Evaluation of Work-Related Musculoskeletal Disorders and Postural Stress of Female "Jari" Workers.

AIMS: The present investigation was aimed to assess the postural stress and the prevalence of musculoskeletal disorders (MSDs) of the "Jari" (golden thread) workers. SETTINGS AND
DESIGN: This cross-sectional study was carried out on 156 female workers in different areas of the Purba Medinipur, Paschim Medinipur, and Howrah districts of West Bengal, India.
MATERIALS AND METHODS: The MSDs of the workers were evaluated by modified Nordic questionnaire method. The postural pattern during work was assessed by direct observation method. The posture of Jari workers has been analyzed by OWAS, REBA, and RULA methods. The joint angle in normal and working posture was observed. RESULTS AND
CONCLUSIONS: The prevalence of MSDs was very high among the workers. The major locations of body pains in Jari workers were lower back, upper back, neck, wrist, thigh, and shoulder. The occurrence of MSDs was higher in lower and higher age group than that of the middle age group. The total work shift of the workers was approximately 13 h including rest pause. The dominant postures adopted by the workers were sitting on the floor with stretched legs, sitting on the floor with folded knees, and kneeling posture. From the results of the postural analysis, the postures of the Jari workers had been categorized as stressful. There were a significant deviation between normal standing angles and working angles. From the overall study, it may be concluded that adoption of stressful postures for longer duration might be the cause of MSDs in different body parts of the Jari workers.

INTRODUCTION

India is based on art and architecture and for those from the age of early civilization changes occurred rapidly in the field of art and architecture. Embroidery work is one of the oldest arts in this country. Some of such works are done by the golden thread. The golden thread workers are group of population that are engaged in making a variety of products of our daily life. The golden thread is called “Jari” in Indian language, and thus the golden thread workers are known as Jari workers. In India, a number of people are being engaged in Jari work. Such works are now being popularly done in ladies and gents garments. As the demand of such garments is increasing, the Jari work is spreading in urban as well as in rural areas. It has taken the shape of a promising cottage industry in the country. The workers are involved in different types of job in Jari work. At first, they fix a cloth piece with a wooden frame which is placed at a certain height from the ground. Then they make drawings on the cloth by placing a perforated drawing sheet and pouring a mixture of drawing powder and oil. Embroideries are made manually using the golden thread on the cloth following the drawings made earlier. After finishing the embroidery all over the cloth, it is washed and dried. During performing those tasks the workers are required to maintain the static body posture for a long time and repetitive movements are caused mainly in forearm and hand. Thus postural stress may be imposed on the Jari workers. The human body can adopt various types of postures according to the need of the job. But awkward work postures are responsible for musculoskeletal discomfort as well as different segmental pain. Bhattacharyya and Chakrabarti [1] reported that ergonomic risk factors for MSDs were faulty work area design, awkward posture, and repetitive nature of work. According to Pal et al.[2] and Goswami et al.,[3] the wrong work posture is one of the major causes of occupational pain. High repetitiveness may be regarded as a causative factor for the development of MSD.[4] Pal et al.[5] and Das and Gangopadhyay [6] reported that prolonged work activity, high repetitiveness, and remaining constantly in an awkward posture for a prolonged period may lead to MSDs. A constant repetitive work imposed a cumulative workload, which could cause pain and weakness and impaired function of the muscles and other soft tissues.[4] Physiological evidence showed that the rate and degree of tissue damage was dependent on the amount of force, repetition, and duration of exposure.[7] The physiological problems that arise from repetitive work or overuse of certain muscles, tendons, and soft-tissue structures have been addressed in terms of muscle fatigue, tissue density changes, and tissue strain.[89] Some studies have identified other variables such as shift work, extended work time, type of employment, second job and job unit, job type as well as work perceptions as factors significantly associated with musculoskeletal complaints.[10] Factors such as increasing age and smoking have also been named as significant predictors.[1112]

The purpose of the study was to investigate the prevalence and features of work-related musculoskeletal disorder (MSD) of Jari workers and compare the findings by age. In addition, an attempt has also been taken to assess the postural stress of the Jari workers during performing their task and to evaluate different parameters in relation to different work postures.

