The nature of work-related neck and upper limb musculoskeletal disorders

The nature of work-related musculoskeletal disorders of the neck and upper limbs is reviewed using both scientific data and the consensus view of experts, union bodies and government agencies across the European Union. Work-related musculoskeletal disorders describe a wide range of inflammatory and degenerative diseases and disorders. These conditions result in pain and functional impairment and may affect, besides others, the neck, shoulders, elbows, forearms, wrists and hands. They are work-related when the work activities and work conditions significantly contribute to their development or exacerbation but are not necessarily the sole determinant of causation. The classification and the need for standardised diagnostic methods for assessment of neck and upper limb musculoskeletal disorders are reviewed. These disorders are a significant problem within the European Union with respect to ill health, productivity and associated costs. The pathomechanisms of musculoskeletal disorders affecting tendons, ligaments, nerves, muscle, circulation and pain perception are reviewed and conceptual models for the pathogenesis of musculoskeletal disorders affecting the neck and upper limbs are presented. The epidemiological evidence on the work-relatedness of these disorders is discussed. A relationship between the performance of work and the occurrence of neck and upper limb musculoskeletal disorders is evident. Intervention strategies in the workplace for the reduction of both exposure and effect should focus upon factors within the work organisation as well as actively involving the individual worker. The current knowledge is sufficient to enable informed decisions to be made on future research needs and prevention strategies at the societal, organisational and individual level.     

The occurrence of musculoskeletal alterations in worker populations not exposed to repetitive tasks of the upper limbs

A total of 749 workers (males: 139 aged between 15 and 35 years, and 171 aged > 35 years; females: 176 aged between 15 and 35 years, and 263 aged >35 years) performing tasks not at risk for work-related musculoskeletal disorders of the upper limbs (WMSDs) underwent a clinical examination using a standardized method. The ‘anamnestic cases’ were defined on the basis of pain or paraesthesia present for at least 1 week during the previous 12 months, or appearing at least once a month, and not subsequent to acute trauma. The anamnestic cases among the males amounted to 4.4% (age 15–35 years) and 12.3% (age> 35 years); among the females, 4.6% (age 15–35 years) and 14.2% (age> 35 years). Of the 1498 limbs examined, the prevalent diseases reported were: suspect narrow chest syndrome: 0.3% among the males > 35 years, 0.6% among the females aged 15 35 years, 1% among the females > 35 years; scapulo-humeral periarthritis: 0.3% among the males aged > 35 years, 0.3% among the females aged 15–35 years, 1.3% among the females aged > 35 years; lateral epicondylitis: 0.3% among the males aged > 35 years, 0.2% among the females aged > 35 years; trapeziometacarpal arthrosis: 0.8% among the females aged > 35 years; wrist-hand tendinitis: 0.9% among the males aged > 35 years, 0.9% among the females aged 15–35 years; carpal tunnel syndrome: 2.5% among the females aged > 35 years. No disorders were detected outside the age ranges indicated. Several workers reported more than one disorder. The number of workers with at least one WMSD was: males 0% in the 15–35 years age range, 3.5% in the > 35 years age range; females 2.3% in the 15–35 years age range, 7.2% in the > 35 years age range; 3.9% of the total sample population. The prevalences were on average quite low, particularly among the older workers, hence the authors recommend that even minimal prevalences detected in particular work environments should not be underestimated.     

