1. ERGONOMICS Recognition of Work-Related Musculoskeletal, Nerve Disease
This presentation is designed to assist trainers conducting OSHA, 10-hour General Industry outreach training for workers. Since workers are the target audience, this presentation emphasizes hazard identification, avoidance, and control – not standards. No attempt has been made to treat the topic exhaustively. It is essential that trainers tailor their presentations to the needs and understanding of their audience.
This presentation is not a substitute for any of the provisions of the Occupational Safety and Health Act of 1970 or for any standards issued by the U.S. Department of Labor. Mention of trade names, commercial products, or organizations does not imply endorsement by the U.S. Department of Labor.

2. What is Ergonomics?
Ergonomics is the science of fitting the job to the worker.
Ergonomics refers to a work environment designed to maximize safety and increase productivity.
Ergonomics is an engineering discipline that addresses the effect work
environments and tasks have on the employee.
Ergonomics involves workstation set-up and design, body posture,
prevention of computer-related injuries and more.

3. What is Ergonomics Gone Bad?
When there is a mismatch between the physical requirements of the job and the physical capacity of the worker, work-related musculoskeletal disorders (MSD) may result.
Clues that indicate ergonomic problems may also suggest the scope of the effort required to correct them. For example, signs implicating multiple jobs in various departments and involving a large percentage of the workforce would indicate the need for a full-scale, company-wide program. Alternatively, signs that the suspected problems are confined to isolated tasks and relatively few workers may suggest starting with a more limited, focused activity.

4. Ergonomic Disease Repetitive motion injury Cumulative trauma disorder
Musculoskeletal disorder (MSD)
Repetitive stress injury
Sprains, strains, tears
Often workers are given little choice and are forced to adapt to poorly designed work conditions, which can lead to serious injury to the hands, wrists, joints, back or other parts of the body. In particular, injuries can result from:
1. repeated use over time of vibrating tools and equipment, such as a
jackhammer;
2. tools and tasks which require twisting hand or joint movements, such as the
work many mechanics perform;
3. applying force in an awkward position;
4. applying excessive pressure on parts of the hand, back, wrists or joints;
5. working with the arms outstretched or over the head;
6. working with a bent back; and
7. lifting or pushing heavy loads.

5. Musculoskeletal Disorders
Injuries or disorders of:
muscles
tendons
ligaments
nerves (compression or entrapment)
spinal discs
joints and cartilage
Physical injuries caused by performing unsafe manual handling tasks.
Includes injuries such as muscle sprains and strains; injuries to muscles,
ligaments and discs in the back; injuries to nerves, ligaments and tendons
in the hands, wrists, arms, shoulders, neck or legs; and abdominal hernias
and long-term pain.

6. Signs and Symptoms Muscle pain Joint pain Swelling Numbness
Restricted motion
Low back pain
Signs and Symptoms:
Numbness or a burning sensation in the hand
Reduced grip strength in the hand
Swelling or stiffness in the joints
Pain in wrists, forearms, elbows, neck, or back followed by discomfort
Reduced range of motion in the shoulder, neck, or back
Dry, itchy, or sore eyes
Blurred or double vision
Aching or tingling
Cramping
Loss of color in affected regions
Weakness
Tension stress headaches and related ailments

7. Musculoskeletal Disorders
Upper Extremities
Upper Back
Lower Back
Feet and Legs
Hands
Arms
Shoulder
Neck
The different types of Musculoskeletal Disorders are as follows:
Repetitive Stain Injury
Carpal Tunnel Syndrome
Other Ergonomic Problems

8. Benefits of Good Ergonomics
Decreased injury risk
Increased productivity
Decreased mistakes/rework
Decreased lost work days
Decreased turnover
Improved moral
Saving Time by Using Good Ergonomic Tools and Practices can help you in many ways. Among other things, it can benefit your life, health, productivity and accuracy. One of the best benefits of ergonomics is saving time. We never seem to have enough of it as it is, so why not try to get a little more out of your day? Ergonomics is about making things more efficient. By increasing the efficiency of a tool or a task, you tend to shorten the length of time it takes to accomplish your goal.

