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Twenty-two female Rhesus monkeys were fed purified diets varying in calcium and fluoride content for five years and studied, using radiographic, photon absorptiometric and histologic techniques. The results suggested that 1) the addition of fluoride (50 ppm) to a diet containing 1 calcium resulted in a reduction in bone growth rate and resorption, without affecting bone size or density nor resulting in fluorosis; 2) a diet containing 0.15 calcium resulted in osteoporosis due to an increase in bone resorption; and 3) fluoride added to a similar low calcium diet prevented osteoporosis by reducing bone growth rate and resorption resulting in bones with normal density, but at the same time fluoride interfered with mineralization of osteoid leading to osteomalacia.

One hundred patients with spinal cord injury had various parameters of bone mineral estimated. The results were compared to a group of matched normals. A Packard Osteodensitometer with a 125I point source was used to measure bone mineral mass in the distal radius. The cortical bone was found to be normal in the spinal cord injury patients as shown by photon densitometry, and radiographic measurement of the metacarpal and clavicular indices. It was not related to the date or the level of the spinal injury and was related to age in a similar fashion to the normals. However, hand radiographs demonstrated marked loss of trabecular bone in 52 patients (including 14 paraplegics). This suggests that, in spinal cord Injury, cortical bone is preserved while trabecular bone is lost, and because this is dissimilar from idiopathic osteoporosis a possible neuronal etiology is postulated.