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14 Articles in Volume 18, Issue #2
Ask the Expert: Is there evidence to prescribe cyclobenzaprine long-term?
Challenging the Chronic Pain Personality Profile
Designer Peptide May Prevent Chemo-Induced Neuropathy
Inside the Cancer Pain Research Consortium
Intrathecal Drug Therapy for Cancer-Related Pain
Managing Cancer Pain in an Era of Modern Oncology
Mapping Complex Pain: A Case Study
Medication Overuse Headache: Inaccurate and Overdiagnosed
Pain and Fall Risk in the Elderly
Reporting Quality of Care in Cancer Pain Management
Sharing the Risk: An Update to DEA & Doctors Working Together
The Intensifying Conflict Between Opioid Control and Pain Control
Two Mobile Apps Aim to Target Patient Compliance & Safety
Why Prescribers Need to Adopt Abuse-Deterrent Opioids

Pain and Fall Risk in the Elderly

Assessment and plan of action may prevent further injury among the 65-and-over population.

Approximately a half-century ago, physiology professor Barry Wyke gave a lecture to the Royal College of Surgeons of England on “The Neurology of Joints.”1 His seminal work identified four primary types of mechanoreceptors in synovial joints and their respective roles in both static and dynamic posture and motor control. Today, physicians continue to use Wyke’s research, as well as that promulgated more recently by Donald E. Ingber, MD, PhD, founder of Harvard’s Wyss Institute for Biologically Inspired Engineering, in their daily practice. Ingber’s research has focused on mechano-biology, or rather, the transduction of mechanical forces into biochemical responses.2 Both repositories of work are crucial to current understanding of joint and muscle neurophysiology, including how biomechanical concepts translate to the maintenance and care of the human body, and prevention of falls. This article relies heavily on the constructs by Wyke and colleagues to describe how pain and swelling may short-circuit strength and lead to painful falls.

Epidemiology & Prevalence of Falls

Falls among the elderly represent a major health risk worldwide. When they occur, falls can be costly, in both healthcare treatment and in resulting, lingering pain. Approximately one-third of seniors over age 65 experience a fall; this percentage rises with age to affect more than 50% of seniors over age 80.3 The rates are higher for those age-matched counterparts residing in assisted living or nursing homes.

Approximately 10% of falls that take place in individuals 65 years and older are serious enough to interfere with mobility and independence.4 As humans age, the number of fall-related risk factors tends to increase, shifting the probability in favor of falling, with fall incidences correlating strongly with age.5 Both musculoskeletal (MSK) and non-musculoskeletal originated pain may contribute to fall risk. Pain, with or without associated swelling from inflammation, may also short-circuit other crucial movement related parameters, such as strength, joint stability, flexibility, and reflexive balance.6

In fact, falls account for 40% of all injury related deaths worldwide.7-9 The actual rates vary by country and studied population. Fall fatality rate for people age 65 and older in the United States, for example, is 36.8 per 100,000 (46.2 for men and 31.1 for women),7 compared to Canada where the mortality rate for the same age group is 9.4 per 100,000.8

Rates of fatal falls among men exceed that of women for all age groups, despite fewer occurrences of falls. This statistic may be attributed to the fact that men in general suffer from more comorbid conditions than women of the same age.7 For example, while the incidence of hip fracture is greater among women, hip fracture mortality is higher among men.10,11

Incidence of some fall injuries, such as fractures and spinal cord injury, have markedly increased by 131% during the past three decades.12 If preventive measures are not taken, this number is projected to be 100% higher by the year 2030.13

Fall-Risk Domains

There are several identified fall-related risk factors that lie in either the causal pathway or are closely associated with a greater likelihood of falling. These factors may be linked to, or modified by, the presence of chronic, severe pain. The World Health Organization’s (WHO) report14 on falls prevention in older age presents a risk-factor model that identifies four domains as having a role in a fall episode:

