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Overview

The very important and influential Institute of Medicine (IOM) report, Relieving Pain in America (Institute of Medicine of the National Academy of Science, 2011), has highlighted the urgent need for the development of better methods for pain management because of the ever-increasing costs associated with current treatment approaches cannot be sustained. This report highlights the fact that musculoskeletal pain is the most common single type of chronic pain. It is therefore fitting to have this initial chapter of the current handbook focus on musculoskeletal pain and disability and what they consist of:

Musculoskeletal disorders involve the musculoskeletal system, the 90 % of the human body devoted to interacting with the external environment. Although linked to all other systems, the musculoskeletal system is less concerned with issues of homeostasis, sensory input and problem solving. The bones and joints provide the frame, with ligament connectors and muscle/tendon pulleys providing the motor power. The peripheral nerves and nerve roots, providing the communication links from the central nervous system, may be included in the paradigm, especially in the upper extremity. Occupational injuries represent an important cost to industry and therefore to the productive capacity of every developing nation. An occupational musculoskeletal disorder provides the most significant component of occupational injury in frequency, disability, loss of productivity, and cost. (Gatchel & Mayer, 2000, p. 3)

As further reviewed by Punnet and Wegman (2004), these musculoskeletal disorders include a wide array of degenerative and inflammatory conditions that affect this system (i.e., muscles, joints, tendons, ligaments, as well as peripheral nerves and the supporting blood vessels). A partial listing of these associated conditions include tendon inflammations, such as bursitis; nerve compression disorders, such as carpal tunnel syndrome; osteoarthritis; and low back pain. As Punnet and Wegman (2004) also highlight, these musculoskeletal disorders are the single largest category of work-related illness in industrialized countries today. Indeed, occupational musculoskeletal pain and disability disorders, especially when they become chronic in nature, are highly prevalent and costly in industrialized countries. Actual statistics on the prevalence of such disorders may vary from one reference source to another, usually due to vagaries in the diagnostic criteria used for these disorders, as well as variations among different jurisdictions in the United States and in other countries. Nevertheless, according to the Bureau of Labor Statistics (2007), the overall rate of nonfatal occupational musculoskeletal disorders in the United States that required time away from work was reported to be 35 per 10,000 full-time employees. Moreover, the median days of work absence was 9, and 27.9 % of these injured workers were absent from work for more than 30 days. In terms of the specific body region affected by musculoskeletal disorders, 48 % were back injuries, 1.6 % were cervical injuries, 14.5 % were upper-extremity injuries, 8.1 % were lower-extremity injuries, and 4.7 % affected multiple body regions (Bureau of Labor Statistics, 2007).

Hult (1954) conducted one of the earliest studies that examined the rates of a very prevalent musculoskeletal disorder (low back pain) in the work environment by comparing its rates among different subsets of workers. He found that 60 % of forest workers reported having low back pain at some time during the study or had a history of low back pain. Pain symptoms generally began after the age of 30. Although the prevalence of low back pain was comparable for both heavy labor and lighter jobs, heavy labor workers were more at risk to develop disability as a result of low back pain. Hult (1954) also found that the rates of occupationally related low back pain were much higher than in the general population. Since that time, there have been numerous other studies evaluating different work environments in order to better understand the various contributing factors for different musculoskeletal disorders among different occupational subsets (Garofalo & Polatin, 1999).

Such studies are important because, in terms of costs, in the United States alone, it is estimated that approximately $100 billion are spent annually on healthcare utilization and concomitant work productivity losses due to patients with the most commonly cited occupational musculoskeletal disorders—back and neck pain conditions (Research and Markets, 2009). It should also be noted that, traditionally, because these are the most prevalent of such disorders, the vast majority of research conducted has focused on the lumbar regions. However, in recent years, there has been increased attention paid to the rising prevalence of non-lumbar occupational musculoskeletal disorders, such as neck, upper-extremity, and lower-extremity disorders. Because of the great prevalence of these various occupational musculoskeletal disorders, there has been a growing need to develop the most effective intervention methods for them. As a result, objective criteria (based on evidence-based research) are being established in order to identify successful treatment outcomes. For example, the Official Disability Guidelines (ODG) provide up-to-date, evidence-based research focused on the benchmarking of duration and treatment of occupational injuries (Official Disability Guidelines, 2012). Objectives of the ODG include the following: a reduction of delayed recovery time from injury onset to return to work, a reduction of medical costs associated with the injury, and helping the injured worker to safely return to work in a reasonable amount of time. These are ambitious goals that will, hopefully, be realized with additional clinical research on the most effective assessment and intervention strategies.

