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Abstract

Purpose: To survey the work-related risk from wood carving and preliminarily assess the effectiveness of an ergonomic implementation program among wood carvers.

Methods: A survey on musculoskeletal disorder (MSD) was conducted by using unstructured conversation, observation, and a focus group. The nature and opinion of the workers, using tools, work station, postures, environment and opinion on adapting to ergonomic factors were investigated and developed for an ergonomic implementation program. Work-related MSD was assessed by the Rapid Upper Limbs Assessment (RULA) at before and after implementation for three weeks. Moreover, the knowledge and, satisfaction on implementation program, and pain sensation were evaluated. Results from the survey result from 25 male wood carvers aged 45.76±8.3 years old showed that. The size, dimension and design of the devices affected to MSD. Most of the wood carvers had low back pain. After ergonomic program was implemented by educated and trained in 14 wood carvers, the knowledge score improved significantly, except total RULA and total pain scores of all regions. But the RULA and pain scores at low back region showed significant improvement.

Conclusion: Low back pain was predominantly in wood carvers and a specific ergonomic implementation program can improve posture and reduce pain.

Keywords: Ergonomic; Wood carving; Work-related musculoskeletal disorder

Introduction

Work-related musculoskeletal disorders (WMSDs) are of interest, and many industries focus on the office [1], with varied prevalence depending on the occupations in each country, such as transport laborers, cooks, storage laborers, shop salespersons, and building structure cleaners in South Korea, [2]. Moreover, some work that needs contact stress, forceful contraction and awkward postures, as in a cashew factory, induces pain at the knee, back and shoulder, respectively [3]. The main problem proposed from WMSDs has been muscle pain from in corrected posture. Upper and lower back pain are still implied, for example, cervical pain was more frequent in tailoring and packing work, whereas lumbar pain was more common in buffing, and press operators [4]. Previous evidence showed that WMSDs was varied and depend on various occupations, for example the frozen food industry in Thailand [5], and low back pain as well as shoulder pain could be detected in Thai women during construction-related work [6]. Unfortunately, whether these problems presented among wood carvers in Chiang Mai had not been surveyed or confirmed. Wood carving is a specific occupation and needs vast experience, especially from its predecessors, as reputable craftsmen produce Thai wood carvings that are famous worldwide, like ceramics, candles, bronze ware, Buddhist sculpture and dragons (Figure 1).

Figure 1: Wood carving handicrafts: graving (left) and floating (right).

The traditional wood carving has been performed by low-sitting on the floor. Thus, the posture of wood carvers does not look safe and possibly provokes musculoskeletal disorder. Slumping and prolong static posture with neck, head and lower back flexion increase the WMSDs, especially with pain caused by contradicting the guideline for good posture [7]. Good posture has been proposed to maintain the head, neck and back in a coronal plane, by keeping joints in a neutral position, using suitable tools and distributing weight while sitting. Working postures that should be avoided for long-duration were informed by Warren & Sanders [8], as follows: neck flexion at more than 20 degrees, shoulder flexion or abduction at more than 30 degrees, shoulder extension and internal rotation, extreme elbow flexion, extreme sup nation and pronation with grasp, extreme wrist flexion or extension, and ulna or radial deviation while grasping tools. Moreover, design of the workstation also is very important for workers and so adjustable tables are used [7]. For example, an adjustable work station was developed for carpet weavers, and results showed that working posture was appropriate, and postural discomfort reduced when the weaving height was adjusted to 20 cm above elbow height and a high seat sloping forward was used [9]. Moreover, hand tools also were shown to influence working posture of the upper limbs of 44 hairstylists [10,11]. Previous evidence proposed that the risk factor from inappropriate posture, either static or dynamic and [8], work environment such as lighting, dust and noise level related to the WMSDs [8]. Finally, previous evidence mentioned that WMSDs such as injuries and pain produced industrial problems, and this was accepted worldwide. Furthermore, poor working postures and movements were the main causes of injuries [12]. Therefore, musculoskeletal injury, pain and fatigue led to a reduction of productivity. Therefore, the aims of study were to survey the WMSDs and risk factors among wood carvers, and evaluate the effectiveness of an ergonomic implementation program after focus group discussion on WMSD problems and satisfaction in posture, pain, and knowledge.

