CUMULATIVE TRAUMA DISORDERS: ARE THEY PREVENTABLE? YES, NO, MAYBE By: Joy Linn Copyright 1995, permission granted for redistribution provided the file isn't altered and credit is granted to the author. Bio: Joy Linn is currently a graduate student in Health and Safety Administration with an emphasis in Safety Management at Oregon State University. Her minor is in human factors engineering. She's looking forward to joining the "pros" soon. (4/2/95) This report was submitted for a class on "Research and Problems in Safety", Fall 1993. ------ TABLE OF CONTENTS Page Introduction 3 Current Status of Cumulative Trauma Disorders 4 Factors Contributing to Cumulative Trauma Disorders 5 Carpal Tunnel Syndrome - Possible Causes and Effects 6 Definitions 7 Preventative Measures 9 Brief History of Ergonomics 12 Examples of Ergonomics Principles at Work 14 Conclusions 15 Bibliography 16 TABLES AND FIGURES TABLES Page 1. General repetitiveness and force 8 controls for reducing ergonomic stresses in manual work FIGURES 1. An Ergonomics Program Plan 10 CUMULATIVE TRAUMA DISORDERS: ARE THEY PREVENTABLE? YES, NO, MAYBE INTRODUCTION In the increasingly automated industrial world, cumulative trauma disorders (CTD) are being reported in record numbers. The increasing cost in dollars, as well as pain and suffering, is causing employers to take a more pro-active position in addressing CTD in the work place. Work practices have been changing with automation to increase productivity. These changes include fewer staff, heavier work loads, more task specialization, faster pacing of work,and fewer rest breaks. These work practices can entail very prolonged rapid or forceful repetitive motions leading to fatigue and overuse of muscles. Cumulative trauma disorders are also known as repetitive strain injuries, overuse syndrome and repetitive motion injuries. They represent a group of diagnoses with a common etiology. Strains, tendonitis and tenosynovitis are the most frequent, however carpal tunnel syndrome is the most well known diagnosis. It represents the more severe end of the disease spectrum. In 1988, CTD accounted for 48% of all occupational injuries according to the U.S. Department of Labor. This group of injuries represents the number one occupational illness. Corporate America is finding it increasingly necessary to address the number of CTD in the work place. Not only are Worker's Compensation costs rising at a rapid pace, worker morale is also being negatively effected. Consequently, corporations are looking into causes and possible preventative measures. Frequently the prevention plan involves incorporating ergonomic principles into the work place. The most common recommendation uses a four pronged approach which includes: work site analysis; hazard prevention and control; medical management; and training and education. Businesses are realizing there is a relationship between injury prevention and improved productivity and quality. Consequently, they are attempting to switch from a reactive to a proactive approach to injury prevention. CURRENT STATUS OF CUMULATIVE TRAUMA DISORDERS Cumulative trauma disorders are emerging as the occupational illness of the automated world. However, they are far from recent occupational hazards. In 1893 "Gray's Anatomy" describes peritendinitis crepitans as occurring in washer women (Barton, 1989). Some old names for CTD from the past include: glass arm, telegraphist's cramp and washer woman's thumb. In the 19th century "traumatic tenosynovitis" and "peritendinitis crepitanis" were acknowledged as pain caused by work activities. Earlier this century morse code operators experienced similar disorders. The recognition of CTD has increased as the numbers of injuries increase worldwide. In 1982, cumulative trauma disorders accounted for 18% of all occupational injuries according to the U.S. Department of Labor. Employers were noting that special attention should be given to those parts of the body which remain relatively still for extended periods of time. By 1988 this had risen to 48%. This change reflects a 600% increase in reported cases since 1981 (Hales, 1991). Since 1987 CTD have been the number one cause of occupational illness. In 1984 the American Academy of Orthopaedic Surgeons conducted a study which estimated that the total of direct and indirect costs of musculoskeletal injuries and all other musculoskeletal conditions was in excess of $65 billion (Louis, 1987). There are several explanations for the increase in reported CTD. These include increased recognition among workers and health professionals, as well as job specialization and the pace of work. In addition, these increases can be attributed to an industry shift to automation. Automation reduces interruptions and the variety of tasks completed by the worker. Computers eliminate breaks and reduce the need for a range of tasks. For example, typewriters require breaks from typing as they need to be provided with paper. Manual typewriters required manual carriage returns and corrections. A wide variety of industries and professions have been effected by the increase in CTD. Some examples include: meat packing, poultry processing, motor vehicles and car bodies, dental hygienists, data entry keyers, hand grinding and polishing, and typists. Some leisure activities that may cause CTD include wind surfing, tennis, needlework, and even lifting children. FACTORS CONTRIBUTING TO CUMULATIVE TRAUMA DISORDERS Repetitive action becomes dangerous when combined with bad posture, force applied excessively or awkwardly and psychological stress. Workers in jobs that offer little relief from repetitive wrist motion or regularly require a force exceeding ten pounds are at high risk for cumulative trauma disorders. The repeated motions need not be strenuous or forceful to cause problems. Cumulative trauma disorders (CTD) appear most often in work involving rapid repetitive movements (eg. key board operators); less frequent but more forceful movements, including pinch grips (eg. electronics assembly); static