Criteria for the reintegration in the workforce of workers with musculoskeletal disorders of the upper limbs,based on preliminary practical experience

This paper presents a preliminary study on the return to the workforce of employees with WMSDs of the upper limbs, and their reallocation to jobs with ‘low exposure’. The study, which is still underway, involves a large engineering firm and includes some 100 workers affected by WMSDs. The trial involved: providing a definition of the criteria for characterizing ‘accommodating’ jobs (i.e. frequency of action < 20 actions/min; virtual absence of other risk factors such as force, awkward posture, inadequate pauses, etc.); effectively identifying jobs meeting such criteria (or jobs which, with minimal modifications, could be made suitable); classifying WMSD workers according to the type and severity of the disorder; matching WMSD workers with the jobs best suited to them; specific training for the workers and their supervisors; carrying out a follow-up of the return of WMSD workers to the workforce in organizational terms (i.e. the need for further modifications to equipment or procedures) and clinical terms (i.e. symptom patterns, acceptability of the condition). The preliminary results, 6–12 months after the start of the trial, are extremely encouraging, and show that when workers return to the workforce in jobs that fully meet defined criteria, a significant prevalence of ‘improvements’ are reported among the workers involved. The investigation will need to be extended but it already shows quite convincingly that it is possible for workers with what can be described as a ‘reduced working capacity’ to remain ‘productive’ (albeit in jobs featuring a lower exposure potential than the acceptable threshold for ‘healthy’ workers).     

Hand-arm vibration syndrome (HAVS) and musculoskeletal symptoms in the neck and the upper limbs in professional drivers of terrain vehicles--a cross sectional study

This study compares the prevalence of symptoms of Hand-arm vibration syndrome (HAVS) and musculoskeletal symptoms in the neck and the upper limbs, between professional drivers of terrain vehicles and a referent group. 769 male professional drivers of forest machines, snowmobiles, snowgroomers and reindeer herders and 296 randomly selected male referents completed a questionnaire about symptoms of HAVS and musculoskeletal symptoms in the neck and the upper limbs. They also gave information about their lifetime exposure duration driving terrain vehicles and their nicotine use. Prevalence odds ratios (POR) were determined and adjusted for age and nicotine use. Results show that there is a relation between exposure to driving terrain vehicles and some of the symptoms of HAVS (POR: 1.2–6.1). Increased odds of musculoskeletal symptoms in neck, shoulders and wrists were also found (POR 1.2–6.4), and it seemed to be related to the cumulative exposure time.     

Impact of physical exposure on neck and upper limb disorders in female workers

Physical workload [muscular load of the trapezius and infraspinatus muscles using electromyography (EMG), wrist positions and movements by electrogoniometers] and neck and upper limb disorders (from, for example, a physical examination) were studied in women with repetitive industrial work (n = 95) and referents (n = 74). The repetitive work displayed higher ratings for wrist movements, but not for EMG. The prevalences of neck, shoulder and wrist/hand disorders were elevated for women with repetitive work [age-adjusted prevalence odds ratios (PORs) 2.0-7.5]. For the left hand, high frequency of wrist movements (mean power frequency 0.53 Hz) was associated with a high prevalence of disorders (56%), as compared to low (0.28 Hz and 26%; POR 3.5). We found no consistent and significant effect of muscular load, on either neck or shoulder disorders. However, selection and other bias may have diminished our possibility to observe such effects. Psychosocial work environment factors were not confounding the results. Measurements of wrist movements may be used for identification of high-risk work tasks.     

Self reported symptoms in the neck and upper limbs in nurses

This paper describes a cross-sectional study which examines musculoskeletal symptoms in nurses working in two similar units in a residential care centre for the developmentally disabled. Amongst the 30 nurses who were administered the Nordic Questionnaire, neck and upper limb symptoms had resulted in considerable inability to perform work. In contrast, a similar incidence of reported back symptoms in these nurses had not prevented them from doing their work.

An examination of the worker's compensation claims made by nurses from the whole facility showed low back claims to be more common than neck and upper limb claims. It appears that nurses are more likely to make a worker's compensation claim for low back symptoms than neck and upper limb symptoms. In other words, worker's compensation claims do not accurately reflect the types of musculoskeletal symptoms actually experienced by nurses and affecting their ability to do their work.

Five nurses from each unit were also observed during the entire morning and afternoon shifts to examine the work load and the effects of fatigue on the musculoskeletal system. Heart rate measurements and ratings of perceived exertion were taken. Activities performed and types of transfers carried out were also recorded.