9. Risk Factors for Ergonomic Hazards

10. Repetitive Motion/Cycle
Same repetitive task
Use of same muscle groups
Short cycle (~<2/min)
A repetitive motion/cycle is an injury to a part of the body that is caused by performing the same motion over and over again thereby straining the body part. Strain occurs when the body part is called on to work harder, stretch farther, impact more directly or otherwise function at a greater level then it is prepared for. The immediate impact may be minute, but when it occurs repeatedly the constant straining cause damage.
The term repetitive motion injury identifies a large group of conditions that result from using the body in a repetitious way and causing injury by the amount it is done.

11. Awkward Posture Twisting Overhead Reach
Deviation from the neutral positions of the different body parts.
Awkward postures typically include reaching above, behind, twisting,
forward or backward bending, pinching, squatting and kneeling
Photo source: OSHA website
Overhead Reach

12. Forceful exertions, pulling, pushing, twisting
Heavy lifting
Force: Performing essentially the same motion or motion patter over and
over again with little variation in task assignment. Repetitive motion task
often involve the use of only a few muscles, tendons and body parts,
which can become strained when the same motion is repeated frequently
(i.e., every few seconds) for prolonged periods (e.g.,  several hours
at a time, the entire work shift, day after day) without adequate
recovery time. The severity of risk depends on how often the motions
are repeated, the speed of the motions, the force required to perform
the motions, and the number of muscles involved.
Source Photos: OSHA
Forceful exertions, pulling, pushing, twisting

13. Contact Stress Using the hand or knee as a “hammer” Source: NIOSH
In the mid-1980s, NIOSH conducted a study of union tradesmen that included questionnaires, interviews, and medical examinations [Thun et al. 1987]. Compared with workers who seldom kneel and do not use a knee kicker, carpet layers more frequently reported bursitis of the knee (20% versus 6%), fluid buildup requiring knee aspiration (knee taps) to remove blood and water (32% versus 2%), skin infections of the knee (7% versus 2%), and a variety of knee symptoms. Furthermore, carpet layers often leave the trade after knee damage
develops and thus would not be included in a cross-sectional study such as this. The actual number of knee injuries and the extent of damage may therefore be greater than these statistics indicate. During a typical installation, carpet layers spend about 75% of the time on their hands and knees. The carpet layer first prepares the floor by nailing tack strips along the perimeter of the room. During this activity the knees are in direct contact with the hard surface. After the padding material is installed, the carpet is spread and cut to the size and shape of the room. The carpet layer then uses the knee kicker to engage an edge of the carpet onto the tack strips. Only mild kicks are required for this purpose. However, very strong kicks are applied when the carpet is stretched from wall to wall. According to a biomechanical study, the average impact of such kicks exceeds 3,000 newtons (675 pounds)--about three to five times the body weight. During a typical installation these strong knee kicks are repeated 120 to 140 times per hour [Bhattacharya et al. 1985].

14. Vibration Whole body vibration Segmental vibration
e.g.., Crane operators, truck drivers
Segmental vibration
Pneumatic tools, grinders
Vibration (generally from a powered hand tool) that goes through the hand, and then travels through the rest of the arm.

15. Risk Factors Also Depend On:
Duration of stress
Amount of recovery time
Temperature
Decrease blood flow to muscles (cold)
The physical work activities and conditions cover the basic physical aspects of jobs and workstations. These aspects include:
Physical demands of work;
Workplace and workstation conditions and layout;
Characteristics of object(s) that are handled or used; and
Environmental conditions.

