AGE-DEPENDENCE OF THE NORMAL ABNORMAL DIFFERENCE OF BONE-MINERAL DENSITY IN OSTEOPOROTIC WOMEN/

Bone mineral density (BMD) is the major factor in bone strength and in the risk of suffering osteoporotic fractures. The aim of this study w as to examine the normal/abnormal difference for antero-posterior (AP) spine, lateral spine, proximal femur and total body BMD to assess if age influences discrimination at three different decades between 50 an d 80 years of age. The BMD was determined in 61 control women and 60 o steoporotic women (at least one vertebral wedge fracture readily visib le in the lateral X-rays of the thoracic or lumbar spine). Measurement s were made by DEXA with a total body scanner. The BMD of the whole gr oup of osteoporotic women was markedly lower than that of age-matched controls at all skeletal areas (P < 0.001) except at the arms where th e difference was smaller (P < 0.02). The Z-score (the difference betwe en osteoporotic patients and age-matched control divided by the intrap opulation S.D.) was similar (similar to -1.7) over the AP spine, femor al neck, Ward's triangle, total body and legs. It was significantly lo wer at the arms (-0.8, P < 0.001), lateral spine (-1.4, P < 0.01) and trochanter (-1.3, P < 0.001) compared with the Z-score of the AP spine . The analysis of the results by decades of age disclosed that the hig her Z-score on the 6th and 7th decades corresponded to the AP lumbar s pine (similar to -2.0). A high descrimination was also observed for th e femoral neck, Ward's triangle and legs while the Z-score of the late ral lumbar spine, total body, trochanter and arms were significantly l ower than that of the AP lumbar spine. However on the 8th decade the Z -score of the AP lumbar spine diminished to -1.2 and was only signific antly higher than the Z-score of the arms (P < 0.01). The study showed that, in women 50-60 years of age - the period where the majority of studies are made for prevention of osteoporosis, none of the other ske letal areas were superior to the AP spine in discrimination for spinal osteoporosis. Proximal femur and legs densitometry gave lower but not significantly different Z-score than the AP spine, while the remainin g areas were significantly inferior to AP spine in separating osteopor otic and normal women.