Materials and Methods

This study was a survey with a preliminary education study model, divided into two phases: Phase I surveyed the characteristics of wood carving work, tools, workplace environment and perceived WMSDs before developing an ergonomic implementation program from brain storming ideas between wood carvers and researchers. Phase II involved a cross-sectional descriptive study of risk, conducted to evaluate the postures, satisfaction, knowledge and area of pain in wood carving workers after educating and teaching them in a3-month ergonomic implementation program. This research was carried out at Baan Tawai, Khun Kong sub-district, Hang Dong district, Chiang Mai province, Thailand. Before the survey or data collection, individual personal contact with the wood carvers was made for obtaining their agreement and informed consent.

Participants: The approved participants in phase I and II were recruited by purposive sampling and snowballing approach. The inclusion criteria were as follows: 25 healthy male wood carvers in Baan Tawai village, who had at least 3 years’ experience in wood carving. Wood carvers who had health problems such as pulmonary or cardiovascular disease (tuberculosis, asthma, chronic obstructive pulmonary disease [COPD], heart failure, etc., or severe musculoskeletal problems such as fracture, etc.), were excluded from this study.

Assessments and Procedures: General information recorded on a form was used initially for the survey, moreover the tools, workstation, environment, and working postures were analyzed from digital photographs. An initial survey questionnaire with related pictures was used for conversations, interviews and probing questions for the wood carving workers and community leaders. Digital camera and voice recorders were used to gather data in this phase. Focus group interviews started 3 months after the initial survey and lasted for 2 days. After data analysis, the overall conclusions were presented to wood carver for agreement in the community. Then, the wood carvers were persuaded to join a health education meeting (Table 2), which was held under the previous criteria [13]. Knowledge of ergonomics was evaluated before starting the health education program and again immediately after the meeting had finished.

The risks found in phase I were presented to all of the woodcarvers for improvement on the ergonomic knowledge and other related topics such as proper working posture, risk of worst posture and a proper workstation and environment. According to a health belief model (HBM) construction [13]. The knowledge from the program was assessed immediately after education and compared to that before the meeting. Finally, brainstorming between the workers and researchers was performed in order to establish ideas on ergonomic factors for designing an ergonomic implementation program that included tools, workstations, work environment, and concept of safety in wood carving work. Baseline data of work, pain during work, knowledge, and satisfaction of the implementation program were assessed in work information questionnaires performed before and after three weeks of ergonomic implementation and in accordance with the Rapid Upper Limb Assessment (RULA), Employee Assessment Worksheet (© Professor Alan Hedge, Cornell University. Nov. 2000). For adherence and control in performing the ergonomic implementation program, a self-recording logbook was used.

Outcomes: Quantitative and qualitative variables in phase I of this study consisted of demographic data (age, duration of working experience, education level, and working condition); unknown in-depth knowledge (reflecting the intelligence of local people regarding wood carving tools); opinion of wood carving workers about the conditions and situations in a working period, body mechanics, workstation and environment; perceived WMSDsfrom wood carving and workers’ recognition; opinion of wood carving workers about the effect of tools, workstation, and work environment on working posture, as perceived by experienced workers; information about adjustment of tools, workstation, and work environment. After brainstorming and ergonomic implementation for three weeks, the knowledge and satisfaction scores were questioned. In addition, total RULA scores, individual RULA region scores, and pain scale were analyzed.

Results

Characteristics of participants

Twenty-five participants from total42 male woodcarvers were interviewed initially in this survey study. Their characteristics are described in Table 1. They were aged between 30 and 59 years with the mean and standard deviation of 45.76±8.3 years. Their work experience ranged from 10 to 40 years with the mean and standard deviation of 27.36±9.17 years. Their level of education was high school (1,4%) and lower level (24,96%), and working period of at least 5 days per week (22,88%) and less than 5 days a week (3,12%).

Statistical analysis: Qualitative data in this survey study were analyzed by using content analysis. The data were transcribed from tape recording into text, and then themes were developed to form a base for probing questions. Checking accuracy and rigor in the analysis was carried out by using methodological triangulation and saturation [14]. Methodological triangulation was performed by checking data using 3 different methods. Data of general information from interviews and observation from the initial survey and two rounds of focus group member checks were analyzed. Whereas quantitative data were represented with frequency, distribution, percentage, mean and standard deviation when using ergonomic implementation and demographic data of the participants. Moreover, before and after initiating the ergonomic implementation program, the total RULA, individual RULA region and knowledge, satisfactory and pain scores were evaluated.

