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Osteoporosis is the result of a progressive decrease in bone density, leading to skeletal weakness. During normal bone disposition, the ratio of bone formation to absorption is approximately equal. As you age, this balance is disturbed and the rate of absorption exceeds that of formation, resulting in a fall in bone mass. However, there is no associated decrease in bone mineralisation.
As we age osteoblast (bone forming cells) activity normal decreases. Women also experience an increase in osteoclast (bone absorbing cells)activity due to a decrease in estrogen, which comes about post-menopause. Men who suffer a premature decrease in testosterone levels many also experience an increase in osteoclast activity. These changes will further add to the loss of bone mass.
Eventually, the amount of bone available is not sufficient to support your weight and fractures, especially to the neck of the femur may result following very minimal or no trauma. Many cases have been seen when an elderly lady gets out of bed and suddenly falls, due to her femur fracturing when she stood up.
Peak bone mass occurs in the mid-to-late 30’s and there after remains constant for roughly 10 years. After this period net bone loss occurs at about 0.3 to 0.5% every year. However, following menopause the rate of bone loss in women increases to about 3 to 5% each year for the first 5 to 7 years.
The main clinical significance of this condition is fractures, which will eventually lead to chronic pain. Bone density can be measured by means of a bone biopsy and so medical professionals will be able to predict a fracture. Falling increases the risk of sustaining a fracture, thus the high frequently of elderly people who fracture their femur. Since most elderly people have poor vision, co-ordination and balance, muscle weakness and are confused. Hip pads are often used to try and help prevent fractures from occurring due to a fall. An increase in daily physical activity may help increase bone density, leading to increased stability and muscle strength, while immobilization has been found to decrease bone mass. People who suffer osteoporosis tend to be lean, weigh less and have less muscle bulk. A deficiency of calcium, phosphorus and vitamin D is associated with age-related osteoporosis. The body’s acid-base balance also regulates bone loss. Other factors that decrease bone mass are late menarche (first period), early menopause, never giving birth, caffeine, alcohol and cigarette consumption. Racial trends have also been found: being less common in African and Latin-Americans and more common in Caucasians. Men also have a higher bone density than women.
Hormones in the body control osteoblasts and osteoclasts activity. Levels of cytokines (a hormone) increases with a decrease in estrogen during perimenopause, leading to an increase in differentiation and activation of osteoclasts.
Non-complicated osteoporosis may be asymptotic (no clinical signs) or the individual may experience pain in bones and muscles, especially of the lower back due to abdominal stress. This may eventually lead to vertebral crush fractures from mid-thorax downwards.
When clinical features do appear pain has an acute onset and does not radiate to the limbs. However, it may be aggravated on standing or walking and local tenderness may be felt which gradually begins to subside within a week. However, pain may be felt anywhere for up to 3 months or longer. If a compression fracture occurs the patient will eventually develop and thorax ‘hump’.
Other fractures, which occur due mainly to a fall, are of the hip and the lower part of the forearm.
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