Observations on the incidence, aetiology, and pathology of senile osteoporosis.

Using previously described methods, lumbar vertebral body slabs were investigated radiologically and histologically from 300 unselected cases coming to necropsy. Calcium estimations were also made on the bones of the first 150 cases. High calcium values were mostly encountered in young adults and the calcium values tended to diminish with age, but a wide range of calcium values was still encountered in older subjects. Radiographic density of bone and calcium content tended to be higher in male than in female bone at all ages. The study showed that in subjects aged 50 years or more bone was osteoporotic in 22.5% of males and in 23.1% of females. This is a higher incidence than has been previously reported, and is the first accurate study to show equality of incidence in the two sexes. Although in the relationship between radiographic density and age there was a highly significant overall regression effect, no significant difference was demonstrated between the separate sexes. There was, however, an accelerated falling away in the bone density readings in the fifth and sixth decades which was more pronounced in females. This drop is considered to be connected more with oestrogen deficiency than with deficiency of dietary calcium. Vertebral biconcavity was measured in all cases but was found to be an unreliable sign of osteoporosis.