16. And a Higher Risk Occurs When:
Risk factors are multiple
The longer motions or job tasks are performed, the less likely that there will be adequate recovery time. The accumulation of exposure leads to muscle fatigue or overuse. In addition, where the intensity of exposure is greater, for example, in repetitive motion jobs that involve exposure to additional risk factors (force, awkward postures, or static postures), the increased forces required for the exertion also increase the amount of recovery time that is needed. Any part of the musculoskeletal system involved in moving the body is subject to injury where there is inadequate recovery time, and the recovery times needed vary by body part. For example, although employees may not be at high risk for forearm injury, if task cycles are 25 seconds long or not repeated more than 3 times per minute, they may be at high risk of shoulder injury under this regimen.

17. Controlling Ergonomic Hazards

18. Control Hierarchy Engineering controls Administrative controls
Physical changes
Administrative controls
Employee rotation
Change of pace
Job enlargement
Work practice controls
Utilization of better procedures, posture
Personal Protective equipment
Work Strategy Controls When an ergonomic hazard has been identified, the Environment, Health and Safety Office will work with the department in eliminating or minimizing the hazard. There are two general approaches to controlling ergonomic hazards: Engineering and Administrative.
Engineering Controls - Are changes made to the workstations, tools, and/or machinery that alter the physical composition of area or process.
Administrative Controls - Are changes made to regulate exposure without making physical changes to the area or process, for example taking frequent breaks and job rotations.

19. Manual Material Handling and Back Protection

20. Acute vs. Chronic Stressors
Where the injury arises from a single identifiable event - when transient loads exceed internal tolerances.
Chronic:
Where repeated trauma (albeit incapable of injury in isolation), after sufficient duration, reduces internal capacity resulting in eventual injury.
Microtrauma
Acute – Occurs immediately
Chronic – Occurs over time

21. Back Injury Muscle Ligament Vertebrae Discs
Your back is an intricate structure of bones, muscles, and other tissues extending from your neck to your pelvis. Back injuries can result from sports injuries, work around the house or in the garden, or a sudden jolt such as a car accident. The lower back is the most common site of back injuries and back pain. Common back injuries include – sprains and strains, herniated disks, fractured vertebrae.

22. Ergonomic Risk Factors for Backs
Awkward posture
Sitting
Static, bent postures
Fatigue/aging
Whole body vibration
The back is made up of 33 individual bones called vertebrae, separated by shock - absorbing disks. The spine is held in place by a large number of muscles and ligaments. By acting together, they give the spine the ability to bend and twist. The spine also protects the spinal cord and acts as a distribution center for the nerves that run between the brain and the other parts of the body.
Anatomically, the spine is an unstable structure. We create the illusion of stability by using muscles groups in the trunk to keep the back stable. If these muscle groups are out of condition, we run the risk of injury from one - time exertions that are beyond our capacity or from prolonged use of the muscles at a slightly elevated level.

23. Ergonomic Risk Factors for Backs
Handling excessive weight/force
Load size
Frequency of lifting
Grip consideration
Poor physical condition
The risk factors for back disorders are the same categories as for RMIs. That is because many back disorders are RMIs — they result from prolonged exposure to micro-trauma, and affect tissues that do not heal quickly. Remember, the more risk factors that are involved and the greater the exposure to each, the higher the likelihood of developing an injury. The primary workplace risk factors for back disorders are:
Force — forceful exertions that do not cause harm with one motion, but which can build up micro-trauma over time. For example, the force generated by sitting for extended periods of time without standing to take a break or altering position is a risk factor for low back pain.
Frequency — too much repetition or too little movement can contribute to micro-trauma. For example, repeated twisting to reach the phone is a risk factor for low back pain, as is prolonged sitting with the back bent forward.
Posture — there are certain postures in which we are more susceptible to injury, especially at the extremes of our range of motion. For example, twisting and bending forward while sitting are risk factors for low back pain.

