VERTEBRAL DEFORMITY IN THE THORACIC SPINE IN POSTMENOPAUSAL WOMEN - VALUE OF LUMBAR SPINE BONE-DENSITY

Differential bone loss in the thoracic and lumbar spine is known to oc cur in some patients with osteoporosis. However, the discriminant valu e of lumbar spine bone densitometry in the detection of thoracic spine fractures in healthy, population-based women has not been established . The relationship between lumbar spine bone mineral density and thora cic spine vertebral deformities in a prospective study of 79 post-meno pausal population-based women aged 45-65 years has been investigated. Lumbar spine bone mineral density was measured using dual energy X-ray absorptiometry, and vertebral morphometry was assessed from lateral t horacic spine radiographs. Seven women (9%) were found to have one or more vertebral deformities in the thoracic spine (reduction in anterio r or posterior height >25%). Only one of these had a lumbar spine bone mineral density T score below -2.5, whilst the T score was between -1 and -2.5 in three and greater than -1 in three. Two of these women al so had lumbar spine vertebral deformity but lumbar spine radiographs w ere normal in the remaining five. There were no significant difference s in age, height, weight; hormone replacement therapy use or bone mine ral density between women with and without thoracic spine fractures. T hese results demonstrate that vertebral deformities in the thoracic sp ine occur in a proportion of healthy post-menopausal women in the abse nce of densitometric or radiographic evidence of osteoporosis in the l umbar spine. Although often asymptomatic, the significance of these fr actures lies in the increased risk of further fractures. In the future , morphometric X-ray absorptiometric techniques may prove valuable in the detection of these fractures and avoid the need for conventional r adiography.