Geriatrics: Aging changes in the bones - muscles - joints

Alternative Names:
Osteoporosis and aging; Muscle weakness associated with aging

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 and become thinner.
• In addition, vertebrae lose some of their mineral content, making each bone 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 to slight loss of height.
• 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.