Bones, joints, and muscles

What is osteoporosis?

Osteoporosis, meaning "porous bone," is a disease characterized by low bone mass and the deterioration of bone tissue. Structural integrity of trabecular bone is impaired, and bone becomes more brittle. Cortical bone becomes more porous and thinner. While thinner bone itself is not more prone to breakage, bone that is both thinner and more brittle is more susceptible to fracture.¹

A major health concern among post-menopausal women, osteoporosis is a condition that has the potential to lead to chronic pain, broken bones, disability, and spinal deformity. Although patients experience no symptoms in the early stages of the disease, osteoporosis, over time, can lead to a high degree of net bone loss. Bones become fragile and more likely to break. Weakening or thinning of bones means that even during normal activities or minor falls, those with osteoporosis are more susceptible to fracture, particularly in the wrist, hip, or spine.²

Because osteoporosis significantly impedes mobility, it can give rise to other diseases linked to physical inactivity.

Spinal deformity occurs because the body of the vertebrae in the spine thins as a result of what is known as trabecular bone collapse. Other spinous processes, however, do not collapse, and it is the inconsistency that leads to curvature of the spine. In addition, crush fractures and wedge fractures occur in the vertebrae, also leading to curvature of the spine, loss of height, severe back pain, and deformity.³

Who's at risk?

Although women are four times more likely to develop osteoporosis, men also suffer from the disease. Osteoporosis affects approximately 55 percent of adults aged 50 or older. Certain people are more likely to develop osteoporosis than others. Risk factors include:⁴

• personal history of fracture after age 50
• low bone mass
• gender—nearly 80 percent of those affected by osteoporosis are women.
• being thin or slight of build
• advanced age—osteoporosis affects people over the age of 50.
• family history of osteoporosis
• estrogen deficiency as a result of menopause
• abnormal absence of menstrual periods
• anorexia nervosa
• low lifetime calcium intake
• vitamin D deficiency
• use of certain medications, such as corticosteroids and anticonvulsants
• presence of certain chronic medical conditions
• sedentary lifestyle
• smoking
• excessive alcohol consumption
• race and ethnicity—women of Asian or European extraction are more likely to develop osteoporosis, while Black women are less likely to be affected

Types of osteoporosis

Osteoporosis may be characterized as being either primary or secondary. Primary osteoporosis can occur in both men and women at all ages, but it most commonly affects post-menopausal women. Secondary osteoporosis, on the other hand, is the result of medications or pre-existing medical conditions or diseases such as glucocorticoid-induced osteoporosis, hypogonadism, hyperthyroidism, and celiac disease.⁵

The remodeling of bones occurs throughout adult life. Osteoclasts resorb old bone while osteoblasts create new bone. Working in concert, these cells continuously renew the skeleton and maintain bone strength and density. However, in post-menopausal women, as hormone levels decline, osteoclasts resorb old bone faster than osteoblasts replace it. In other words, post-menopausal bone loss is the result of an increase in both the number and the activity of osteoclasts.⁶

Prevention of osteoporosis

Most women will have acquired 98 percent of their skeletal mass by about age 20. Therefore, building strong and healthy bones during childhood and adolescence is the best defense against developing osteoporosis later in life. Diet and regular exercise are vital to the development of strong bones. Diet should be rich in calcium and vitamin D. Physical activity that includes weight-bearing exercise and a healthy lifestyle with no smoking and alcohol in moderation are also important. Bone density testing and medication when appropriate can also help ensure bones remain healthy.⁷

Diagnosis and treatment of osteoporosis

Bone density tests can assist your doctor in detecting osteoporosis. Such tests measure bone density in various sites of the body and can help detect osteoporosis before a fracture occurs. These tests can also help predict your likelihood of developing fractures in the future and can also determine your rate of bone loss.⁸

Although currently there is no cure for osteoporosis, the following medications have been shown to be effective in the prevention and/or treatment of osteoporosis in post-menopausal women:⁹

• bisphosphonates such as Fosamax® and Actonel®
• calcitonin, also known under the name Miacalcin®
• estrogen or hormone therapy which includes:
  • estrogens such as Climara®, Estrace®, Estraderm®, Estratab®, Ogen®,Ortho-Est®, Premarin®, and Vivelle®
  • estrogens and progestins such as Activella™, FemHrt®, Premphase®, and Prempro®
• parathyroid hormone such as Teriparatide (commonly known as Fortéo®)
• selective estrogen receptor modulators (SERMs) such as Raloxifene (commonly known as Evista®

Osteoporosis requires more than simply balanced hormones. While prevention is the most important step, women of all ages should be encouraged to increase their daily intake of calcium, taking between 1000 and 1500 mg of supplemental calcium every day. Regular weight-bearing exercise and the avoidance of medications known to compromise bone density are also recommended. As with prevention, treatment of osteoporosis involves smoking cessation and only moderate intake of alcohol.¹⁰

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1. What is Osteoporosis? ProjectAWARE.org. (2003)
2. What is Osteoporosis? Osteoporosis in the Older Person. University of Ottawa.
3. Osteoporosis in Trabecular Bone. Hansma Research Group, Department of Physics, University of California, Santa Barbara (2003)
   
4. Disease Statistics. National Osteoporosis Foundation. (2004)
   What is Osteoporosis? ProjectAWARE.org. (2003)
5. What is Osteoporosis? ProjectAWARE.org. (2003)
6. What is Osteoporosis? ProjectAWARE.org. (2003)
7. Disease Statistics. National Osteoporosis Foundation. (2004)
8. Disease Statistics. National Osteoporosis Foundation. (2004)
9. Disease Statistics. National Osteoporosis Foundation. (2004)
10. What is Osteoporosis? ProjectAWARE.org. (2003)