.05) and between OAc- and OAc+ (0.05<P<0.01) but no difference between OAc+ and OP except TbN (P<0.01). The connectivity was higher in OAc- comparatively to OAc+ and OP. The DA were significantly different between OA and OP cases (P<0.01) but not between OAc- and OAc+ specimens. The DMs (mean+/-SD) were 0.817+/-0.142 g/cm(3), 0.873+/-0.161 g/cm(3), 0.906+/-0.156 g/cm(3) for OAc-, OAc+, OP (P<0.01), respectively.
  
  
  CONCLUSIONS
  Subchondral bone changes were mainly observed in advanced OA, when cartilage has been deleted and preserved in adjacent area. These data suggest that subchondral bone changes would be rather secondary to the cartilage deterioration than a primitive mechanism of OA. Nevertheless, longitudinal data could bring more accurate conclusions.
authors.affiliation: Inserm, U 658, Centre Hospitalier Orleans, 45032 Orleans, France. christine.chappard@chr-orleans.fr
authors.forename: C
authors.initials: C
authors.lastname: Chappard
authors.forename: F
authors.initials: F
authors.lastname: Peyrin
authors.forename: A
authors.initials: A
authors.lastname: Bonnassie
authors.forename: G
authors.initials: G
authors.lastname: Lemineur
authors.forename: B
authors.initials: B
authors.lastname: Brunet-Imbault
authors.forename: E
authors.initials: E
authors.lastname: Lespessailles
authors.forename: C-L
authors.initials: CL
authors.lastname: Benhamou
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002358:Cartilage, Articular / Q000000981:diagnostic imaging / Q000473:pathology; D005270:Femur Head / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D008852:Microradiography / Q000379:methods; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000473:pathology*; D017356:Synchrotrons; D014057:Tomography, X-Ray Computed / Q000379:methods