56

3

C H A P T E R

Post

ure

& S

tres

s

Assessment of Work-related Musculoskeletal Disorders

& Postural Stress

57

Background: The goldsmiths used to work in particular working postures for

prolonged time. The workers reported to have discomfort in body parts during general

health investigation by the WHO-QoL 100 questionnaire. The discomforts were

assumed to be the effects of long work hour in static postures. Secondly, the

significant predominant postures were also needed to be identified to confirm whether

those could actually impart musculoskeletal problems among the workers.

Methods: Out of a total 276 screened personnel, 147 actively involved in

the jewellery manufacturing units responded to have discomfort. Based on consent,

minimum experience criterion and active medical condition, 12 were excluded and

135 personnel were finally recruited. They were categorized as

fabricator/manufacturers (n=89), melting staffs (n=14) and polishing/buffing staffs

(n=32) according to their specific jobs. A modified version of Nordic musculoskeletal

disorder questionnaire was administered to seek information on body parts discomfort

and a body parts discomfort (BPD) scale was used to rate the degree of discomfort.

The most predominant working postures were analysed using two posture assessment

tools, rapid entire body assessment (REBA) and rapid upper limb assessment

(RULA).

Results: The workers reported discomfort in the trunk, especially the

back and waist. Upper and lower back and waist were the three regions where the

workers used to maximum discomfort and the trend was continuous among the

workers of all the three groups. Over 30% of the manufacturing staffs reported

discomfort in these three areas whether the response rates were low in the other two

groups. The posture assessment tools identified all the predominant working postures

as moderate to high risky. Although the frequency of response varied between the

groups and the working postures were found risky, the degree of discomfort did not

differ much by job type. Median values of the BPD ratings for all the body parts areas

were below the midline value of the scale and none of the regions was found under

high stress.

Conclusion: As a result of continuous work in sitting posture, the

goldsmiths developed musculoskeletal problems in different body parts although the

problems were not found alarming. The posture assessment tools although indicated

the postures highly risky, those assessment tools were not very much appropriate to

evaluate the classical Indian postures. Therefore, there is a necessity to design a

posture assessment tool for Indian and Asian ethnic postures.

Abstract 3.1.

58

Acute or chronic musculoskeletal problems among industry workers are

generally either the outcomes of improper design of the workstations or long work

hours in awkward postures. It has long back been reported by the National Institute of

Occupational Safety and Health (NIOSH) that the prevalence of low back pain is

mainly due to inappropriate workplace (NIOSH, 1997) and there are innumerable

studies, which have also demonstrated that the rates of low back disorders vary

greatly by industry, occupation and job type within a given industry or facility.

It has earlier been observed that the workers engaged in jewellery

manufacturing industries used to work in congested workplaces for a long work hour

(Chapter 2). Most of the workstations in this industry are poorly designed and such

workstations can also contribute to the probability of work-related musculoskeletal

disorders (WMSDs) among the workers. As obtained from the health and quality of

life related questionnaire (WHO-QoL 100 questionnaire), the prevalence of body

parts discomfort was found significant among the goldsmiths although the responses

varied greatly in respect to the degree of severity. It is well-known fact that the

knowledge of proper material handling as well as the physiologically suitable posture

is lacking in the developing countries and therefore the prevalence of musculoskeletal

disorders is very obvious (Asogwa, 1987), especially in the unorganized sectors.

Many times, it has also been observed that the discomfort increases with the

advancement of age as workers refuse to undertake new ideas of a modern workplace

(Acheson, 1972).

There are still very few reports available, which have described the health-

related issues of the workers associated with small-scale jewellery manufacturing

industries. Although, some initiatives have been taken till date to evaluate the working

postures in several small-scale informal sectors of India, there is merely any

significant report that has evaluated the probabilities of work related musculoskeletal

disorders among the goldsmiths in a systematic way. This present study was aimed to

identify the predominant postures adopted by the goldsmiths and evaluate those

postures in terms of severity of risks. Similarly, the feelings of discomfort of the

workers for those postures were also evaluated.

3.2. Introduction

59

In this chapter, the postures, which the goldsmiths have adopted for their

work, have been scrutinized. The main purpose of the study was to-

(i) Evaluate the prevalence of discomfort/pain in any body part due to work.

(ii) Rate the feeling of discomfort by a discomfort rating scale.

(iii) Study the postures and identify the awkward ones.

(iv) Evaluate the awkward postures by standard posture assessment tools.

