Manual Material Handling

How many spinal discs between each vertebrae?

1

How many people are currently experiencing low back pain?

1 in 7

Three worker capacities that require consideration when evaluating manual material handling tasks

1. Biomechanical capacity 2. Physiological capacity 3. Psychophysical capacity

Guidelines for risk reduction

1. Limit weight of load 2. Limit horizontal distance of lift 3. Limit vertical distance of lift 4. Optimize vertical location of hands 5. Limit asymmetric lifting 6. Optimize coupling 7. Maximize object stability 8. Maximize use of lifting aids

Women can support _______ less spinal compression force due to the smaller size of their vertebrae

17%

The compression tolerance of a spinal disk is between _____________

2-12kN

spinal anatomy - how many vertebrae?

24

In the UK, __________ of all reported accidents involved manual material handling and were associated with ____________ million workdays

27%, 12.3

Aerobic capacity is _________ lower at age 65 than at age 25

30%

Women have ______ lower aerobic capacities than men

30%

Wearing a single pair of gloves can reduce grip strength up to ____

40%

According to US department of labor, ________ of all back injuries due to lifting occurred in manufacturing settings

42%

Economic consequences range between _____________ dollars per year

45-54 billion

Lack of proper handles or handhold cutouts reduces strength by _____________

5-10%

Of all injuries attributed to overexertion, ______ occur during lifting

52%

What percentage of overexertion injuries during lifting are to the back?

56%

Breakdown of incidents causing back pain (2)

56% occurred while bending; 33% while twisting/turning; 27% while standing

Wearing two pairs of gloves at once can reduce your grip strength up to ______

60%

MSDs account for nearly ______ of doctor's visits per year in the U.S.

70 million

A person has a _______ chance of developing low back pain during their lifetime

70%

A survey of _____________ showed that lifting equipment was not available in _______________ of the cases

708 injury cases; 60%

Overexertion injuries account for _______ of musculoskeletal injuries occurring in the workplace

76%

Breakdown of incidents causing back pain

77% occurred while lifting; 16% while placing; 15% while carrying

Physiological capacity

As aerobic capacity increases, more oxygen can be sent to cells to create energy for muscles

Degenerative joint disease

As spinal discs compress, vertebrae come in contact, causing painful bone damage and the eventual fusion of vertebrae; Occurs over time; associated with aging.

Recommended handle dimensions

Be 4.5" or longer and 0.75"-1.5" wide Have at least 2" of clearance between the handle and the object Be of cylindrical shape to fit the hand Made of a non-slip material

lifting "power zone"

Below the shoulders and above the knees and close to the body

Recommendations to reduce weight of a load

Consider packaging material in smaller containers where possible Establish team lift policies in situations where loading exceeds recommended limits Use lifting aids where possible

Examples of transportation devices

Conveyors, Carts, Turntables, Hand trucks, Forklifts

Examples of lifting devices

Cranes, Lift/tilt/scissor tables, Vacuum lifting device, Self leveling tables, Tool balancers

Back belt Cons

Do not relieve stress to the spine or back muscles Do not reduce the severity of work-related injuries May give workers a false sense of strength

NIOSH advantages

Easy to apply Low cost Requires no special equipment Allows for quick comparison between tasks Can be used to guide and formulate ergonomics initiatives

NIOSH limitations

Evaluates two-handed lifting and lowering only Assumes worker is not in restricted workspace Does not apply to seated or kneeling workers

annulus fibrosus

Fibrous outer layer if the disc

Lifting a load with a high weight can cause

High compression in the discs of the back Higher strength requirements Higher energy expenditures Higher stresses on tissues and joints

Asymmetrical lifting results in:

High spinal disc compression, Reduced strength, Increased cardiovascular demands

Job Enlargement

Increasing the variety by combining jobs or adding tasks to a job

Recommendations for weight lifting

Modify lift so that it can occur within their power zone Perform heavy work tasks without bending, stooping, or reaching

Spinal stenosis

Narrowing of the spinal canal - most often in the lower back. Involves irritation or injury of the spinal cord or nerves.

NIOSH lifting equation origin

Originally developed by Waters at al. in 1981; revised in 1993

Herniated disk risk factors

Overuse, Exercise, Heavy lifting

Risk factors for back strains

Overuse, Overextension, Exercise, Heavy lifting

Examples of administrative controls

Providing safe lifting training Job rotation Job enlargement Adjustment of work schedules, work pace, or work practices Providing adequate recovery time

The NIOSH lifting equation assigns a ______________________ to a specific task

Recommended Weight Limit

Risk factors for back sprains

Repetition, Overextension, Sudden movements

Job Rotation

Rotating employees through different jobs

Which of these lifting techniques is safe?