The current chapter will present four important areas related to occupational musculoskeletal pain and disability disorders: (1) a brief description/discussion of the most prevalent of these disorders, (2) a review of some causal theories/models of these disorders, (3) workers’ compensation issues related to an occupational injury, and (4) an overview of the most common and effective treatment methods for these disorders.

The Most Prevalent Occupational Pain and Disability Disorders: A Brief Description

Most recently, Hernandez and Peterson (2013) have provided a comprehensive review of the most prevalent work-related musculoskeletal disorders and pain. Such disorders can range from well-defined ones, such as disc herniation, tendonitis, and carpel tunnel syndrome, to those less well defined, such as facet syndrome, to nonspecific disorders such as cumulative trauma disorders or fibromyalgia syndrome. The reader is referred to that chapter for a more thorough understanding of these disorders. Also, at the outset, it should be noted that diagnostic imaging tests (such as magnetic resonance imaging or MRI) are often used as confirmation evidence that a “true” pathological underpinning is involved in a musculoskeletal injury (after a thorough history and physical examination is administered). However, one must keep in mind that such tests are not necessarily 100 % reliable to serve as a “gold standard” for the presence or absence of an injury. Results of such tests that need to be interpreted by a radiologist have to be combined with other parts of the physical examination and patient self-report in order to make most comprehensive evaluation. Indeed, there have been numerous studies that have demonstrated the “fallibility” of diagnostic imaging tests, as listed below:

  • In the lumbar spine, 22 % of subjects younger than 60 years of age with no symptoms (i.e., asymptomatic) of back pain, and 57 % of those older than 60, had significantly abnormal MRIs that suggested spinal disc herniations and stenosis (Goldsmith & Wiesel, 2000).

  • In the cervical spine, 19 % of asymptomatic patients have positive MRI evidence of bulging or herniated intervertebral discs (Goldberg, Singh, Van, Garretson, & An, 2002).

  • For asymptomatic subjects over the age of 60, MRI scans will show positive evidence of rotator cuff tears in 50 % of them (Wiesel, Sankar, Delahay, & Wiesel, 2010).

  • Likewise, 24 % of subjects without knee symptoms will yield MRI findings to suggest a torn meniscus (LaPrade, Burnett, Veenstra, & Hodgman, 1994).

Obviously, these above false-positive rates (i.e., identifying an injury when it is not present) are a persistent medical problem that makes precise and reliable diagnoses difficult. Indeed, inherent in the process of any diagnostic testing such as MRI is the concept of validity. Validity is the ability of a diagnostic test to correctly identify those individuals who have some pathology (e.g., a rotator cuff tear) and those who do not. The more valid the test is, then the better that test is at differentiating: test-positive results (often call sensitivity, defined as the probability of a test being positive when the pathology is present) and test-negative results (often called specificity, defined as the probability of a test being negative when the pathology is not present). Conversely, when a test suggests the presence of pathology when it is not there, it is called a false positive; or when a test suggests the absence of pathology when it actually is present, it is called a false negative.

The Lumbar Spine

It should be noted that the spine, as a whole, consists of four major zones: the craniocervical spine, the subaxial spine, the cervicothoracic junction, and the thoracolumbar spine. It is beyond the scope of this chapter to review all of the anatomic and muscular landmarks of these zones (this can be found in Rao & Smuck, 2012). Also, for the thoracolumbar spine, we will focus primarily on the lumbar section because this area is associated with the most costly and prevalent occupational problems of all musculoskeletal disorders (accounting for 48 % of all occupational musculoskeletal injuries; Bureau of Labor Statistics, 2007). Indeed, low back pain is a common condition, with a lifetime prevalence of over 80 % and a 1-month prevalence of 23 % (Hoy et al., 2012). Moreover, annually, low back (lumbar) pain is primarily responsible for over 20 million ambulatory medical care visits (Licciardone, 2008), and $100 billion in costs (Katz, 2006) in the United States. Although most of low back pain is of nonspecific etiology in terms of what our current available technology/laboratory skills can determine (Deyo & Weinstein, 2001), it is considered chronic when it lasts more than 3 months, at which time it may cause progressively more disabling physical and psychosocial deficits (e.g., Manek & MacGregor, 2005). It has been estimated, though, that approximately 95 % of low back pain cases are the result of muscle, tendon, and ligament sprains or strains (e.g., Agency for Health Care Policy and Research, 1994). Patients will present with limitations in range of motion, localized tenderness, and spasm along the paravertebral muscles (Wiesel et al., 2010). Indeed, most of the episodes of back and neck pain will be uncomplicated cases of muscle sprain or strain that resolve in a few weeks. In fact, uncomplicated acute low back pain (without any pathological signs such as nerve root involvement on spinal cord compression) should be treated conservatively. Indeed, clinical practice guidelines recommend the use of nonsteroidal anti-inflammatory drugs or acetaminophen, instructions to remain active, and reassurance that the prognosis for recovery is good. Moreover, any extended bed rest is to be avoided (Koes et al., 2010). Such a general conservative approach is usually also initially recommended for other acute musculoskeletal disorders.

