Institute for Occupational Safety and Health of the German Social Accident Insurance

Workshop Ergonomic Work Design and Prevention of Work-Related Musculoskeletal Disorders

(MSDs)

– The Use of Databases –

Dirk Ditchen

XIX World Congress on Safety and Health at WorkSeptember 11-15, 2011 - Istanbul

11.09.2011Dirk Ditchen, XIX World Congress 2011 page 2

Introduction

• Why shall we use databases for preventive purposes?

• What kind of databases are suitable for our purpose?

• How can databases help me?

• Example: Database of work-related knee- straining postures

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Why databases?

• Risk factors for diseases of the knee: e.g. work-related activities like kneeling or squatting.

• To research dose-response-relationships or similar there is a need for detailed information on working activities in the past, partly decades ago.

• Epidemiological studies: Retrospectively self-assessed data on the daily amount of work-related stresses are a common method in occupational science and medicine.

How valid is such information?

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Method Comparison: 1. Field Measurements

CUELA*

knee joint (flex./ext.)

hip joint (flex./ext.)

lumbar spine (flex./ext./lat.flex.)

torsion

thoracic spine (flex./ext./lat.flex.)

trunk bending, lateral flexion,

trunk inclination

*Ellegast, RP, Hermanns I, Schiefer C. Workload Assessment in Field Using the Ambulatory CUELA System. In: Duffy, V.G. (Ed.) Digital Human Modeling HCII. 2009, Springer, Berlin 2009: 221-226

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Analysis of Knee Straining Postures

knee postures in total

kneeling (unsupported)

kneeling (supported)

sitting on heels

squatting

crawling

Percentage of time [%]

Example:floor tiler

IFA-Activity-Code

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Reference period: Measurement duration (mean: 118 min (± 44min)

N=190

Method Comparison: 2. Self-Reports

Questionnaire (extract)Have you worked in one or more of the following postures during today‘s measurement: kneeling, squatting, sitting on heels or crawling?

No Yes

If yes, please complete the table on the right hand.

no

yes

no

yes

no

yes

no

yes

no

yes

kneeling (unsupported)

kneeling (supported)

squatting

sitting on heels

crawling

Posture FrequencyNo/yesAverage duration

of one event

times

times

times

times

times

…… min

…… min

…… min

…… min

…… min

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M Q M Q M QKneeling (unsupported)

20,9 52,8 15,3 20,0 20,3 116,6

Kneeling(supported)

9,2 44,9 2,9 11,0 14,3 115,1

Sittingon heels

4,2 16,7 1,4 1,5 6,8 46,0

Squatting 5,0 17,3 0,9 2,5 11,5 37,8

Crawling 0,2 19,2 0,0 0,0 0,9 90,5

TOTAL 39,3 152,2 32,7 60,0 32,3 279,4

Mean[min]

Standard Deviation [min]Posture

Median [min]

Results: Means and Variance

M = measurement, Q = questionnaire

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Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet.1986(i):307-10.

Knee postures in total (without 8 „outliers“, n = 182)

Results: Bland-Altman-PlotD

iffer

ence

: mea

sure

men

t -qu

estio

nnai

re

Average of measurement and questionnaire

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• Job Exposure Matrix (JEM):

Occupational loading for a whole job category

• Task Exposure Matrix (TEM):

Occupational loading for different tasks (within a job category)

What sort of databases?

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Example: Screed layer

0,0 (±0,0)7,8 (±2,1)8,4 (±0,1)0,2 (±0,1)1,3 (±0,3)17,7 (±2,5)85 (±10)2Sand & cement screed:Mixing the screed(2-Men)

0,0 (±0,0)0,0 (±0,0)0,3 (±0,1)0,0 (±0,1)0,0 (±0,0)0,4 (±0,1)0 (±0)2Sand & cement screed:Mixing the screed(3-Men)

0,5 (±0,4)19,6 (±11,8)9,4 (±6,7)2,7 (±1,9)1,0 (±0,9)33,3 (±13,6)160 (±65)3

Sand & cement screed:Planing the screed(3-Men)