MATERIALS AND METHODS

Site and participants

This cross-sectional study was conducted on 156 female Jari workers from different villages of the Purba Medinipur, Paschim Medinipur, and Howrah districts of West Bengal state, India. The subjects were selected randomly from different cottage industries of the above-mentioned places. All subjects volunteered for the study. The age range of the workers was 18–60 years. The subjects were further subdivided into three groups, according to their age: <25 years, 25–40 years, and above 40 years.

Musculoskeletal disorder

The MSDs of the workers were evaluated by the modified Nordic musculoskeletal questionnaire technique.[13] The frequency and percentage of different musculoskeletal problems were determined.

Evaluation of work–rest pattern

The work–rest pattern of the workers was determined by directly observing their work as well as by taking interviews of the workers.[14] The total work shift was divided into work cycle and rest cycle. The actual work time was calculated by subtracting the actual rest pause from total work time. It was recorded carefully from beginning to end of the work by direct observation method employing video-photography of the task performed by the workers.

Determination of postural pattern

The postural pattern of the Jari workers during performing their tasks was studied by direct observation method.[14] The duration of each posture in working period was determined. The duration of adopting each posture was expressed in terms of total duration of the work shift.

Postural analysis

Various techniques have been applied for postural analyses to identify the stress of the work. The posture of Jari workers was analyzed by OWAS method.[15] Although the OWAS method has a wide range of use but the results can be poor in detail.[16] Therefore, the REBA [16] and RULA methods [17] were also applied for analysis of work postures of the Jari workers. The postures were chosen from the working images recorded with camera (Sony Handycam and Nikon SLR). When taking pictures of working postures, the camera was positioned at a suitable angle to the operator so that three-dimensional working postures could be identified during playback. The selected postures used in this study were those that the field observers classified as stressful to the human musculoskeletal system.

Measurement of joint angle

In working condition, different joint angles of the body, e.g. neck, shoulder, elbow, wrist, hip, and knee, were measured in normal erect and in different working postures by a goniometer (Lafette, USA, Model No. APM-I). The joint angles were measured in the right and left sides of the body, respectively. The deviations of different joint angles of different working postures from the normal erect posture were calculated in all the cases.

Statistical analysis

Frequencies and percentages were used for categorical variables and mean and standard deviation were used for continuous variables to summarize data. Differences were assessed by employing Student's t-test and Chi-square test for continuous and categorical variables, respectively. Statistical analyses were performed using the statistical software IBM SPSS version 20. Statistical significance was set at P < 0.05.

RESULTS

The prevalence of MSDs in the Jari workers was studied and from the results it was revealed that the prevalence of MSDs was very high among the workers [Table 1]. Problem in the lower back was the most prevalent MSD among the workers. More than 88% of the workers reported pain in their lower back. More than 50% of the workers reported pain in their wrist and neck. About 49 and 52% of workers reported pain in their shoulder and thigh regions.

Table 1

Frequency and percentage of MSDs in different segments of body of female Jari workers (n=156)

A comparison of the occurrence of MSD among different age groups of the Jari workers has been made [Table 2]. Results indicated that the occurrence of MSD in most of the segments of the body was higher in lower and higher age group than that of the middle age group of workers. From the results it was noted that the lower age group (<25 years) had significantly higher prevalence of discomfort in neck (P < 0.01), shoulder (P < 0.05), wrist (P < 0.05), upper back (P < 0.01), and lower back (P < 0.001) compared to the middle age group (25–40 years). The higher age group (>40 years) had also significantly higher prevalence of discomfort in neck (P < 0.01), shoulder (P < 0.05), and upper back regions (P < 0.05) compared to the middle age group (25–40 years).

Table 2

Age-related comparison of MSDs of Jari workers

The work–rest patterns of Jari workers have been presented in Table 3. The workers used to join the work within 7 a.m. and continued the work for about 13 h. The work time was around 83.1% and the rest time was around 16.89% of the total work shift. The rest period of the worker included the food break. The Jari workers performed their work mainly in sitting posture. The workers used to adopt four major postures, viz., sitting on the floor with stretched legs, sitting on the floor with folded knees, kneeling posture, and squatting posture. In most of the work time they used to work on sitting on the floor with stretched legs and sitting on the floor with folded legs. It was 30.91 and 27.93%, respectively, of their total work time [Table 4]. They also had to adopt kneeling posture for about 19.05% of the work time. The workers would spend a little time for adopting squatting posture during work, which was around 4.0% of the total work time.

