Charles A. Bertrand, M.D., FACP, DIM-CD (Ret.)
Associate Clinical Professor of Medicine at New York Medical College
and at the Medical University of South Carolina



UNDERSTANDING OSTEOPOROSIS

Osteoporosis is a major national health problem. It is defined as a systemic skeletal (bone) disease characterized by low bone mass and micro architectural deterioration of bone tissue; it leads to increased bone fragility and consequently increased risk to fracture. It affects more than 25 million Americans with women being particularly susceptible. The disease can have serious consequences for both individuals and society. It can devastate quality of life and cause isolation. Osteoporosis-related fractures are responsible for significant morbidity and mortality. In addition, osteoporosis can place a severe financial strain on patients and families, as well as on the health care system.

Osteoporosis is the result of an abnormality in the bone re-modeling process. The mechanisms of bone remodeling are important in understanding bone loss and the development of osteoporosis. Bone remodeling consists of "resorption" and "formation."

Bone cells called "osteoclasts" resorb old bone, creating a cavity on the bone surface (resorption). After the cavity is created, the osteoclasts leave the area and are replaced by other bone cells called "osteoblasts," which fill the cavity with new bone (formation). In patients who develop osteoporosis, the newly formed bone does not completely fill the cavity, thereby resulting in an imbalance between bone resorption and bone formation, leading ultimately to a decrease in total bone mass with associated bone fragility.

As a whole, individuals tend to reach their peak bone mass between the ages of 30-35 years. There are a number of genetic and environmental factors that influence peak bone mass and rate of bone loss. Risk factors for osteoporosis include:

1. Post menopausal status.
2. Thin-small framed build.
3. History of rheumatoid arthritis (independent of medications used in treatment).
4. Family history of osteoporosis.
5. Caucasian race or Asian ethnicity.
6. Medications - most commonly steroids, certain anticonvulsants and excessive thyroid hormone.

In addition, lifestyle factors such as tobacco use, excessive alcohol or caffeine intake, an inactive lifestyle and dietary deficiency of calcium or vitamin D increases the likelihood of developing osteoporosis.

The end result of osteoporosis is a fracture: this can also be the initial presenting symptom. There are over 1.3 million fractures annually at the cost of greater than $10 billion per year due to osteoporosis. The incidence of all osteoporotic fractures increases dramatically with age. The most common areas for fracture are the back (vertebrae) and hip. Vertebral fractures occur at a rate of greater than 500,000 annually. They are associated with a loss of height, back deformity and severe pain. Pain results from collapse of the vertebrae and associated muscle spasm. Multiple areas of collapse result in a deformity of the back known as Dowager’s Hump.

Fracture of the hip is the most catastrophic type of osteoporotic fracture. It is estimated that more than a quarter of a million occur each year. There is an excess mortality of up to twenty percent in patients with hip fracture within one year of the event; approximately fifty percent never fully recover. Of those who do survive, mobility and quality of life are often severely impaired.

Epidemiologic studies indicate that bone mass is the most accurate available predictor of fracture risk. It has been shown that the association between bone mass and fracture risk is stronger than that between serum cholesterol and coronary artery events and that between systolic blood pressure and stroke-associated mortality.

Bone mass testing is therefore useful in establishing a diagnosis of osteoporosis and assessing its severity. A very popular way of measuring bone mass is through the use of a dual-energy x-ray absorptiometry or DEXA. DEXA measures bone mass at clinically relevant sites and offers precision, low radiation and correlation with fracture risk. An ordinary x-ray should not be used to assess bone mass since it may not detect bone loss until thirty percent or more has occurred.

Bone mass measurement should be considered for a patient when it influences a clinical decision. Bone mass measurement should be considered in the following situations:

1. When a risk factor for osteoporosis is present.
2. When there is evidence of vertebral deformity or a history of osteopenia (decrease in bone cells).
3. When there has been a previous fragility fracture.
4. For use in monitoring therapy.

Finally, management of osteoporosis should not begin when a fragility fracture occurs but rather should be looked at as a preventable process. Therapy should begin in our second to third decades of life by trying to obtain our highest peak bone mass possible. In addition, physical exercise not only helps to prevent bone loss but also promotes mobility, agility, and muscle strength to prevent falls. Conditions that contribute to falling - postural hypotension (low blood pressure), poor vision, and arthritis should be treated, and drugs that affect equilibrium should be avoided. Hazards in the home - loose throw rugs, exposed cords and slippery floors - should be eliminated (many falls causing hip fractures occur indoors).

Nutritional supplementation with calcium and vitamin D is recommended and, finally, pharmacologic therapy.

The mainstay of pharmacologic therapy begins with early hormonal replacement therapy - with estrogen. This both prevents bone loss as well as enhancing bone formation. If estrogen replacement therapy is contraindicated for some reason and the patient demonstrates significant bone loss based on bone density measurement, medications which are anti-resorptive - such as bisphosphonates (e.g. Olendronate) - or calcitonins - should be instituted.

The advice provided on this website is intended to be general in nature and should not be relied upon for specific treatment. If you need personal medical attention please contact your physician.