Osteoporosis is a reduction in bone density that increases the risk of fractures; particularly of the spine, hip and wrist. Osteoporosis is estimated to affect 200 million women worldwide - approximately one tenth of women aged 60, one-fifth of women aged 70, two-fifths of women aged 80 and two-thirds of women aged 90. Treating osteoporosis and the associated fractures costs the NHS more than two billion pounds per annum.