load (eg. welding, and also key board operators who hold wrists and shoulders in the same position for long periods); awkward postures of the upper body; localized contact area between the work or work station and the worker's body; excessive vibration from power tools; and cold temperatures. The mechanism of injury is unclear. The injuries involve mostly soft tissue damage and consequently they are difficult to measure. Pain tends to be subjective which contributes to the difficulty. CTD effect a variety of body areas: the neck, shoulder, elbow and the hand/wrist area. There are many potential factors influencing the current increase in CTD. Several types of variables have been looked at to determine if there is any link with CTD. Three major areas explored were worker characteristics, equipment design and training (ergonomics) and work practices. Some worker characteristics that have been found are small wrist size, oral contraceptives, pregnancy and menopause. However, this is misleading as most CTD sufferers in the research seem to be women (Kiesler and Finholt, 1988). There is currently no conclusive research supporting worker characteristics as being correlated with the incidence of CTD. Work station configuration is believed to be a leading factor in the incidence of CTD. Changing work areas to reduce injuries frequently involves ergonomic principles. At this time a lot of energy and money has gone in to redesigning work stations but there is no conclusive evidence that these ergonomic changes alone reduce the incidence of CTD. Some work practices have shown a positive correlation with CTD rates. These include overtime and poor posture. Improved posture has been documented to dramatically reduce the number of CTD. There is also believed to be a link between the frequency of breaks from repetitive and sustained tasks. As the number of breaks increase, the susceptibility to injury decreases. Computing in clerical jobs is highly correlated with CTD, especially in women (Kiesler and Finholt, 1988). The left little finger may be extended thousands of times a day to hit control and shift keys. Typewriters tend not to cause CTD because they elicit more wrist movement than computer keyboards. They also require breaks to add paper, adjust margins, etc. With data entry and word processing, files are accessed through the computer rather than in filing cabinets. Computer power allows management and workers to increase productivity. However, this also tends to increase monotony, muscle strain and fatigue. In addition, computers make it possible to cut the work breaks and increase the pace of work. These changes also apply to other areas of automation such as assembly lines. Carpal Tunnel Syndrome Possible Causes and Effects As the most infamous of cumulative trauma disorders, carpal tunnel syndrome (CTS) warrants a little extra consideration. The National Institute of Occupation, Safety and Health show more than 23,000 manual laborers in a cross-section of positions are afflicted with carpal tunnel syndrome each year (Blair & Allard, 1983). The syndrome has many possible occupational causes: poor posture, forceful repetition of awkward movements, bad gripping, weak muscles, physical injuries and predisposing physical factors. Other causes of carpal tunnel include fracture, arthritis, obesity, congenital defects, and vitamin deficiency as well as repetitive motion (Kiesler and Finholt, 1988). There is some belief that ulnar deviation is a major cause of CTS and related disorders (Pinkham, 1988a). Ulnar deviation occurs when the wrist is twisted from side to side, as when a typist twists the hand towards the little finger. In addition, flexion and extension of the wrist are also major contributing factors. To address the ulnar deviation factor, Stewart Herzog (Pinkham, 1988a) devised a new keyboard which inserts an inverted V-shaped space between T-V, G-H and B-N. Herzog believes the original keyboard design causes the left hand to be in a position causing ulnar deviation 40% of the time. His new design shifts the keys to allow the wrist to be in amore neutral position. Proper postures and positions can reduce syndrome incidence by at least half. It has been documented that proper posture can lead to a 56% to 97% drop in the rate of CTS incidence (Pinkham, 1988b). Current methods of relief from the symptoms of carpal tunnel yndrome include: surgery, medication, exercise, rest, immobilization, physical therapy, and work modification. The surgery, known as carpal tunnel "release", relieves pain but may not improve grip. If permanent nerve damage has occurred, surgery will not necessarily provide relief from symptoms. Surgery is generally considered the most extreme form of treatment. DEFINITIONS Ergonomics is defined "as the application of anatomical,psychological and physiological knowledge to the problems of human within the environment (social or occupational)" (Leamon, 1987). Ergonomics, human-factor engineering, is the study of the capabilities and limitations of people as they relate to products and their environment. Cumulative trauma disorders (CTD) are also known as repetitive strain injuries, overuse syndrome and repetitive motion injuries. This is a label given to a variety of painful, debilitating conditions believed to be caused by repetitive movements of the hands or arms. CTD affects the muscles, tendons or nerves and is caused by repetitive exertions of the body over time. The terms associated with cumulative trauma disorders imply the etiology to be repetitive work. This is an important risk factor but not the only one. Vibrating tools, forceful motions, motions in awkward postures, static muscle contractions and direct trauma are five other very important occupational risk factors. * Carpal tunnel syndrome (CTS) involves damage to the nerve that runs through a narrow channel in the wrist. The nerve shares the channel with 8 tendons which, when aggravated, swell and put pressure on the nerve. * Tendonitis and tenosynovitis are inflammations