Vertebral wedge angle measured by morphometric X-ray absorptiometry.

Vertebral wedge angle is greater in older men than in women of similar age, and increases with age in men. Wedge angle may depend less on bone size than other methods (for example, height ratios), and thus could be more effective at identifying wedge deformities. We aimed to compare mean wedge angle measured by morphometric X-ray absorptiometry (MXA) in young men and women, to assess the effect of age on wedge angle in women, and to compare wedge angle and anterior-posterior (ha/hp) height ratios for the identification of vertebral deformities. Mean wedge angle was similar in normal men (n = 46) and women (n = 106) ages 22-50 years, and did not change significantly with age in normal women ages 22-83 years (n = 222). MXA reference intervals for ha/hp ratios (trimmed mean minus 3.0 SD) and wedge angle (trimmed mean +/- 3.0, 2.5 and 2.0 SD) were used to identify vertebral wedge deformities in 83 women with osteoporosis, ages 49-87 years. For agreement with semiquantitative assessment of radiographs (SQ), kappa (kappa) = 0.76 for wedge angle mean plus 2.0 SD, and 0.74 for ha/hp height ratio mean minus 3.0 SD. Sensitivity was marginally better for wedge angle plus 2.0 SD than for ha/hp when all SQ grades of deformity were included, but there was no difference between methods for detection of moderate to severe deformities (grades 2 to 3). Diagnostic values for the two approaches were broadly similar. The results of this analysis do not provide strong evidence for the preferential use of the wedge angle approach.