3.3. Objective

60

3.4.1. Study population

The present study recruited participants from the large population of the

goldsmiths screened previously. Detailed information about the recruitment of the

study participants were discussed in the previous chapter (Chapter 2). In brief, a total

of 276 persons were preliminary screened that included 198 jewellery manufacturing

workers and 78 reference personnel who were mainly the sales persons and office

workers at the jewellery houses. Of those 198 participants actively involved in the

manufacturing processes, 8 had withdrawn from the study. Among the rest, 147

reported to have any discomfort/pain in the body parts during general health study.

Out of those 147, 135 personnel were recruited in this study based on the inclusion

criteria: (1) having a minimum one year exposure in jewellery industries; (2) not

having any serious medical injury/active medical condition in last three months; and

(3) willingness to cooperate. Figure 3.1 illustrated the schematic diagram of the

selection process of the participants.

Figure 3.1. Schematic representation of recruitment of the study participants

Recruited participants were categorized as manufacturers/fabricators (n=89),

melting staffs (14) and polishing staffs (32) based on their types of job. Working

postures adopted by the melting staffs were same as of the polishing staffs and due to

very small number of participants from former group they were merged with the

polishing staffs. Reference staffs (sales persons and office workers) were not included

Polishers (n=32)

Withdrawn (n=8)

Melters (n=14)

Recruited (n=135)

Discomfort reported (n=147)

Goldsmiths (n=198)

Total Screened (n=276)

Fabricators (n=89)

Excluded (n=12) Experience<1 year: n=3 No consent: n=6 Active medical condition: n=3

Sales staffs (n=78)

3.4. Methods

61

for comparative analysis as they did not have comparable work schedules and

working postures like the workshop staffs.

3.4.2. Anthropometric measurements

Height and weight of the participants were measured by standard

anthropometric rod and properly calibrated weighing machine respectively. Body

mass index (BMI) and body surface area (BSA) were calculated according to the

formulae reported previously

3.4.3. Questionnaire study

An interviewer-administered Nordic musculoskeletal questionnaire was used

to seek information about the power and zone of discomforts [Kuorinka et al. 1987].

The questionnaire was translated to Bengali and then back translated into English.

The Bengali-translated version of this questionnaire was pre-validated [Sett and Sahu

2010]. The questionnaire contains several open and close-end questions that help

acquiring information about discomfort at neck, shoulder, upper and lower back,

hand, buttock, knee and ankle before, during and/or after work [Annexure-IV]. Those

observational data were analysed further to find out the areas of feeling of maximum

discomfort.

To rate the degree of discomfort, a body parts discomfort rating (BPD) scale

was used [Jacquelin et al. 1994]. It is an 11 point rating scale from 0 to 10, where 0

and 10 indicate no and maximum discomfort at a particular location of the body,

respectively. This tool is frequently used to get score-based information of subjective

feeling of discomfort by rating in this 0-10 point scale (Figure 3.2). The workers were

asked to rate their feeling of discomfort in that scale. The same practice of rating a

particular zone of discomfort during a particular work was repeated for each

individual for minimum three times after 1 day interval to avoid variability.

Deviations of the ratings more than 1% (e.g. if individual’s first rating was 5 and

second was 3 or 7), were not considered as true score and were eliminated.

62

Figure 3.2. Body parts discomfort (BPD) Scale.

3.4.4. Assessment of the working postures

Two standard methodologies, rapid entire body assessment (REBA) and rapid

upper limb assessment (RULA) were used to assess the stress of workers for all

predominant postures by scoring them according to their severity of stress.

REBA was first described by Hignett and McAtamney in the year 2000 and is

one of the most widely used posture assessment tools. It is a score-based information

assessment tool comprising of items including required or selected body posture,

forceful exertions, type of movement or action, repetition, and coupling. Responses of

the selected items are given specific scores, which altogether undergo a systematic

process to evaluate whole body postural stress and risks associated with job tasks. The

REBA worksheet has been provided in the annexure [Annexure-V].

Since, the goldsmiths belonged to sedentary class of workers and their tasks

needed more usage of upper limbs (neck, shoulders, arms) compared to the lower

limbs (legs), a more proficient posture assessment tool, rapid upper limb assessment

(RULA) was used to stratify the postural patterns of the upper limbs only. RULA first

described by McAtamney and Corlett (1993) is also a score-based information tool

containing items of upper and lower arm position, wrist twist and position and neck

and trunk position. Like REBA, this also evaluates the scores systematically for a

particular job task. RULA worksheet has also been provided in the annexure

[Annexure-VI].