  • Behavioral Risks involve considerations in which a person has direct control and may self-intervene (eg, use of certain medications, alcohol, or recreational drugs; physical activity; and footwear). With regard to medications, certain sedatives, narcoleptics, opiates, and central nervous system depressants or antidepressants may adversely affect cognition and attention in a way that makes daily activities more risky.
  • Environmental Risks include lighting, stairs, wet floors, and trip hazards, as well as poor building design (eg, cracked sidewalks and slippery surfaces).
  • Biological Elements encompass determinants such as age and gender, as well as certain comorbidities (eg, arthritis, diabetes, pulmonary disease, vertigo, migraine) and one’s cognitive status pose strong contributors to a fall.
  • Socioeconomic Status involves low income, lack of education, social isolation, healthcare access barriers, and inadequate housing.14,15

Considering all of these factors, practitioners may develop a greater appreciation for the need to assess patient risk and intervene, as needed, with an effective, comprehensive fall prevention program. All four categories should be adequately addressed as part of a patient assessment/evaluation. Some physicians may choose to outsource this type of plan development to a physical therapy clinic or an external company with expertise in balance programs. See also an intervention program example herein.

The Role of the Musculoskeletal System

The musculoskeletal system plays a major role in minimizing fall risk. Proper posture, tone, reflex activity, and adaptive motor strategies contribute to a person’s ability to maintain balance and prevent falls. A general decline in MSK functioning with age is consistent with the more global systems’ decay that occurs for many as part of growing older. For example, age-related sarcopenia, or progressive loss of lean body mass, may become problematic when adequate strength to support locomotion and daily activities are compromised.

As muscles atrophy and joints lose mobility, individuals may be more prone to injury during bouts of muscular events such as physical stress, exertion, or exercise.16 From a biomechanics perspective, the presence of pain (acute or chronic) may further endanger movement capability, but the precise mechanism(s) by which the body reacts and adapts to the presence of pain is not fully understood in this regard.

Previous research has highlighted both increases and decreases in muscular activity, along with alterations in neuronal activity of motor control, in individuals experiencing pain.7 Depending on the body region (ie, hip, knee or ankle), the pattern of motor activity appears to vary based on the demands of the environment and the neuromuscular integrity of the individual.17 Lumbar/pelvic core weakness of the transverse abdominis (trunk flexor) or multifidus (trunk extensor) secondary to injury, disease, surgery, or deconditioning as occurs with sarcopenia, for example, produces an electromyography pattern in which target muscles show little activity; the more global muscles surrounding the smaller, thinner core muscles show greater tonic muscle firing.18 This phenomenon has been described as a compensatory mechanism whereby the larger global musculature in the lumbar/pelvic region assists the smaller, thinner deep-core muscles.18

To better understand the function of motor control and muscle pain, a research group in Australia proposed a Neuromuscular Activation Model.19 The model focused on the ability of muscles to perform their primary function as agonists and their secondary function as a synergist or stabilizer. It is arguably the secondary function of muscles acting as synergists that supports activities involving joint stabilization and posture control. To illustrate this point, consider lower extremity joint stabilization when one attempts to walk on an icy surface; the body automatically shifts to a muscle stabilization mode, in much the same way that a vehicle moves into four-wheel drive. Individuals co-contract their hip, knee, and ankle joints when ambulating on unstable surfaces.20

Contemporary theories developed out of clinical and experimental data suggest that there is more to motor adaptation stemming from chronic pain than once thought. The original theory of excitation and inhibition of muscle activity has expanded to recognize “redistribution” of muscle activity between and within muscles whose function is to protect tissue from further injury or trauma.21 Evidence further supports changes that occur at various and multiple levels of the motor control system, which may help or hinder clinical goals.21 However, long-term goals such as reduced magnitude and variability of movement, including shifting loads to other areas, may lead to potential secondary pain sites.21

Figure 1. The Dynamic Arc Functional Balance System (Courtesy SafeBalance).Figure 1. The Dynamic Arc Functional Balance System (Courtesy SafeBalance).

Strength, Balance, and Pain Intensity

Pain has a number of sequelae, including an increased likelihood of falling due to musculoskeletal inhibition also known as arthrogenic or reflex inhibition (RI).22 In some cases, the body may react to protect itself from further movement-related harm by interfering with the ability to achieve maximum voluntary muscle contraction (MVC) after physical injury has occurred. While RI functions as a protective action, it also poses a threat during circumstances in which safe and necessary movements are required.

