The effect of overlying calcification on lumbar bone densitometry

Abstract

We studied bone mineral density (BMD) of the spine using dual photon absorptiometry, as well as standard anterior-posterior and lateral lumbar spine X-ray film in 113 ambulatory elderly male volunteers with a mean age of 72 years (range 66–91 years). Each subject had three measurements taken for lumbar vertebrae 1 through 4: BMD, length of aortic calcification (AC), and degenerative facet sclerosis graded 0–3. A separate statistical model was fit to BMD for each vertebra using analysis of covariance. AC did not contribute significantly to BMD. BMD was increased by 0.28–0.03 g/cm² (L1–L4) with a sclerosis score of 2, and by 0.47–0.25 g/cm² with a sclerosis score of 3,P<0.001. The association between increased BMD and overlying facet sclerosis may be related to the bone density within the sclerosis itself or to an association between degenerative joint disease and a generalized increase in subchondral bone.