Condition Kit - Osteoporosis
CAN WE WIN THE BATTLE AGAINST OSTEOPOROSIS?
Scope of the Disease
Number and gender of individuals affected
Osteoporosis is a chronic disorder that predisposes individuals to fractures with minimal or no trauma. Approximately 10 million Americans have osteoporosis and about 34 million additional men and women are at an increased risk of developing osteoporotic fractures because of low bone mass, which is 55% of people over the age of 50. Of the 10 million people with osteoporosis, 8 million are women and 2 million are men. (1)
Most women enter the menopause in good general health. Yet, it is at this time that bone loss begins and can eventually lead to fractures at some time in the future. One in three women will have an osteoporotic vertebral compression fracture by age 65 and a hip fracture by age 85. Overall, the lifetime risk of any osteoporotic fracture is approximately 40% for women and 25% for men.
The number of fractures annually due to osteoporosis in the United States is: (1)
· 300,000 hip fractures
· 700,000 vertebral fractures
· 250,000 wrist fractures
· 300,000 fractures at other sites
Mortality and morbidity
The 12-month mortality rate for complications of osteoporotic hip fractures in women is about 25%, which exceeds that for ovarian and uterine cancer combined. Increased mortality also results from vertebral fractures. Every vertebral and hip fracture carries with it a decrease in the quality of life for the individual. Vertebral compression fractures result in loss of height, persistent pain, spinal deformity, involvement of visceral organs, pychosocial issue and a loss of self-esteem. Thus, the decreased quality of life and loss of independence are common complications of women and men with osteoporotic fractures.
Annual direct expenditure for care of patients with osteoporotic fractures exceeds $17 billion dollars (2001) and is predicted to double by 2025. 90% of the expenditures of osteoporosis are related to the costs of treating the fractures. Currently, only 10% is being spent on prevention and treatment of established osteoporosis to prevent additional fractures. (1)
What causes skeletal fragility?
Bone formation and resorption (breakdown) continue throughout our lifetime. This continual cycle of breakdown and renewal permits the skeleton to repair itself and at the same time provide calcium to maintain blood calcium levels within the normal range. Bone formation and resorption are linked to each other and referred to as bone turnover. Peak bone mass is reached in the mid-20's and then maintained over the next 2-3 decades as bone formation and resorption are matched. The maximal bone mass is largely dictated by genetic factors. At the time of menopause, the rates of bone formation no longer match the rates of bone resorption leading to an increased rate of bone loss. In men, bone turnover is balanced until the mid-60's, at which time, bone resorption may gradually increase and cause bone loss. Bone loss is silent, and so osteoporosis only causes symptoms when there are fractures.
Bone density decreases to the point of fracture
Postmenopausal bone loss can be detected early in the menopause using noninvasive bone density scanning. The loss of bone extending over decades causes progressive loss of bone mass and a decline in bone strength. Eventually, the strength of bone can no longer resist the forces placed on it and fractures appear.
Post menopausal and secondary osteoporosis
Bone is lost most rapidly in women after onset of menopause and loss of estrogen and in men who lose testosterone at any time in their lives. In addition to loss of estrogen in women and testosterone in men, several other causes of bone loss can result in osteoporosis and fractures. These include, the effects of a number of medications, and an excess para-thyroid hormone and adrenal steroid hormones.
Life style, diet and physical activity
Osteoporosis can also occur in people who become deficient in vitamin D and in whom calcium intake is poor. Cigarette smoking and excess alcohol decrease bone mass and increase fracture risk.
The lack of physical activity is also a risk factor for this disease. Thus, the predisposition to osteoporosis in adults may commence during childhood and adolescence, when most of the skeleton is formed.
Diagnosis of osteoporosis
Bone Mineral Density (BMD) by dual energy x-ray absorptiometry
Methods developed during the past 25 years have permitted accurate measures of bone density, which are excellent predictors of fracture risk. The most widely used clinical procedure for measuring BMD is a non-invasive, low-energy x-ray based technique that accurately measures the density of the skeleton at the lumbar spine, proximal femur and other skeletal sites.
Continued research in the diagnosis of osteoporosis indicates that BMD is only one contributor to bone strength. Bone architecture, geometry, material properties, the extent of mineralization, and rates of remodeling are also factors that enter into the evaluation of fracture risk. Progress in measuring these aspects of bone metabolism will permit a better estimate of fracture risk.
There are no laboratory tests that are diagnostic of osteoporosis. Measures of bone formation and resorption are useful in monitoring the response to some medications. Several disorders that may cause bone loss and increase fracture risk can be detected by laboratory testing and are therefore useful in evaluating patients with osteoporosis.
Treatment and prevention of osteoporosis
Although estrogen, with or without progesterone, can decrease hip fractures, its use as a treatment for osteoporosis has recently come into question.
Antiresorbing agents (bisphosphonates) decrease fractures at all sites of the skeleton through a decrease in bone resorption. Because of their efficacy in reducing fractures and preventing the recurrence of fractures in those with established osteoporosis, bisphosphonates have become the most widely used agents for osteoporosis prevention and treatment. This group of agents has few side effects and is therefore suitable for long-term use.
Teriparatide, a derivative of a naturally occurring hormone, is the first agent approved by the FDA that stimulates bone formation. Marked increases in bone density are associated with significant decreases in the risk of vertebral fractures. However, teriparatide can have more side effects than the bisphosphonates and is more difficult to administer. Although this approach to the treatment of osteoporosis is novel and holds great promise, more research in this area is warranted.
Prevention of osteoporosis through preservation of bone mass is the best way to avoid fractures. The maintenance of an active life style with regular weight-bearing exercise, maintenance of adequate calcium and vitamin D intake, moderate use of alcohol and avoidance of tobacco slow the rate of bone loss and thereby reduce the risk for fractures. These measures along with medications are the mainstays in the management of fracture risk.
Scientific advances in our knowledge of bone cell function and regulation has offered hope for the millions who now have osteoporosis The possibility that further research will lead to identification of the genetic basis for osteoporosis holds the possibility of a cure of the disease, perhaps by reestablishing normal bone cell function.
Future Research Directions - Areas of Discovery
Advances in osteoporosis will come from several areas of investigation including improved methods for diagnosis of osteoporosis; measurement of the genes that dictate hereditary factors; and more information on the management of nutrition and life-style contributions. Tests to identify those at risk of fracture at an earlier stage of the disease will provide the opportunity to better prevent bone loss. Additionally, research into controlling bone cell function and a better understanding of the mechanics of bone will provide opportunities to prevent osteoporosis and restore bone in those who have lost large amounts of skeleton.
National Osteoporosis Foundation
NIH Osteoporosis and Related Bone Diseases - National Resource Center
Condition Kit on Osteoporosis
Produced by the United States Bones and Joint Decade, NFP, July 2004
(1) National Osteoporosis Foundation
The Progression of Osteoporosis: An Orthopaedist's Challenge
© by Geoff Higgs, MD, photographer
provided by the American Academy of Orthopaedic Surgeons