Table 3

Mean±SD and percentage of work and rest time (min) of Jari workers

Table 4

Mean±SD (percentage) of time (min) for adopting different postures in a work shift by Jari workers

The postural stress of female Jari workers has been analyzed by different posture analysis methods, viz., OWAS, RULA, and REBA, and from the results [Table 5] it is revealed that the workers adopted stressful postures during performing their jobs. The dominant postures adopted by the workers were sitting on the floor with stretched legs, sitting on the floor with folded knees, and kneeling posture. From the results of postural assessment by OWAS method, it was found that the sitting on the floor with stretched legs and sitting on the floor with folded knees needed corrective measures in the near future and kneeling posture needed corrective measures as soon as possible. Similarly, from the results of postural assessment by RULA and REBA methods, it was found that the sitting on the floor with stretched legs and sitting on the floor with folded knees have been categorized as high risk and needed further investigation. However, kneeling posture has been categorized as very high risk and needed investigation and immediate change. So, from the results of postural analysis by three methods, it revealed that the workers who sat on the floor with folded legs or stretched legs showed lower action level than that of kneeling posture.

Table 5

Results (action level and risk levels) of postural analysis of the Jari workers working in different work postures

Joint angle study revealed that the shoulder joint angle had a maximum deviation (72.55°) while adopting kneeling posture; the deviation of the angle was minimum when the subjects were working on sitting on the floor with stretched leg [Table 6]. The deviation of the right shoulder angle was greater than that of the left shoulder angle. The maximum deviation of elbow joint angle was noted in sitting on floor with folded knee and minimum deviation was noted in kneeling posture. The highest deviation of the wrist joint angle (30.64°) was noted in the kneeling posture and minimum deviation was noted during sitting on the floor with stretched leg. Minimum deviations of the wrist angle were noted in left hand in all working postures. From the result it has also been noted that the mean working hip joint angles has been decreased from that of normal erect posture. The deviations of hip angle were extremely high in case of sitting on the floor with stretched legs. The deviation of working neck angle from normal erect standing posture was more or less same in three types of working postures.

Table 6

Mean±SD of joint angle (in degree) of Jari workers

DISCUSSION

The MSDs were highly prevalent among the Jari workers. The major locations of body pains in Jari workers were lower back (88%), upper back (46%), neck (57%), wrist (56%), thigh (52%), and shoulder (48%). In a study on handloom weavers,[18] it was reported that the occurrence of MSDs was high in lower back (75%), upper back (73.4), shoulder (68%), elbow (65%), wrist (70.3%), and neck (57.8%). The prevalence of MSDs among the Jari workers might be related to the poor postures adopted by the workers. They had to maintain those postures for a long duration of time. It was noted that the total work shift of the workers was too long (approximately 13 h including rest pause), that is, they had to perform the task for a prolonged period of time with lesser period of rest. This might be one of the reasons for the high percentage occurrence of MSD among the workers. Pal et al.[2] also found higher incidents of MSDs in agricultural workers because of the longer working hours. Lack of proper workplace layout, receptiveness, and prolonged work at awkward posture causes different segmental pain. The higher prevalence of MSDs at different body segments of the workers might be related to their postural pattern as well as longer duration of work in awkward posture.[2519]

Problems in the lower back were the most prevalent MSD among the workers. In the present study, it was found that the workers used to perform their task in poor body postures, such as kneeling, squatting, and bend postures, which might be the possible cause of back pain. Gallagher et al.[20] reported that the prevalence of lower back pain (LBP) symptoms increased significantly while performing the task in awkward posture. They concluded from their studies that all three awkward postures (stooped, squatting, and kneeling) increased the load on the spine. The LBP was commonly associated with decrease in muscular strength, spinal flexibility, incapacity, and eventually, activity limitation due to sick leave and corresponding high costs to the society, which was also reported by Volpato et al.[21] The above facts are also evident from the joint angle study. The deviation of hip angle was extremely higher than that of other joint angles. This indicated that the worker had to work in forward bend posture. Prolonged static sitting postures may have a negative effect on the nutrition of the intervertebral disc.[22] This is likely due to the turning mechanism of the hips in the sitting position which produces a kyphosis in the lumber region of the spine. The kyphosis of the spine increases the disc pressure as well as the load on the back muscle,[23] which also might be responsible for the lower back MSD as well as the pain in the lower back region.