Nurses in one of the units had significantly more reported neck and shoulder symptoms than their counterparts. Observations of a sample of five nurses from each unit also showed higher ratings of perceived exertion in this unit. These differences were possibly confounded by the fact that nurses in the unit which experienced these problems were about 8 cm shorter and about 5 kg lighter than their counterparts. Differences in the work practices in the two units, especially methods of manual handling and use of ergonomic interventions were identified as important contributing factors.     

Updating reference values and predictive models of the OCRA method in the risk assessment of work-related musculoskeletal disorders of the upper limbs

A database has been established combining existing data for 23 groups of workers with different level of exposure to repetitive movements of the upper limbs. For all groups, data were available regarding an exposure index (OCcupational Repetitive Actions - OCRA index) and clinically determined UL-WMSDs outcomes (PA = Prevalence of workers affected by one or more UL-WMSDs; PC = Prevalence of single diagnosed cases of an UL-WMSDs). Using these data, new critical values of the OCRA index have been estimated for discriminating different exposure levels (green, yellow, red areas) and new forecasting models of expected PA and PC in exposed populations based on OCRA exposure indexes. The new critical values of the OCRA index were estimated by an original approach in which data for the effect variable (PA) in a reference population not exposed to the relevant risks are combined with the regression function between OCRA and PA. The best simple regression functions between OCRA exposure indexes and health outcomes variables (PA; PC) were researched to obtain forecasting models of effects starting from exposure. Discussion of the results obtained considers their intrinsic limitations, as they are based on prevalence studies, as well as providing recommendations and cautions in the use of the proposed classification system and forecasting models when the OCRA method is applied.     

Gender differences in prevalence of upper extremity musculoskeletal disorders

A literature review was conducted on the current literature base to determine the strength of support for the hypothesis that women experience higher prevalences of upper extremity musculoskeletal disorders (UEMSDs) than men. Fifty-six articles were reviewed for data on gender differences in frequency, incidence or prevalence rates for musculoskeletal disorders specific to the upper extremities. These articles included both general and working populations. The majority of the studies showed that women had significantly higher incidences of various types of UEMSDs than men. This trend was consistently observed in studies based on self-report or plant/workers compensation records, with and without physical examination, and after adjusting for potential confounders such as age and physical work factors. With men as the referent, the odds ratio (OR) or prevalence ratio (PR) for UEMSDs ranged from 0.85 to 10.05 for self report. For self report combined with physical examination, the OR/PR ranged from 0.66 to 11.4. The OR/PR for carpal tunnel syndrome (CTS) ranged from 0.6 to 2.87 with confounder adjustment. These findings suggest that women do have significantly higher prevalences than men for many types of UEMSDs, even after controlling for the type of data source and confounders such as age or work factors.     

Gender differences in prevalence of upper extremity musculoskeletal disorders

A literature review was conducted on the current literature base to determine the strength of support for the hypothesis that women experience higher prevalences of upper extremity musculoskeletal disorders (UEMSDs) than men. Fifty-six articles were reviewed for data on gender differences in frequency, incidence or prevalence rates for musculoskeletal disorders specific to the upper extremities. These articles included both general and working populations. The majority of the studies showed that women had significantly higher incidences of various types of UEMSDs than men. This trend was consistently observed in studies based on self-report or plant/workers compensation records, with and without physical examination, and after adjusting for potential confounders such as age and physical work factors. With men as the referent, the odds ratio (OR) or prevalence ratio (PR) for UEMSDs ranged from 0.85 to 10.05 for self report. For self report combined with physical examination, the OR/PR ranged from 0.66 to 11.4. The OR/PR for carpal tunnel syndrome (CTS) ranged from 0.6 to 2.87 with confounder adjustment. These findings suggest that women do have significantly higher prevalences than men for many types of UEMSDs, even after controlling for the type of data source and confounders such as age or work factors.     