Only a small number of patients will develop more serious spinal conditions that require surgical intervention (Wiesel et al., 2010). As a result, multiple biopsychosocial risks factors have been identified, as will be discussed later in this chapter. Table 1.1 presents a summary of many specific diagnoses that relate to lumbar spine injuries. It should be noted that, for nonspecific low back pain, 80–90 % of the cases will resolve within 6 months, although patients who have poorer general health, psychiatric disorders, and/or prior episodes of neck pain are at higher risk for developing chronic low back pain (Chou & Shekelle, 2010).

Table 1.1 Specific diagnoses for lumbar spine injuries
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The Cervical Spine

Many of the same painful conditions that affect the lumbar spine may also affect the cervical spine, and the symptoms and treatments may be similar (e.g., Stauffer, 1991). However, the symptoms of cervical spinal disorders tend to be more widespread and vague, relative to those of lumbar spinal disorders (that tend to be more localized and discrete). Also, as a consequence, the physical findings of cervical disorders are more difficult to isolate and to precisely document the actual anatomic location based on objective physical examination (Kang, Sowa, & Woods, 2012). As noted by Wiesel et al. (2010), cervical pain resulting from structural pathology is more persistent and may require more intensive intervention. For example, cervical radiculopathy (i.e., related to the nerve root) results from the compression or irritation of a cervical spine nerve root and usually produces symptoms of pain and paresthesia (i.e., an abnormal sensation, such as burning, prickling) along the nerve root distribution. In 25 % of these patients, persistent and/or recurrent neck pain occurs, and surgery may be needed. Cervical myelopathy (i.e., functional disturbance of the cervical spine) results from compression of the entire spinal cord, rather than from an isolated nerve root, and is a much more serious condition. Symptoms include numbness and impaired fine motor function of the fingers and hands, as well as weakness in the lower extremities, gout, and balance difficulties, and often urinary systems dysfunction. If there are no signs of nerve root compression or other neurological symptoms, then there is no firm evidence that surgery is beneficial for cervical pain (Carragee et al., 2009).

Often, symptoms of neck pain, shoulder pain and headache can co-occur, so that it may be difficult to isolate the specific anatomic, nerve root and sensory areas that are involved. Thus, there is a wide array of symptoms that can be reported, including pain, tenderness, stiffness, muscle spasms, and headache. With the above caveats in minds, it has been estimated that 1.6 % of all occupational musculoskeletal injuries are in the cervical region (Bureau of Labor Statistics, 2007). It should also be noted that, with the growth in occupations that involve more repetitive movement types of work (such as keyboard operations, small assembly lines), there has been an increase in cervical, as well as upper extremity, injuries that result in workers’ compensation claims. Table 1.2 presents a summary of many specific diagnoses related to cervical spine injuries.

Table 1.2 Specific diagnoses for cervical spine injuries
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Finally, one specific type of cervical/neck disorder that is receiving increased attention today is whiplash and neck pain-related disability (Schofferman & Koestler, 2005). Although many such injuries are caused by motor vehicle accidents, other occupationally related causes may produce it, such as falls and head-related collisions/accidents. Such injuries are of great concern because approximately 4–8 % of neck whiplash patients become partially or totally disabled over time (Schofferman & Koestler, 2005). Thus, they need to be appropriately treated at the acute stage before they become more chronic and disabling.

