Prevalence of musculoskeletal discomfort among the workers engaged in jewelry manufacturing.

BACKGROUND: The workers engaged in jewellery manufacturing exposed to various occupational risk factors that lead to development of musculoskeletal disorders. But there is scarcity of reporting the prevalence of the musculoskeletal disorders among them. AIMS: To evaluate the prevalence of musculoskeletal discomfort among the workers engaged in jewellery manufacturing in India. SETTING AND
DESIGN: Case Control Study.
MATERIALS AND METHODS: This study was divided into two phases. First phase: prevalence rate were calculated using Modified Nordic musculoskeletal questionnaire and compared with the control group. Second phase: strength, flexibility and tightness of the muscle groups (neck, lower back and knee) were evaluated through physical examination for the subjects who reported positive prevalence. STATISTICAL ANALYSIS: A comparative inferential statistics was used.
RESULTS: This study was divided into two phases. First phase: prevalence rate were calculated using Modified Nordic musculoskeletal questionnaire and compared with the control group. Second phase:strength, flexibility and tightness of the muscle groups (neck, lower back and knee) were evaluated through physical examination for the subjects who reported positive prevalence.
CONCLUSIONS: The musculoskeletal disorders among the workers engaged in jewellery manufacturing were found to be specific to the occupation.

INTRODUCTION

Musculoskeletal disorders (MSDs) are injuries or disorders of the muscles, nerves, tendons, joints, cartilage, and supporting structures of the upper and lower limbs, neck, and lower back that are caused, precipitated or exacerbated by sudden exertion or prolonged exposure to physical factors such as repetition, force, vibration, or awkward posture.[1] Costs of MSDs are well-accepted in the industry in developing and developed countries.[12345] The risk factors of MSDs are divided into occupational and nonoccupational factors. Sedentary work population is prone to various MSDs as there are various risk factors present at the workplace.[6] Disk herniation for sedentary people, who work in a sitting condition is well reported in the literature.[78] Health and safety executive and European agency of safety and health at work suggest that sedentary work style has an association with the low back pain.[910] The same concept is also accepted in recent literature.[11] The jewelry manufacturing process is sedentary in nature and requires prolonged sitting occupying the same posture. There are various studies available, which reports that there are risk factors are present, for developing the MSDs, at the workplace of jewelry manufacturing.[12] The prevalence rate of various MSDs is not reported well in literature for the workers engaged in jewelry manufacturing. Even though, large number of workforce is engaged, and the profession is engaged in substantial economic activity, jewelry manufacturing has received very little attention with reference to occupational health related problems, especially MSDs.[131415161718] Therefore, a study need was felt to evaluate the prevalence rate of various musculoskeletal discomfort among the workers engaged in jewelry manufacturing.

SUBJECTS AND METHODS

Selection of subjects

Selection of the workers engaged in jewelry manufacturing (Group 1)

Minimum 1-year experience in the same job (jewelry manufacturing) was the inclusion criteria for Group 1.

Selection of the control group (Group II)

Graduate students, who were engaged in the post bachelor study considered as a control group and were selected based on following criteria.

Age-matched

They occupy mostly sitting posture during normal work schedule

The activities are sedentary in nature.

Study location

Workers engaged in jewelry manufacturing: Various jewelry manufacturing units, Mumbai, India

Control group: Educational Institutes, Mumbai, India.

Approval of the study from ethics committee

The study was duly approved by the Institutional Human Ethics Committee, Department of Physiology, University of Calcutta, Kolkata, India.

Signed informed consent

After explaining the purpose of the study and the study protocol, signed informed consents were obtained from all the participants, who participated in this study (workers engaged in jewelry manufacturing and control group).

Statistics

Descriptive and analytical statistics were computed using NCSS, 2004.

