Osteoporosis. Artwork of a spine with fractured vertebrae due to osteoporosis, the loss of protein matrix tissue from the bones. The vertebra at centre is cutaway to show its loss of bone mass. This and its increased brittleness have caused it to fracture. While bone density naturally falls with age, the effects are greatest in post- menopausal women as they no longer make the horm- one oestrogen that helps to maintain strong bones.