Impact of degenerative radiographic abnormalities and vertebral fractures on spinal bone density of women with osteoporosis

CONTEXT: Measurements of bone density taken by dual-energy x-ray absorptiometry are the most accurate procedure for the diagnosis of osteoporosis. This procedure has the disadvantage of measuring the density of all mineral components, including osteophytes, vascular and extra vertebral calcifications. These alterations can influence bone density results and densitometry interpretation. OBJECTIVE: To correlate radiography and densitometry findings from women with osteoporosis, analyzing the influence of degenerative processes and vertebral fractures on the evaluation of bone density. DESIGN: Retrospective study. SETTING: Osteoporosis outpatients' clinic at Hospital das Clínicas, Universidade Estadual de Campinas. PARTICIPANTS: Ninety-six postmenopausal women presenting osteoporosis diagnosed by bone density. MAIN MEASUREMENTS: Bone mineral density of the lumbar spine and femoral neck were measured by the technique of dual-energy x-ray absorptiometry, using a LUNAR-DPX densitometer. Fractures, osteophytes and aortic calcifications were evaluated by simple x-rays of the thoracic and lumbar spine. RESULTS: The x-rays confirmed vertebral fractures in 41.6%, osteophytes in 33.3% and calcifications of the aorta in 30.2%. The prevalence of fractures and aortic calcifications increased with age. The mean bone mineral density was 0.783g/cm² and the mean T-score was --3.47 DP. Neither fractures nor aortic calcifications had significant influence on bone mineral density (P = 0.36 and P = 0.09, respectively), despite the fractured vertebrae having greater bone mineral density (P < 0.02). Patients with lumbar spine osteophytes showed greater bone mineral density (P = 0.04). Osteophytosis was associated with lumbar spine bone mineral density after adjustment for fractures and aortic calcifications by multiple regression (P = 0.01). CONCLUSION: Osteophytes and lumbar spine fractures can overestimate bone density interpretation. The interpretation of densitometry results should be carried out together with the interpretation of a simple lumbar spine x-ray in elderly women.