Upper Extremities

As can be seen in Table 1.3, there are a great number of upper-extremity injury diagnoses, ranging downwards from the shoulder, elbow, wrist, and hand. As a result, there are physicians who specialize in only specific injury area. Many of these injuries are caused by repetitive work or recreational activities (such as continuous neck, arm and/or hand movements that can negatively affect the muscles/nerves of these areas). Again, as we discussed earlier for the other musculoskeletal injuries, there is still some lack of consensus as to what precise criteria to use in diagnosing many upper-extremity injuries. On a global level, the general approach to diagnosis involves the following: a clinician’s physical examination of the injured area; the assessment of the range of motion, strength, and palpation of muscle tendons/ligaments of the area; and the evaluation of self-reported pain while performing these evaluations. Quite often, imaging tests may be ordered if the patient experienced a blunt trauma, or if there are other signs of serious pathophysiology.

Table 1.3 Specific diagnoses for upper-extremity injuries
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Two well-known upper-extremity disorders are rotator cuff injury and carpal tunnel syndrome. In terms of the former, the rotator cuff is a set of four muscles that are responsible for the rotation and elevation of the shoulder while providing stability to the humerus (i.e., the bone that extends from the shoulder to the elbow). Damage to the rotator cuff may be the result of a traumatic injury, or due to a more cumulative trauma due to repetitive overuse. One or more of the four tendons connecting the rotator cuff muscles to the bone may be torn, and patients will report pain over the anterior lateral shoulder. This pain may awaken the patient from sleep and may be exacerbated by overhead activities. Complete tears of the tendons may require surgery, especially if patients start to develop atrophy and weakness of the shoulder muscles. It has been reported that patients who were receiving workers’ compensation, and those with prior surgical procedures, are more likely to need revision surgery (Piasecki et al., 2010). Also, they are less likely to return to work or display improvement in self-reported pain, disability, and strength (Holtby & Razmjou, 2010).

The most frequent cause of occupational wrist pain (with carpal tunnel syndrome being the most commonly diagnosed disorder) is cumulative trauma or overuse. Carpal tunnel syndrome occurs when the transverse carpal ligament compresses the median nerve as it passes though the wrist, resulting in symptoms such as decreased sensation and paresthesia (i.e., an abnormal sensation, such as burning and prickling, to the three radial fingers). As symptoms progress, atrophy to the thenar muscles of the thumb may develop (Wiesel et al., 2010). It should be noted that the incidence of the diagnosis and resultant surgery for this syndrome has been significantly increasing during the past decade, both in the United States and other industrialized countries (Atroshi, Englund, Turkiewicz, Tägil, & Petersson, 2011).

Lower Extremities

Table 1.4 presents various lower-extremity disorders. Again, as can be seen, there are a great number of them, ranging downwards from the hip to the feet. Of these, knee disorders are extremely prevalent in adults, accounting for approximately three million healthcare visits per year. In fact, knee trauma is the second most common occupational injury (second only to low back strain). Acute knee injuries include damage to the ligaments (especially the anterior collateral ligament) or damage to the cartilage (especially the meniscus). As noted by Wiesel et al. (2010), the rates of knee surgeries have dramatically increased over the past few decades, particularly in younger patients. They now make up a patient population who undergo some of the most frequently performed orthopedic procedures.

Table 1.4 Specific diagnoses for lower-extremity injuries
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Similar to the upper-extremity disorders, because there are so many types of lower-extremity disorders, there are different physicians who specialize in assessing and treating specific injury sites. Likewise, the general approach to diagnosis is similar to that discussed for upper-extremity injuries. As noted by Hernandez and Peterson (2013), various disorders of the knee (such as meniscal tears in lesions, bursitis, and osteoarthritis) and the ankle (e.g., osteoarthritis) are most common for workers in occupations that have high physical demands on the lower limbs, such as construction workers and carpet and floor layers.

Review of Causal Theories/Models of Occupational Musculoskeletal Disorders

Over the past two decades, there has been a plethora of research studies attempting to isolate specific risk factors that may be associated with the development and maintenance of various types of musculoskeletal pain and disability disorders. Hernandez and Peterson (2013) characterized such risk factors into three broad categories: (1) biomechanical risk factors (such as ergonomic variables in the workplace that increase repetitive body part movements or that increase repetitive body part movements or that demand improper and/or static postures/positions), (2) psychosocial risk factors (such as high work demands, low job control, lack of workplace/supervision support), and (3) individual risk factors (such as gender, age, sedentary lifestyle, personality characteristics). Indeed, the face validity of these three categories can be readily seen from earlier models/causal theories presented in the scientific literature, as will be delineated below. Likewise, Wright and Gatchel (2002) outlined a general list of various risk factors, as presented in Table 1.5.