24. Kinds of Back Injuries
Back strains-When weak or tense muscles are stretched beyond their limit
Back sprains-A partial or complete tear of a back ligament
Herniated discs-Resulting when stress, strain or gradual deterioration on a disc causes it to stick out between the vertebrae
Ruptured discs-When the wall of a disc breaks open.
Strains and sprains are damage to the tendons and ligaments caused by one - time exertions such as lifting or carrying heavy objects. These can lead to very noticeable back pain, but the pain usually begins to subside within a few days if properly addressed and managed.
Facet joint pain results from irritation of the area where the ribs meet the spinal column. Typically, there is muscle swelling in the affected area and it can become very painful to sit or stand up straight.
Disc erosion occurs from prolonged pressure on the spinal discs, which causes them to become permanently compressed. The space between the vertebrae becomes smaller, which can lead to impingement of the nerve roots leading out from the spine. Sitting puts more pressure on the spinal disks than standing, and sitting with the back unsupported can lead to high levels of disk pressure.
Sciatic nerve impingement, also called sciatica, is common in people who sit for prolonged periods of time. The sciatic nerve runs from your lower back down the back of your leg and down to your feet. Swelling or tension in certain muscles in the buttocks can put pressure on the sciatic nerve, causing pain down the leg.
Herniated discs occur when the inner portion of the disc protrudes, putting pressure on the nerve roots leading from the spine. Pain or numbness in the legs is a common symptom of herniated discs in the lower back.

25. Upper Extremities Work-Related MSDs

26. Effects Pain Inflammation Swelling Numbness
Decrease in range of motion
Loss of function
Cycle of injury
Redness (rubor), heat (calor), swelling (tumor), pain (dolor) and dysfunction of the organs involved.

27. Awkward Wrist Postures
UECTD Risk Factors
Awkward Wrist Postures
Awkward wrist postures.

28. Tendon Disorders Tendonitis:
Fibers can become inflamed, fray or tear apart, tendons can thicken, become bumpy and irregular and without sufficient recovery time become permanently weakened
Tendon disorders are medical conditions that result in the tendons not functioning normally. These disorders occur in two types of tendons: tendons without sheaths, and tendons with sheaths. Tendinitis is a disorder of tendons without sheaths and tenosynovitis is a disorder of tendons with sheaths.
Tendinitis (also called tendonitis) is the term used to describe an inflammation of tendons. Tendons are rope-like structures made of strong, smooth, shiny fibers. With repetitive or prolonged activities, forceful exertion, awkward and static postures, vibration, and localized mechanical stress, the tendon's fibers can tear apart in much the same way a rope becomes frayed.

29. Tendon Disorders Epicondylitis Lateral epicondylitis
- tennis elbow
(inflammation of
tendon fibers -
outside of elbow)
Source: American Society for Surgery of the Hand
Lateral epicondylitis or tennis elbow - inflammation of the tendon that attaches some forearm muscles to a "bump" or projection [lateral epicondyle] on the side of the humerus, just above the elbow.
Medial epicondylitis or
golfers elbow (inside)

30. Source:NIH, Medline Plus
Tendon Disorders
Rotator cuff tendonitis
Repetitive overhead work
Elevated elbows
Rotator cuff tendinitis - inflammation of the tendons that rotate the humerus [upper arm bone] and help raise the arm.
Source:NIH, Medline Plus

31. Tendons
Stenosing Tenosynovitis (progressive restriction of the synovial sheath)
De Quervain’s disease (thumb tendons)
Tenosynovitis is an inflammation of the tendon sheath. The inner walls of the sheath produce a slippery fluid, called synovial fluid, which lubricates the tendon. With repetitive or prolonged activities, forceful exertion, awkward and static posture, vibration, and localized mechanical stress, the lubrication system may malfunction. It may not produce enough fluid, or it may produce a fluid with poor lubricating qualities. Friction between the tendon and its sheath results when the lubricating system fails. This leads to inflammation and swelling of the tendon sheath. Repeated episodes of inflammation cause fibrous tissue to form that thickens the tendon sheath and hinders tendon movement. .
De Qyervain’s disease - inflammation of the tendon sheaths at the base of the thumb.