First, all the different tasks were captured into motion pictures using a

camcorder (Sony, India). Then, the recordings were freeze-framed and the awkward

postures were selected. Freeze-framed images were analyzed using ergonomical

63

assessment software, ErgoFellow V2.0 (Brothersoft Inc., USA). REBA and RULA

scores were obtained from that software. Stick diagrams of the postures were made

for visual perception and critical evaluation of those postures.

3.4.5. Statistical analyses

Demographic measures were presented as means (SD). Comparisons of

baseline characteristics between the three groups (fabricators, melting staffs and

polishing staffs) included Kruskal-Wallis test for non-normal distributions. Group-

wise comparison of feeling of discomfort of a particular body part was analysed by

chi-square (χ2) test. Individual responses of body parts discomfort ratings for a

particular location of the body during a particular job were obtained from all

respondents (average values of the BPD scores were calculated from who responded

only) and median value was calculated. Individual responses of discomfort of all body

parts during a particular task were also obtained and expressed as median. Level of

significance for all pair-wise comparison was taken as P<0.05. All analyses were

performed in SPSS (version 20).

64

3.5.1. Demographic features

Demographic features of the all participants have been presented in Table 3.1.

Although, the polishing staffs were of higher age group than the fabricators, the

difference did not turn out statistically significant. Although the polishing staffs were

having higher BMI than the manufacturing/fabricating staffs (23.5 vs. 22.1 kg/m2),

the difference was not found statistically significant. Other anthropometric variables

(height, weight and BSA) were found moderately similar among the fabricators and

the polishing staffs.

Table 3.1. Baseline characteristics of the personnel identified for the study

Parameters

Manufacturers

(n=89)

Melting staffs

(n=14)

Polishing staffs

(n=32)

P value

Age (Year) 36.3 (2.4) 35.8 (2.9) 37.3 (3.8) 0.43

Height (Meter) 1.67 (0.15) 1.70 (0.11) 1.66 (0.18) 0.17

Weight (Kg) 62.4 (5.6) 62.7 (4.1) 63.2 (8.1) 0.29

BMI (Kg/M2) 22.4 (2.5) 21.7 (3.1) 22.9 (2.8) 0.61

BSA (M2) 1.77 (0.26) 1.79 (0.31) 1.77 (0.38) 0.31

Data presented as mean (SD). P values were calculated by Kruskal-Wallis test of non-normal data. Significance level P<0.05. Abbreviations were mentioned previously.

3.5.2. Assessment of the questionnaire responses

Categorical information of feeling of discomfort by the study participants as

assessed from the questionnaire has been presented in the following figure (Figure

3.2). The rates of response for the neck and shoulder regions were moderately higher

among the melting staffs (21.4% for each of the regions) compared to the fabricators

(12.4% and 5.6% for neck and shoulder, respectively) and the polishing staffs (9.4%

and 6.3% for neck and shoulder, respectively) although the difference was not

statistically significant (p values for neck and shoulder: 0.52 and 0.11). However, it

was observed that the areas of maximum discomfort among the goldsmiths had been

upper and lower back and waist. The percentages of discomfort in those areas were

higher than all other body parts and the trend was consistent even after stratification

3.5 . Results

65

of the goldsmiths by their job type although the statistical difference between these

three groups were not established (P values for upper back, lower back and waist were

0.13, 0.11 and 0.15, respectively).

Figure 3.3. Prevalence of body parts discomfort among the goldsmiths by work category

Table 3.2. Complaint of discomfort by the goldsmiths in different body parts

Body parts Fabricators (n=89) Melting staffs (n=14) Polishing staffs (n=32)

N

BPD

N

BPD

N

BPD

Head 7 3 (2-4) 2 1.5 (1-2) 4 1.5 (1-3)

Neck 11 4 (2-6) 3 2 (1-2) 3 2 (1-3)

Shoulder 5 3 (1-5) 3 2 (2-3) 2 3 (2-4)

Upper Back 27 2 (1-4) 3 2 (2-3) 4 2.5 (2-4)

Lower Back 39 4 (2-5) 5 4 (3-5) 8 4 (4-5)

Waist 28 3 (1-4) 4 3 (2-4) 5 3 (2-3)

Knee 8 2 (1-4) NR - 2 1.5 (1-2)

Data presented as n (%) [Discomfort] or median (range) [BPD rating] unless otherwise indicated. P values were obtained from χ2

test. Values for maximum discomfort do not add up to 100% due to multiple non-exclusive response categories. N: frequency of responses; NR: No Response

66

The perceived discomfort levels of the goldsmiths for each of the selected

body parts were presented in the table 3.2. The degree of discomfort felt by the

workers was not found high for any of the body parts for any kind of specific activity,

e.g., fabricating, melting or polishing of the jewellery products. The median values of

the BPD scores were in the safer zone (less than the middle value, 5), which indicated

that the personal discomfort level was not very acute in terms of the job-associated

musculoskeletal problems.

