Cumulative trauma disorder (CTD) claims are a growing concern. However, because knowledge of CTDs is quite limited, a magnified effort is being implemented to learn more about the cause and prevention/treatment of these injuries throughout industry.
As research has shown, this situation is more complex than it seems. No one cause can be cited, nor does one diagnosis or prevention approach apply to all CTDs. Each case is unique. Consequently, it is impossible to prescribe a universal solution. Despite identification of risk factors that appear to be common to most CTDs, the topic continuous to spark controversy and debate.
CTDs are injuries that result in small, but cumulative, soft-tissue damage sustained through the repetition of (or overexertion during) certain tasks. Many different terms are used to describe these disorders, including repetitive strain injuries, regional musculoskeletal disorders, repetitive musculoskeletal injuries and overuse syndrome.
According to a 1995 Bureau of Labor Statistics report detailing workplace injuries and illnesses, some 62 percent (308,000) of workplace illnesses were associated with repeated trauma, such as carpal tunnel syndrome (CTS). This reflected an actual seven-percent decline from 1994--the first decline in such injuries since 1982 ("Workplace injuries" 1).
Of 31,457 reported cases of CTS resulting in lost worktime, 62 percent involved 21 or more days away from work. Of particular note, one-half of all workers suffering from CTS missed 30 or more workdays ("Lost-Worktime" 1, 2).
What are the primary contributors to formation of CTDs? This has been the topic of much controversy. Most researchers agree that CTDs are not caused by a single variable. Many factors contribute to the final development of a disorder (Hadler 38; Mackinnon and Novak "Repetitive Strain" 2). Some of the most heated debate arises when trying to pinpoint the most-significant contributor, since this often determines who will pay for medical and disability costs (Mackinnon and Novak "Repetitive Strain" 2).
Some believe that individual parameters of a person's body play a key role in CTD development. For example, the primary contributors to CTS include obesity, body mass index, age, wrist dimensions, hand dominance, physical fitness, illness and previous injury (Nathan, et al "Obesity" 382; Rempel 839; Nathan, et al "Longitudinal" 855).
Some suggest that "health of the median nerve is closely linked to health of the rest of the body" (Nathan, et al "Obesity" 382). In addition, several studies have found that non-occupational factors are more important in predicting nerve conduction status, a key diagnostic tool for CTS. Five years after onset in one case, no occupational factor contributed to the prediction (Nathan, et al "Obesity" 382; Nathan, et al "Longitudinal" 856).
Most literature available to the public contends that primary predictors of CTDs are associated with the workplace. These predictors reportedly include repetition, high force, awkward joint posture, prolonged constrained posture, direct pressure, vibration and cold (Rempel 838; Gauvey 2). Studies have associated these conditions with CTDs, and many confirm the role that occupational factors play in development of musculoskeletal injuries.
Although CTS is one of the most-publicized CTDs associated with the workplace, it is not the most common, accounting for only two percent of all reported repetitive motion cases (Mackinnon and Novak "Repetitive Strain" 6). Activities that are less strenuous, but highly repetitive (e.g., keyboarding), do not have a high likelihood of contributing to injury; conversely, activities that require greater force and repetition do have a compounded likelihood of contributing to injury (Mackinnon and Novak "Repetitive Strain" 6; Silverstein 353). Vibration also appears to have a definite effect on development of injuries (Rempel 838; Silverstein 356).
Many complaints of musculoskeletal discomfort are associated with specific job activities and job types (e.g., keyboarding for extended periods of time). This advances the perception that injuries that cause this discomfort are job-related (Higgs and Mackinnon 8). Sometimes, these injuries are caused by the continuation of certain stressful activities until the body can no longer adapt to the stress being placed on it (Mackinnon "Repetitive Strain" 4; Dobyns 589).
For example, maintaining improper posture for prolonged periods can cause muscle imbalance; this, then, perpetuates itself because opposing muscles are constantly overused or underused. Certain positions either increase the pressure around a nerve or stretch the nerve, which causes nerve compression and, thus, pain (Higgs and Mackinnon 4).