The study was conducted in two phases. In the first phase, the prevalence rate was identified among the workers engaged in jewelry manufacturing and compared with the control group. In the second phase of the study, physical assessment was carried out for the subjects, who were having positive responses for musculoskeletal discomfort and then again compared with the control group. Tools and methods followed in the study were as follows:

Questionnaire study using modified Nordic musculoskeletal disorders

Nordic musculoskeletal questionnaire (NMQ) was developed by a group of researchers to screen the MSDs as a part of the ergonomic program and epidemiological studies on MSDs.[19] The questionnaire is used for identifying the presence of physical troubles including ache, pain, and discomfort for past 12 months and past 7 days in each of the body parts (neck, shoulders, elbows, wrists/hands, upper back, low back, both hips/thighs/buttock, both knees, ankle/feet). It also evaluates grades of frequency by using a measure of functional status: “How often you get or had (specific body parts) the trouble?.” Length of the persistence of the trouble also evaluated by asking “what is the total length of time that you had (specific body parts) trouble during the last 12 months?” Severity of the trouble is also evaluated by using a three-point scale (mild, moderate, and severe). NMQ is used in the present study as it is accepted universally as a screening tool to evaluate the work related MSDs.[20] MSD survey was carried out using modified NMQ[21] on the workers engaged in jewelry manufacturing and the control group. Annual and weekly prevalence data were obtained and compared for both the groups using statistical software (NCSS, 2004). In the present study, the difference in the prevalence of musculoskeletal discomfort between the workers engaged in jewelry manufacturing and control group were calculated using Chi-square test.

Experimental procedure

The purpose of this part of the study was explained to all the participants. Furthermore, it has been explained to the owners of the jewelry manufacturing units. The responses were obtained at the workplace for the workers engaged in jewelry manufacturing and at the classrooms for the control group.

Physical examination for musculoskeletal disorders

In order to ascertain the nature of specific musculoskeletal problems, specific MSD diagnostic tests were carried out. The examinations were carried out under the supervision of a qualified physical therapist. The strength, range of motion (ROM), and tightness of the specific muscle groups were tested for back, neck, and knee. The test protocol[2223] was as follows:

Inspection (observation): An inspection is an organized examination or formal evaluation. Observing any specific body discomfort or pain or any deformities in the body parts considered as inspection

Palpation (the examination of the body using the sense of touch): Palpation is used as part of a physical examination in which an object is felt (usually with the hands) to determine its size, shape, firmness, or location

Range of motion: ROM refers to the number of degrees of motion that are present in the joint. ROM is classified in three groups; active, passive, and resistant

Muscular and neurological examinations: It is a systematic examination that surveys the functioning of nerves delivering sensory information to the brain and carrying motor commands (peripheral nervous system) and impulses back to the brain for processing and coordinating (central nervous system)

Strength of specific body parts: Strength of back, neck, and knee muscles were measured using preferred method (Appendix 1). Grade represents an examiner's assessment of the strength of a muscle group.

RESULTS

Phase I – self-reported MSD problems using standardized NMQ

The response rates were 81.4% (407/500) and 89.09% (89/110) for workers engaged in jewelry manufacturing and control group respectively. However, 385 (workers engaged in jewelry manufacturing) and 79 (control) results were included in the study as rest of the questionnaires were incomplete. Figures 1–7 represent the data of prevalence, frequency, and the severity of the musculoskeletal discomfort among the workers engaged in jewelry manufacturing and control group.

Figure 1

Annual prevalence data of musculoskeletal disorders (workers engaged in jewelry manufacturing, N – 385; control, N – 79)

Figure 7

Length of the discomfort (Group 1, N – 385; Group 2, N – 79)

