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Ergonomics

Ergonomics_SSErev01/34

European Education PlanModule 1

Ergonomics, the work place and the spine

Presenter:

Guillem Saló Bru MD,

Barcelona, Spain

Ergonomics


WORK HEALTH

• Unemployment is bad for

physical and mental health

• Work can reverse the adverse

health effects of unemployment

• Strong case that work is

generally good for health

• True for people of working age

generally and for most people

with common health problems

(LBP!)

Waddell G, Burton K

tsoshop.co.uk

Ergonomics


Some back pain = ‘injury’

• Sudden onset back pain

– Probably strain/sprain to soft tissues

• Muscle coordination fault; local stress concentrations;

minor injury?

• Often no obvious event/trigger

• Severe pain; marked activity limitation

– Interference with work

• BUT, that doesn’t necessarily mean the work was

dangerous!

Ergonomics


Cumulative trauma?- purported exposure-impact gradient

Impact

Exposure

symptoms

reporting

absence

chronicity

long-term incapacity

care-seeking

reasonable concept, but it's not that simple

Ergonomics


Low back pain at work

• It is important to distinguish between the different presentations of LBP:

• Presence of symptoms

• Reporting of symptoms

• Attribution to work

• Work caused

• Work aggravated

• Spinal 'damage'

• Sickness absence

• Long-term incapacity

• They have differing determinants

Ergonomics


Ergonomics

• Ergonomics is the science and practice of designing jobs and workplaces

to match the capabilities and limitations of the human body.

• As operationalized, ergonomics has the dual concerns of 'safety' and

'health'.

• These are different concepts:• Preventing accidents is very different from preventing ill-health

• Most back pain episodes cannot be prevented

Ergonomics


Theoretical benefits of ergonomics

• Ergonomics helps to prevent injuries

• Ergonomics has other benefits

• Improved quality of work

• Improved quality of life

• Reduced fatigue and discomfort

Risk control:

• Simple principles:

• avoid

• reduce exposure

• (weight/frequency)

• redesign the task

• use more people

• training/information

Ergonomics


What are the ergonomic hazards?

• Lifting (objects,

creatures)

• Push/pull

• Stretching / reaching

• Carrying

Ergonomics


What are the ergonomic hazards?

• Sitting

• Whole body vibration

• Standing

• Slips/trips/falls

• Work posture

Ergonomics


• Lw and Lp should be as low as is possible.

• The idea is to keep the weight (W) as close to the axis of rotation as possible

• The spine bending should avoided.

Biomechanics of Lifting

Ergonomics


Lifting technique

• Recommended technique substantially

changed in UK, in response to biomechanics

evidence-base

• Think first

• Keep load close to waist

• Adopt a stable position

• Ensure good handhold

• Moderate flexion of back, hips and knees

• don't flex any more during lift

• Avoid trunk twist or side-bend

• Keep head up

• Move smoothly

• Only lift what you can manage

• Put down, then adjust position

• Do-able?

Ergonomics


Biomechanics of Carrying

• Carry the object closer to the body

• Bending the spine should be avoided.

Ergonomics


Biomechanics of Standing.

• B: Relaxed standing: the angle of inclination of the sacrum (sacral angle) is 30 to the transverse plane

• A: Posterior pelvic tilt reduces the sacral angle or flattens the lumbar spine (reduces lordosis). Causes the thoracic spine to extend which adjusts line of gravity such that muscle expenditure is minimized. Increases the ligament strength.

• C: Anterior pelvic tilt increases sacral angle. accentuate lumbar lordosis and thoracic kyphosis. This adjusts line of gravity to increase muscle energy expenditure

Pelvic Tilt and Lumbar Loading

Ergonomics


Biomechanics of Sitting.

B: Sitting (relative to standing)• pelvis posteriorly tilted

• lumbar curvature is flattened

• line of gravity (already ventral to lumbar

spine) shifts further ventrally

• increases the moment created by body

weight about the lumbar spine

• increased muscular support increases

the load on the spine.

C. Erect sitting• pelvis tilts anteriorly

• increases lumbar curvature

• reduces the moment arm of body weight

• reduces need for muscular support

• reduces load on lumbar spine

• however, pelvis still much more tilted than

during normal erect standing.

Ergonomics


• Apparent that lumbar load is strongly related to support needed to maintain lumbar lordosis

• In erect, supported sitting the addition of a back rest reduces lumbar load

• Reclining seated position reduces disc pressure even further

Biomechanics of Sitting.

Ergonomics


Disk pressure

• Lowest when lying supine

• Normal when standing upright

• 140% when sitting with no back

support

• 150% when hunched over

• 180% when sitting hunched

over with no back support

Ergonomics


What does training achieve?

• Not a lot!

• Training can improve perceptions of

safety and ‘caring’

• Training can change the way people do

things.

