The impact of degenerative conditions in the spine on bone mineral density and fracture risk prediction

Abstract

We examined the impact of degenerative conditions in the spine (osteophytosis and endplate sclerosis) and aortic calcification in the lumbar region on bone mineral content/density (BMC/BMD) measured in the spine and forearm by absorptiometry and on fracture risk prediction. The radiographs of 387 healthy postmenopausal women, aged 68-72 years, were assessed in masked fashion for the presence of osteophytosis, endplate sclerosis and aortic calcification in the region from L2 to L4. Vertebral deformities/fractures were assessed by different definitions. Osteophytes larger than 3 mm and in numbers of 3 or more resulted in a significantly (12%) higher spinal bone mass (p < 0.001). Endplate sclerosis had a similar effect (p < 0.001). In subjects with both degenerative conditions the BMC/BMD in the spine and forearm were significantly higher than in unaffected women (19% in the spine, 10% in the forearm; p < 0.001). The spinal BMD values were significantly lower in fractured women if both degenerative conditions were absent (p < 0.001), whereas fractured and unfractured women had similar values if degenerative conditions were present. Degenerative conditions did not alter the ability of forearm BMC to discriminate vertebral or peripheral fractures. Receiver operating characteristic (ROC) curves (true positive fraction versus false positive fraction) were generated for BMD of the lumbar spine and BMC of the forearm with regard to the discrimination between women with vertebral and peripheral fractures and healthy premenopausal women. The ROC curves for women without degenerative conditions were consistently above the curves for women affected by osteophytosis and endplate sclerosis in the lumbar spine (p < 0.001). In conclusion, osteophytes and endplate sclerosis have a considerable influence on spinal bone mass measurements in elderly postmenopausal women and affect the diagnostic ability of spinal scans to discriminate osteoporotic women. Our data suggest that in elderly women, unless the spine is radiologically clear of degenerative conditions, a peripheral measurement procedure should be considered an alternative for assessment of bone mineral content/density.