Table 1.5 Various risk factors for occupational musculoskeletal pain and disability disorders (from Wright & Gatchel, 2002)
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Punnet and Wegman (2004) have also highlighted such risk factors, in stating that musculoskeletal disorders:

… occur in certain industries and occupations with rates up to three or four times higher than the overall frequency. High-risk sectors include nursing facilities; air transportation; mining; food processing; leather tanning; and heavy and light manufacturing (vehicles, furniture, appliances, electrical and electronic products, textiles, apparel and shoes)… Upper extremity musculoskeletal disorders are also highly prevalent in manual-intensive occupations, such as clerical work, postal service, cleaning, industrial inspection and packaging… Back and lower limb disorders occur disproportionately among truck drivers, warehouse workers, airplane baggage handlers, construction traders, nurses, nursing aides and other patient-care workers, and operators of cranes and other large vehicles…. (p. 14)

Howard (2010) has provided a comprehensive review of the various models to be presented next. For example, in an early conceptual model of neck and upper-extremity musculoskeletal disorders, proposed by Armstrong et al. (1993), a number of individual characteristics (e.g., personality/coping skills, health status, work experience) were identified as important variables that directly moderated the effects of the work environment on stress and strain reactions. Subsequently, Sauter and Swanson (1996) extended this model into a broader ecological model of causation of upper-extremity injuries. They not only incorporated physiological and psychosocial variables but also included cognitive component factors (such as fear of losing one’s job, poor performance, not meeting personal goals, as well as frustration with control and confidence issues) that could mediate the effects of work demands and workplace psychosocial stress on muscle tension and poor posture. An additional feature of their ecological model was the presence of a “positive feedback mechanism.” That is to say, if an injury occurred, then the psychosocial impact of that injury would further exacerbate the symptoms, thereby leading to additional increased disability.

Feuerstein (1996) also proposed a work-style model in conceptualizing occupational upper-extremity disorders. There are three work-style factors in this model: physiological changes, behavioral changes, and cognitive changes. If these factors are occupationally altered by psychosocial stress, high-demand tasks, and/or ergonomic factors, then the probability of developing an upper-extremity musculoskeletal injury will be increased. In essence, this model again emphasizes the importance of the interaction between psychosocial and physical stressors (and their feedback) on the development/exacerbation of upper-extremity injuries.

For occupational musculoskeletal disorders in general, these aforementioned interactional processes have been highlighted by many other investigators. For example, earlier work by Hagbert et al. (1995) emphasized the dynamic interaction between psychosocial factors (such as mental fatigue, the ability to cope with stress) and physical factors (such as ergonomic features of the workplace, duration and intensity of work activities) as potentially causing a physical injury. Taking a slightly different perspective of workplace characteristics, Burton and Main (2000) indicate that, in addition to certain psychosocial “yellow flags” (such as workers’ levels of distress, depression, coping strategies, and beliefs) that may serve as obstacles to recovery, certain “blue flags” may also work alongside these “yellow flags.” These “blue flags” refer to two categories of work-related obstacles to recovery. Individual worker-specific variables refer to beliefs about the work/injury relationship (i.e., how it occurred), attribution of blame (e.g., the poor work environment “caused the injury”), and psychosocial aspects of work (e.g., level of stress). Work-specific issues refer to managerial attitudes towards workers, return-to-work policies, work organizational structure, and perceived work demands.

Thus, various different levels of interactions are viewed as important. Likewise, Carayon, Smith, and Haims (1999) and Kumar (2001) emphasized the importance of other dynamic interactions. According to Kumar (2001), four different causal-factor theories were proposed to account for the development of occupational musculoskeletal disorders:

  • The multivariate interaction theory proposes the importance of evaluating the interactions among genetic, psychosocial, and biomechanical factors in better understanding their effects on the musculoskeletal system.

  • The differential fatigue theory more specifically focuses on the strain of various occupational activities on the joints and muscle tissues. Thus, if the intensity of such strain surpasses the capability of the joints and muscles to safely handle it, then short-term results (e.g., fatigue) and long-term results (e.g., injury to the joint and/or muscle) can occur.

  • The cumulative load theory emphasizes that one must consider the actual amount of strain that the musculoskeletal unit can tolerate before it loses its ability to accommodate to it and thus its ability to mend. The continuation of increased strain on the musculoskeletal unit(s) causes the joints and muscles to deteriorate, often resulting in injury.

  • The overexertion theory emphasizes that if the physical stress factors (e.g., increased force, repetitive motion, long duration of activities) exceed the level that the joints and muscles can tolerate, this will result in an injury.

