Musculoskeletal Disorders

Musculoskeletal disorders (MSDs) are a group of inflammatory and degenerative conditions, which are a direct consequence of repetitive movements, heavy lifting, prolonged static postures, awkward postures, etc. MSDs mainly affect the soft parts of the musculoskeletal system: muscles, tendons, nerves, ligaments and joints, and cause discomfort and pain in the affected areas. In contrast to other types of injuries which also occur in the workplace, MSDs demand longer recovery time and cause substantial lost workdays (^{Nabi et al., 2021}). In the Iranian textile industry, MSDs are recognized as a highly prevalent problem, specifically in spinning, tasks with repetitive movements, overhead and shoulder activity, handling of heavy loads, among others, are observed, causing pain in the shoulder, neck, hands, as well as in the lumbar and thoracic areas (^{Shahbazi et al., 2020}). In Latvia, the textile industry is made up of approximately 12 000 people, studies indicate that workers suffer MSDs caused not only by physical loads, but also by mental effort, work precision and visual fatigue (^{Kalkis et al., 2020}).

Prevention of Musculoskeletal Disorders

Workers in the textile industry are exposed to awkward postures, repetitive work and constant handling of materials; to avoid the risk factors associated with MSDs, it is suggested that an adequate environment for workers to rest, as well as training programs that promote safety at work, be implemented (^{Hossain et al., 2018}).

^{Sakthi Nagaraj et al. (2019}) recommend performing stretching routines and designing work areas ergonomically. Likewise, ^{Barbosa et al. (2022}) propose robotic collaboration, i.e., encouraging robot-human collaboration to eliminates monotonous, dangerous and repetitive work. Job rotation is also recommended, as it prevents overloading certain body parts by alternating jobs with different types of risk levels.

Posture

According to ^{Litardo et al. (2020}), the term “posture” refers to the position adopted by each part of the body in relation to adjacent segments and to the body as a whole. Neutral posture is the best position for the human body, as it reduces stress and provides greater control and strength. In this position the body exerts less pressure on the joints, tendons, muscles and nerves; moreover, the muscles are in an ideal position, as they are neither contracted nor stretched. In summary, neutral posture is one that provides a proportionate alignment of body landmarks (^{Stack et al., 2016}).

Ergonomics

Ergonomics is a field of science based on the application of knowledge related to the biomechanical, physiological and psychological capacities and limitations of the human being. The knowledge acquired is used to plan, design and evaluate work areas, tools and equipment to increase the performance and health of a company’s workers. In short, ergonomics adjusts workplaces for employee comfort to prevent MSDs through the identification, evaluation, and control of risk factors related to workplaces (^{Stack et al., 2016}).

Risk Factors Associated with MSD

Risk factors are those factors that, due to high exposure or intensive presence, which can be of organic, physical, psychological or social origin, lead to the development of MSDs. Historically, force, posture, repetitiveness and insufficient rest were catalogued as the most common risk factors (Instituto Nacional de Seguridad y Salud en el Trabajo, 2019). According to ^{Siddiqui et al. (2021}), heat, noise, light, odor and dust should also be considered risk factors as they contribute to the development of MSDs.

Personal Risk Factors

Personal risk factors also contribute to the occurrence of injuries in the work area, for instance, age influences the body’s recovery process. Duration is another relevant factor. The gender of the worker is also taken into account due to hormonal and anatomical differences, hobbies, obesity, previous injuries and pregnancy are also considered relevant (^{Stack et al., 2016}).

In West Bengal, handloom weavers suffer from low back pain, which was directly related to the number of years of work. Similarly, in Varanasi, workers in the same sector suffer from MSD which is caused by age and years of service (^{Siddiqui et al., 2021}).

Force

Force refers to the amount of physical effort required to perform an activity or movement. Any activities that require greater force increase the mechanical loads on the muscles, joints and tendons. Also, if there are risk factors involved, such as vibration or speed, the force required to perform the movements also increases, quickly leading to fatigue at times (^{Stack et al., 2016}).

Awkward or Unsupported Postures

Awkward or unsupported postures are non-neutral positions that, being unsupported, force the limits of the body, compressing the nerves and irritating the tendons. Awkward postures increase the risk of MSDs because they demand greater strength and cause fatigue, because the body is actively working to maintain the posture. The greater the difference in posture from neutral, the greater the risk of injury (^{Stack et al., 2016}).

Static Postures

Static postures are those maintained for prolonged periods of time, which prevent adequate blood flow. The effort required to maintain a static posture puts an increased load on the tendons and muscles, causing fatigue. Blood flow transports nutrients to the muscles and removes waste products. As waste products accumulate due to muscle contraction, fatigue ensues, which is a precursor to injury (^{Stack et al., 2016}).

Repetitive Movements

Repetitive movements are a risk factor, because the same movement or group of actions is executed repeatedly. They occur when the same set of muscles is used, thus muscles do not rest and are overused. Repetition is not a problem of great magnitude; however, it should be carefully considered when combined with other risk factors (^{Stack et al., 2016}).

REBA-RULA Integration

The Rapid Entire Body Assessment (REBA) method was jointly developed by a group of ergonomists, nurses and physiotherapists after identifying and analyzing approximately 600 different postures. REBA method allows for the joint analysis of the upper limbs, which include the wrist, forearm and arm, as well as the neck, trunk and lower limbs. The advantage of this method is that muscle activity and grip type are both included in the analysis. REBA considers five (5) levels of risk, ranging from “negligible” to “very high”. An important prerequisite for this evaluation is the worker’s permission, since evaluators must obtain the relevant information about the work performed. Evaluators can conduct observation directly or by recording videos and taking photographs (^{Hita et al., 2020}).