Although the link between chronic pain and the occurrence of falls remains poorly understood, clinical observation suggests that the presence of pain, especially long-term, may undermine muscular function and joint integrity. In the same regard, chronic pain may interfere with dynamic balance, mobility, and cognition, thereby accelerating functional decline.23

The intensity of pain is important in studies demonstrating a threshold whereby RI is triggered. There may even be various degrees of inhibition controlled by central and peripheral nervous systems according to some research.24 Studies have confirmed that strength levels in patients with knee osteoarthritis (OA) represented a critical determinant of dynamic balance, for example.24

Clinical observations have aligned with this research, expanding on the understanding that measurement of static and dynamic balance is a complex interaction of variables. These variables involve the presence of pain (proximal or distally), muscular strength levels (as both a primary mover and secondary stabilizer), and visual, auditory, and sensorimotor integrity. There are also a myriad of secondary factors that may modify the psychomotor aspect of balance test performance, including psychological factors (ie, fear, anxiety), medications, comorbid complications, and cognitive status.

Bennell and Hinman,25 however, presented some interesting variations in this line of investigation. They found that in experimentally induced knee pain among 50- to 60-year-old subjects with no history of knee pain, standing balance was not significantly altered, nor was there any relationship between reported pain scores and balance scores.25

The presence of edema or joint effusions is crucial to this discussion. Edema arises in many forms of arthritis, as well as in chronic MSK conditions. There is evidence that even a miniscule amount of fluid in the knee joint (ie, 20 to 30 ml to initiate reflex inhibition in vastus medialis quadriceps muscle22 and 40 to 50 ml of fluid for the vastus lateralis and intermedius muscles)26,27 may produce substantial pain. Independently, both pain and swelling may elicit arthrogenic inhibition. When pain and swelling co-exist, the potential for a weight-bearing joint to buckle, leading to an injurious fall, rises significantly. Trauma, disease, obesity, and genetic predisposition have also all been linked to osteoarthritis, which may ultimately lead to joint effusion and subsequent pain, predisposing individuals to falls.

Image courtesy HUR USAFigure 2. The HUR SmartBalance (Courtesy HUR-USA).

Incorporating a Fall Prevention Intervention

Reducing fall risk in the aging population has become a national health priority across many federal agencies.28 As a result, fall prevention programs have become accessible to medical and rehabilitative providers with more attention paid to balance as an interventional target. There are no universally accepted standards for a comprehensive fall prevention program, yet, the literature demonstrates their effectiveness, including through single service (exercise-based) and comprehensive (multimodal) approaches.29 For instance, the US Centers for Medicare and Medicaid Services has endorsed the Rand Corporation’s evidence-based, multifactorial fall prevention interventions, which include: fall-risk assessment; supervised exercise focused on strength and mobility; and environmental modification and patient education.30

In clinical practice, a cost-effective assessment device that meets the Rand recommendations is the Dynamic Arc: Functional Balance System (SafeBalance, Birmingham MI, see Figure 1). The device may be used in a physical therapy setting and/or transported to a facility where many patient assessments may be performed in a single day. The data captured by the device is instantly converted into a Medicare defined category based on the severity of the balance dysfunction, which enables a clinician to immediately convert the test score into a meaningful impairment category that both quantifies the problem and allows for reimbursement. The Dynamic Arc uses a reach type test validation based on the functional reach test of Duncan et al,31 with an expanded test item list. In the author’s clinical setting, the device has shown very high sensitivity and good responsiveness as a measure of static balance among senior patients with chronic pain.

An additional device is the HUR SmartBalance (Northbrook, IL), an all-inclusive testing and treatment system (see Figure 2). The company manufactures a line of pneumatic strength machines engineered specifically for medical fitness and for senior strength and conditioning programs.

To conclude, falls are a major cause of injury and disability in those age 65 years and older, often leading to fractures, loss of independence, early institutionalization, and even death. Aggressive pain management combined with a comprehensive fall prevention program may help mitigate risk factors associated with falling and prevent further injury.

Last updated on: April 12, 2019
Continue Reading:
Mapping Complex Pain: A Case Study
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