The impact of degenerative spinal changes on the correlation of peripheral and axial bone density.

Results of bone density measurements by quantitative computed tomography of the peripheral skeleton (pQCT) were compared with those of measurements at the axial skeleton with a view to study the effects of degenerative spinal changes on the validity of bone densitometry of the lumbar spine. 556 consecutive patients were examined by dual-energy x-ray absorptiometry (DXA) of the spine and by peripheral quantitative computed tomography (pQCT) of the distal radius. There were significant differences between the bone mineral values at the distal radius and those at the spine, depending on the degree of spinal degeneration. As expected, spinal degenerations showed a highly significant age dependence. With increasing degeneration the correlations between the radius total bone mineral concentration and the bone density of the lumbar spine decreased from r = 0.45 to 0.23 in women and from r = 0.64 to 0.28 in men. We conclude that the value of spinal DXA is reduced in patients with degenerative spinal disease, compared to the pQCT at the peripheral skeleton.