Bone and Fall-Related Fracture Risk

Fig. 13.1

Risk factors for a fracture

The risk of falling increases with the number of prevalent risk factors and with a history of previous falls. An important point is that half of the subjects who have fallen have fear to fall again, and one quarter reduces daily activities because of this fear [2, 10] which has a negative impact on social life and physical fitness which again increases the risk of falling and fall-related fractures (Fig. 13.2).

Fig. 13.2

Consequences of a fall

Physiology of Balance and Postural Strategies

To maintain balance during everyday activities, it is necessary to keep the body’s center of gravity over its base of support during upright standing, movement, and walking. Balance is regulated and controlled via interplay of the sensory and motor systems. The central nervous system (CNS) steadily receives information from visual, acoustic, vestibular, and proprioceptive perceptions. This afferent component of the sensory-motor system leads the CNS to induce continuous reactive efferent mechanisms, changes of the motor system. Thus, postural control underlies a continuous feedback mechanism.

Since the regulation is very complex, it is susceptible to flaws. With increasing age we experience a decline in all components of this mechanism. Loss of vision and hearing and a decline in several peripheral receptors reduce the input to the CNS. The age-associated loss of muscle mass and function has an impact on the efficacy of the efferent part of this sensory-motor system. The CNS also underlies age-associated loss of function, and the vigilance of the superior management system is often reduced because of interfering factors like pain or fear. Additionally, an increase of the thoracic kyphosis, shortening or weakness of some muscles, and reductions in hip and knee extension lead to a displacement of the center of gravity; it is shifted forward. All these age-related changes lead to deficits in balance with increased swaying and to more complex postural reactions compared to subjects at younger age.

In young subjects, small disturbances of balance lead to an activation of the muscular activity in the ankle region (i.e., ankle strategy); older people tend to activate muscles in the hip region (i.e., hip strategy) [2, 10]. If it is not possible to regain balance with these postural strategies, one has to take a step. Elderly have to do so at a lower amount of perturbation, and older subjects have to take multiple smaller steps to restore balance, whereas younger subjects respond by a compensatory single step [10]. Apart from anterior-posterior perturbations, disturbances of the equilibrium in the lateral direction have been investigated [11]: Young subjects responded with large roll movements of the trunk in the opposite direction of the tilt platform and abduction of the ipsilateral arm to keep the center of gravity over their base of support. In the elderly, trunk roll was in the same direction as support-surface motion with abduction of the arm in the direction “downhill,” making elderly subjects more prone to losing control of their balance.

A large proportion of falls in the elderly occur while walking, a balance-displacement activity. Older adults may be less capable of weight shifting, and, thus, the gait tends to be stiffer with slower velocity, increased double support time, and smaller steps. Another important point leading to an increased risk of falling induced by an unevenness of the ground is that the minimum foot clearance (distance between lowest point of the foot of the swing leg and the ground) is lower and shows a higher variability during walking in elderly compared to younger men [12, 13].

Screening and Fall Risk Assessment

A key component in preventing falls is the identification of important factors which may increase the risk of falls. An assessment of fall risk should be integrated into the history and physical examination of all geriatric patients, including those not specifically being seen for a problem with falling [14]: All older patients (65 years and more of age) should be asked at least once a year about falls, frequency and circumstances of falling. Older individuals should be asked about difficulties with walking or balance. Older persons presenting with a single fall should be evaluated for gait and balance. A multifactorial fall risk assessment should be performed for community-dwelling older persons who cannot perform a standardized gait and balance test or who report recurrent (two or more) falls in the past year or who report difficulties with gait or balance or who seek medical attention or present to the emergency department because of a fall.

Multifactorial Fall Risk Assessment

The multifactorial fall risk assessment should be performed by a clinician (or clinicians) with appropriate skills and training. It should include a comprehensive history, a physical examination, a functional assessment, and an environmental assessment (Fig. 13.3).

Fig. 13.3

Prevention falls algorithm. Adapted from: The Prevention of falls in Older Persons: Clinical Practice Guideline from the American Geratrics Society. www.americangeriatrcs.org

Several studies report that the most important consideration in the history is a previous fall, which places the patient at increased risk of future falls. For patients presenting with a fall, important components of the history include the activity of the faller at the time of the incident; prodromal symptoms, like lightheadedness, imbalance, and dizziness; and where and when the fall occurred. Loss of consciousness is associated with injurious falls and may be caused by orthostatic hypotension, cardiac disease, or neurologic disease. Identification of underlying chronic diseases that increase fall risk is important. Examples of these age-related chronic conditions include Parkinson disease, chronic musculoskeletal pain, knee osteoarthritis, dementia, stroke, and diabetes.

Information on previous falls should be collected to identify patterns that may help target risk factor modification strategies. A complete medication history should be taken, with specific focus on psychotropic medications, sedative hypnotics, antidepressants, and antihypertensive medications. Timing of medication administration and alcohol use to past falls should be determined. Environmental factors that may have contributed to the fall should also be identified; information on lighting, floor covering, door thresholds, railings, and furniture may add important clues.

The physical examination should include neurologic and joint functions, muscle strength, cardiovascular status, vision, the feet, and footwear. The most important aspect of the physical examination in the patient who has fallen is an assessment of integrated musculoskeletal function. This can be obtained by performing one or more tests of postural stability.

