A Guide to Practical Ergonomics

What is Ergonomics?

The word "ergonomics" comes from the Greek words ergon (work) and nomos (laws) or "laws of work". It is the science of work station design. The ultimate goals of ergonomics are to: Minimize work-related stress Control work-related cumulative trauma illnesses and injuries Increase job efficiency, productivity and quality Reduce product damage Raise employee morale Reduce turnover and absenteeism rates The objective of ergonomics is to adapt the job and workplace to the worker by designing tasks within his or her work capabilities.	Experience has shown that instituting programs in ergonomics has not only reduced cumulative trauma illnesses, but simultaneously improved productivity and product quality. Effective ergonomics considers these factors: Equipment - The characteristics of the equipment workers must use (such as tool handles and arrangement of controls). Environment - The physical surroundings in which the equipment must be maintained and operated and in which the worker must perform (such as lighting, noise level and temperature).	Task - The characteristics of the jobs that employees must perform (length and complexity of operating procedures). Personnel - The capabilities and limitations of workers (training and experience in operation of the equipment). The purpose of this manual is to explain the most prevalent ergonomic problems in the meat industry. These are cumulative trauma illnesses and injuries to the: Hands and wrists Arms and shoulders Back
This manual also will tell you where to look for these problems as well as how to begin to solve them.

Cumulative Trauma Illnesses
of the Wrists and Hands

A worker spends much of her day on the boning line. She has been using a knife with the same poorly designed handle for about a year. At night, she suffers tingling sensations and pain in her fingers and thumb. Lately, she's been dropping her knife a lot. Another worker operates a power saw. His fingers are exposed to sustained periods of vibration. Lately, both of his hands have become numb and pale. He's also complained that his hands need time "to warm up" before he comes to work.

The hands and wrists are made up of a variety of fragile bones, nerves, blood vessels, tendons and ligaments that can be easily damaged if they are misused. The following are some of the occupational conditions that can cause hand and wrist illnesses:

• Frequent or repetitive movement of the hand or wrist, usually associated with awkward wrist angulation
• Inappropriate tool and equipment design
• Vibrating knifes and saws
• Poor work station design and arrangement
• Cold environments

You should not be overly concerned with the exact illness. The purpose here is not diagnosis. What is important is removing or modifying the injury-causing process, instrument or work station design.
The illnesses that follow are some of the most common repetitive trauma disorders that affect the hands and wrists of meat industry workers.

Carpal Tunnel Syndrome

The worker in the opening vignette who had problems controlling her knife displayed symptoms of Carpal Tunnel Syndrome. Carpal Tunnel Syndrome is often caused by bending or twisting of the wrists, especially under force. It affects the median nerve, which runs through a channel in the wrists. The channel is called the Carpal Tunnel. Symptoms of Carpal Tunnel Syndrome include:

• Nighttime pain in hands and wrists
• Burning in the affected areas
• Prickling or tingling feelings in the first three fingers and thumb
• Sensory change in the affected fingers
• Wasting (atrophy) of some muscle groups in the palm (in severe cases)
• An overall weakness in the hand

There are many approaches to treating cumulative trauma illnesses and injuries. The AMI will address these methods in the future. At this time, however, we will focus primarily on engineering issues.

Tenosyvitis

Tenosyvitis, often referred to as Tedinitis, is a predominant cumulative trauma illness in the meat industry. The tendons in the wrists and fingers become sore and inflamed due to repetitive twisting motions. The affected areas in Tenosyvitis are often characterized by:

• Pain
• Swelling
• Cracking sounds Tenderness
• Some loss of function.

Trigger Finger

Flexing the fingers for extended periods can cause Trigger Finger, another form of Tendinitis. Eventually, the tendons in the fingers become inflamed, and dexterity might be adversely affected. Involved areas are often characterized by:

• Pain and swelling
• Redness and tenderness
• Inability to open fingers from a flex position

Trigger Finger is often associated with tools that have power actuated switches, such as rib saws. This condition may also result from using a hand tool with too large a handle.

White Finger Syndrome

The worker in the opening vignette who needed "to warm up" his hands probably suffered from White Finger Syndrome. Repetitive manual tasks can be reduced with the use of power-assisted tools. However, some tools tend to vibrate too much and can damage blood vessels, causing what's known as Raynaud's Phenomenon (White Finger). As a result, skin and muscle tissues are deprived of a sufficient amount of oxygen and eventually deteriorate. Vibration can also contribute to Carpal Tunnel Syndrome. In addition, vibration can lead to degenerative problems in the bones, joints and tendons. The onset of extensive damage may be prolonged, however. Symptoms of White Finger Syndrome include:

• Blanching of the fingers
• Numbness and pain in affected fingers
• Loss of precision in finger control

In the early stages of White Finger, the disease may disappear if exposure to the injury-causing source is avoided. Cold environments can stimulate the symptoms or make them worse.

All of the preceding cumulative trauma illnesses should be taken seriously. If allowed to progress to a critical stage, they can cause permanent disability. Even surgery is no guarantee that the individual will fully recover the normal functioning of the hands.

