Osteoporosis: Are you at risk from brittle bone disease?

As the disease is “silent” it is often first identified as the result of a fracture from a fall. Research has shown that osteoporosis is the most common type of bone disease. In the USA around 15-20m people are affected by the disease and over 1.5m fractures per year in people of over 50 are attributable to the disease.¹

Osteoporosis is characterised by a low bone mass and deterioration of the bone tissue. Over time this leads to the bone becoming fragile and weaker which in turn increases the risk of fractures. In simple terms the disease drains the bones of their mineral content (calcium and phosphate) and increases their susceptibility to fractures.²

Osteoporosis - the facts and figures

• Osteoporosis affects 44m Americans, 68% of whom are women.
• One in two women and one in eight men over the age of 50 will have an osteoporosis-related fracture in their lifetime.
• Osteoporosis is responsible for more than 1.5m fractures annually.
• Estimated national direct expenditures (hospitals and nursing homes) for osteoporosis and related fractures are 14bn each year. ¹⁴

Researchers estimate that about 20% of American women over the age of 50 have osteoporosis. In addition, another 30% of them have osteopenia, which is abnormally low bone density that may eventually deteriorate into osteoporosis if not treated. About half of all women over the age of 50 will suffer a fracture of the hip, wrist, or vertebra.⁴
Primary osteoporosis – bone loss attributed to ageing – may occur in two types:

• Type I osteoporosis (post-menopausal): The accelerated reduction in bone mass – 3 to 7% per year for five years – occurs after menopause when oestrogen levels decrease.
• Type II osteoporosis (age-related): The inevitable loss of bone mass that occurs with age in both men and women.

Secondary osteoporosis may develop at any age as a consequence of hormonal, digestive and metabolic disorders as well as prolonged bed rest.⁶

Osteoporosis affects both men and women although it is more common in women. One out of every four women over the age of 60 suffers from the disease and half of all women who have had a hysterectomy will develop the condition. According to the National Osteoporosis Foundation, the disease is so pervasive among females that the risk of developing an osteoporosis-related facture is equal to a woman’s combined risk of developing breast and ovarian cancer.⁷

Often in the early stages of osteoporosis there are no symptoms and it is not until people reach their 60s and 70s that obvious signs appear. Symptoms occurring late in the disease include:

• Fractures of the vertebrae, wrists, or hips (usually the first indication)
• Lower back pain
• Neck pain
• Bone pain or tenderness
• Loss of height over time
• Stooped posture causing kyphosis, often called Dowger’s Hump

These have a profound effect on the quality of life of older adults and sufferers are sadly at risk of losing their independence and suffering psychologically.⁸

Osteoporosis and bone development

Bone is a living tissue with a rich supply of minerals such as calcium and phosphorous which are essential for normal bone growth. As bones form there is a delicate interplay between bone formation and bone resorption (loss). In healthy individuals bone eroding cells called “osteoclasts” are constantly being removed from the bone tissue while new bone cells called “osteoblasts” are being made. If the delicate balance between bone formation and resorption is altered and more bone is lost than is formed, osteoporosis will occur. Usually, this loss occurs gradually over a period of years and a person will sustain a fracture before becoming aware that the disease is present. By the time this occurs, the disease is in its advanced stages and the damage is profound.

Two types of bone tissue

There are two types of bone tissue in the human body: trabecular (cancellous) bone and cortical (compact) bone. Cortical bone is relatively dense and solid and forms the shaft of long bones such as the femus and humerus. Trabecular bone, or spongy bone, is much less dense and is found in the ends of the long bones.

Bone health in adults

There are two mechanisms that determine bone health in adults. These are peak bone mass, which is achieved during growth and into early adolescence, and the rate of bone lost with advancing age – with the menopausal period being a time of considerble concern for women.⁹

During the perimenopausal period osteporosis affects mainly the trabecular bone which predisposes it to compression fractures of the vertabrea and also fractures of the wrist after a fall. In older adults there is a progressive loss of both trabecular bone and compact bone which predisposes to hip fractures.⁵

Osteoporosis - risk factors

Some people are more likely to develop osteoporosis as they are predisposed to certain risk factors that are likely to increase their risk of the development of the disease.

Non-modifiable risk factors for osteoporosis

• Age
• Gender
• Body size
• Ethnicity
• Genetics

Modifiable risk factors for osteoporosis

• Hormonal levels, particularly low estrogen
• A diet low in calcium and vitamin D
• Lack of weight-bearing physical activity
• Having an eating disorder such as anorexia
• Medications such as glucocorticoids or anticonvulsants
• Cigarette smoking
• Excessive use of alcohol¹⁵

Treatments for osteoporosis

Treatments for osteoporosis focus on slowing down or stopping bone loss, preventing bone fractures by minimising the risk of falls, increasing calcium intake, and controlling pain associated with the disease and exercise.
Exercise can benefit the skeleton and reduce the risk of osteoporosis by:

1. Increasing bone mass through adolescence which will result in higher bone mass levels through the lifespan.
2. Improving and maintaining bone density during early childhood.
3. Reducing or slowing the rate of age-related loss during middle/older age.

As early as 1892 Julius Wolff described how changes in the internal structure of human bone was directly related to the amount of stress placed on it. He theorised then that load-bearing activites would have a positive effect on the shape, size and thickness of the bone tissue. Placing mechanical stress on bone tissue seems to stimulate osteoclast activity but as long as this remains well coordinated with osteoblastic activity, the bone will become strengthened along the lines where the stress has been applied.¹¹

The benefits of exercise as an integral part of a healthy lifestyle contributes positively to the treatment and rehabilitations of many medical and psychological conditions.¹²

As muscle mass, strength and coordination all decline with age so the risk of falls increases. Exercise programmes that improve muscle strength and neuromuscular coordination will help develop static and dynamic posture. Participation in exercise activities, which will increase muscle strength, improve neuromuscular coordination, balance and flexibility will significantly improve the everyday function of the older adult.¹³

Osteoporosis is a crippling disease and the foundations for building bone strength and health begin early in life and it is important that children are encouraged to be active during their adolescent years. Resistance training activities will increase strength and coordination and reduce the risk of falls and fractures in later life.

References

1. Layne JE, Nelson ME (1999) The Effects of Progressive Resistance Training on Bone Density: A Review, Medicine & Science in Sport & Exercise 31:25-30.
3/5/9. Spirduso WW, Francis KL, MacRae PG (2005) Physical Dimensions of Aging.
4/8. www.nln.nih.gov.medlineplus
6/7. Sato M et al (1999), Emerging Therapies for the Prevention and Treatment of Postmenopausal Osteoporosis, Journal of Medicinal Chemistry 42:1-24.
10. National Osteoporosis Foundation USA (1999) Information (800) 223-9994
Katz WA., Sherman C (1998) Osteoporosis: The role of Exercise in Optimal Management. The Physician and Sports Medicine 26:33-41
11. Shepherd RJ, Aging Physical Activity and Health.
12. Young & Harris: Royal College of Physicians, Physical Activity for Patients.
13. IDEA Health & Fitness Resource Series, Exercise for the 50+ Adult.
14. National Institute of Health Osteoporosis and related Bone Disease, National Research Centre.
15. Spirduso, Francis, Macrae (2005) Physical Dimensions of Aging.

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