3.5.3. Evaluation of the working postures

The most widely used posture in the jewellery manufacturing industries is the sitting

posture especially the ground sitting. Other postures depend on the type of the task,

varying from semi-squatting to standing. Analyses of the most frequent working

postures as assessed by REBA and RULA were presented in Table 3.3. From the table

below, it was obtained that all of the predominant postures were medium to high risky

according to the scores of REBA. Scores obtained from RULA also indicated all the

predominant postures under moderate risks. However, median body parts discomfort

scores of all of the predominant postures ranged between 2-4 and the minimum and

maximum score given by the workers for any of those postures remained within 0-6

of the BPD scale. These scores reached maximally up to the midpoint of the BPD

scale (medium level of discomfort), which meant that the degree of discomfort were

not significantly higher for those postures adopted by the workers. Area-specific BPD

scores for each of those predominant postures were also found within permissible

limit and did not deviate much from the mid-value. Workers who generally required

sitting on the ground for minute and precision works complained about mild to

moderate discomfort at neck, upper and lower trunk although the median values for

all BPD scores remained within safe limit. Standing postures that involve bending or

twisting of trunk might have some effects on the waist but did not have influence on

other body parts significantly. Secondly, those standing postures were for very short

duration (not more than 10 minutes at a stretch) and thus, those postures did not affect

any body part significantly.

67

Table 3.3. Characterization of the predominant postures and assessment of postural strain

Type of posture

Posture Stick

diagram

Score (Risk level) BPD rating (whole body)

Organ specific BPD rating REBA RULA

Semi-squatting

5

(Medium)

5

(Change

needed)

4 (2-5)

Head

Neck

Shoulder

Upper Back

Lower Back

Waist

Knee

1 (0-2)

3 (1-5)

3 (2-5)

2 (1-4)

4 (3-5)

3 (2-5)

3 (3-5)

Ground sitting

with crossed

legs

8

(High)

3

(Change

needed)

4 (3-6)

Head

Neck

Shoulder

Upper Back

Lower Back

Waist

Knee

1 (0-2)

4 (3-6)

2 (1-3)

4 (3-6)

4 (4-6)

3 (2-5)

2 (1-4)

Ground sitting

with crossed

legs

7

(Medium)

3

(Change

needed)

3 (2-4)

Head

Neck

Shoulder

Upper Back

Lower Back

Waist

Knee

0 (0-0)

3 (2-4)

2 (1-3)

2 (1-4)

4 (2-4)

2 (1-3)

1 (0-2)

Table continued…

68

Type of posture

Posture Stick

diagram

Score (Risk level) Score (Risk

level) Organ specific BPD rating

REBA REBA

Standing with

bent waist

10

(High)

5

(Change

needed)

4 (3-5)

Head

Neck

Shoulder

Upper Back

Lower Back

Waist

Knee

0 (0-0)

0 (0-0)

4 (3-5)

3 (1-4)

0 (0-0)

3 (2-4)

0 (0-0)

Front bent

9

(High)

5

(Change

needed)

2 (0-3)

Head

Neck

Shoulder

Upper Back

Lower Back

Waist

Knee

0 (0-0)

0 (0-0)

2 (1-3)

1 (0-2)

0 (0-0)

0 (0-0)

0 (0-0)

Ground sitting

with crossed

legs

7

(Medium)

3

(Change

needed)

4 (3-6)

Head

Neck

Shoulder

Upper Back

Lower Back

Waist

Knee

2 (1-4)

5 (4-6)

3 (1-4)

2 (1-4)

4 (2-4)

4 (3-6)

1 (0-2)

Values of BPD scales were presented as median (range).

69

The study presented an insight of the prevalence of musculoskeletal disorders

among manual jewellery manufacturing workers. This study also highlights the

predominant postures adopted by the goldsmiths for their regular work and the

relationship between the postures and postural stress.

It was observed that the feelings of discomfort in the upper and lower back

and waist were mostly prevalent among the goldsmiths even after stratification by

their job types. The most predominant posture, which has been adopted by the

goldsmiths, is sitting on the ground. According to them, this is the most relaxed and

appropriate posture for their job. However, according to necessity of different other

tasks, they move around and adopt some different other postures while operating

some specific instruments.

