From 2005 to 2008, the prevalence of osteoporosis in women aged 50 years and older at either the femur neck or lumbar spine was 9%, with 4% with osteoporosis at the lumbar spine only, 3% with osteoporosis at the femur neck only, and 2% with osteoporosis at both the lumbar spine and femur neck. The prevalence of low bone mass at either skeletal site was 49%, with 10% having low bone mass at the lumbar spine, 22% with low bone mass at the femur neck, and 17% with low bone mass at both the lumbar spine and femur neck.
Age is a significant factor in the presence of osteoporosis and low bone mass in both men and women, but particularly in women. By the age of 70 years, virtually all women have low bone mass, with 27% or more having osteoporosis. In men, the prevalence of osteoporosis does not begin to increase until the age of 80 years, although low bone mass begins to climb for men in their 70s.