Abstract

Vertebral fractures occur most frequently in thoracolumbar region, especially D11- L2, while L4 contributes minimally to this event. That cannot be explained by differences in loading during daily activities or bone quality between vertebrae. Differences exist in vertebral size.
The aim of the study was to evaluate in female lumbar spines if vertebrae which most
frequently fracture are smaller than L4.
We analyzed BMD (DXA) of 48 women (W) and 45 men (M). The width of the segment L1-L2 (S L1-L2) and of L4 was considered a surrogate of vertebral bodies
Results: Width S L1-L2: Men: 4,32 ± 0,33 cm; Women: 3,78 ± 0,23 cm, p < 0,001.
Width L4: Men: 5 ± 0.37; Women: 4,66 ± 0,38 cm, p < 0,001.
Difference between L4 and S L1-L2: Men: 0,69 ± 0,25cm, Women: 0,88 ± 0,27 cm p < 0,001. Relative width (S L1-L2/L4) Men: 0,86 ± 0,04 Women: 0,81 ± 0,04 p <0,001.
Conclusions: the study shows, as already known, that women have smaller vertebrae than men. The differences are not uniform in the lumbar spine, L1 and L2 being particularly smaller compared to L4. These structural differences between women and men should be considered to explain, within the multifactorial context of vertebral fractures, the greater incidence in female, particularly L1 and L2.

Key words: vertebral fractures, vertebral size, DXA (Dual-Energy X- Ray Absorptiometry).