It should be noted that Kumar (2001) indicates that these above four theories/models of occupational musculoskeletal injuries can “run simultaneously,” so that any of the factors within each model can lead to an injury, depending on the particular worker and the specific circumstances of the job.

The one common thread that runs through the fabric of all of the above reviewed models/theories is the importance of comprehensively taking into account the potential dynamic interaction of multiple factors that can result in the initial development, exacerbation, and chronicity of an occupational musculoskeletal pain and disability disorder. As a result, a biopsychosocial model needs to be embraced in order to effectively take into account these interactions. Indeed, the biopsychosocial model has rapidly developed during the past decade in all areas of medicine and is now considered the most comprehensive and heuristic approach to the evaluation and treatment of medical disorders, including those of the musculoskeletal system (e.g., Gatchel, 2005; Mayer, Gatchel, & Polatin, 2000; Wright & Gatchel, 2002). This model will be further discussed later in this chapter.

Workers’ Compensation Issues Related to Occupational Injuries

Workers’ compensation insurance, and its various forms, was initially developed as a means to protect employees from the burden of lost wages and medical costs after an injury. Private insurance carriers are the largest providers of workers’ compensation policies. As summarized by Butler (2000), in the United States, each State is required to have workers’ compensation insurance in order to provide medical care, monetary benefits, and rehabilitation services to employees who experience an injury or illness as a result of their employment. It is important to note that each State has its own specific workers’ compensation law so that one cannot expect similar compensation benefits from one State to the next. It should be also pointed out that monetary benefits that are paid for workers in lieu of lost wages is not completely comparable in the sense of replacing all lost wages. Usually, only roughly two-thirds of weekly wages are replaced for those wages that are between specific minimum and maximum amounts. Such minimum and maximum amounts, as well as a particular waiting period between the date of injury and when the worker is eligible to receive these cash benefits, are also determined separately from one State to the next. In addition, one would be remiss without mentioning that workers’ compensation laws associated with such issues are quite complex from one State to the next.

At the outset, readers should also be aware of the differences among the three major constructs of pain, disability, and impairment because they are usually referred to in workers’ compensation claims. Pain is a psychophysiologic construct based primarily on an experiential or subjective evaluation that some sort of bodily injury has occurred. Impairment is a physical/medical term that refers to an alteration of the injured workers’ usual health status (i.e., some objective anatomical or pathological abnormality) that is evaluated by physical and medical means. This evaluation of impairment has traditionally been a medical responsibility in which there is an attempt to objectively evaluate structural limitations, through techniques such as a thorough medical examination and imaging results. Unfortunately, however, as we have noted before, current technology does not automatically allow a totally accurate or objective physical impairment evaluation. It relies on methods that may not have good validity (e.g., in terms of sensitivity and specificity as discussed earlier in this chapter), as well as not being completely reliable, and sometimes subject to examiner bias. Finally, disability has traditionally been an administrative term that refers to the diminished capacity or inability to perform certain activities of everyday living. It is the resulting loss of function due to impairment. Disability evaluations, too, are often not totally unreliable and are subject to various examiner and patient response biases (e.g., Gatchel, 2005). The assessment of disability is usually based on subjective self-report measures of restrictions on activities of daily living, such as walking, work and recreational activities, and sleep. Because pain, physical impairment, and disability are separately assessed, they are often not highly correlated with one another. Thus, for example, one patient may verbally report a significant amount of pain but show little impairment that can be objectively evaluated, with disability perhaps lying somewhere between the two in severity. In contrast, another patient may report little pain but displays great disability and some impairment. As a result, this can create a legal/bureaucratic “nightmare” in terms of determining how much impairment and disability resulted from an occupational injury and, thus, the amount of workers’ compensation that is paid to the injured employee. This, in turn, can create an adversarial and emotional distressing interaction between the injured worker and his/her employer and company. Is the injured worker being “truthful” in terms of how much pain is being experienced in order to get some time off work and receive workers’ compensation disability payments? As a result, the term malingering has often been used to suggest that some workers may intentionally project exaggerated physical and/or psychosocial symptoms for the purpose of gaining some external rewards/secondary gain such as workers’ compensation payments or a “lump-sum” monetary settlement for their pain and suffering. From a medicolegal standpoint, the presence of such financial reward/secondary gain following an occupational injury may potentially provide a worker with the motivation to “malinger” or to exaggerate physical and psychosocial symptoms. In point of fact, though, the presence of true malingering in chronic occupational pain populations has been shown to be fairly low (Howard, Kishino, Johnston, Worzer, & Gatchel, 2010). Unfortunately, many workers are still assumed to be malingering if they do not immediately return to work after an injury when there is no “objective” medical evidence of impairment. They are perceived as taking advantage of the medical, insurance, and legal systems. However, as we discussed, impairment evaluations are not necessarily totally reliable or valid. As Hadler (1996) has noted: If you have to prove you are ill, you can never get well… (p. 2397). Therefore, there may be additional external pressure on patients to prove that they are really ill, thus lessening their motivation to rehabilitate and return to work as soon as possible. This often creates another significant barrier to recovery that needs to be addressed in any comprehensive treatment program. Readers are referred to a recent chapter by Schatman (2013) which provides a more comprehensive review of the many potential problems in the workers’ compensation systems, as practiced in the United States today, that may often perpetuate disability and nonreturn to work.