Suggested Ergonomic Solutions

Hand/wrist Positioning

A worker's hand/wrist positions while performing a given task are important in preventing cumulative trauma illnesses of the hands and wrists. An improper hand/wrist position can can cause undue stress on the muscles, tendons and nerves. Tasks should be designed so that the hand and wrist are not in awkward positions. The wrist should be kept as close to the neutral (straight) position as possible. Overextension and flexing of the fingers should be avoided.

Tool Grip

Good grips for knives and tools are also important in preventing cumulative trauma illnesses to the hands and wrists. A good handle diameter generally ranges from 1 1/8" to 1 1/2". Stress at the base of the palm should be minimized. Most of the pressure should be distributed over the fleshy part of the palm. Tools with textured surfaces are recommended because they aid in sensory feedback. The worker can then tell exactly how much force is needed to perform a task. Gloves that are too thick or or fit improperly can sometimes reduce blood circulation and sensory feedback as well as cause slippage. Trigger Finger can be reduce by utilizing tools with triggers that depress easily and handles that fit the hand comfortably. Also, pneumatic tools that use thumb triggers, full-hand triggers, strip triggers etc., can reduce the risk of Trigger Finger. The AMI is currently working with scientists to develop better tool and knife grips. [Editors note: PersonaGrip's adjustable grips allow end users to add all these issues on an individual per-application basis. Be sure to check out our web page on this exciting revolutionary grip system.]

Reducing Repetition

Some jobs, regardless of wrist position and tool grip, are highly repetitive. Methods must be found to reduce the number of wrist or hand repetitions per hour. For example, in packaging operations, repetitions can be reduced by improved layout; the product can be slid into the package rather than picked up and placed in it.

Fixturing

Restricting an object's movement, or fixturing, can allow the worker to perform tasks with two hands - instead of one hand operating the tool and the other holding the product in a static position. The hand and wrist performing the static work can be injured if the task is done for prolonged periods. In other industries, fixturing has dramatically reduced Carpal Tunnel Syndrome. The challenge for the meat industry will be to develop both innovative and fixturing methods as well as unconventional two-handed tools.

Reducing Amount of Force

The amount of force required to perform a task should be minimized by altering the the task or the equipment being used. The amount of force that is needed to perform specific tasks is related to several factors:

• Hand position
• Characteristics of the tool being grasped (size and shape of handle)
• The amount of friction between the hand and the object
• Type of gloves worn
• Workplace dimensions

By altering the tool, force can sometimes be reduced. Force also can be reduced by holding the object at its center of gravity so that the object's weight does not twist it from the worker's hand. If your tools do not conform to these specifications, a solution to your problem may be tool redesign. The amount of friction between the hand and the tool can be increased by utilizing tools with textured handles and by wearing gloves. The amount of friction also will be increased if tool handles and gloves are kept free of grease, oil, blood and other substances that may cause slipping. Equipment (knives, gloves, etc.) should be replaced when it is no longer effective. Because worker's hands are different sizes, highly grooved handles are not recommended. The grooves may place stress on the nerves, if a worker's hand does not fit them properly. Workers should be provided with a variety of sizes and styles of tools, so they can select the ones that fit their hands most comfortably. [Editor's Note: Personal moldability changes the traditional perspective on tool design. see its web page for details.]

Protection Against Cold Temperatures

Cold temperatures constrict blood vessels, which can adversely affect a worker's grip. The hand and wrist should be sufficiently protected from cold ambient air and cold objects with appropriate personal protective equipment without sacrificing comfort or safety.

Knife Sharpening

A truly sharp knife can reduce the effort needed to make a cut and thus reduce stress on the wrist. This factor emphasizes the importance of an effectual knife-sharpening system and a well established employee training program.

Reducing Vibration

The vibration of pneumatic and other power tools should be reduced so that workers are exposed to the lowest vibration levels possible. Some industries have determined that wrapping tool handles or grips with rubber insulation material reduces the transmission of vibration. Insulation materials however, should not interfere with hand/grip friction. [Editor's Note: Personagrips leveraging surfaces allow workers to relax their grips without losing control.]

Redesigning the Work Station

To reduce the frequency of cumulative trauma illnesses, work stations should be arranged so that workers are not performing awkward hand and wrist movements. Consider your boning operations. Many workers of different heights may be performing the same tasks at the same work station. Even if your knives and power tools have been designed to reduce awkward hand or wrist movements, the fixed height of the work station may cause some workers to accommodate to this height by bending the wrist, shoulder or back in an unnatural way.

Let's say you have one worker who is five feet tall and another who is six feet tall. Your boning line is somewhere between 31 to 36 inches from the floor. What's going to happen? Because of the variance in their heights, these workers are going to be working in awkward positions. Over a period of time, their hands, arms and shoulders will be stressed. And, it's only a matter of time before the accumulated stress takes its toll. One temporary solution is the selection and placement of employees based on their physical characteristics. Some companies are experimenting with placing workers of similar heights on the same side of the table and raising or lowering work stations accordingly. Making work stations adjustable is the key to accommodating your work force's varying heights and reaches and just may be one of the viable solutions to some of the cumulative trauma illnesses and injuries in the meat industry.