32. Tendons Tenosynovitis (injury of the synovial sheath)
Trigger finger (stenosing
tenosynovitis crepitans)
Ganglionic cyst (swelling of the synovial fluid)
Swelling and inflammation of the sheath that surrounds certain tendons. The sheath produces a lubricating fluid for the tendon; tenosynovitis results from a decreased capacity to produce this lubricating fluid.
Source: Cleveland Clinic

33. Nerve Disorders Injuries or disorders of the median nerve:
Carpal tunnel syndrome (compression of he median nerve as it passes through the carpal tunnel)
Pronator syndrome (compression of median nerve as it passes between the two heads of the pronator teres muscle)
Carpal tunnel syndrome occurs when the median nerve, which runs from the forearm into the hand, becomes pressed or squeezed at the wrist. The median nerve controls sensations to the palm side of the thumb and fingers (although not the little finger), as well as impulses to some small muscles in the hand that allow the fingers and thumb to move. The carpal tunnel - a narrow, rigid passageway of ligament and bones at the base of the hand ¾ houses the median nerve and tendons. Sometimes, thickening from irritated tendons or other swelling narrows the tunnel and causes the median nerve to be compressed. The result may be pain, weakness, or numbness in the hand and wrist, radiating up the arm. Although painful sensations may indicate other conditions, carpal tunnel syndrome is the most common and widely known of the entrapment neuropathies in which the body's peripheral nerves are compressed or traumatized.

34. Cubital Tunnel Pain/Numbness
Cubital tunnel syndrome is a condition brought on by increased pressure on the ulnar nerve at the elbow. There is a bump of bone on the inner portion of the elbow (medial epicondyle) under which the ulnar nerve passes. This site is commonly called the “funny bone”.  At this site, the ulnar nerve lies directly next to the bone and is susceptible to pressure. When the pressure on the nerve becomes great enough to disturb the way the nerve works, then numbness, tingling, and pain may be felt in the elbow, forearm, hand, and/or fingers.

35. Bursitis Shoulder Bursitis Bursa irritated and thickens with overuse
Inflammation of one or both of the two major bursae (fluid-filled sacs) in the shoulder. Treatment typically includes rest, ice, and medications for inflammation and pain. Bursitis from infection is treated with antibiotics, aspiration, and possibly surgery.

36. Neurovascular Disorders
Thoracic outlet syndrome
- Caused by compression of the neurovascular bundle from repetitive activities overhead or with the arm pulled down towards the back
Pertaining to both nervous and vascular elements, or to nerves controlling the caliber of blood vessels.

37. Neck Disorders
Tension or ache in the neck (local muscle tightness/spasm)
Numbness in the arms or hands (nerve impingement)
Neck pain is the sensation of discomfort in the neck area. Neck pain can result from disorders of any of the structures in the neck, including the cervical vertebrae and intervertebral discs, nerves, muscles, blood vessels, esophagus, larynx, trachea, lymphatic organs, thyroid gland, or parathyroid glands. Neck pain arises from numerous different conditions and is sometimes referred to as cervical pain.

38. Lower Extremities Work-Related MSDs

39. Knee Disorders Bursitis of the knee
Inflammation of a bursa of the knee joint. A bursa is a fluid-filled sac that functions as a gliding surface to reduce friction between moving tissues of the body. There are three major bursae of the knee. Bursitis is usually not infectious, but the bursa can become infected. Treatment of non-infectious bursitis includes rest, ice, and medications for inflammation and pain. Infectious bursitis is treated with antibiotics, aspiration, and surgery.
A roughening of the cartilage surface. Best known for the roughening of the underside of the kneecap.
Chondromalacia: degeneration (softening) of the cartilage on the posterior aspect of the kneecap