About 57% of worker reported neck pain during performing their task. Flexion of the head and neck may be causes of neck pain. The prolonged static muscle load has appeared as the major risk factor in the development of load-related problems. It has been reported by the subjects that the major parts of the upper limbs, viz., shoulder, wrist, and elbow were affected. The workers performed the task with their upper arm raised for a long time and as a result static load was imposed on the shoulder. The raising of arms during work was evident by the large deviation of the shoulder angle from that of reference position (normal erect). The duration for which such deviation of shoulder angle was required to be maintained for about 85% time of the work shift was for about 11 h. This might evoke shoulder muscular tenderness disorder, which might be due to the static fatigue of the Trapezius muscle and multifactorial identification, including static and awkward posture and work practices.[24] When the arms were raised to some extent for doing the task, there might be a shoulder muscle tenderness disorder. The static strength has the capacity to produce force by maximal voluntary isometric muscular contraction.[25] In this type of muscular contraction total strength was applied on a particular muscle. So the concerned muscles became fatigued quickly. An appreciable percentage of workers reported pain in their wrist. There were dorsiflexion of wrist joint during performing Jari works. The left hand of the workers was required to hold a thread and the right hand is used to hold a needle during performing embroidery work. The wrist of the right hand usually remained in dorsiflexed condition during the whole operation imposing static load on it. High values of dorsiflexion and radial deviation might induce an increased risk of carpal tunnel syndrome.[26]

The lower limb was another affected part in most of the workers. The most affected part of lower limb was the thigh. During performing tasks, the workers had to fold their legs at the knee joints due to adopting kneeling and squatting postures as well as sitting on the floor with folded knees. Due to sustenance of flexed hips and knee, the high pressure was exerted between the thigh and lower legs gastrocnemius muscle.[27] The kneeling and squatting postures in the workplace are significant contributors to MSD of the knee and lower back.[28]

The postural pattern of the workers might be related to the high incidence of upper and lower limb disorders. The Jari workers adopted four major postures. Among them, two very awkward postures, viz., kneeling and squatting postures together, lasted for about 23% of the work time. Adoption of such poor postures for longer duration might be the cause of pain and discomfort in different body parts, especially lower limbs. Further, from the joint angle study it was revealed that the shoulder and elbow angles showed maximum deviation during adopting kneeling posture, which might be the reason for the occurrence of upper limb disorders.

The occurrence of MSD exhibited variation in the subjects of different age groups. The occurrence of MSD was lower in the subjects of the middle age group than that of the lower and upper age groups. The higher prevalence of MSD in the workers of the lower age group might be due to lesser experience and skill. From the study of the Häkkänen et al.,[29] it has been revealed that among trailer assembly workers a higher rate of sick leave due to disorders of the upper limbs was found in new workers compared with experienced ones. The highest incidence of MSD in the workers of upper age groups might be due to reduced muscle strength and endurance with the advancement of age.[30] Aweto et al.[31] studied work-related MSDs in highway sanitary workers and found that increasing age has a significant role on the development of MSDs. In another study Weston et al.[32] reported that the total number of days lost from work due to injuries was increased with worker age.

CONCLUSION

Although the workload of the Jari work was light, the incidence of MSDs was high, which indicates that there were definite ergonomic factors responsible for the MSDs. Adoption of stressful postures for longer duration might be the cause of MSDs in different body parts. So based on the observations made in this study, it can be concluded that there is a scope for improvement in work design and working conditions of the Jari workers under study from the ergonomic viewpoint with periodic training and awareness programs for educating the workers about the appropriate posture for different tasks, recognition of MSDs, and the importance of rest pauses while performing their tasks.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.