0,2 (±0,2)35,4 (±6,3)14,0 (±3,6)2,1 (±1,6)0,4 (±0,3)52,2 (±8,0)250 (±40)3Sand & cement screed:Screeding the floor(3-Men)

0,0 (±0,0)0,4 (±0,7)3,2 (±3,2)0,4 (±0,9)3,3 (±4,7)7,3 (±6,5)35 (±30)5Flowing screed:Installing flowing screed

3,2 (±2,6)12,3 (±8,4)27,2 (±12,4)3,3 (±2,9)3,3 (±3,8)49,3 (±7,3)235 (±35)4Flowing screed:Installing insulation

Crawling [%]

Supported kneeling

[%]

Unsupported kneeling

[%]

Sitting on heels [%]

Squatting [%]

Total knee load [%]

Total knee load [min]

nTask

Range: 0 min to 250 min per shift (shown: arithmetic means and SD)

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Example: Roofer

0,1 (±0,1)2,5 (±3,7)8,5 (±4,7)0,6 (±0,6)10,5 (±14,5)22,1 (±17,4)105 (±85)3Installing PVC membranes

0,0 (±0,0)20,8 (±20,1)39,9 (±21,4)3,5 (±0,8)0,4 (±0,3)64,7 (±0,7)310 (±5)2Sealing roof to wall

0,0 (±0,1)3,6 (±2,4)11,5 (±6,5)1,3 (±1,5)1,7 (±3,0)18,1 (±10,9)85 (±50)4Torch-on roofing

0,0 (±0,0)0,0 (±0,0)3,6 (±6,0)0,0 (±0,0)0,1 (±0,1)3,7 (±6,0)20 (±30)3Reed roofing

0,0 (±0,0)0,2 (±0,3)3,8 (±6,6)0,3 (±0,6)2,7 (±3,6)7,0 (±6,0)35 (±30)3Installing corrugated panels

0,0 (±0,0)0,2 (±0,2)6,8 (±5,9)9,5 (±5,2)2,1 (±2,5)18,7 (±8,3)90 (±40)3Mansard slate roofing

0,0 (±0,0)16,1 (±9,1)29,2 (±9,5)3,1 (±2,6)0,3 (±0,1)48,7 (±16,1)235 (±75)2Slate roofing

0,0 (±0,0)7,2 (±5,7)17,4 (±16,0)0,7 (±0,8)2,0 (±2,6)27,2 (±18,8)130 (±90)4Installing plain tiles

0,1 (±0,2)1,9 (±1,8)3,5 (±3,9)1,3 (±2,2)0,5 (±0,6)7,2 (±7,6)35 (±35)3Installing roof tiles

0,2 (±0,2)8,2 (±5,1)36,8 (±5,7)1,0 (±0,9)2,6 (±2,0)48,9 (±13,5)235 (±65)2Installing insulation

0,0 (±0,0)0,9 (±1,8)2,9 (±2,6)0,1 (±0,1)0,3 (±0,3)4,2 (±4,0)20 (±20)4Installing battens

Crawling [%]

Supported kneeling

[%]

Unsupported kneeling

[%]

Sitting on heels [%]

Squatting [%]

Total knee load [%]

Total knee load [min]nTask

Range: 20 min to 310 min per shift (shown: arithmetic means and SD)

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How can databases help me?

• To find situations or tasks where preventive measures are needed.

• To focus preventive measures on key aspects of occupational loading.

• To develop suitable measures of prevention.

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How can databases help me?

• Examples:

How can knee-straining activities be avoided?

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Example 1:

e.g. Readjustment of working height

Pipe laying (welding)

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Example 2:

e.g. use of special equipment

Floor layer, preparing the floor

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Example 3:

e.g. use of special equipment

Truck tarp maker, welding tarps

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No chance of avoiding!

(as long as the belly of the aircraft has a heigth of

approx. 1 m)

Example 4

Ramp agent, loading luggage

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Example 4

Ramp agent, loading luggage

Solution: e.g. job-rotation

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THANK YOU !

dirk.ditchen@dguv.de

http://www.dguv.de/ifa/de/pub/rep/pdf/reports2009/ifar0110/report1_2010.pdf