Annual prevalence

Figure 1 represents the values of annual prevalence of musculoskeletal discomfort for both the groups (Group 1 – workers engaged in jewelry manufacturing, Group 2 – control). The result revealed that the neck (33.51%), low back (66.49%), and knee (76.10%) were the most affected body parts among the workers engaged in jewelry manufacturing. The percentage of responses for upper back, wrist, shoulder, and elbow were reported <10% for the workers engaged in jewelry manufacturing. For the control group, these values were just above 10%. Therefore, these responses were not considered for further analysis. For the control group low back, neck, upper back, and wrist were the most affected body parts. The prevalence rate of knee, low back and neck of both the groups were compared using statistical software NCSS 2004. The Chi-square tests were performed. The χ2 values for knee, low back and neck were 129.29, 37.09, and 6.17, respectively. The results of the Chi-square tests showed that the annual prevalence of knee (P < 0.001), low back (P < 0.001), and neck (P < 0.02) of the workers engaged in jewelry manufacturing were significantly higher than the control group.

Weekly prevalence

Figure 2 represents the values of weekly prevalence data of musculoskeletal discomfort for both the groups (Group 1 – workers engaged in jewelry manufacturing, Group 2 – control group). The figure revealed that the responses for all the body parts were <10% or just above 10%. Therefore, further analyses were not been conducted.

Figure 2

Weekly prevalence data of musculoskeletal disorders (workers engaged in jewelry manufacturing, N – 385; control, N – 79)

Comparison of prevalence data of current study with literature

The prevalence data of the present study of low back, neck, and knee were compared with the data available in literature and presented in Tables 1–3.

Table 1

Comparison of low – back prevalence data with literature

Table 3

Comparison of Knee prevalence data with literature

The above result [Table 1] revealed that the annual prevalence of low back pain of the present study significantly higher in most of the cases as compared to other literature. Result of weekly prevalence is lower than the values reported in the literature.

The above table revealed that the annual prevalence of neck pain of the present study in some cases significantly lower and in some cases significantly higher as compared to other literature. Result of weekly prevalence is significantly lower.

The above table revealed that the annual prevalence of knee pain of the present study mostly significantly higher as compared to other literature. Result of weekly prevalence is comparable with the literature.

Annual disability

The result of the NMQ revealed that no one was absent from work due to discomfort or pain in any part of the body (neck, back, shoulder, elbow, wrist or knee).

Self-reported causes of the musculoskeletal problem

From the questionnaire analysis, it was observed that the daily work was perceived by the workers engaged in jewelry manufacturing (100%) as the main activity which resulted in the development of low back, neck, and knee discomfort or pain. No one reported any kind of accident caused musculoskeletal discomfort or pain in the respective body parts, whereas, the respondents of the control group informed that the discomforts at neck were due to work (20%), activities at home (40%), supporting activity (10%), and other reasons (30%). For low back pain, these responses were work (45%), activities at home (25%), supporting activity (30%), and other reasons (40%). For the knee, the responses were work (10.53%), activities at home (36.82%), accident (42.11%), and other reasons (20.99%).

Frequency of musculoskeletal discomfort

Low back

Figure 3 represents the frequency of discomforts at low back for both the groups. It revealed that the workers engaged in jewelry manufacturing perceived low back discomfort mostly (93.44%) “one or more times a week” (odds ratio [OR] – 68.37, confidence interval [CI] – 26.53–176.19), whereas control group experienced low back discomfort mostly “one or more times a year” (37.93%). Workers engaged in jewelry manufacturing did not experience any discomfort or pain in low back “daily” or “only one episode of trouble.”

Figure 3

Frequency of discomfort of low back (Group 1, N – 385; Group 2, N – 79)

Neck

Figure 4 presents the frequency of the discomfort at the neck region. It showed similar kind of results as observed in low back discomfort. For neck, the workers engaged in jewelry manufacturing experienced pain or discomfort mostly “one or more times a week” (OR – 57.35, CI – 22.56–145.78). The workers engaged in jewelry manufacturing didn't experience the pain or any discomfort at neck “daily,” whereas, control group experience “one or more times a month” (20%), “one or more times a year” (20%), “one or more times every few year” (5%), and “only one episode of trouble” (30%).