The Biopsychosocial Model of Occupational Musculoskeletal Disorders: Treatment Applications

As introduced earlier in this chapter, the biopsychosocial model focuses on the complex interaction among biologic, psychosocial, and medicolegal variables that patients encounter when coping with persistent and distressing occupational musculoskeletal disorders. This complex interaction may perpetuate or worsen the patient’s medical condition, and negatively affect various aspects of the patient’s life. This approach is in striking contrast to the formerly embraced biomedical reductionist approach, which mistakenly assumed that most medical/musculoskeletal disorders can be separated into distinct, independent physical and psychosocial components. However, every patient experiences a musculoskeletal injury uniquely, and the complexity of an injury can be especially evident when it persists over time, as a host of psychological, social/occupational, and economic factors comes into play. These factors interact with the physical pathology (much of which was briefly reviewed earlier in this chapter) to modulate the patient’s discomfort and disability. Individual patients differ significantly in the frequency with which they report physical symptoms, their tendency to visit a physician for identical symptoms, and their response to identical treatment approaches (e.g., Gatchel, Kishino, & Strezak, 2006). As a consequence, the nature of a patient’s response to treatment often has little to do with his or her objective physical condition.

The especially significant contribution of the biopsychosocial model has been its use in developing effective interdisciplinary assessment and treatment methods (Gatchel, 2004, 2005). Before discussing such methods, though, it is important to distinguish among primary, secondary, and tertiary musculoskeletal pain and disability because each of these types requires substantially different biopsychosocial assessment and treatment (e.g., Gatchel & Kishino, 2012):

  • Primary care is usually applied to the treatment of acute pain of limited severity. Basic symptom-control methods are used for relieving pain during the normal healing period. Moreover, basic psychosocial reassurance that the acute pain is temporary, and that it soon will be resolved, frequently is effective.

  • Secondary care represents a reactivation treatment for a patient whose musculoskeletal pain has not improved through the normal healing process. Secondary care is administered during the transition from acute (primary) care to the patient’s return to work. This treatment is designed to promote a return to occupational productivity before the patient develops advanced physical deconditioning and significant psychosocial barriers to returning to work. A patient whose musculoskeletal pain does not appear to be decreasing may need more active psychosocial intervention (e.g., Turk & Monarch, 2002).

  • Tertiary care is intended for patients who are physically deconditioned and have chronic pain and disability. This stage of care requires a comprehensive interdisciplinary intervention approach (Gatchel, 2005).

Interdisciplinary tertiary care, patterned after the pioneering functional restoration program developed by Mayer and Gatchel (1988), has been found to be extremely efficacious and cost-effective for treating patients with various occupational musculoskeletal pain and disability disorders (Gatchel, 2005; Gatchel & Okifuji, 2006; Wright & Gatchel, 2002). Table 1.6 outlines the major therapeutic elements of such a program.

Table 1.6 Major therapeutic elements of a functional restoration program for chronic occupational musculoskeletal pain and disability disorders
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In striking contrast to interdisciplinary pain management programs, traditional unimodal medical treatment approaches for these musculoskeletal disorders have not been consistently therapeutically or cost-effective. Indeed, as comprehensively reviewed by Gatchel and Okifuji (2006), interdisciplinary programs such as functional restoration (based on the biopsychosocial model of pain and disability) have been shown to be effective not only for self-reported measures of pain and disability but also for more objective measures of function, such as range of motion, strength, and aerobic capacity. Even as important have been the significant positive effects it has had on important socioeconomic outcomes, such as return to work, subsequent healthcare utilization, surgery rates, and case closure, relative to conventional medical treatment approaches.