Tests of Postural Stability

The “Get Up and Go” test is one of the best known tests. A 2013 meta-analysis of 53 studies (n = 12,800) showed a mean difference of 3.59 s between institutionalized fallers and non-fallers [15]. However cutoff points distinguishing fallers from non-fallers showed considerable variation between the studies. The test is best used as part of a global assessment of an individual’s fall risk. In practical terms, the observation of deficiencies in various individual components may isolate areas for targeted intervention. The test is performed by observing the subject rising from a standard arm chair, walking a fixed distance of 10 ft. (3 m) across the room, turning around, walking back to the chair, and sitting back down. Observation of the different components of this test may help to identify deficits in leg strength, balance, vestibular dysfunction, and gait. The timed part of the test records the mean time (in seconds) from initial getting up to reseating. Patients are compared to the mean time of adults in their age group [16] (Table 13.1).

Table 13.1

Reference values for the Timed Up and Go Test

Age (years)	Mean time (s)
60–69	8.1 (7.1–9.0)
70–79	9.2 (8.2–10.2)
80–99	11.3 (10.0–12.7)

Bohannon RW. Reference Values for the Timed Up and Go Test: A descriptive metaanalysis. J Geriatr Phys Ther 2006; 29(2):64–8 [16]

The “Performance Oriented Mobility Assessment tool (POMA or Tinetti Assessment Tool)” is a scored instrument that assesses balance and gait, using an ordinal scale from zero to two (“0” for the most impaired performance, “1” if slight impairment, and “2” if independent) [17]. The items range from being able to maintain balance when someone slightly pulls on an individual to walking normally with assessment of step continuity and path deviation. No reliable cut point has been established for the POMA score in the prediction of falls.

The “Functional Reach” test is another practical approach to testing integrated neuromuscular base of support that has predictive validity for falls [18]. Functional reach is the maximal distance one can reach forward beyond arm’s length while maintaining a fixed base of support in the standing position. The individual makes a fist and extends the arm forward as far as possible without taking a step or losing balance. The total reach is measured along the yardstick and recorded. In its original description, the functional reach correlated with other physical performance measures, including walking speed, tandem walking, and standing on one foot.

The “Short Physical Performance Battery (SPPB)” characterizes lower extremity function [19]. It includes measures of standing balance (timing of tandem, semi-tandem, and side-by-side stands; four-meter walking speed and ability; and time to rise from a chair five times). The SPPB captures a wide range of functional abilities, and summary scores <9 have independently predicted disability in ADL and mobility at one to 6 years of follow-up and are also predictive of falls.

Other tests are the “Berg Balance test.” It is performed easily in the rehabilitation setting or outpatient clinic [20]. The scale predicted risk of multiple falls in older patients in one study. A more comprehensive performance-oriented assessment of balance includes measures of sitting and standing balance, ability to withstand a nudge on the sternum, and ability to reach up, bend down, and extend the back and neck. Each of these performance measures attempts to identify components of postural stability that complement the standard physical examination. Difficulty in performing divided attention tasks such as “walking while talking” may also identify individuals at high risk for falling. A preliminary study in 60 older people found that those who had difficulty walking while reciting the alphabet or walking while reciting every other letter of the alphabet were at significantly increased risk for falls (odds ratio [OR] 7.02 and 13.7, respectively) [21].

General Physical Examination

Other aspects like orthostatic hypotension should be excluded. The blood pressure and heart rate should be taken supine and after one and 3 min of standing. Some information may be derived from sitting vital signs if the patient is unable to stand. An assessment of visual acuity should be performed. Hearing may be assessed using the whisper test or a handheld audiometer. Eighth cranial nerve deficits may be associated with vestibular dysfunction. Examination of the extremities may uncover deformities of the feet that contribute to the risk of falling, such as bunions, callouses, arthritic deformities, and sensory neuropathies. A targeted neurologic examination including evaluation of lower extremity strength, gait, and postural stability may identify persons with an increased risk of falls. Individuals who report a history of falls in the past year tend to have a greater number of abnormalities on a neurologic examination [22]. Leg weakness may increase the risk of falling by more than fourfold.

Diagnostic Testing

Diagnostic testing may be indicated based upon the history and physical examination, including evaluation of postural stability, gait, and mobility. There is no standard diagnostic evaluation of an individual with a history of or at high risk for falls. Only balance problems can be tested by posturography. Laboratory tests such as a hemoglobin concentration and serum urea nitrogen, creatinine, and glucose concentrations can help to rule out causes of falling such as anemia, dehydration, and neuropathy related to diabetes. Serum 25-hydroxyvitamin D levels can identify individuals with vitamin D deficiency who will benefit from vitamin D supplementation. There is no proven value of routinely performing ambulatory cardiac monitoring in individuals who have fallen. Similarly, the decision to perform echocardiography, brain imaging, or radiographic studies of the spine should not be considered routine, but should be driven by findings during the history and physical examination.

Preventing Falls

In general, evidence suggests that interventions individually tailored to target risk factors and impairments are more effective than those applied as a standard package [23].

In reviewing the studies of fall prevention, many trials use the number of fallers in active versus placebo groups, whereas other studies use the rate of falls in the active versus placebo groups. Since individuals who sustain multiple falls have a different risk profile than individuals who sustain a single fall, it seems more relevant to clinical practice to favor those studies that examined fall rates as the outcome [24]. A 2012 systematic review evaluated 159 randomized trials of interventions to reduce the incidence of falling and involved 79,193 older persons living in the community [25]. Authors concluded that group- and home-based exercise programs and home safety interventions reduce rate of falls and risk of falling in community-dwelling elderlies. Exercise both reduces risk of falls and prevents injuries related to falls. In care facilities, mostly vitamin D supplementation is effective in reducing the rate of falls [26]. Exercise in subacute hospital settings appears effective, but its effectiveness in care facilities remains uncertain due to conflicting results, possibly associated with differences in interventions and levels of dependency. There is evidence that multifactorial interventions reduce falls in hospitals, but the evidence for risk of falling was inconclusive. Evidence for multifactorial interventions in care facilities suggests possible benefits.

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