of the tendon and tendon sheath respectively. These occur when the tendons or tendon sheaths of the forearms become swollen and no longer slide easily past each other. * Peritendinitis crepitans is a tender swelling in the wrist which can be felt when the wrist is moved. PREVENTATIVE MEASURES A cumulative trauma disorder prevention program may involve simple to complex changes. Some changes may entail considerable financial investment, while others next to nothing. A variety of areas need to be considered including work station design changes and behavior modifications. Lack of break time is a vital factor in contributing to CTD. Automation often removes natural breaks from work situations. It is important to reinstate breaks as the body needs to have frequent opportunities to change positions and remove itself from repetitive actions. The causes of ergonomic problems are most often the position, height and angle of the point of operation; and the size, shape and angle of handles of tools and equipment. (See Table 1.) In applying ergonomics to the work place, the process and the product, all changes should accommodate a wide range of the population. This can be accomplished with the use of adjustable equipment. Changes should be evaluated and monitored closely to ensure that they are appropriate and do not cause other problems. When specifically addressing computer operators the National Institute of Occupational Health and Safety (NIOSH) has several recommendations. They recommend that computer operators be able to adjust the height of the keyboard, screen, chair seat and backrest, screen brightness and contrast, leg room viewing distance and room lighting levels. They also recommend a 10 minute break every hour. In general, injury prevention requires a multi-disciplinary approach. An ergonomic program of this type would include work site analysis; hazard prevention and control; medical management; and training and education. This multifaceted approach has been suggested by many as the best approach to reducing the incidence of CTD (Barrer, 1991; Naderi, 1991; Gross, 1991; OSHA, 1991). They emphasizes complete support by management as being a crucial first step in implementing a successful ergonomics program. Corporate teams that incorporate many aspects of the company are useful in encouraging participation and in making the best use of information available. In addition, line workers should be encouraged to provide feedback to generate feelings of teamwork. One such program is outlined in Figure 1 (Naderi, 1991). When analyzing work stations for possible changes it is important to address worker posture. Posture can be altered through the use of foot stools, different chairs, altering the heights of work surfaces, and arm rests. The use of protective products such as preventative splints are an additional consideration for use in high-risk positions. Hazard prevention and control is concerned with the job's bio-mechanical hazards such as repetition, force, posture, vibration and direct trauma. This aspect of the program would address such things as work station and tool design as well as work practice techniques. It also looks at some administrative controls such as job rotation and rest pauses. Ergonomists have found that tools should be designed to extend and reinforce strength and range. A tool should enhance the existing physical strengths of the extremity rather than fight against it. Redesigned tools and the use of power tools, or light and balanced tools can reduce injuries. Training and education needs to be conducted on five levels: management, engineering, medical, supervisory and line employees. It is important to train employees to recognize ergonomic stressors. The medical management program is involved with early detection, conditioning and rehabilitation programs. A process for early detection should be established that ensures swift capable treatment for employees in a non-threatening manner. Procedures should be established allowing new or reassigned employees time to condition their muscles and tendons before working at full capacity. When possible, employees with symptoms should be reassigned until their jobs have been modified. This program should also provide wellness programs that encourage employees to warm up their hands before they begin work, continually educate workers on ergonomically correct habits of position and movement and the use of equipment that will protect workers from ergonomic hazards. If all phases are implemented together with the full support of management and workers, then the rate of CTD should be reduced and those already afflicted should gain some relief. A philosophy promoting continual improvement of job design, employee education and medical follow-up will assist in the successful implementation of an ergonomic preventative program. Such a systematic approach to bringing ergonomics into the manufacturing process is now termed Total Ergonomic Quality (TEQ) (Gross, 1991). This is a complete corporate-wide program for ensuring ergonomic quality throughout design, production and marketing. Several factors explain the need to emphasize ergonomics, including the increase in injuries and illnesses as well as the changing demographics. Currently, the work force is aging. By 2050 one third of the US population will be at least 55 years old. As the work force ages, ergonomics becomes more important in reducing musculoskeletal injuries. Older workers have decreased muscle performance, flexibility and joint mobility. Many corporations are beginning to taking ergonomics seriously. Consequently, ergonomics is becoming a mainstream responsibility for safety professionals as an integral part of any injury prevention program. Ergonomic designs have been shown to increase work efficiency and productivity by making the machine or tool fit the user or the worker's capabilities. BRIEF HISTORY OF ERGONOMICS The International Labor Organization defines ergonomics as "the application of human biological sciences to the worker