• But training alone has no impact on

injury rates or sick leave

Ergonomics


Beware the ergonomic ‘solution’

• Throwing furniture at the problem

is based on the questionable idea

that:

– there is an ideal posture

– That a chair can replicate that

posture

– That people will sit in that

posture

• Actually, left untampered, people

don’t sit in one posture for very

long, and certainly not in the ‘ideal’

posture......

• Throwing furniture not a good

idea?

Ergonomics


Other ergonomic hazards

• Organisational

• Repetitive handling

• Work rate paced by process

• Lack of breaks

• Individual

• male v female

• tall v short

• strong v weak

• Environment

• lack of space

• poor flooring

• Clothing

• Software and systems

Ergonomics


Psychosocial hazards

Self-report LBP prevalence v.

operator satisfaction

Stress of work............best not go there!

Ergonomics


Is there an occupational cause for back pain?

In some instances, maybe:

But, systematic reviews of common

occupational risk factors, based on

prospective studies using strict Bradford

Hill criteria, fail to show any substantial

evidence of occupational causation for

most back pain.

Ergonomics


Work caused or work-relevant?

• Whilst some (episodes of) low back pain may be caused by work, most are

not.

• Yet, symptoms may affect workability

• work can be difficult/painful because of symptoms

• consequences are driven more by psychosocial than physical factors.

• LBP can be highly work-relevant, yet not caused by the work

• Reflect this in your reports and practice

Ergonomics


UK occupational health guidelines

• Individual and psychosocial findings are a risk factor for the incidence

(onset) of LBP, but overall the size of the effect is small.

• Unsatisfactory psychosocial aspects of work are risk factors for reported

LBP, health care use, and work loss, but the effect size is modest.

• Individual and psychosocial aspects of work play an important role in

persisting symptoms and disability, and also influence response to

treatment.

Carter & Birrell 2000: www.facoccmed.ac.uk

Ergonomics


• We need to be realistic about what

ergonomics can and can’t deliver

• Ergonomics doesn’t prevent back pain/injury

• Undue emphasis on ergonomic solutions can

generate unhelpful beliefs

• But, application of ergonomics principles can

lead to ‘good’ jobs

• So, how can ergonomics be helpful for

back pain?

• Make work comfortable when we’re well

and accommodating when we’re ill or

injured’• Hadler (1997)

The ergonomic solution?

Ergonomics


Control: common sense?

Ergonomics


Should people with back pain go to work - YES

• Work is generally therapeutic

• Helps to promote recovery

• Counters the harmful physical and mental effects of long-term absence, and

risk of chronic disability

• Reduces poverty and social exclusion

• Be cautious about suggesting the work was harmful

Ergonomics


We need to shift the culture

• Many people are at work with symptoms

• Most recover whilst without sick leave

• Otherwise nobody at work!

• Some will struggle off sick

Early RTW is therapeutic

Awaiting 100% pain free is a major obstacle

• Reflect this in your advice

tsoshop.co.uk

Ergonomics


PERSON

WORKPLACE

CONTEXT

© Kendall & Burton 2009

Flags are about:

identifying obstacles to being active and working

figuring out how these can be overcome or bypassed

implementing evidence-informed solution-focused

approach

RTW/SAW: psychosocial issues predominateTackling musculoskeletal problems - a guide for clinic and workplace

-identifying obstacles using the Psychosocial Flags Framework

Ergonomics


Accommodating WorkplacesWhat is reasonable?

Light duties

Alternative duties

Modified work

Selected duties

Duration - temporary vs. long-term

Ergonomics


1. Alter the work tasks or environment to reduce physical demands

Examples

• Reduce reaching

• Provide seating

• Reduce weights

• Reduce pace of work

• Reduce task frequency

• Enable co-worker help

• Increase task variety

Ergonomics


2. Alter the work organisation

Examples

• Flexible start/finish time

• Reduced work hours/days

• Added rest breaks

• Graded return to work (achievable

level, increase on regular quota)

Ergonomics


3. Change the job

Examples

• Allow work at home

• Selected duties

• Co-worker as ‘buddy’

Ergonomics


4. Flexibility

Examples

• Achievable goals, scheduled at

start of each day

• Allow reasonable time to attend

therapy appointments

Ergonomics


Key messages

• Individual and psychosocial aspects of work play an important role in

persisting symptoms and disability, and are key to early RTW

• Advice on benefits of work are helpful, blaming is not

• Sedentary occupations have higher risk of low back pain

• ‘Fitness’ and ‘conditioning’ are important

• Ergonomics cannot prevent most episodes of back pain

• But, it can help reduce sickness absence for most episodes

Ergonomics


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European Education Plan Module 1 Ergonomics, the work ...guillemsalo.cat/wp-content/uploads/2015/09/1-ergonomia-en-el... · European Education Plan Module 1 Ergonomics, the work place