Importancia relativa de las modificaciones del contenido mineral óseo y del área en la determinación del descenso de la densidad mineral ósea del cuello femoral en la posmenopausia

Abstract

Bone mineral density (BMD) of the femoral neck (FN) is determined by two variables: bone mineral content (BMC) and area (A). We evaluated the changes of these two factors in women after menopause. In a cross sectional study, BMD, BMC and A of the FN were measured with DXA (Lunar Prodigy) in 191 women who required bone evaluation. The population was divided in two groups: group 1 (≤ 60 years old) and group 2 (> 60 years old). The effect of age on BMD, BMC and A were evaluated by univariate analysis regression in the whole population and in both groups and means of the three variables were compared between groups. Results: BMD: 0,897±0,12 vs. 0,80±0,11 and BMC: 4,2±0,7 vs. 3,87±0, 53 were significantly higher (p<0.01) in group 1 than in group 2 respectively, while A was smaller in group 1 than in group 2: 4,69±0,3 vs. 4,81±0,3 (p<0.01). BMD, BMC and A correlated with age in whole population: r = -0,49, -0,34 and 0,26 respectively (p<0,01). BMD correlated significantly with age, r = -0,38 and -0,34 in groups 1 and 2 respectively, while BMC only did so in group 1, r = -0.27 and A only did so in group 2, r = 0.3. BMC and A did not correlate with age in group 2 and 1 respectively. Conclusions: loss of bone mass (decrease of BMC) and periosteal expansion (increase of A) are respectively the principal determinants of the decrease of BMD in the early and late stages of menopause.