Risk of neck musculoskeletal disorders among males and females in lifting exertions

Work-related neck disorders are common among various occupational groups. Despite clear epidemiological evidence for the association of these disorders with forceful arm exertions, the effect of such exertions on the biomechanical behavior of the neck muscles is currently not well understood. In this study, the effect of lifting tasks on the biomechanical loading of neck muscles was investigated for males and females. Twenty-six participants (13 males and 13 females) performed bi-manual isometric lifting tasks at knuckle, elbow, shoulder, and overhead heights by exerting 25%, 50%, and 75% of their maximum strength. The activity of the cervical trapezius and sternocleidomastoid muscles was recorded bilaterally using surface electromyography. Higher activity of the cervical trapezius muscle (10% MVC–43% MVC) compared to the sternocleidomastoid muscle (4% MVC–18% MVC) was observed. Females tend to use the sternocleidomastoid muscle to a greater extent than males, whereas, higher cervical trapezius muscle activation was observed for males than females. The main effect of weight and height, and weight by height interaction on the activity of neck muscles was statistically significant (all p < 0.001). The results of this study demonstrate that the neck muscles play an active role during lifting activities and may influence development of musculoskeletal disorders due to resulting physiological changes.     

Low-back disorders in agricultural tractor drivers exposed to whole-body vibration and postural stress

The occurrence of low-back pain (LBP) was investigated in a population of 1155 tractor drivers exposed to whole-body vibration (WBV) and postural stress (response rate 91.2%) and in a control group of 220 office workers (response rate 92.2%). The subjects were questioned about several types of low-back symptom (LBP, sciatic pain, acute LBP, transient and chronic LBP) and various work- and individual-related risk factors, by using a standardized questionnaire. Vibration measurements were performed on a representative sample of the vehicles driven by the tractor drivers in the last ten years. Vibration magnitude and duration of exposure were used to calculate a vibration dose for each tractor driver. Perceived postural load was assessed in terms of frequency and/or duration of awkward postures at work. The prevalence of LBP was found to be greater in the tractor drivers than in the controls. After controlling for potential confounders by logistic modelling, low-back disorders were found to be significantly associated with both vibration dose and postural load. Back accidents and age were also significant predictors for LBP. Quantitative regression analysis indicated that vibration exposure and postural load were independent contributors to the increased risk for LBP according to a multiplicative model. The exposure levels for WBV recently recommended by a proposal of European Directive on physical agents seem to be more adequate to prevent long-term health effects on the lower back than the exposure limits suggested by the International Standard ISO 2631/1.     

A test of two training interventions to prevent work-related musculoskeletal disorders of the upper extremity

We investigated, on behalf of a large electronics manufacturer, two types of worker training interventions for their efficacy in preventing unnecessary muscle tension and the symptoms of work-related musculoskeletal disorders. The first intervention, Muscle Learning Therapy (MLT), used electromyographic (sEMG) feedback and operant conditioning to decrease muscle tension during complex work tasks. The second intervention used adult learning and cognitive behavioral techniques in small group discussion to advance the worker's capabilities for symptom and stress management and problem-solving. Workers were randomly assigned to a control group or one of the two treatment conditions. Prior to training, baseline data were collected using symptom diaries and sEMG recordings of the trapezius and forearm muscles of the left and right arms. The training interventions were conducted for 6 weeks with reinforcement training provided at 18 and 32 weeks post-baseline. Follow-up data were collected after the initial 6-week training period and at 32 weeks, prior to the reinforcement training. Symptom outcomes demonstrated significant differences at 6 weeks, increasing in severity for the control group and declining modestly for the educational group, with little change for the MLT group. These differences were not maintained at further follow-up. The MLT group was consistently effective in reducing muscle tension in the trapezius areas after 6 and 32 weeks, and was partially effective for the forearms. Further testing is recommended of these training interventions, especially with the inclusion of strategic, periodic reinforcement of the worker's learning.     

