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WorkshopErgonomic Work Design and Prevention

of Work-Related MusculoskeletalDisorders (MSDs)

Prinicipal Methods for Risk Assessmentof Work-Related MSDs

Dr. Rolf Ellegast

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


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Dr. Rolf Ellegast -IFA- 2011

Physicalfactors

Environ-mental

factors

Individualfactors

Psychosocialfaktors

Work-related MSD risk factors


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Classification of physical MSD risk factors

Manual material handling tasks, e.g. lifting, holding, carrying,

pulling and pushing

Working in awkward postures (overload and underload), e.g.

awkward trunk postures, crouching, kneeling, squatting, armsabove shoulder level, lack of physical activity: sitting, standing,

lying

Repetitive work

Work involving high exertion and/or exposure to force, e.g.

climbing, knocking,

Whole body vibration and hand arm vibration


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Manual Material handling

lifting, holding, carrying


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Manual Material handling

pushing and pulling


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Working in awkward postures,

awkward trunk postures




arms above shoulder level, lying




lack of physical activity, underload



Repetitive work



Work involving high exertion and/or exposure

to force, use of working tools



Work involving high exertion and/or exposure

to force, climbing


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Work involving whole-body and hand-arm vibration


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Muscular load static work


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Statitic load (trunk muscles): plasterer

Trunk angle ()

Thoracis spine (BWS)

Lumbar spine (LWS)

Time [h:min:s]


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Maximum duration of static muscle force in

dependance of percentage of maximum holding force


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The spine


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Intervertebral disc

NucleusFibres


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Intervertebral disc: nutrition, sponge

Quelle: NMBG


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In Vivo-measurement of

intervertebral disc pressure

Quelle:(Nachemson, 1964)


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Intervertebral disc loads

Quelle: NMBG


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Application of muscle force,

tendon lever arm


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Giovanni Borelli

(1608-1679)

Biomechanical models


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Biomechanical models to estimate

spinal workloads

Quelle: M. Jger,


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Principale assessment tools

for physical workload assessment


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Example: Checklist medical

check up

G 46

Questionnaire, self reported data

http://www.arbeitssicherheit.de/servlet/PB/show/1227589/bgi7011.pdf


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Load weight

+ Posture

+Ergonomic

condition

= Sum x Time/Duration = Risk points

4

2

2

8 4 32

Risk evaluation:25-50 Points

Screening method: The Key Indicator Methods (KIM)

Example: Holding, Lifting Carrying

The KIM Tool Key Indicator Method. German version: www.baua.deEnglish version available at: http://www.pip.gov.pl/handlingloads/en/19.htm
http://www.baua.de/http://www.pip.gov.pl/handlingloads/en/19.htmhttp://www.pip.gov.pl/handlingloads/en/19.htmhttp://www.baua.de/


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Observational expert methods

Example: The Finnish OWAS method

OVAKO Working PostureAnalysing System


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Risk class:

OWAS: risk assessment

OVAKO Working PostureAnalysing System


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Classes of risk - 4 OWAS* risk categories(as percentage of working time):

Class 1: No intervention requiredClass 2: Corrective action should be taken during next regular reviewClass 3: Corrective action should be taken as soon as possibleClass 4: Corrective action should be taken immediately

* OVAKO-Working-Posture-Analysing-System

9,1%

84,8%

1,4% 4,7%

OWAS: risk assessment


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RULA

HAL TLVs

OCRA Index

Observational expert methods

Example: Upper limbs


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Upper limb assessment tools

http://www.dguv.de/ifa/de/pub/rep/rep07/bgia0207/index.jsphttp://www.dguv.de/ifa/de/pub/rep/rep05/bgia0405/index.jsp
http://www.dguv.de/ifa/de/pub/rep/rep07/bgia0207/index.jsphttp://www.dguv.de/ifa/de/pub/rep/rep07/bgia0207/index.jsp


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accuracy

duration and frequeny of single load situations

frequency distribution of overloading and

underloading situations

Quantifying of repetitive workloads

Limitations of observational methods

Trunk

InclinationRumpf-

Neigung[]

Time [hh:mm:ss]


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Field measurements:

The CUELA system

(Computer-supported registration andlong-term analysis of musculoskeletal loads)

Registration of body kinematics and kinetics

for long measuring periods (whole working shift - 8 h) with a high resolution (sampling rate 50 Hz)

usable for field analysis directly at the work place withoutinterference of the working process

Computer-supported data analysis

software includes a set of different evaluation methods

efficient data postprocessing interface to a database for specific work load parameters

S CUELA


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memory card

data logger

168 Ch/ 50 Hz

video documentation

FR

Setup CUELA

Ambulatory Measurement System

pressure sensitive insoles (GRF)

Gyroscope,

accelerometers,

potentiometers

S t CUELA


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motion detection of the

following body parts/joints:

head

shoulder blade

shoulder joint

elbow joint

forearm and wrist

thoracic spine

lumbar spine hip joint

knee joint

pressure sensitive insoles

Setup CUELA

Ambulatory Measurement System


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Different versions of the CUELA system

Incl. 3D-upper limb Sedentary work Activity systemBasic

O ti l d l


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Optional modules

(synchronous measurement)

EMG 3D Force WBVECG


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Synchronised

video file

Data visualisation and assessment

CUELA software

Measurement data, e.g. angle time graph

3D-Puppet


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Examples

Assessment of CUELA data

Criteria

Quantification

of mechanical risk factors

awkward postures

manual materials handling

static postures

high dynamic working

repetitive work

impact of high forces

Integrated evaluation methods:OWAS, MDD, RULA, OCRA

Assessment

Standards, e.g. EN1005

Physiological andbiomechanical models

I t d t f bi h i l


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Input data for biomechanicallink segment models

L5/S1

Compression

Force[N/10]

Time [h:min:s]

Estimation of lumbar load variables: e.g. moments, compression forces


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Fields of application - CUELA system

occupationaldiseaseprevention rehabilitation


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Laboratory measurements

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