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This chapter addresses the following Geriatric Fellowship Curriculum Milestones: #14, #16, #29, #42, #52, #53


Learning Objectives

  • Identify the biomechanical factors that affect mobility.

  • Recognize the factors that determine the performance of mobility tasks.

  • Determine the biomechanical factors that are amenable to intervention.

Key Clinical Points

  1. Patients need to know they should avoid falling directly onto their greater trochanter—it is a major cause of hip fracture on a hard surface.

  2. Maintenance of adequate muscle strength reserve, and, at times, the ability to deploy this strength rapidly enough are crucial for many mobility tasks.

  3. Walking speed is a powerful predictor of patient outcomes.


Problems with mobility in older adults are common. In the United States, among noninstitutionalized persons 65 years and older, approximately 13% have difficulty in performing activities of daily living. Approximately 9% have difficulty with bathing, 8% have difficulty with walking, and 6% have difficulty with bed or chair transfers. The rate at which these problems occur increases progressively after the age of 65 years and climbs sharply after the age of 80 years, so that, for example, more than 34% of noninstitutionalized persons who are 85 years or older have mobility problems.


Perhaps the most serious problem of mobility impairment is the tendency of older adults to fall and to be injured by falls. Death rates from falls per 100,000 persons in 1999 were 9.1 for those between 65 and 74 years, 31.7 for those between 75 and 84 years, and 109.7 for those 85 years or older. For comparison, in those aged 75 years and older, the death rate from falls (67.9 per 100,000) is more than double that from motor vehicle accidents (29.8 per 100,000). Falls and fall injuries are of substantial concern because of their frequency and because of their physical, psychological, and social consequences. Even a fall that does not result in injury can have a substantially adverse effect on an older person’s self-confidence, mobility, and independence. Indeed, fear of falling, which can accompany decreased mobility, can lead to decreased physical activity outside and avoidance of social activities because of the possibility of embarrassment as well as injury in connection with a fall.

Older females are substantially more prone to fall and to be injured in a fall than are older males. Three studies of rates of falls, involving more than 4500 adults ages 65 years or older, found those rates to range from 137 to 690 falls per 1000 persons per year, with older females falling from 1.3 to 2.2 times more often than older males. Three studies of rates of fall injuries requiring medical attention, involving more than 38,000 adults, found that fall injuries leading ...

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