SYNOPSIS 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.Osteoporosis, which may be defined as a reduction of calcified bone mass per unit volume of anatomical bone, the remaining bone apparently being normally calcified, occurs in a number of different forms. The commonest variety, called senile osteoporosis, affects women over 45 and men over 55 years of age (Ball, 1960) in the absence of obvious aetiological factors such as Cushing's syndrome or hyperthyroidism.It seems to be generally agreed that in this type of osteoporosis the spine is affected earliest and most severely, followed by the pelvis, then the peripheral limb bones, and occasionally even the skull bones. Assessment during life is difficult, and is usually made by clinical radiography of the spine which has inherent inaccuracies, not the least of which is, that before diagnosis is possible the vertebral bodies must already have lost about 50% of their bone mass (Fusi, 1953). Although a useful assessment may be made during life by histological examination of bone biopsy material (Beck and Nordin, 1960), only a limited field can be studied, and this is a disadvantage, because as will be shown, osteoporosis does not lPresent address: Department of Pathology, Princess Alexandra Hospital, Brisbane, Queensland, Australia. Received for publication 27 April 1962. always occur uniformly even within the same bone.Authorities agree that senile osteoporosis is a more common condition than is generally suspected, but fairly wide differences of incidence and sex distribution continue to be described. Cooke (1955) reviewed over 800 reported cases and found that females predominated over males in the ratio of 6: 1. Lawrence (quoted by Ball, 1960) from a clinical radiographic su...
