geriatrics
Gait Disorders in Older Adults
Normal Age Related Changes in Gait
Some elements of gait normally change with aging; others do not. Gait velocity(speed of walking) remains stable until about age 70; it then declines about 15%/decade for usual gait and 20%/decade for fast walking. Gait velocity is a powerful predictor of mortality—as powerful as an older adult's number of chronic medical conditions and hospitalizations. After age 75, slow walkers die ≥ 6 years earlier than normal velocity walkers and ≥ 10 years earlier than fast velocity walkers. Gait velocity slows because older adults take shorter steps at the same rate (cadence). The most likely reason for shortened step length (the distance from one heel strike to the next) is weakness of the calf muscles, which propel the body forward; calf muscle strength is substantially decreased in older adults. However, older adults seem to compensate for decreased lower calf power by using their hip flexor and extensor muscles more than young adults. Cadence(reported as steps/minute) does not change with aging. Each person has a preferred cadence, which is related to leg length and usually represents the most energy-efficient rhythm. Tall people take longer steps at a slower cadence; short people take shorter steps at a faster cadence. Double stance time(ie, time with both feet on the ground during ambulation—a more stable position for moving the center of mass forward) increases with age. The percentage of time in double stance goes from 18% in young adults to≥26% in healthy older adults. Increased time in double stance reduces the time the swing leg has to advance and shortens step length. Older adults may increase their double stance time even more when they walk on uneven or slippery surfaces, when they have impaired balance, or when they are afraid of falling. They may appear as if they are walking on slippery ice. Walking posturechanges only slightly with aging. Older adults walk upright, with no forward lean. However, older adults walk with greater anterior (downward) pelvic rotation and increased lumbar lordosis. This posture change is usually due to a combination of weak abdominal muscles, tight hip flexor muscles, and increased abdominal fat. Older adults also walk with their legs rotated laterally (toes out) about 5°, possibly because of a loss of hip internal rotation or in order to increase lateral stability. Foot clearance in swing is unchanged with advancing age. Joint motionchanges slightly with aging. Ankle plantar flexion is reduced during the late stage of stance (just before the back foot lifts off). The overall motion of the knee is unchanged. Hip flexion and extension are unchanged, but the hips have increased adduction. Pelvic motion is reduced in all planes. 