Osteoporosis. Coloured frontal X-ray of the upper lumbar (lower) spine of a fifty-eight-year-old patient with osteoporosis. The first and second lumbar vertebrae (third and fourth blocks from top) have become compressed and are touching each other, also the second lumbar vertebra is significantly smaller than the others. In a healthy spine the vertebrae are all evenly spaced. Osteoporosis is characterised by loss of bone density and deterioration of bone tissue, and causes pain and immobility. It is most common in post-menopausal women. It may be prevented by a diet rich in calcium, and regular weight-bearing exercise.