The Rapid Upper Limb Assessment (RULA) method was designed by McAtamney and Corlett in 1993 with the aim of identifying the risk factors to which the upper limbs of workers are exposed during work activities. The factors considered in this method are posture of the body areas, the load exerted and the muscle activities, including repetitive movements and static posture. RULA focuses on a specific body region, which is divided into two groups: Group A (wrist, wrist rotation, arm and forearm) and Group B (legs, neck and torso). This method has four (4) levels of action, ranging from “no action needed” to “urgent measures needed” (^{Gómez et al., 2020}).

As mentioned above, REBA performs an analysis of the whole body taking into account muscle activity and the type of grip. In contrast, RULA focuses only on the upper limbs, considering body posture, force exerted, repetitive movements and static posture. The joint use of these two evaluation methods to analyze the risk factors associated with MSDs in the textile industry is extremely important, as they suppress each other’s limitations and complement each other’s results. Since REBA has a general approach and RULA is more specific, a successful integration of these two methods provides a broader picture and more accurate information, which contributes to making better recommendations for addressing MSDs.

Ergonomic Method in Garment Companies

The method designed in this study is based on the integration of ergonomic techniques to reduce the risk of MSDs in the operators of the garment manufacturing SME after implementing preventive and corrective measures. Figure 1 shows the proposed method. The contribution of REBA and RULA methods consists of assessing the situation before and after the improvements and comparing the scores obtained to identify the results.

Source: Prepared by the authors.

Figure 1 Proposed Method. 

Ergonomic Assessment

Evaluation Using REBA

The first evaluation was conducted on the operators of the sewing workshop according to their positions (Table 1), using the REBA method with the Ergoniza software. The questions shown in Table 2 were answered following the observation.

Table 2 Evaluation using REBA. 

Source: Prepared by the authors.

The levels of risk obtained after entering the information requested by the Ergoniza software are shown in Table 3, evidencing the risk of MSDs faced by the operators of the sewing workshop under study.

Upon obtaining the score and risk level of each operator, the performance level according to Ergoniza was reviewed as shown in Table 4.

Evaluation using RULA

The evaluation was conducted using the RULA method with the information requested by the software, which is shown in Table 5.

Table 5 Evaluation Using RULA 

Source: Prepared by the authors.

The results obtained upon entering the data in the software are shown in Table 6.

Following the results, the level of risk was analyzed with the information obtained from Ergoniza, which is shown in Table 7.

Improvements and Hypothesis Testing

Upon obtaining the results of the ergonomic evaluation, a series of corrective and preventive measures were devised to reduce the latent risk of MSDs, as shown in Table 8.

Table 8 Corrective and Preventive Proposals in the Sewing Workshop. 

Source: Prepared by the authors.

Upon implementing of the corrective and preventive proposals, the second evaluation was conducted on the workshop operators using the REBA method with the Ergoniza software. The questions shown in Table 9 were answered following the observation.

Table 9 REBA Ergonomic Evaluation in the Sewing Workshop upon Implementing the Preventive and Corrective Measures. 

Source: Prepared by the authors.

Following the second evaluation, the risk levels shown in Table 10 were obtained via Ergoniza software.

Similarly, following the implementation of the improvements, the evaluation was conducted using the RULA method. The results are shown in Table 11.

Table 11 RULA Ergonomic Assessment in the Sewing Workshop after Implementing Preventive and Corrective Measures. 

Source: Prepared by the authors.

Following the second evaluation, the risk levels shown in Table 12 were obtained via Ergoniza software.

To determine the effectiveness of the proposed ergonomic method, we measured the improvement comparing the scores obtained in the first and second evaluations. For this purpose, the RE (reduction of MSDs) indicator was used, calculated using the following formula:

RE = (Initial score - Final score) / Initial score *100%

Table 13 A Comparison Before and After the Improvements.  

Source: Prepared by the authors.

After calculating the geometric mean, it was concluded that the risk of developing MSDs was reduced by approximately 44.97%.

Hypothesis Testing

The research question was “Is the ergonomic method able to reduce the risk of MSDs in a textile manufacturing SME?” In response to this question, the following general hypothesis was formulated:

H₀ = There is no significant change in MSD risk reduction before and after the implementation of the ergonomic method.

H_a = There is significant change in MSD risk reduction before and after the implementation of the ergonomic method.

A normality test was conducted before and after implementing the improvements to determine whether the data collected followed a normal distribution. Statistical software MINITAB 2018 was used for this purpose, and the normality of the data was tested using an Anderson-Darling test at a significance level of 5%.

P value ≤ α, data follow a normal distribution

P value > α, data do not follow a normal distribution

The normality test yielded a p-value of 0.161, a value higher than the significance coefficient, demonstrating that the data have a normal distribution. Upon determining the distribution of the data, the pertinent statistical test was performed.

The Student’s t-test yielded a t-value of 7.46 and a p-value of 0.0000.

As the t value is greater than the p value, H₀ is rejected and H_a is accepted; therefore, there is a significant change in MSD risk reduction before and after the implementation of the ergonomic method in the textile industry. The method complies with its main objective.