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UMY

UniversitasMuhammadiyah

Yogyakarta

www.umy.ac.id

Ergonomic#1 Cumulative Trauma Disorder

Gunawan Setia prihandana, PhD Eng.

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CUMULATIVE TRAUMA DISORDERS (CTD)

The cost of work-related musculoskeletal disorderssuch ascumulative trauma disorders (CTDs) is quite high.

15-20% of workers in meatpacking, poultry processing, autoassembly, and garment manufacturing are at potential risk for

CTD.61 %t of all occupational illnesses are associated withrepetitive motions.

The worst industry is manufacturing, while the worst

occupational title is butchering, with 222 CTD claims per100,000 workers

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Injuries to the musculoskeletal system that develop

gradually as a result of repeated micro trauma due to poor

design and the excessive use of hand tools and other

equipment. These problems are a collection of a variety of problems,

including repetitive motion disordersandcarpal tunnel

syndrome.

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Four major work-related factors lead CTD:

excessive force,

awkward or extreme joint motions,

high repetition, and duration of work.

The most common symptoms associated with CTD include:pain, joint movement restriction, and soft tissue swelling.

In the early stages, there may be few visible signs; however, ifthe nerves are affected, sensory responses and motor controlmay be impaired. If left untreated, CTD can result inpermanent disability.

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Tenosynovitisis the inflammation of the tendon sheathsdue to overuse or unaccustomed use of improperlydesigned tools.

Carpal tunnel syndrome is a disorder of the hand caused

by injury of the median nerve inside the wrist. Repetitiveflexion and extension of the wrist under stress may causeinflammation of the tendon sheaths.

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White finger results from excessive vibration from powertools, inducing the constriction of arterioles within the digits.The resulting lack of blood flow appears as a blanching ofthe skin, with a corresponding loss of motor control

Short-term fatigue and discomfort have also been shown toresult from poor handle and work orientation in hammering,and improper tool shape and work height in work withscrewdrivers.

Typically, a poor tool grip design leads to the exertion ofhigher grip forces and to extreme wrist deviations, resultingin more fatigue)

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Position of the hand and arm(From: Putz-Anderson, 1988)

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CTD RISK FACTORS

CTD risk factors can be divided into two main classes: physical factors and nonphysicalfactors.

Physical factors commonly involve external factors imposed on the individual (jobrequirements, job layout, equipment/tools used, etc.).

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CTD RISK FACTORS Nonphysical factors tend to be more focused on the

personal attributes, behaviors, and capacities of theindividual.

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SURVEILLANCE METHODS

- To identify the existence of or potential for CTD risk factors.

Surveillance consists of the periodic collection and analysis of data

to determine if health and safety problems exist or if risk factors

are present.

Surveillance can be performed for an entire company (multipleplants), a given plant, certain jobs, or classes of jobs within a plant.

Surveillance classified into passiveand activesurveillance.

- Passive surveillance includes activities that use existing data.

- Active surveillance involves collecting data at the workplace

such as exposure data for various risk factors, checklists, worker

interview data, and medical examinations.

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PASSIVE SURVEILLANCEPassive surveillance is typically less expensive and less time consuming

than active surveillance because the data already exists.The sources of information:

OSHA 200 Log and Summary of Occupational Injuries and Illnesses,

OSHA 100 Supplementary Record of Occupational Injuries andIllnesses, etc

- Availability of the different types of data will vary from plant to plant -Minimum information include:

. The total number of CTD cases reported;

. The date each case was reported;

. The department or job of each injured worker; and . The number of workers on the same job or in the same department.

A factor that can be useful for calculating incidence rates is thenumber of hours worked by all employees in the previous year, orseveral years if workers are doing the same job for that long.

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ACTIVE SURVEILLANCE

Active surveillance are more extensive than passive surveillance.

Active surveillance consist of worker healthand workplace surveillance.The simplest form of worker health surveillance is questionnaires which iscolleting information concerning pain, discomfort, swelling, etc., for eachbody part.

The health surveillance involves activities like medical screenings, physicalexams, and worker interviews.Another surveillance is workplace risk factor assessment by using checklistsand job analysis. Checklistsshould be filled out by a person knowledgeable about the risk

factors and ergonomics.

Job analysis requires measurement of specific levels of various riskfactors.The primary risk factors for CTDs are force, posture, and repetition, cold andvibration.Other factors: task invariability, cognitive demands, organizational andpsychosocial factors, and static muscle loading.

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PREVENTION AND CONTROL OF CTDS

IN INDUSTRYControl and prevention of CTDs in industry can be accomplishedthrough two major categories of controls:

Administrative

Administrative controls are worker-focused changes where management

or medical staff makes an effort to reduce the effects of both physicaland nonphysical risk factors.

Administrative controls usually focus on modifying the functions ofworkers through training, job rotation, and job assignment

Engineering.

Engineering controls are job-focused changes where an attempt ismade at redesigning the job, equipment used, or workplace layout tocontrol CTD physical risk factors

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Practice tips to avoid injuryAlways warm up your body as an athlete would before a practice or event.