Figure 4

Frequency of discomfort of neck (Group 1, N – 385; Group 2, N – 79)

Knee

Figure 5 presents the frequency of the discomfort at knee region. For knee, the workers engaged in jewelry manufacturing experienced mostly pain or discomfort, “one or more times a week” (OR – 119.39, CI – 30.579–97.62). Both the groups didn't experience the pain or any discomfort at knee “daily.”

Figure 5

Frequency of discomfort of knee (Group 1, N – 385; Group 2, N – 79)

Severity of musculoskeletal discomfort

The result of the severity of musculoskeletal discomfort is presented in Figure 6.

Figure 6

Severity of the discomfort (Group 1, N – 385; Group 2, N – 79)

The above figure showed that 82.24% of the workers engaged in jewelry manufacturing (Group 1) experience “mild” low back pain. On the contrary, 68.97% among the control group (Group 2) experience “mild” low back pain. Statistical treatment showed that the difference was significant (OR – 2.08, CI – 1.07–4.05). For neck pain majority of the subjects of both the groups experience “mild” pain/discomfort (OR – 1.16, CI – 0.56–2.82). The result of the severity of the knee discomfort showed that the majority of the workers engaged in jewelry manufacturing has “mild” knee pain (OR – 5.377, CI – 2.13–13.56).

Length of musculoskeletal discomfort

This study was also carried out to find out the total length of the discomfort suffered by both the groups during last 12 months. The result [Figure 7] revealed that the workers engaged in jewelry manufacturing were experienced discomfort in the low back (OR -46.32, CI – 19.21–111.72), neck (OR – 204.08, CI – 60.52–688.17), and knee (OR – 38.23, CI – 9.76–149.73) for “1–7 days,” whereas, for control group these values for “1–7 days” discomfort were 20.51%, 11.54%, and 52.63%, respectively. No one from the workers engaged in jewelry manufacturing experience any discomfort (low back, neck, and knee) for “more than 30 days” or “every day.”

Phase II – Physical examination (under the supervision of a physical therapist)

For physical examination neck, low back and knee were considered. The results of modified NMQ revealed that the discomfort or pain in shoulder, upper back, wrist, and elbow regions were not observed to be severe among the workers engaged in jewelry manufacturing. The annual and weekly prevalence rates of shoulder were 7.01% and 0.26%, respectively. For upper back, the values were 8.31% and 1.56%, respectively. For wrist and elbow also similar results were observed. Therefore, it may be concluded that all these body parts were not much affected and were not included in the further study.

Range of motion, strength and tightness of neck muscles

Range of motion (neck)

Majority of the workers engaged in jewelry manufacturing had full ROMs (neck flexors – 99.25%, extensors – 98.50%, lateral flexors (right) – 64.42%, lateral flexors (left) – 64.42%, lateral rotators (right) – 98.50%, and lateral rotators (left) – 98.50%). For the control group also similar values were observed. The ROM for lateral flexor (left and right) of the workers engaged in jewelry manufacturing was significantly lower than that of control group (OR – 27.06, CI – 6.29–116.37) [Figure 8].

Figure 8

Result of range of motion of neck (Group 1, N – 267; Group 2, N – 50), *Significant difference

Strength (neck)

Strength testing of neck muscle groups showed that all muscle groups had “grade 5” strength for both the groups (the workers engaged in jewelry manufacturing and the control group).

Tightness (neck)

68.91% workers engaged in jewelry manufacturing and 80.00% of the control group had flexible neck muscles without any tightness (OR – 1.80, CI – 0.94–3.45) [Figure 9].

Figure 9

Neck muscle tightness – physical examination (Group 1, N – 267; Group 2, N – 50)

About 31.09% and 20.00% respondents from the workers engaged in jewelry manufacturing and control group, respectively, had tightness in the neck muscles. The result of the tightness of the neck muscles were presented in Figure 10. It revealed that the workers engaged in jewelry manufacturing had higher level of bilateral trapizitis tightness, although the difference was not statistically significant (OR – 1.44, CI – 0.74–2.78). Among the other types of tightness, lateral flexors, and lateral rotators tightness were present among the workers engaged in jewelry manufacturing, which were absent among the control group.

