title: The effect of vertebral rotation of the lumbar spine on dual energy X-ray absorptiometry measurements: observational study.
abstract: OBJECTIVE
  To estimate how axial rotation of lumbar vertebrae quantitatively affects bone mineral density, as measured by dual energy X-ray absorptiometry in the anteroposterior plane.
  
  
  METHODS
  Observational study.
  
  
  METHODS
  University teaching hospital, Hong Kong.
  
  
  METHODS
  Cadaver lumbar vertebrae (L2 to L4) were removed from four adults.
  
  
  METHODS
  Using dual energy X-ray absorptiometry, the bone mineral content, bone area, and bone mineral density were measured in the neutral position and with vertebral axial rotation in increments of 7.5 degrees, up to a maximum of 45 degrees.
  
  
  RESULTS
  Correlation analysis showed a significant positive correlation between the degree of rotation and measured bone area, a significant negative correlation between degree of rotation and bone mineral density measurements, but no significant correlation between degree of rotation and measured bone mineral content. The measured bone area increased approximately 24% and the bone mineral density decreased approximately 19% when the vertebrae were rotated by 45 degrees.
  
  
  CONCLUSIONS
  These results suggest that for patients with rotational deformity of the spine, such as scoliosis, measurements of lumbar spine bone mineral content by dual energy X-ray absorptiometry is not affected, while bone mineral density measurements are not reliable.
authors.affiliation: Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong.
authors.forename: J C
authors.initials: JC
authors.lastname: Cheng
authors.forename: H L
authors.initials: HL
authors.lastname: Sher
authors.forename: X
authors.initials: X
authors.lastname: Guo
authors.forename: V W
authors.initials: VW
authors.lastname: Hung
authors.forename: A Y
authors.initials: AY
authors.lastname: Cheung
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D015519:Bone Density; D002102:Cadaver; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000737:chemistry*; D008297:Male; D012399:Rotation