Applying the K-nearest neighbor technique to the classification of workers according to their risk of suffering musculoskeletal disorders

The K-nearest neighbor (KNN) technique is a widely used classifier because of its simplicity and high efficiency. We adapted this technique and applied it with success to predict work-related musculoskeletal disorders. Among the general working population, the algorithm was able to identify workers that had reported work-related musculoskeletal complaints in the last twelve months. According to the model that was developed, poor lighting conditions, exposure to vibrations, an uncomfortable chair and a high mental demand are the factors that have the strongest influence on the development of this type of health problem.Relevance to industry:The approach described in this paper allows the KNN technique to be implemented for the prediction of musculoskeletal disorders among the general working population. The model is able to overcome the limitations of other traditional statistical learning techniques to predict this type of disorder with accuracy and effectiveness. The results may be used as a decision support tool for the prioritization of resources dedicated to ergonomic intervention programs.     

Risk of slaughterhouse workers developing work-related musculoskeletal disorders in different organizational working conditions

Job rotation is defined as workers rotating between tasks with different exposure levels and occupational demands. The aim of the present study was to analyze the risk factors for the development of upper-limb work-related musculoskeletal disorders (UL-WMSDs) in poultry slaughterhouse workers as well as compare the score of the OCRA Checklist in different organizational working conditions. In this cross-sectional study, 118 workers were involved, 68 women (32.3 ± 10.7 years) and 50 men (29.5 ± 10.5 years). Three organizational configurations (“without job rotation”, “with job rotation – tasks >1h” and “with job rotation - tasks <1h”) were evaluated using the OCRA Checklist method, totaling 36 tasks and 28 job rotation schemes composed of 2–3 tasks. The OCRA score of the right upper limbs (17.8 ± 3.2) was significantly higher (p = 0.046) relative to the left upper limbs (16.4 ± 3.6). The median score was significantly lower in the “with job rotation - tasks <1h” condition (18.6) when compared to the “job rotation – tasks >1h” (19.4) (p < 0.001) and the “without job rotation” (19.0) (p = 0.038) conditions. However, there was no significant difference between the condition “with job rotation - tasks >1h” and “without job rotation” (p = 0.155). Thus, job rotations with intervals <1h reduced the risk of developing UL-WMSDs. Job rotations with <1 h intervals in poultry slaughterhouses are recommended along with further studies to verify the effectiveness of rotations with more than two tasks, involving mild or non-repetitive tasks.     

Clinical trials among worker populations: the value and significance of anamnestic findings and clinical and instrumental tests for diagnosing work-related musculoskeletal disorders of the upper limbs (WMSDs)

The authors discuss the value and significance of symptoms in WMSDs, in view of the fact that the anamnestic threshold proposed in epidemiological investigations cannot be used as clinical and diagnosing criteria. Some useful clinical procedures are suggested for cases where there is a suspicion of musculoskeletal disorders of the cervical spine and upper limbs, bearing in mind that they are to be applied within the framework of health surveillance programmes undertaken by health care practitioners who are not specialists in orthopaedics, physiatrics or neurology. The recommendations for instrumental tests and specialist referrals are also discussed for the various disorders. The authors also provide flow charts for the diagnostic procedures pertaining to WMSDs. The appendix shows a sample patient chart illustrating the proposed procedures; it also permits the findings to be encoded so that they can be stored in a dedicated database. The codes for diagnosing WMSDs are also reported for the same epidemiological purposes.     