Figure 10

Types of tightness of neck muscles – physical examination (Group 1, N – 267; Group 2, N – 50)

Range of motion, strength and tightness of back muscles

Range of motion (back)

Majority of the workers engaged in jewelry manufacturing had full ROMs (back flexors – 94.38%, extensors – 86.89%, lateral flexors (right) – 73.03%, lateral flexors (left) – 73.03%, lateral rotators (right) – 92.88%, and lateral rotators (left) – 92.88%). For control group also similar values were observed (back flexors – 100.00%, extensors – 98.00%, lateral flexors (right) – 98.00%, lateral flexors (left) – 98.00%, lateral rotators (right) – 100.00% and lateral rotators (left) – 100.00%). The values of full ROM for lateral flexors (left and right) of the workers engaged in jewelry manufacturing were significantly lower than that of control group (OR – 18.09, CI – 4.17–78.55) [Figure 11].

Figure 11

Range of motion of back – physical examination (Group 1, N – 267; Group 2, N – 50), *Significant difference

Strength (back)

Muscle strength testing showed that there was a reduction of strength of back extensors. However, the strength of back flexors, lateral flexor (right and left), and rotators (right and left) were at “grade 5” that is normal.

From the Figure 12, it was observed that there were significantly (OR – 2.02, CI – 1.12–3.55) less numbers of workers engaged in jewelry manufacturing, who are having back extensor's strength in good to normal range. It was also revealed that the workers engaged in jewelry manufacturing were having significantly (OR – 1.99, CI – 1.13–3.50) more number of respondents with back extensor's strength in the range of “fair.” The data of back extensor's strength also showed that none of the subjects (workers engaged in jewelry manufacturing and control group) had back extensor strength values in the categories of “poor,” “trace” and “no movement.” Therefore, it may be concluded that the back extensor strength of the workers engaged in jewelry manufacturing were reduced substantially, but it had not been reduced to the level of disability.

Figure 12

Back muscle extensor's strength – physical examination (Group 1, N – 267; Group 2, N – 50)

Tightness (back)

Figure 13 revealed that 84.64% subjects of the workers engaged in jewelry manufacturing had full flexibility of back muscles, whereas, none of the subjects of the control group had tightness of the back muscles. Therefore, the result further suggested that 15.36% workers engaged in jewelry manufacturing have had tightness of the back muscles and they were the affected group.

Figure 13

Back muscle tightness – physical examination (Group 1, N – 267; Group 2, N – 50)

Range of motion, strength and tightness of leg muscles

Range of motion (knee)

Physical examination showed that both of the groups had full ROM of the knee joints.

Tightness (knee)

Results of tightness of leg muscles (hamstring and quadriceps) presented in Figure 14. It revealed that 34.83% of the workers engaged in jewelry manufacturing and 20.41% of the control group had “normal” flexibility of the hamstring muscle group. Approximately, half of the population of both the groups (workers engaged in jewelry manufacturing and control) had “mild” tightness in the hamstring muscle group (OR – 0.70, CI – 0.40–1.22). The result also revealed that the workers engaged in jewelry manufacturing had a higher percentage of respondents, who had “severe” tightness in the hamstring muscle group. However, statistical result showed that the difference was not significant (OR – 1.80, CI – 0.64–5.08). The result of the tightness of the quadriceps muscle groups showed that the workers engaged in jewelry manufacturing had significantly higher quadriceps tightness (OR – 12.36, CI – 4.26–35.99). The control group had significantly more numbers of subjects, who had “mild” tightness in the quadriceps muscle group (OR – 10.29, CI – 3.36–31.56).