Another important piece of evidence for the robustness of such interdisciplinary pain and disability management programs has been provided by the repeated independent replication of functional restoration outcomes in randomized clinical trials conducted in different parts of the United States, as well as in Canada, Denmark, France, Germany, and Japan (Bendix et al., 1996; Corey, Koepfler, Etlin, & Day, 1996; Hazard et al., 1989; Hildebrandt, Pfingsten, Saur, & Jansen, 1997; Jousset et al., 2004; Patrick, Altmaier, & Found, 2004; Shirado et al., 2005). Thus, the therapeutic robustness and utility of this approach has been independently confirmed by different treatment teams functioning in regions and countries that have markedly different economic, social, occupational, and workers’ compensation conditions/systems.

Summary and Conclusions

As we discussed, occupational musculoskeletal pain and disability disorders are highly prevalent and costly in industrialized countries. In terms of the specific musculoskeletal body region affected, 48 % are back injuries, 1.6 % are cervical injuries, 15.5 % are upper-extremity injuries, 8.1 % are lower-extremity injuries, and 4.7 % affect multiple body regions. In the United States alone, it is estimated that approximately $100 billion is spent annually on healthcare utilization and concomitant work productivity losses due to patients with the most commonly cited occupation musculoskeletal disorders. The current chapter presented four important areas related to these disorders. The first part reviewed the most prevalent of these disorders according to body part area: the lumbar spine, the cervical spine, the upper extremities, and the lower extremities. We then reviewed some of the causal theories/models that had been proposed to account for how these occupational injuries can become disabling and chronic in nature. Taken together, all these models emphasized the interaction of various physical, psychosocial, and socioeconomic variables that make the study of potential risk factors and treatment approaches quite difficult. Indeed, the third part of this chapter reviewed workers’ compensation, secondary gain, and malingering issues that have led to additional complexities when addressing occupational injuries. We noted that workers’ compensation laws are active in each State in order to pay for medical care, rehabilitation, and partial wage losses incurred by these injuries. However, this often creates an adversarial, emotionally and economically stressful interaction between employees and employers that can also greatly affect long-term disability and recovery related to the injury. Finally, an overview of the most common and effective treatment methods for these disorders was presented. Specifically, the biopsychosocial model was introduced as the most heuristic and effective approach for the treatment of occupational musculoskeletal disorders. This biopsychosocial model focuses on the complex interaction among biologic, psychosocial, and medical/legal variables that patients encounter when coping with persistent and distressing disorders. This complex interaction may perpetuate or worsen the patient’s medical condition and negatively affect various aspects of the patient’s life. One important product of this biopsychosocial model was the development of comprehensive interdisciplinary pain management programs that were patterned after the functional restoration approach initially developed by Mayer and Gatchel (1988). This approach has been found to be extremely efficacious and cost-effective for treating patients with various occupational musculoskeletal pain and disability disorders.

In conclusion, musculoskeletal pain is still the most common cause of short-term and long-term occupational disability (Melhorn, Lazarovic, & Roehl, 2005). Indeed, the near-epidemic dimensions of occupational musculoskeletal disorders in the United States have continued to remain unabated. Fortunately, however, some major advances in clinical research, with the new emphasis on the biopsychosocial conceptualization of pain, disability, and impairment, are beginning to provide solutions to this problem (Schultz & Gatchel, 2005). The interdisciplinary functional restoration approach is one such example. However, what is still needed is the examination of what combination of variables are most important in being able to prescribe the most effective therapeutic “package” in an interdisciplinary treatment program for specific types of musculoskeletal injuries.

Finally, in providing an overview of these disorders, Stowell and McGeary (2005) have concluded that:

Regardless of the cause of the musculoskeletal injury, the disability, or the decisions to return to work, the progression of the disabled person through the CDD (Cause, Disability, Decision—AUTHORS’ INSERT) stages, is populated by an array of individuals, many with different points of view. Whether it is the provider, the employer, the caretaker, or even society as a whole, the patient is bombarded with intricate communications and varying belief systems, concerning injury, compensation, risk, and litigation… Cause, Disability, and Decision: a continuum that spans the full range of a person’s disability. Each individual stage in the musculoskeletal injury continuum must be thoroughly understood in part and in whole if we are to appreciate and apply the most effective and efficient treatment plans for disabled individuals. (p. 136)

The various other chapters in the present handbook will touch upon many of the above issues in order to provide the reader with a comprehensive understanding of the broad array of issues involved in occupational musculoskeletal pain and disability disorders.