PSYCHOLOGICAL & PSYCHOSOCIAL FACTORS
Many researchers believe that psychological or psychosocial factors are involved in the occurrence of these disorders. If CTDs were mainly caused by occupational factors, it would follow that ergonomic improvements and modifications would help; this is not always the case (Hadler 39).
For example, at U.S. West, company facilities and jobs were virtually the same, yet one facility experienced CTD problems while others did not ("U.S. West Communications" 11). Researchers found that the employees more likely to develop injury were generally unsatisfied with their jobs; under stress; or placed in (what they felt was)an unpleasant workplace (Hocking 221; Hadler 39; "U.S. West Communications" 20-22).
Other studies have found that a person may manifest psychosocial problems in bodily complaints (somatization), and that some pre-existing symptoms can be exacerbated by the psychophysiology of stress (Osterweis 155, 157).
Some studies have found psychological variables that do not directly involve the workplace. These include a person's view of pain; personal matters (e.g., marital problems); ability to adapt to/cope with an injury; or whether s/he might receive monetary compensation for the pain (Osterweis 155, 157; Flor 227; Fordyce 139; Scalia 18).
PREVENTIVE & TREATMENT MEASURES
Though opinions on causation are many, ideas for preventing CTDs are fewer. The easiest and most common is to adjust the workplace in order to improve its ergonomic quality.
However, as noted, ergonomic problems are not necessarily the cause of injury in every case (Rempel 839). Ergonomic modifications, though effective in many cases, do not appear to improve the condition of someone who has already developed a "serious" cumulative trauma case (Rempel 839; "Interventions" 2; Mackinnon and Novak "Clinical Commentary" 878). Furthermore, some preventive measures may not offset the actual cause; instead, they merely create a placebo effect among various affected parties (Hocking 221).
Surgery has been a frequent treatment for those with CTS, but research shows that surgery is not always the best option. Often, it is not necessary and provides no significant relief (Flor 228; Scaha 16).
New research has shown that "conservative management" seems to work better. This involves initial stretching and strengthening of the weak muscle; using soft splints at night to decrease pressure around the median nerve; weight reduction; and, if necessary, breast reduction (which decreases weight across the suprascapular region in the back and discourages flexing the neck and shoulders) ("Interventions" 1).
Patients report that they feel "significantly better" two months after beginning the conservative program. However, although this method helps, patients are never truly cured; they must make a continuous commitment to good posture, good work habits and exercise ("Interventions" 2).
Research has also found that extensive periods of inactivity may impede the healing process.
Inactivity reduces effective muscle mass and makes the patient more vulnerable to subsequent strains. Thus, the patient should stay as active as possible, while not overworking injured muscles (Fordyce 139; Mackinnon and Novak "Clinical Commentary" 878).
In some cases, the patient may exhibit no visible symptoms (test results are normal or show only borderline abnormalities), yet still complain of pain. If the patient does not respond to any measures taken, the injury may be psychological in origin. Appropriate action in such cases may include reducing the patient's workload (Higgs and Mackinnon 3). Managemerit should also try to create a supportive, positive environment.
Based on these findings, it appears that some combination of medical and psychological perspectives and interventions is the best strategy to understanding and treating musculoskeletal injuries (Osterweis 202).
Additional research must be performed before the scope of CTS is fully understood. As the following quotes show, many researchers agree that current knowledge is still quite limited.
"The definitive cause (or even strong association) of work-related musculoskeletal disease has yet to be established" (Mackinnon and Novak "Repetitive Strain" 12).
"Because of the scarcity of medical research on CTDs, many physicians are unable to identify patients working in high-risk environments and are inadequately prepared to treat patients with symptomatic disorders" (Rempel 838).
"From the beginning of medical interaction with these problems, it has been more difficult than usual to separate the physiologic problems from the psychologic problems, and this ambivalence continues" (Dobyns 588).
Clearly, both the physiological and psychosocial/psychological aspects of these disorders must be recognized. Many factors contribute to development of these injuries. Since each case is unique, it is difficult to develop definitive, universal prevention and treatment protocols for CTDs (Rempel 839).