Job Rotation

In certain cases, job rotation may be a temporary solution or part of an overall program to reduce cumulative trauma disorders. A worker can be periodically removed from a repetitive motion of a given body part to allow him or her to recover from the stress experienced. For example, a boner can be moved to a service and supply job several times over the course of the day. By doing so, the employee utilizes different muscle groups. That way the worker's hands and wrists are not constantly involved in the same movement. Keep in mind that if job rotation is between tasks that involve the same muscle groups, minimal benefit will be derived. Note: There may be contractual issues (seniority, job rights, etc.) that must be worked out with the local bargaining unit before a job rotation program can be implemented. These issues can be minimized if the benefits of such a program are explained to employee representation.

Tool and Equipment Design

The main objective with tool design is to bend the tool, not the wrist. Hand tools and other equipment should be designed to keep hands and wrists in their most natural (straight) position. Various knives are currently being used that allow the worker to make cuts with a straight wrist. Tools should be maintained to operate in good working order. As we know knives should be sharpened and steeled so the blade does the work, not the worker's wrist and hand. A well organized knife-sharpening program, whether centralized or individualized, can increase the work efficiency and reduce injuries. If power-assisted tools are used, counter balances suspended by overhead racks can reduce the amount of force needed to operate and control the tool. These tools must also be maintained properly.

Automation

There have been some current developments in mechanization that have replaced some of the more ardous tasks in the meat industry. Such implements as automated deboners and snout markers are currently being utilized. The AMI is examining the realm of automation to see if this technology can be implemented in other areas that require laborious tasks.

Minimal Work Motions

Some employees, particularly senior employees, have learned certain work motions which reduce the effort needed to do the job. These workers should be used to help others, especially new hires, learn to do their jobs with the least effort. Some companies videotape the work motions of senior employees to instruct others.

Cumulative Trauma Illnesses
of the Shoulders and Arms

Like hands and wrists, the arms and shoulders are also prone to cumulative trauma illnesses. Some of the major causes of these types of illnesses include: Muscle fatigue due to improper tool design and work methods Overextension of the arms and elbows due to inadequate tools and machinery Repetitive motion tasks that require the arms to be raised above the shoulders These movements can damage muscles, nerves, tendons and joints, causing such debilitating injuries as Tennis Elbow (Epicondylitis) and Tendinitis.

Suggested Ergonomic Solutions

Job Design

Job tasks should be designed so that workers are not continually raising their arms above their shoulders. Workers should be able to:

• Keep arms at a level between normal elbow and knuckle heights
• Keep elbows close to the body

Work should be designed to suit the body's natural mechanics. For example, pushing an object away from the body or pulling an object toward the body are common movements - as long as the weight isn't too heavy and the action is done with correct body position. But, moving an object across the body is unnatural and may cause injury, because the torso is twisted.

The man in the illustration on the right, is repeatedly lifting his arm above shoulder height to place scraps on a conveyor belt. He is also leaning across a table to be able to reach. He will most likely sustain injuries to his lower back and/or his neck and shoulders.

Tool Design

In some cases, tools can be redesigned to ensure good posture and decrease the amount of force placed on joints and tendons. Mechanical assists can prevent workers from raising arms above shoulders on a regular basis. Counterweights that support rib saws and neck breakers also can minimize the force necessary to raise and lower power tools.

Work Station Redesign

This may involve elevating or lowering work stations or changing the location of controls. It should be noted that the horizontal distance between the worker and the work to be performed should not be greater than 18 inches. Ideal working heights can be provided to workers of different height by utilizing tables with adjustable legs and risers, and grates.

Job Rotation

Alternate tasks between repetitive motion and non-repetitive motion jobs. See Job Rotation above.

Protection Against Cold Temperatures

Workers should wear proper protective clothing if the ambient air temperature is known to affect performance or comfort. Temperatures in meat industry operations range from 0° Fahrenheit to 40° Fahrenheit on processing floors. If workers are not adequately protected and insulated, these temperatures can induce stress on overworked joints more quickly than normal temperatures.

Ergonomics: the Wave of the Future

The time has come to recognize the benefits of human element engineering. Ergonomics works. It has been proven over and over again. It doesn't have to cost a lot. It doesn't require a crew of rocket scientists to fashion a workable policy. The meat industry has been the subject of enough denunciation. We've had our share of unfavorable media coverage. We've been compared to Upton Sinclair's The Jungle more times than is palatable. Now we are taking the first steps towards doing something about it. Realize, however, that this manual will not solve all of your problems. It merely introduces you to the benefits of ergonomics and offers some viable solutions to many of your existing problems. In the future, the AMI will supply you with more detailed information that will benefit your organization. In the meantime, we hope you see fit to participate in this program and venture to undertake some of the suggested solutions - for the good of your company, your employees, and the meat industry as a whole.

---

---

---