Bone Diseases

Bone diseases have a major impact on affected individuals and their families, as well as on the population as a whole. Although some bone diseases lead directly to pain and deformity, bone disease is often a “silent” disorder until it causes fractures. The 1.5 million osteoporotic fractures in the United States each year lead to more than half a million hospitalizations, over 800,000 emergency room encounters, more than 2,600,000 physician office visits, and the placement of nearly 180,000 individuals into nursing homes. Hip fractures are by far the most troublesome type of fracture, accounting for about 300,000 hospitalizations each year. Caring for these fractures is expensive. Studies show that annual direct care expenditures for osteoporotic fractures range from $12 to $18 billion per year in 2002 dollars. Indirect costs (e.g., lost productivity for patients and caregivers) likely add billions to this figure. These costs could double or triple in the coming decades.

From an individual's perspective, bone disease has a devastating impact on patients and their families. While few die directly from bone disease, for many individuals a fracture can lead to a downward spiral in physical and mental health that for some ultimately results in death. Bone diseases dramatically affect functional status. Many individuals who suffer fractures experience significant pain and height loss, and may lose the ability to dress themselves, stand up, and walk. These individuals are also at risk of complications such as pressure sores, pneumonia, and urinary tract infections. Nearly one in five hip fracture patients end up in a nursing home, a situation that a majority of participants in one study compared unfavorably to death.

Many bone disorders other than osteoporosis add greatly to the burden of bone disease in the population. Thousands of Americans are affected by other bone diseases such as rickets and osteomalacia, renal osteodystrophy, primary hyperparathyroidism, osteogenesis imperfecta, Paget's disease, bone cancer, and other developmental and acquired skeletal disorders. Estimates of the societal burden of these conditions are not readily available. The impact of these conditions on individuals, moreover, varies enormously, and is largely dependent upon the severity of the disease.

Paget's disease of the bone is a chronic bone disorder in which bones become enlarged and deformed. Bone may become dense but fragile because of excessive bone breakdown and deformation. Named for Sir James Paget (1814–1899), this disease affects 1 to 3 percent of people over 50 years of age, but affects over 10 percent of people over 80 years of age. Paget's disease is the second most common bone disorder in people over 50 after osteoporosis. It is rarely diagnosed in young adults. Paget's disease can affect one or more bones in the body. Most often, the pelvis, bones in the skull, the long bones (the large bones that make up the arms and legs), and the collarbones are affected. In addition, the joints between bones (e.g., the knees or elbows) can develop arthritis because of this condition.

Normally, cells that break down old bone (osteoclasts) and cells that form new bone (osteoblasts) work in balance to maintain bone structure and integrity. In Paget's disease, more bone breaks down than usual and more new bone forms than usual. These changes in the bone can lead to bone enlargement and deformity. The new bone growth tends to be softer and more fragile than normal bone, and can develop in a haphazard pattern. Because of this, the bone can fracture. The long bones, especially the legs, tend to bow, and the skull may enlarge, particularly over the forehead.

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