Squat lift, not stoop lift

Types of back injury

Strain, Sprain, Spinal stenosis (Disc herniation/Degenerative joint disease)

spinal stenosis symptoms

Tingling, numbness, and weakness to severe pain and paralysis. Cramping and numbness in legs, back, neck, and arms

Asymmetric lifting occurs when there is:

Twisting, Lateral bending, Asymmetric placement of hands, Asymmetric center of mass, Lifting with one hand

Object stability recommendations

Use manual material handling tools (i.e. pallet trucks, hand trucks, etc.) to move awkward or dangerous objects Contain objects in rigid containers for lifting where possible

Lifting Index and ranges

Used to determine recommended action >3: Unacceptably Hazardous - Engineering Changes Required 1-3: Requires Task or Administrative Changes 0-1: Acceptable

Cracks in the spinal disc occur...

With age and with exposure to manual material handling

Sprains in the back occur when...

a ligament is overstretched or torn

Strains in the back occur when...

a muscle or the tendon that connects it to a bone is overstretched or torn.

Factors that influence aerobic capacity

age, gender, fitness, nature of work

frequency of lift

an important risk factor related to the prevalence of low back pain

nerve impingement can occur in the spinal disc when...

as pressure increases, fluid from the nucleus pulposus seeps through the outer layer

Biomechanical capacity

calculated by measuring the forces and movements on body joints and soft tissues, concerns compressive and sheer force

Label each of the curves in the spine (ignore last one, it's sacral)

cervical, thoracic, lumbar

Engineering controls

changes to job design, workstation layout, and tool use to reduce employee exposure to ergonomic risk factors

______________________ on the spinal discs caused by ____________________ can cause back injury

compressive forces; poor lifting position

Contents can shift during a lift, which as a result...

drastically changes loads to the body

Lifting loads near floor level can result in ________________________ in the lower back.

high compressive forces

Sagging objects or unstable contents present...

higher risk of injury

Which image is better and why?

image (B) because the reduced moment arms result in 18% less disc compression force

A combination of heavy loads with frequent ___________________________ will result in physical fatigue and greater risk of injury

lifting, walking, and carrying

What are the names of the 3 natural curves in the spine?

lumbar, thoracic, cervical

Administrative controls

management-dictated work practices and policies to reduce or prevent exposures to ergonomic risk factors

NIOSH assumptions

maximum compressive force: 3.4kN Working height: 75cm Physiological criteria: 9.5 kcal/min Psychosocial criteria: lifts should be acceptable for 75% of female workers and 99% of male workers

(In a survey) Lifting equipment was available but not used in __________ of the cases because the equipment was:

more than 30% Not practical to use Not deemed necessary Not working Too time consuming to use

A team can handle ____________ than one person could alone, but __________ than the sum of an individual's capacity

more weight, less weight

A worker's strength is influenced by their

motivation and willingness

Overexertion injuries are linked to

physical and psychological stress

Aerobic capacity increases with...

physical fitness

Calculations for the NIOSH equation are performed twice, once for the ________________________ and once for the _______________________

point of origin; point of destination

Scissor lifts ________________________________________________ , eliminating the need to reach for the object

raise and lower the height of the work surface

Lifting above the shoulder results in __________________ and _____________________ in the lower back

reduced strength; concentrates compressive forces

Things that reduce grip:

slippery surfaces and pinch grip

Use _________ to lift smaller loads.

squat lift

As the horizontal distance between the load and the hands increases, ___________________________________ and __________________________________________.

strength decreases; spinal disc compression increases

Ligament

strong bands of inelastic fibrous tissue that connect bone to bone

L4/L5

the area where most lower back injuries occur (bottom disc)

Overexertion injuries occur when...

the load of a job exceeds the capacity of the worker

Herniated disk occurs when...

the outer ring of an intervertebral disc is torn, allowing the soft central portion to leak or bulge out.

Recommendations for asymmetrical lifting

turntable inserts allow the worker to easily reach the items without having to rotate or twist the body

NIOSH lifting equation

used to determine maximum recommended weight of lift based on calculations of compressive forces in the L5/S5 discs of human cadavers

the spinal disc is strongest in __________________ and weakens with age

young adults