Conventional tools and workstation during wood carving

Initial survey results showed that wood carving tools were designed from traditional culture and wisdom with a selection of tough and forced absorbed wood such as that from lemon, pomelo, guava or tamarind trees for chisel handles (Figure 2). Moreover, the wood carvers worked in stationary and prolong sitting positions on the floor (Figure 3). Therefore, this posture presented a humpback and neck and knee flexion induced back pain. Furthermore, chisel handles, iron hammerheads, sew Ngon (curved chisel), or iron stamps can be unsafe tools. Wood carvers often used a slouching posture for a low workstation, which relates to their pain. This survey found that common areas of pain are a result of using a slouching posture, for example, pain and ache at the neck, back, shoulders, scapulars, arms, elbows, wrists, hands, knees and calves; tension at the anterior thighs, numbness in the hands, cramping of the feet, and foot injury due to wood falling on the feet. Moreover, the focus group found all wood carvers preferring work environments that had a comfortable temperature, good ventilation and atmosphere, and peaceful surroundings.

Figure 2: Wood carving tools; chisel handle (A), iron hammer head covered with rubber (B), Sew Ngon(curved chisel) (C), iron stamps (D).

Figure 3: Sitting posture of wood carvers.

Preliminary education and the ergonomic implementation program

From the survey, brainstorming and ideas from previous data, education under the health belief model construction (Table 2) and the ergonomic implementation program (Table 3) were designed and performed.

The program for education was divided into six constructed items; perceived susceptibility, perceived severity, perceived benefits, perceived barriers, cues to action, and self-efficacy (Table 2). Firstly, in order to perceive susceptibility, a one and half hour lecture and practice were performed, with the main objective of finding the risk factors of wood carving work, proper postures and relationship between poor working postures and musculoskeletal disability. Secondly, perceived severity of functional impairment and disability was carried out by a lecture and shared views for 20 minutes. Thirdly, perceived benefits showed how to improve work safety, proper working conditions and benefit of risk reduction by discussion, lecture, and one-hour of practice. Fourthly, the types of perceived barriers and how to get rid of those barriers were dealt with in a 20-minute brainstorming session, discussion and advice. Fifthly, cues for action were activated by two hours of facilitating and sharing ideas in order to design a preliminary ergonomic implementation program. A three-week preliminary ergonomic implementation program (Table 3) applied to 14 wood carvers. Finally, 30 minutes of self-efficacy was constructed among the wood carvers.

The ergonomic implementation program was designed (Table 3) and consisted of 4 domains; (1) tool adaptation with hammer handles having grooves for fitting fingers or the hammerhead wrapped in rubber (Figure 4), (2) workstation management by designing a tilting adjustable desk and stool for individual carvers (Figure 5), and the desk should be cleaned every time after use and the wood chips kept in a separate area (Figure 6), (3) work guideline for instruction on the basics even stretching patterns and two strengthening patterns (Figure 7), and cooling down exercise program, and (4) self-massage as an individual activity for anyone who has an area of pain and prefers to massage using traditional Thai wooden instruments.

Figure 4: Hammer handle with grooves for fitting fingers (left) and rubber wrapped around hammerhead and/ or handle and chisel handle (right).

Figure 5: The original or conventional workstation with sloping work surface (A) and a tilting adjustable desk and stool prototype (B).

Figure 6: Environmental adjusted (left) and tilting adjustable tasks (right) are provided.

Figure 7: Seven stretching exercise programs composed of abdominal and thigh stretching (A), upper thoracic stretching in long sitting (B), lateral trunk and forearm stretching in standing (C), scapular stretching (D), lateral neck and shoulder stretching (E), pectoralis with neck stretching (F), and elbow and wrist stretching (G).Strengthening exercise with standing and stretching arm against the wall (H) and standing and bending the knee (I). Each pattern performed is repeated 10 times and held for 10 seconds. (The photos were presented by co-author, MsKanokporn who has permitted them for academic publication in this study).