40. Lower leg disorders
Shin splints: involve damage to one of two groups of muscles along the shin bone (caused by standing for a long time or repetitive stress to the lower leg)
A term used loosely to describe an overuse injury characterized by a dull aching pain brought on by exercise. The pain is felt on either the inside or outside of the shin bone (tibia). Shin splints are commonly caused by repetitive loading of the front of the lower leg. This often results from overtraining (particularly at the start of a season's training), running on hard surfaces in poor shoes, or poor running technique. The term ‘shin splints’ is applied to several conditions in which either soft tissues or bones are damaged. These conditions include stress fractures of the tibia or fibula, inflammation of the tendons on the outer side of the ankle (peroneal tendinitis), increased pressure within muscle compartments (see anterior compartment syndrome), or inflammation of the membrane covering the tibia (medial tibial stress syndrome). Some physicians apply the term only to medial tibial stress syndrome. In all cases of shin splints, the irritation and pain spreads, and continues throughout activity. The symptoms stop only when activity ceases but the leg usually remains tender to the touch.

41. Foot Disorders
Plantar fasciitis (inflammation of the plantar fascia--the tissue that forms the arch of the foot)
Inflammation of the plantar fascia (fasciitis), the "bowstring-like" tissue in the sole of the foot stretching from the heel to the front of the foot.
Plantar fasciitis (and heel spurs) may occur alone or be related to underlying diseases which cause arthritis (inflammation of the joints) such as Reiter's disease, ankylosing spondylitis, and diffuse idiopathic skeletal hyperostosis.
Plantar fasciitis is often associated with a bony spur projecting from the underside of the heel that makes walking painful. Spurs under the sole (plantar area) typically cause localized tenderness and pain that is made worse by stepping down on the heel.
Entrapment of the tibial nerve at the medial ankle which may be the result of conditions such as diabetes, inherited abnormalities, trauma or mass injury.
Tarsal tunnel syndrome
(entrapment of the tibial
nerve)

42. Work Tool Design Reduce forces
Design tools to reduce the amount of force to different parts of the body.

43. Work Tool Design Use power grip
Use power grips to reduce stress on hands, wrists and arms.

44. Work Tool Design Use optimal grasp span
The optimal grasp span uses all the muscles and nerves in the hand to reduce stress.

45. Work Environmental Concerns (Heat Stress,Energy Expenditure and Vibration)

46. Heat Disorders Heat stroke Heat exhaustion Heat cramp Heat collapse
Heat rash
Heat fatigue
Heat disorders occur when work conditions causes undue stress. To avoid heat disorders, work practices need to be adjusted.

47. Heat Stress Operations
Iron and steel foundries
Nonferrous foundries
Brickfiring and ceramic plants
Glass product facilities
Rubber product factories
Are there other operations that could affect heat disorders?

48. Factors Affecting Susceptibility to Heat
Age
Weight
Degree of physical fitness and acclimatization
Metabolism
Why would age or weight affect your reaction to working in heat?

49. Environmental Factors
Air movement
Humidity
Conduction
Radiant heat exchange
If lack of air, high humidity etc. can affect workers, what would be some alternative methods to increase air flow or reduce the heat factor in the work environment?

50. Engineering Controls Ventilation Air cooling Fans Shielding Insulation
Use of these engineering controls can reduce heat, stress factors.

51. Types of Vibration Whole Body Hand-Arm (HAVS)
Ask your employees for some examples of ‘whole body’ vibrations.
Ask your employees for some examples of hand-arm vibrations.

52. Summary
When there is a mismatch between the physical requirements of the job and the physical capacity of the worker, work-related musculoskeletal disorders (MSD) may result.
Risk Factors for ergonomic hazards:
Repetitive motion cycle
Awkward posture
Force
Contact stress
Vibration
Upper extremities work-related MSD’s
Lower extremities work-related MSD’s
Recognize the risk factors for MSD and adjust the work environment to avoid future MSD.