Score-based evaluation systems (REBA and RULA) have graded those

predominant working postures as moderate to high risk. It is inevitable that sustained

working in those postures could contribute extensively to the occurrences of MSDs in

the trunk, including back and waist. Apart from the sitting postures, other standing

postures during handling of different instruments were also found strenuous, but the

most important fact is that apart from the sitting postures, the durations of the

handling of machines are relatively very low. This very short time fails to impose

significantly to the bones and muscles of the workers in spite of the exposure to those

postures.

Musculoskeletal problems are one of the most predominant physiological

hazards among the small-scale industries, especially in India. Sitting for a long work

hour may impose load on the vertebral column leading to the musculoskeletal

problems in the upper and lower back regions. There are a number of studies, which

are similar in the settings and are relevant to the present studies in regard to the

postural pattern of the workers and nearly all of those studies have shown that

continuous sitting on ground affects to the vertebral column. Roy and Dasgupta

(2008) found prevalence of musculoskeletal disorders among a group of home-based

food products (papad) makers in which the workers used to sit on the ground for a

prolonged working hour. Similarly, among a group of garment factory workers, Saha

and colleagues (2010) found musculoskeletal problems as one of the commonest

Discussion 3.6.

70

morbidities. In another preceded study on the garments factory workers by

Bandyopadhyay and colleagues (2012), more than 30% workers reported to have

discomfort in the upper and lower back regions. Zari industry workers whose working

patterns and postures match largely to those of the goldsmiths also complained to

have work-related musculoskeletal disorders in different body parts [Sharma and

Mahajan, 2013]. The investigators found alarmingly high (almost 100%) prevalence

of pain in the upper and lower back of the workers who spent more than 30 years in

that industry. The lower experienced group (who had 10-30 years experience) also

showed had a significantly high prevalence of pain in the upper limbs. Of those

workers, a significant number of respondents complained about neck and shoulder

pain, which are other target organs of WMSDs. In 2010, Ghosh and colleagues

received a significant complaint rate of musculoskeletal problems from the jewellery

manufacturing workers. In their study, 75% of the workers complained to have low

back problems, the rate being higher than that of the present study (overall 39%

workers complained about low back pain). This might be because in their study, they

did not follow any inclusion-exclusion criteria in the selection process. Furthermore,

they did not divide the goldsmiths by work type, which according to the present study,

played important role in the assessment of discomfort.

A number of systematic studies have been conducted to evaluate various

working postures among Indian unorganized working groups and nearly all of those

studies have identified Indian standard sitting postures (mainly the ground sitting

posture) highly strenuous, however, many researchers believe that traditional Indian

sitting style is beneficial. Although the goldsmiths used to work in sitting posture for

a long work hour, they do not work continuously for a long time. Thus, their

responses on the BPD scale did not go very high.

Although, the MSDs related to awkward sitting postures have been

extensively studied in various aspects as well as in various industrial setups, Indian

traditional ground sitting postures have not been studied. In one report, Bae and

colleagues (2012) described the structural aspects of sitting on chair and sitting on

ground. Although they showed that ground sitting may reduce lordosis of the spinal

curve thus attribute to low back pain, they also concluded that sitting on ground with a

lordotic lumber groove may reduce the chance of low back pain. Apart from the study

there is no report that has been able to describe the Indian postures clearly. Moreover,

71

the classic posture assessment tools such as REBA, RULA or OWAS (Ovako

working posture analysis system) best describe the western sitting postures, but fail to

evaluate the Indian postures. Thus, these western posture assessment tools are not

very much appropriate to evaluate these postures. That is why in spite of high risk

ratings of the postures, the complaint of musculoskeletal problems was relatively low.

72

There is a prevalence of musculoskeletal problems among the goldsmiths

engaged in the manual jewellery manufacturing processes. The long work hour in the

cross-legged ground sitting postures impose adverse effects on different body parts of

the workers such as the upper and lower back and waist. The most predominant

working postures adopted by the goldsmiths were found to be in the moderate to high

zones of risk according to two posture assessment tolls, REBA and RULA, however

the subjective feelings of discomfort among the workers were not found very high.

Although, the posture assessment tools are widely used in the western parts of the

globe, these are not much useful to assess typical Indian sitting postures. Thus, more

detailed studies are required with biomechanical monitoring systems to assess those

postures.

3.7. Conclusion