Muscles need a good warm up in order to function at their best.

Begin with gentle stretches and playing passages of music slowly.

Do not practice or perform when you are physically or mentally tired.

Almost all CTDs are caused when fatigued tissue receives inadequaterecovery and is forced to perform in spite of fatigue.

Make sure that your technique and training is top notch.

As a musician grows and the technical difficulty of the music increases, goodtechnique and training are the foundation for continued ability to performwithout injury.

Approach a concert as a performance athlete.

Determine the physical requirements of the repertoire.

Approach it as a marathon runner whosystematically increases the numberof miles he can run over a period of months in order to befully prepared for

the 26 miles the day of the race.

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Practice tips to avoid injuryAllowyour body to move freely to the music while you are playing.

Static posture, and the requirements of some instruments to be heldagainst gravity can cause fatigue in selected muscle groups anddecreased time to recovery.

While learning a new technique, be mindful of the fact that the musclesare being asked to learn a new skill and will fatigue faster.

Therefore, avoid excessive repetition. Learn new passages slowly andgradually increase the tempo as the muscles become conditioned torequirements.

Instrument transport.

If you play an instrument that requires transporting it from site to site,this needs to be a part of your whole body physical training as well.

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VIBRATION-INDUCED CTDs

THE NATURE OF VIBRATION

Vibration is an integral part of our everyday lives.

As we drive our cars and motorcycles we feel vibration.

At work, machinery vibrates, lift trucks vibrate, pneumatic- and electrically-powered tools all vibrate.

Little is thought about vibration since it is so common; until somethinghappens to make us take notice.

Vibration refers to the directional motion of an object.

There are actually up to six directions at anyone point front-to-back, side-to-side, up or down, and three corresponding rotations: pitch, yaw, and roll.

What we see with our eyes as an object moves is called displacement; what wedon't see is the object's speed, or velocity, the time rate of change of a movingobject..

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WHOLE-BODY VIBRATION Whole-body vibration (WBV) or head-to-toe vibration is usually experienced by

operators of trucks, buses, locomotives, lift trucks, heavy equipment operation, farm

vehicle operation, overhead cranes, and found near vibrating machinery such as punchpresses or mold shakeout areas in foundries.

Studies of diseases in large worker populations have indicated that WBV exposure isassociated with various musculoskeletal diseases including, but not limited to, low-backpain, degenerative intervertebral disc diseases, and herniated and slipped discs.

In addition, some studies show that females exposed to WBV have additional

gynecological risks, especially during pregnancy. Some medical consequences of WBV exposure appear as CTDs, where WBV

exposure is experienced by the worker with no apparent difficulties for an extendedperiod of time.

Then, problems such as a slipped disc might occur for no apparent reason or from aninnocuous event like leaning over to pick up a light object

WBV exposure can cause both safety and health problems.These problems are more likely at human resonance frequencies where humans areespecially vulnerable. At that point, a small amount of impinging vibration can produce alarge effect because of the internal involuntary amplification of this vibration by thehuman body.

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HAND-ARM VIBRATION Hand-arm vibration (HAV) exposure usually arises when workers use vibrating

pneumatic-, electrical-, or gasoline-powered hand tools such as chain saws,

grinders, chippers, drills, nut tighteners, jack hammers, demolition tools, etc.

Cases:

Some of the medical effects of HAV exposure were discovered in the early 1900swhen stone cutters who used pneumatic cutting hammers were experiencing

tingling and numbness in their fingers.Due to increased vibrating tool exposure, and triggered by cold temperatures,these workers next experienced a far worse stage of the disease, episodicattacks of finger blanching or whitening, resulting from a loss of finger bloodsupply.

If this condition is left untreated and the worker is not removed from the HAV

exposure, in the extreme case it can eventually result in possible digit amputation.

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CONTROLLING VIBRATION IN THE

WORKPLACEControlling vibration is usually includes vibration reduction and ergonomics

Check and maintain vehicle suspension systems, tires, and tire pressure.

After long periods of driving/riding in vehicles, do not lift or bend immediately.Rather, first walk around and stretch for a few minutes. Use minimum twistingwhen exiting a vehicle

In fixed plant situations, mechanically isolate vibrating equipment, machinery from

floors and workers' bodies. Where possible, keep workers away from vibrating equipment by using remote

controls, switches, closed circuit TV.

As appropriate, use WBV standards and guides.

If signs and symptoms of back pain and back disorders occur, consult a physician.

If possible, use antivibration (A/V) tools. Try not to use vibration-damping materials externally wrapped around

conventional vibrating tool handles.

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Risk Factors for Musculoskeletal Disorders

Excessive Forces

Lifting and carrying

Pushing and pulling Reaching to pick up

loads

Prolonged holding Pinching or squeezing

Awkward Postures

Working overhead

Kneeling all day Reaching to pick up

loads

Twisting while lifting

Bending over tofloor/ground

Working with wrist bent

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