Efficacy of education and the ergonomic implementation program

After the 14 woodcarvers had completed their education and the ergonomic implementation program, the knowledge score increased significantly from 3.21±1.05 to 4.07±0.83 after one month of implementation, but there was no immediate statistical difference in education (3.42±1.40) (Table 4). In addition, the satisfaction score on implementation was the highest (5 out of 5) in all items: education and brainstorming, work guideline, total adjustment, workstation adjustment, environmental adjustment, and stretching and strength exercise program.

RULA was used to investigate effectiveness of the ergonomic implementation program. After the ergonomic implementation program, the total RULA score from risk assessment in 14 woodcarvers was equal to 6.5 (range 5-7). Although this score indicated poor working posture with risk of injury, but there was no statistical difference between after and the ergonomic implementation, However, when the individual RULA score for each region, was reassessed after the ergonomic implementation, the score of upper limbs (median=4.0), neck (median=3.0) and lower limbs(median=1.0) was not statistically different from before implementation (4.0, 3.0 and 1.0), except the trunk scores (median=3.0 and 3.6) (p=0.034) (Table 5).

The results of total pain score for all regions at baseline and at the end of implementation showed no significant difference (3.93?1.98 and 3.43?2.28). However, when regions were separated, 9 of the 14wood carvers presented pain at the lower back (9,64%), when compared to other regions such as the shoulder (3, 21%), knee (3.21%), neck (2,14.28%), wrist (2, 14.28%), and claves (2, 14.28%). Other areas such as the elbow, hand and thigh also presented pain (1, 7.14%). After three weeks of the ergonomic implementation program, the pain scale showed that only the lower back had significantly less pain than before implementation (p< 0.05).

Discussion

This was a preliminary study of wood carvers in Chiang Mai province, Thailand. Previous data showed some WMSDs among wood carvers at Baan Tawai, which is the most famous work place for handicraft and souvenirs in Chiang Mai [15,16]. Previous survey results showed that wood carving tools, work posture, workstations and environment are the same as the sequence of action for jobs related to WMSDs [12]. In practical theory, complex repetitive tasks are associated with upper extremity disorder [17], especially from bad posture such as crossed-legged and heel sitting, which induce slow back pain among handicraft workers [18]. This preliminary study also found that wood carving tools derive from cultural wisdom, and are made from the wood of lemon, pommel, guava and tamarind trees. Moreover, most wood carvers work sitting on the floor or in a stationary sitting position during prolonged carving sessions, therefore, back pain was presented in this survey. Furthermore, common pain areas at the neck, back, shoulders scapulars, arms, elbows, wrists, hands and calves; tension at the anterior thighs, numbness in the hands and cramping of the feet also were shown because of prolonged sitting in a slouching posture. This result of pain at lower back region was consistent with a previous study that showed significant increase of backache from prolong low-sitting in people who worked with furniture in school [19]. On the other hand, sitting on heels or on the floor with the lower back in a slouching posture is similar to the standing posture of rice farmers in the field [20], which presents predominate pain in the lower back area, as in a previous study on  day/3 times a week, with each session lasting approximately 10-15 min. Each individual strengthening exercises was performed 10 repetitions of 3 sets (with a rest of 60-120 s between sets). All of the exercise sessions took place at the worksites of the wood carvers at any time during the working day. Finally, the ergonomic implementation program included self-massage for anyone who had pain. Although there is no evidence supporting immediate benefits of self-massage on wood carvers, self-myofascial release on a latent trigger point on the lateral gastrocnemius muscles [32] could reduce the sensitivity of pain significantly. Interesting results showed higher knowledge and satisfaction scores in all 14 wood carvers when all of the education and ergonomic implementation program were presented. However, knowledge in preventing musculoskeletal disorder among wood carvers must be of concern because a previous study claimed that lack of knowledge on ergonomics in 102 hospital personnel, whose primary job was on computers, affected job performance [33]. Moreover, appropriate postures, work environment and workstation design were important factors for improving on the job designs in the workplace [34]. Unfortunately, this study could not conclude that job performance involved knowledge and satisfaction in education, and this should be studied in the future.