Quantitative and qualitative assessment of musculoskeletal disorders and socioeconomic issues of workers of brick industry in Pakistan

Brick industry, in Pakistan, is prominent and provides job to 3.1 million people only in one province. The industry hires different percentage of workers for different stages of brick formation and these stages trigger musculoskeletal disorders (MSDs) in workers. This study identifies relation between 5 work stages and MSDs in 9 body parts and also finds socioeconomic sufferings inflicted by the industry and removal of research gap at national level. We conducted both qualitative and quantitative research. 105 men and 45 women from 15 brick kilns were selected as subject. Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA) sheets, Standard Nordic MSDs Questionnaire along with general questionnaire, still photography and video recording were used to carry out the study. About 96% workers involved in mixing & molding complained tiredness at end of day. Similarly, 90% male and 83% female staff performing spreading task suffered tiredness after their duty hours. Workers engaged in different tasks reported varying levels of pain in observed body parts. Digging and carrying jobs caused significant pain in body parts including neck, upper back, shoulders, lower back and hips. Mixing and molding emerged most dangerous activities for most of the body parts and exhibited 7 score on RULA. Furthermore, mixing and molding demonstrated high to very high risk level by showing 9 and 13 higher score on REBA, respectively. The current study divulged that all observed work tasks during manufacturing and transportation of bricks are equally dangerous for pain generation in lower back. Many socioeconomic issues like residency of workers in muddy house (83%) low monthly income (<90.3 $) of 83% workers, higher tendency of alcoholism and smoking in men, lack of health facilities and higher illiteracy rate were also identified. The enhanced musculoskeletal disorders during brick making process render the brick industry unhealthy for work. This dismal picture requires an improvement in quality of life and occupational environment of workers of the industry. Well organized duty timings, modified working posture, job rotation and preliminary training perhaps manage these miseries and the output of the brick industry may increase many fold.     

Investigation of oil palm harvesting tools design and technique on work-related musculoskeletal disorders of the upper body

The oil palm industry is one of the important sectors in Malaysia. The growth and development of this industry shows that Malaysia is the world second-largest oil palm producers. However, in the fresh fruit bunch (FFB) harvesting process, the harvesters are exposed to many types of work-related musculoskeletal disorders (WMSDs). The FFB harvesters tend to develop WMSDs especially the shoulders and trunk. Hence, it is important to identify the exposure levels, awkward postures and the reaction forces of muscle activity based on the posture and movement of the harvesters when using pole, chisel and loading spike during the harvesting process. The objective of this study was to investigate the effect of the design of oil palm FFB harvesting tools on WMSDs of the upper body. Rapid Upper Limb Analysis (RULA) was used to investigate and assess the exposure level on the harvester body during the harvesting process. The assessment showed that the shoulders and trunk have high exposure level and undergo awkward posture. Human Musculoskeletal Model Analysis (HMMA) was used to identify the reaction force exerted on the muscle during the FFB harvesting process. In this study, 4 muscles were analysed including Triceps, Biceps, Erector Spinae and Psoas Major. The highest reaction force of 16.36 N was found on the left triceps when handling a loading spike. In conclusion, it is important to address the risks by reviewing all possible aspects that contribute to the WMSDs and interventions on the tool design, task and working shifts may be required.     

An assessment of neck and upper extremity disorders by questionnaire and clinical examination

Abstract

To study the usefulness of a screening questionnaire for neck/upper extremity complaints, 165 women in either repetitive industrial, or mobile and varied work, were studied by the questionnaire and by a detailed clinical physical examination. A total of 94 subjects recorded complaintsin the questionnaire. In 140 subjects findingswere recorded at the examination. Most subjects with findings at the clinical examination of shoulders reported complaints in the questionnaire (sensitivity 80%). For the other anatomical regions, the sensitivity was rather low (42– 65%). For all regions, most subjects without findings reported no complaints (specificity 77–97%). A total of 75 subjects were given clinical diagnoses according to a set of predetermined diagnostic criteria. The capacity of the questionnaire to identify diagnoses of shoulders was higher (sensitivity 92%) than for the other regions (66–79%). Of subjects who did not qualify for diagnosis, a majority (specificity 71–81%) did not report complaints in the questionnaire. We conclude that the questionnaire approach gives a fairly good picture of the neck/upper extremity status of a working female population. However, a clear view of the size of a problem is obtained only by a detailed clinical examination, particularly as regards the neck, elbows and hands, for which the questionnaire gave an underestimate.