and his working environment, so as to obtain maximum satisfaction for the worker which, at the same time, enhances productivity" (Ong, 1992). Simply, it involves the study of humans and their relationship to machines. The term "ergonomics" has been around since 1950 when it first emerged in England. It is derived from the Greek words "ergon" meaning work, and "nomos" meaning law or rule. The idea behind ergonomic principles first surfaced 150 years ago in Poland. Ergonomics grew out of a need to better accommodate military personnel during World War II. It is now the preferred technique for preventing musculoskeletal injuries in the workplace. The goal in the application of ergonomics is to provide a work place that keeps the stresses of the job within the limits of the worker and at the same time capitalize on the worker's unique capabilities. Ergonomic principles involve designing the work place tasks to minimize awkward positions and reduce grip force requirements. This includes designing and selecting hand tools to fit the hand and the task. Some things to avoid include triggers with high tension springs and vibration. Ergonomics is the recognized engineering approach to solve cumulative trauma disorders. Proper work place design can prevent tendonitis, carpal tunnel syndrome, bursitis and spinal disc failure. The objective of ergonomics has been to satisfy the need for a problem-oriented, multi-disciplinary approach to human performance. It is important that any attempt to modify the job include follow-up evaluations of the workers. Sometimes apparent solutions result in further difficulties that may need to be addressed. The effectiveness of preventative job design is still to be demonstrated. Ford Motor Company was a pioneer in 1982 with ergonomics awareness training (Brandon, 1992). In the mid-1980's they started a program of participatory teams. Teams followed step-by-step procedures which included documenting results and monitoring long range consequences. It was found that the teams with line workers involved were much more successful in implementing programs than those without. No studies have yet been done to measure the success of Ford's program in dollars but it has the commitment of the company which is a crucial first step in it's success. Examples of Ergonomic Principles at Work Congleton Boenigk (1991) provides the range of adjustments necessary for an ergonomic chair. * The chair must go up and down with a range of five inches. * The seat should have an angle adjustment with at least an 8 degree forward tilt and a 15 degree rearward tilt. * The backrest depth should be adjustable by 2.5 inches fore and aft so that a clearance of 2-4 inches is allowed between the back of the knee and the seat pan. * The backrest should have a built in lumbar support and should be adjustable in height a minimum of 2.5 inches. * The back rest should be changeable to adapt to various postures. There should be at least 8 degrees of forward and 15 degrees of rearward tilt. This adjustment should be independent of the seat angle adjustment. * All adjustments should be easily made while seated in the chair and they should all be independent. These ranges of adjustment will allow workers to attain a variety of sitting positions while in the chair. By having the controls accessible while sitting, the chair can be adjusted throughout the day. It is important to make frequent adjustments to reduce injuries caused by prolonged periods in one position. Gloves are useful protective measures. They can provide wrist support. In addition, there are a variety of materials that diffuse vibrations. Gloves need to dissipate heat and moisture but also keep the wrist warm when necessary. Neoprene, as used in wet suits, is effective in providing adequate warmth in cooler working conditions. The glove design must allow the worker to be comfortable wearing them. Consequently, the right fit is important in reducing tension and fatigue. Modifications such as polymer dots on the gloves can help reduce the grip strength needed for certain tasks. In a meat packing plant preventative measures that were suggested included small changes in several areas. * Proper stoning of knives is important to keep the blades sharp. * Cotton gloves combined with a grain pattern on the knife handles help absorb moisture and increase friction which will reduce the grip necessary on the knife handle. * The knife handle should be curved to better fit the hand. * The height of the conveyer and work surfaces should be adjusted to minimize the amount of wrist deviation while using the knife. CONCLUSION Employers are becoming increasingly sympathetic to the situation of employees. They are devising ways to minimize time-loss and to allow workers to return to work. Frequently, the work must be modified or changed all together. Employers are also realizing that good prevention programs make happier workers. And happier workers have higher production levels. Industry is trying to switch from a reactive to a pro-active position in addressing injuries. Changes are being made to the work force and the work place in response to the current epidemic of CTD. The major occupational factors that contribute to CTD are position, force and frequency. Ergonomic principles can often be used to address most of these problems. It appears as though a multi-disciplinary approach to reducing the incidence of CTD in the work place will be most successful. The program which involves behavioral changes in conjunction with increased education of the work force and ergonomic improvements to the work place will be the most effective at reducing cumulative trauma disorders. Present research in to the causes and methods of preventing cumulative trauma disorders is fairly young. It would appearas though some cumulative trauma disorders are preventable through changes in work practices and in the work place. However, not all injuries are preventable due to the wide range of causes. 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