Finally, the interesting results of clinical improvement on posture in this study was evaluated by using the RULA sheet. Previous studies found that RULA is standardized and reliably good for evaluating posture in various populations, such as computer posture in children [35]. In addition, the RULA is a better assessor in presenting musculoskeletal disorders in the lower back and neck area, when compared to assessments from the Rapid Office Strain Assessment (ROSA) [36], Novel Ergonomic Postural Assessment (NERPA) and Rapid Entire Body Assessment (REBA) [37]. In addition, it has been used for health-risk assessment of musculoskeletal disorders and is related to overall posture disorder [38]. It also can be used to evaluate postures (arms, forearms, wrists, neck, trunk, and legs), number of movements, and static muscle work and force [39]. The procedures are composed of scoring and recording the postures by using a scoring sheet, body-part diagrams, and tables. Then, the scores are converted to one of the four action levels, which indicate the time frame needed for risk control to be initiated (posture acceptable to changes is required immediately) [40]. The RULA is used to assess tasks including computer work, manufacturing, or jobs that entail sitting or standing without moving about [40]. It plays different roles in many studies such as investigation of work-related disorders [41], ergonomic indicators [42-44], risk factors [45-47], risk levels [48] and physical demands [49], and was used for evaluation in this study, as the intra- and inter-testers of RULA were rechecked and acceptable with an ICC of 0.7. Thus, good assessment with good reliability was confirmed, as in previous studies in children [35] and adults [50]. In this study, the median RULA score, with 5-7 ranges, was 6.5, indicating very high risk and a need to implement change with consistency now for low back pain in both sites (64.28%) [40], but not in other regions such as the neck, shoulder or knee. In addition, the ergonomic implementation program also includes management of environments and workstation adjustment to see whether these issues can reduce musculoskeletal disorder, which still needs to be confirmed. However, this study proposed that poor postures, bad workstations and environment are the main risk factors in wood carving work. Appropriate postures, work environment and workstation design are important factors for improving job designs in the workplace [34], especially regarding adaptive workstations that ideally should be supported yearly, as suggested previously [19]. However, the ergonomic implementation program was designed after the woodcarver participants had trained for a short period of time, but this was consistent with a previous pilot study, which confirmed awareness of physical stains and workplace interventions, including physical exercise having significant benefits on stressful trunk postures in 6 nursing homes [51]. However, non-significant results in this study are possibly from the short period of intervention, when compared to a six-month study by Kozak.

Innovation from this research and Conclusion

The innovative tool and workstation from this research were formed from participatory development between woodcarvers and researchers using low cost technology, which was appropriated for small and flat woodcarving designs. Therefore, there were some limitations in using a variety of woodcarving designs. If the funding and technology are available, a fixed wooden desk that is easily adjustable should be developed. In this study, a tilting adjustable desk was designed from an old workstation with a comfortable lower back and leg position. Furthermore, the stand stools on both sides were for easy management that should be safe for woodcarvers. Whereas, the arm support was not designed by following a previous study, which preferred sitting with pivotal transfer [52], because of the need for wood carvers to move freely during working hours. Interesting results in a previous study proposed that stand stools are a good alternative for workers who change frequently from sitting to standing while working [53]. Whereas, in this study, most of the wood carvers worked sitting on a seat. Therefore, an adaptable seat should be more preferable for those workers than a stand seat. Moreover, improving occupational health and safety has been suggested in a participatory model, and as in this study, participatory approaches to preliminary assessment, observation of informal practices, group discussion and [54]. However, this study can conclude that musculoskeletal disorder, especially pain, is presented predominately at the lower back in wood carvers, and specially implemented in the ergonomic implementation program with education. Management of instruments, environments and seating during carving work can reduce musculoskeletal problems, especially pain severity, which is consistent with previous evidence of102 hospital personnel, who received education intervention that showed a significant decrease in pain intensity [33].Therefore, the results of this preliminary study combined education and implementation with ergonomic knowledge and adjustment on devices and equipment for wood carvers. They also showed health benefits that protect wood carvers in Chiang Mai province, Thailand, from musculoskeletal disorder.

Limitation of study and suggestions

Due to the small sample size of woodcarvers in the local area of Chiang Mai province, the results in this study showed non-significant changes.There also were carving jobs at a low- and high-floor work-status, and the varied results must be repeated for evaluation in the future, especially adaptation of a specific workstation, which must be considered for individual work.

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