Aging changes in the bones - muscles - joints

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Changes in posture and gait are as universally associated with aging as changes in the skin and hair.

The skeleton provides support and structure to the body. Joints are the areas where bones come together. They allow the skeleton to be flexible for movement. In a joint, bones do not directly contact each other. Instead, they are cushioned by cartilage, membranes, and fluid.

Muscles provide the force and strength to move the body. Coordination, although directed by the brain, is affected by changes in the muscles and joints. Changes in the posture and gait, weakness, and slowed movement are caused by changes in the muscles, joints, and bones.

AGING CHANGES

Bone mass or density is lost as people age, especially in women after menopause . The bones lose calcium and other minerals.

The spine is made up of bones called vertebrae. Between each bone is a gel-like cushion (intervertebral disk). The trunk becomes shorter as the disks gradually lose fluid, making them thinner.

In addition, vertebrae lose some of their mineral content, so each bone also becomes thinner. The spinal column becomes curved and compressed (packed together). Bone spurs, caused by aging and overall use of the spine, may also form on the vertebrae.

The shoulder blades (scapulae) and other bones may become porous -- on an x-ray they may look "moth eaten." The foot arches become less pronounced, contributing (slightly) to height loss.

The long bones of the arms and legs, although more brittle because of mineral losses, do not change length. This makes the arms and legs look longer when compared to the shortened trunk.

The joints become stiffer and less flexible. Fluid in the joints may decrease, and the cartilage may begin to rub together and erode. Minerals may deposit in some joints (calcification); this is common in the shoulder.

Hip and knee joints may begin to lose structure (degenerative changes). The finger joints lose cartilage and the bones thicken slightly. Finger joint changes are more common in women and may be hereditary.

Some joints, such as the ankle, typically experience little change with aging.

Lean body mass decreases, caused in part by loss of muscle tissue ( atrophy ). The rate and extent of muscle changes seems to be genetically determined. Muscle changes often begin in the 20s in men and the 40s in women.

Lipofuscin (an age-related pigment) and fat are deposited in muscle tissue. The muscle fibers shrink. Muscle tissue is replaced more slowly, and lost muscle tissue may be replaced with a tough fibrous tissue. This is most noticeable in the hands, which may appear thin and bony.

Muscle tissue changes, combined with normal aging changes in the nervous system , cause muscles to have reduced tone and contractility. Muscles may become rigid with age and may lose tone even if exercised regularly.

EFFECT OF CHANGES

Bones become more brittle and may break more easily. Height decreases, primarily caused by shortening of the trunk/spine.

Inflammation, pain, stiffness and deformity may result from breakdown of the joint structures. Almost all elderly people are affected by joint changes, ranging from minor stiffness to severe arthritis .

The posture may become progressively stooped (bent) and the knees and hips more flexed. The neck may become tilted, and the shoulders may narrow while the pelvis, on the other hand, may become wider.

Movement slows and may become limited. The walking pattern (gait) becomes slower and shorter. Walking may become unsteady, and there is less arm swinging. Fatigue occurs more readily, and overall energy may be reduced.

Strength and endurance change. Loss of muscle mass reduces strength. However, endurance may be enhanced by changes in the muscle fibers. Aging athletes with healthy hearts and lungs may find that performance improves in events that require endurance, and decreases slightly in events that require short bursts of high-speed performance.

COMMON PROBLEMS

Osteoporosis is a common problem, especially for older women. Broken bones occur more readily, and compression fractures of the vertebrae can cause pain and reduce mobility.

Muscle weakness contributes to fatigue, weakness, and reduced activity tolerance. Joint problems are extremely common. This may be anything from mild stiffness to debilitating arthritis (see osteoarthritis ).

Injury risk is greater because of falls related to gait changes , instability, and loss of balance .

Some elderly people have reduced reflexes. This is most often caused by changes in the muscles and tendons rather than changes in the nerves. Decreased knee jerk or ankle jerk is not unexpected.

Some changes, such as a positive Babinski's reflex , are always considered abnormal.

Involuntary movements (muscle tremors and fine movements called fasciculations ) are more common in the elderly. Inactive or immobile elderly people may experience weakness or abnormal sensations ( paresthesias ).

Muscle contractures may occur in those unable to move voluntarily or to have their muscles stretched through exercise. Restless leg syndrome may occur.

PREVENTION

Exercise is one of the best ways to slow or prevent problems with the muscles, joints, and bones. A moderate exercise program can help you maintain strength and flexibility. Exercise helps the bones to remain strong.

Consult with your health care provider before beginning a new exercise program.

A well-balanced diet with adequate amounts of calcium is important. Women need to be especially careful to get enough calcium as they age. Postmenopausal women need 1,200-1,500 mg of calcium per day. If you have osteoporosis, talk to your doctor about prescription treatments.

RELATED TOPICS

• Aging changes in body shape
• Aging changes in hormone production
• Aging changes in organs, tissues, and cells
• Aging changes in the nervous system
• Osteoporosis
• Calcium in diet

Update Date: 11/3/2002