According to Heinrich, 88% of accidents are the result of human behavior and therefore preventable. ² The American Public Health Association states that the cornerstones of prevention are anticipation of the potential for disease or injury, surveillance (accurate identification, reporting, and recording of occupational disease and injury), analysis of collected data, and control. ³

Traditional methods of controlling or eliminating workplace hazards include engineering out or removing the hazard, using personal protective equipment (PPE), administrative interventions, and training in the proper and safe use of equipment. Engineering is frequently quite costly and therefore cannot be used in many potentially hazardous environments. If the hazard cannot be engineered out, administrative controls may limit worker exposure time through job rotation or schedule changes. Worker selection strategies may limit exposure of workers who are incapable of performing certain jobs. Job training is essential to provide workers with instruction in safe and efficient performance of required duties; workers must be trained to minimize risk of injury or illness.

Anthropometric data are used ergonomically to determine reach and clearance measurements when designing the workplace. Data analysis shows variations between sexes in average heights, weights, reaches, and other parameters. The following are examples of height and weight averages reported in the U.S. populations10^{11 and 12}:

NASA:	Male 70.8 inches, 181 lb	Female 61.8 inches, 113.5 lb
Chaffin:	Male 69 inches	Female 63.7 inches
Selan:	Male 69 inches	Female 63.9 inches

The Golden Rule of Design states that clearance allowances must be designed for the largest users and reach capabilities must be designed for the smallest users. Incorporating adjustability whenever possible is important.

Physical and emotional risk factors associated with low back pain (LBP) in the workplace are highly relevant to chiropractic practice. Correlations have been found between LBP and the following¹³:

Key risk factors associated with cumulative trauma disorders (CTDs) include repetition or frequency of motion, force of exertion, posture of the body, duration of task, recovery or cycle time, exposure to cold temperatures, and exposure to vibration.^{9141516171819 and 20}

Gilkey and Williams provide a detailed synopsis of key points in the proposed Occupational Safety and Health Administration (OSHA) ergonomic standards. ²¹ Of particular importance are the following signal risk factors for CTDs:

Other risk factors associated with developing CTDs include age (50% of claimants are over age 50), hypertension, coronary heart disease, stroke, hyperlipidemia, genetic factors, alcohol and tobacco use, lack of exercise, and poor diet. ²² Researchers have recently identified a carpal tunnel gene, suggestive of a genetic predisposition for carpal tunnel syndrome (CTS) that may exist in certain populations. The MCP-1 gene might be a candidate for the genetic marker of CTS development. Individuals with this gene are at increased risk for developing CTS. ²³

Implementation of ergonomic controls endeavors to fit the job to the worker. When possible, the first step is to engineer out the hazard. Today’s technological marketplace offers a wide array of ergonomic devices and equipment for both manufacturing and sedentary workplaces. Design solutions are specific to each work site. Recommendations may include engineering interventions such as mechanical lift assist devices, power-driven hand tools, and adjustable workstations; ergonomic PPE such as friction-enhancing gloves, protective eye wear, and hearing-conservation wear; ergonomic training in proper work postures, proper lifting techniques, and fitness instruction; and administrative interventions, including job rotations and changes in break schedule and production rate.

Some ergonomic challenges require only simple intervention, while others entail complex and costly solutions. Communication with company management and all affected individuals is essential. Once intervention has been completed and an ergonomic program is underway, results may be measured by the same passive and active analysis methods used earlier. Programs should be monitored on an ongoing basis and audited every 2 years to document results and the need for further intervention. ¹¹

Between 60% and 80% of the general population will suffer from LBP at some point in their lives, and 5% to 30% experience LBP at any given time. ²⁷ The burden to social and financial systems is significant. Estimates suggest that 22.4 million cases of back pain occur annually, equaling a 12-month period prevalence of 17.6% in the general populations, and 65% are work related. ²⁸ Back pain is the most frequently cited reason for worker’s filing injury claims. According to the National Safety Council (NSC), low back disorders make up 30% to 40% of all WC injuries. ²⁹ The National Institute for Occupational Safety and Health (NIOSH) reports that 19% to 25% of all WC claims are for back pain. ³⁰ Back pain is the second most frequently recorded reason for lost workdays in America, the common cold being first. ³¹ The Bureau of National Affairs (BNA) reports that back pain accounts for more than 500 million lost workdays each year. ³⁰ On any given day, an estimated 6.5 million people are home from work, in bed, as a result of back pain. New back pain cases are generated at a rate of 1.5 million per month. ³¹

Equally significant as the prevalence of back pain and injury are the costs associated with it. The average cost of a work-related lower back injury in Ohio was $23,716 in 1990, which increased to $30,000 by 1994. ^32,33 In addition, NSC reports that the total actual costs of all work-related injuries was $122.6 billion in 1999. ²⁹ Most WC carriers agree that back injuries are the most expensive claims, comprising 65% to 90% of benefit costs. ³² The real economic impact of back pain also includes hidden costs, bringing total back pain expenses as high as $100 billion annually.^{3334 and 35} Because of the prevalence and costs, a growing shift in awareness and concern has occurred about NMS injury and illness in the workplace. Although back pain clearly remains the number one challenge to industry, CTDs have emerged as a sleeping giant.

Review of the literature from the United States shows a sharp rise in the number of CTDs affecting upper extremity (UE) between 1981 and 1994:

BLS, NIOSH, and OSHA began to consolidate the injury and illness data in 1994 by combining NMS disorders for both UE and lower back related to ergonomic risk factors such as overexertion and repetitive motion. These conditions are now identified as musculoskeletal disorders (MSDs):

A 770% increase in CTDs was reported between 1983 and 1993, a trend attributed to increased public awareness of CTDs, broader definitions of compensable claims, increased numbers of service industry workers, and increased use of video display terminals (VDTs).³⁸

A decreasing trend has been evident since 1994 with nearly an 18% drop in the number of reported MSDs reported between 1994 and 2000. Explanations for this encouraging trend may include a positive response by industry to the increased emphasis by OSHA and labor organizations on curtailing the MSD epidemic in American workplaces. OSHA had allocated significant resources to developing the Ergonomic Standard, resulting in increased public awareness and concern over the number of workers affected with MSDs. The Standard, short lived as it was (discontinued in 2001), served as motivation for many businesses to engage prevention strategies to reduce ergonomic risk factors.

CTDs are reported as occupational illnesses, not injuries. CTDs make up only 4% of the reported work-related injuries but constitute approximately 60% of work-related illnesses. ^46,47 Despite the alarming numbers, some experts believe that CTDs may be underreported, with IR as much as 130% higher. ⁴⁶

CTDs are not only the fastest growing workplace illness, but also one of the most expensive occupational illnesses to treat. Cost estimates have recently been established at $20 billion to $27 billion per year in the United States. ^36,48,49 The National Council on Compensation Insurance has stated that the average CTD case costs $29,000, including wage loss and treatment, in the early 1990s. Litigation and settlement costs exceed the medical and lost wage expenses, averaging $50,000 per case. ⁵⁰ Costs for managing MSDs have risen to an average of $84,000 for surgical cases, with basic medical management averaging approximately $23,000 per case⁵¹ (Fig. 18-1).