title: Trapezium trabecular morphology in carpometacarpal arthritis.
abstract: OBJECTIVE
  In thumb carpometacarpal osteoarthritis, current evidence suggests that degenerative, bony remodeling primarily occurs within the trapezium. Nevertheless, the pathomechanics involved and the most common sites of wear remain controversial. Quantifying structural bone morphology characteristics with high-resolution computed tomography CT (micro-CT) infer regions of load transmission. Using micro-CT, we investigated whether predominant trabecular patterns exist in arthritic versus normal trapeziums.
  
  
  METHODS
  We performed micro-CT analysis on 13 normal cadaveric trapeziums and 16 Eaton stage III to IV trapeziums. We computationally divided each specimen into 4 quadrants: volar-ulnar, volar-radial, dorsal-radial, and dorsal-ulnar. Measurements of trabecular bone morphologic parameters included bone volume ratio, connectivity, trabecular number, and trabecular thickness. Using analysis of variance with post hoc Bonferroni/Dunn correction, we compared osteoarthritic and normal specimen quadrant measurements.
  
  
  RESULTS
  No significant difference existed in bone volume fraction between the osteoarthritic and normal specimens. Osteoarthritic trapeziums, however, demonstrated significantly higher trabecular number and connectivity than nonosteoarthritic trapeziums. Comparing the volar-ulnar quadrant of osteoarthritis and normal specimens collectively, this quadrant in both consistently possessed significantly higher bone volume fraction, trabecular number, and connectivity than the dorsal-radial and volar-radial quadrants.
  
  
  CONCLUSIONS
  The significantly greater trabecular bone volume, thickness, and connectivity in the volar-ulnar quadrant compared with the dorsal-radial and dorsal-ulnar quadrants provides evidence that the greatest compressive loads at the first carpometacarpal joint occur at the volar-ulnar quadrant of the trapezium, representing a consistently affected region of wear in both normal and arthritic states.
  
  
  CONCLUSIONS
  These findings suggest that trapezial trabecular morphology undergoes pathologic alteration. This provides indirect evidence that changes in load transmission occur with thumb carpometacarpal joint arthritis development.
authors.affiliation: Department of Orthopaedic Surgery, Robert A Chase Hand and Upper Limb Center, Stanford University School of Medicine, Stanford, CA 94304, USA.
authors.forename: Arthur T
authors.initials: AT
authors.lastname: Lee
authors.forename: Ariel A
authors.initials: AA
authors.lastname: Williams
authors.forename: Julia
authors.initials: J
authors.lastname: Lee
authors.forename: Robert
authors.initials: R
authors.lastname: Cheng
authors.forename: Derek P
authors.initials: DP
authors.lastname: Lindsey
authors.forename: Amy L
authors.initials: AL
authors.lastname: Ladd
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015519:Bone Density / Q000502:physiology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D050279:Metacarpal Bones / Q000000981:diagnostic imaging*; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging*; D012016:Reference Values; D051222:Trapezium Bone / Q000000981:diagnostic imaging*; D014955:Wrist Joint / Q000000981:diagnostic imaging*; D055114:X-Ray Microtomography