Figure 14

Tightness of hamstring and quadriceps – physical examination (Group 1, N – 267; Group 2, N – 50)

DISCUSSION

Annual prevalence results revealed that almost two third of the workers engaged in jewelry manufacturing were complaining about the low back pain. The result was compared with different studies available in the literature which showed that the annual prevalence data varied from 18% to 66.7%.[242526272829303132333435] The comparable work groups were office workers, computer operators, carpenters involved in finishing, bank officers, carpet weaver, workers in communication company. It revealed that the workers engaged in jewelry manufacturing had a high prevalence (66.49%) of low back pain.

Weekly prevalence data available in the literature are very rare. The literature showed that the weekly prevalence data varies from 4.5% to 30.3%.[303536] The present study showed that the weekly prevalence data (10.65%) for low back was also comparable to the data available in the literature.

Chyuan et al. found in their study that the observed work population (workers of hotel and restaurant) experience low back pain “2–3 times” (30.9%) and “more than 3 times a week” (29.6%).[29] In another study carried out by Atlas et al. showed that the jeepney drivers experience mainly “1–7 days” pain during last 12 months.[37] Similar kind of responses was also obtained in a study carried out by Alrowayeh et al.[38] In the present study, a large number of the subjects (93.44%) indicated that they were experiencing back troubles one or more time a week. This suggests more number of respondents having similar problems.

The present study showed that the majority (82.24%) of the observed subjects (workers engaged in jewelry manufacturing and control) experienced “mild” low back pain. Similar results were also observed in the literature. Hillman et al., Omokhodion and Sanya, Spyropoulos et al., reported that 26.5%, 68%, and 24% of the observed population experience “mild” low back pain, respectively. In their study, the values for “moderate” and “severe” low back pain were 40.8%, 12%, and 27% and 32.6%, 73%, and 9%, respectively.[242728]

The study revealed that workers were suffering from the back problem; frequencies of such episodes were on higher side. The severity of the problem may categorize as mild, which was corroborated by the physical examination. ROM of the back muscles for majority of the workers was within the normal range. Strength of back extensors of none of the workers was found to be poor and below, even though, a substantial percentage (OR – 1.99, CI – 1.13–3.50) of the workers had a reduced back strength at fair level (grade 3). Thus, it can be stated that the workers engaged in jewelry manufacturing were suffering from back related problems even though, it was not severe in nature.

Annual prevalence rate reported in literature showed that the neck pain varied from 9.1% to 64.7% among the office workers, finishing workers of the carpentry, data processing workers, bank workers,[25262930313539] whereas, the availability of the weekly prevalence data of neck pain is rare and varies from 21% to 27%.[35] In the present study, annual and weekly prevalence were observed to be 33.51% and 3.85% for jewelry manufacturing workers and control group, respectively.

Chiu et al. in their study carried out among the general population at Hong Kong, found that 38% observed population reported the “moderate” to “severe” neck pain.[40]

In the present study, responses were mild (87.68%). The physical examinations of the neck muscles also corroborated with this finding. It revealed that the ROM, strength, and tightness of the neck muscles were within the normal range.

Chee and Rampal carried out a study on bank office workers reported that annual prevalence of knee pain was 31.9%.[26] In some other studies on office workers, computer operators, papad makers the value varied from 12% to 30%. In another study, on the carpet menders who carry out their job in seated cross-legged posture (similar to the posture adopted by the workers of the present study) showed the annual prevalence of knee pain as 23.6%.[3233] In the present study, such values were observed to be 76.10%.

CONCLUSION

Back was an area of concern as the majority of the respondents were complaining about the low back, which was supported by the physical examination. However, problems did not result in any disability. Even though workers were reported neck troubles, but problems were “mild” in nature which was supported by physical examination. The self-reported responses for knee prevalence showed higher values than the other comparable group although; the physical examination revealed that the severity of the knee was not predominant. Results were compared with the control group and with the data available in the literature. The problems were found to be specific to the occupation. Almost all the workers had indicated that low back, neck, and knee problems were due to their work and not due to other causal factors.

Table 2

Comparison of Neck prevalence data with literature