osteoporosis

A deterioration of bone tissue which appears most often in aged people. It is due to a significant decrease (one to two thirds) of the bone's mineral density, particularly in terms of calcium and phosphorous. It is characterised by an enlargement of the medullary cavity (the central part of the bone) and the appearance of spaces between the lamellae which form the compact bone. People suffering from osteoporosis (particularly women after the menopause) see their risk of having fractures increase (hip, vertebral column). The link with vitamin D is more controversial than for osteomalacia, where the link is clearly established. Osteoporosis is partly the consequence of a drop in oestrogen levels following menopause in the absence of substitution treatment.