biologia - Studia

R. TOROK OANCE, V. NICULESCU, M.N. FILIMON
values (Marzillier, 1990): p < 0.05 = significant, p < 0.01 = highly significant, p <
0.001 = extremely significant and p > 0.05 = nonsignificant.
Results and discussion
94
Modification of bone mineral density with age and skeletal region
Since osteoporosis is directly connected with the decrease of bone mineral
density, we analyzed the evolution of the bone mineral density with increasing age,
at the patients who have been diagnosed with osteoporosis. We calculated the mean
value of the bone mineral density for each age group. We observed (Fig. 1.A) that the
bone mineral density decreases with age, both for the determinations performed at
the vertebral column, and for those performed at the hip bone. We noticed a
beginning of the decrease in the bone mineral density after the age of 40. Our
results correspond to what has been observed in other studies, namely the fact that
bone reduction starts after the age of 40 (Center and Eisman, 1997).
Although the reduction of the bone mineral density both at the vertebral
column and at the hip bone is obvious, we observed that, between the age of 50 and
65, the decrease is more significant at the vertebral column, while after the age of
65 the decrease at the hip bone surpasses that at the vertebral column.
It is well known that in the first 5-10 years after the installation of
menopause, the reduction of the spongy bone tissue is predominant (25-30%), as
opposed to the compact bone tissue, which undergoes a reduction of 10-25% in this
period (Pajouhi et al., 2004). This reflects in the greater decrease of the bone mineral
density at the vertebral column, because the spongy bone tissue is dominant here,
with only a thin covering of compact bone. There are also studies (Arlot et al., 1997)
that show that, after the age of 75, a massive bone reduction takes place in most parts
of the skeleton. We noticed the same thing in what concerns the vertebral column
and the hip bone: a massive decrease occurs, in both these regions, after the age of 70.
We analyzed the connection between the mean value of the bone mineral
density at the vertebral column and the mean age determined for each of the age
groups in discussion. The calculated correlation quotient has a negative value (R =
-0.8193, while R 2 = 0.6713), which demonstrates the fact that there is an inverted
connection between these two parameters: an increase in the age leads to a
decrease of the bone mineral density. Since the value of the correlation quotient is
high, the connection is tight and very significant (p=0.0038) (Fig. 1.B).
We performed the same analysis for the mean value of the bone mineral
density at the hip bone and the mean age for each age group. In this case, the
correlation quotient is -0.853 (R 2 = 0.7276), the connection is inverted as well, even
tighter than in the case of the vertebral column, and very significant, the p-value
being smaller than in the previous case (p=0.0017) (Fig. 1.C).
Modification of T and Z- score values with age and skeletal region
We also analyzed, for all patients, the existence of a connection between
the bone mineral density determined at the vertebral column and that determined at the