New Concepts in the Pathogenesis and Treatment of Osteoporosis

Abstract

Osteoporotic fracture is a major cause of morbidity in older people. For example, in the United States there are over one million fractures related to diminished bone density each year. There are 250,000 hip fractures and the morbidity (pain, immobility, need for nursing home placement and rehabilitation, loss of autonomy and depression) and mortality due to complications of fracture including infection, pulmonary embolus or cardiovascular compromise are estimated to be 20% at one year (1). These, of course, are of major importance for the patients, their families and society at large. For example, the estimated costs associated with the short and long-term care of patients with osteoporotic fracture exceeds $10 billion/year (2). Although osteoporosis is nearly always discussed in relation to postmenopausal women, there has developed an increased awareness of osteoporotic fractures in men (3). Notably, 17% of men 55–64 years of age are osteopenic (4) with the average man losing 20% to 30% of cortical and 30% to 40% of trabecular bone (about 65% of the lifetime loss in women) (5). In the U.S. there are 700,000 vertebral fractures, 250,000 distal forearm fractures, 250,000 hip fractures, and 300,000 fractures of other limb sites. At age 50 the prospective lifetime risk of hip, distal radius, and symptomatic spine fractures has been estimated at 40% (2) to 50% (6) in women and 13% in men (2) (i.e. nearly one-third of these fractures occur in men). Spinal fractures, which occur in 25% of Caucasian women by age 65 years, cause substantial pain, deformity, and disability. Of osteoporosis-related fractures, hip fractures are most likely to result in death, functional dependence, and social cost (7). An estimated 1.66 million hip fractures occurred world-wide in 1990 and the lifetime risk of a hip fracture is 16%-18% in white women and 5%-6% in white men (8). Hip fracture is associated with a 10%–20% mortality rate within 6 months (1); 50% of survivors are unable to walk without assistance; and 25%–30% require long-term domiciliary care (2). Notably, men have a higher mortality after hip fracture than do women (9).