The aim of this article is to present the risk factors in hand-arm tasks leading to neck and upper limb musculoskeletal disorders (MSDs). Hand-arm tasks include all types of tasks performed using hands and arms actively, such as: assembling, sorting, packaging, woodwork sanding, hair styling. A large number of people may be affected, with socio-economic consequences, at the individual and enterprise level and society as a whole.
This article also presents the evidence that associates the work-related neck and upper limb disorders (WRULDs) with exposure to hand-arm tasks. Understanding these associations and relating them to disease aetiology is critical to identify the workplace exposures that should be reduced or prevented.
The main work-related upper limb disorders pathologies
Work-related Upper Limb Disorders (WRULDs) comprise a heterogeneous group of conditions that can affect any region of the neck, shoulders, arms, forearms, wrists and hand. Some of WRULDs, such as tendonitis, carpal tunnel syndrome, osteoarthritis, vibration white finger and thoracic outlet syndrome have well-defined signs and symptoms, while others are less well-defined, involving only pain, discomfort, numbness and tingling .
Many of the musculoskeletal conditions are non-specific indicating that a specific diagnosis or pathology cannot be determined by physical examination but pain and/or discomfort, numbness, tingling in the affected areas are reported. Other symptoms which can be exacerbated by cold or use of vibrating tools include swelling in the joints, decreased mobility or grip strength, changes in skin colour of the hands or fingers. These complaints can lead to physical impairment and even disability. Symptoms may take weeks, months or in some cases years to develop, so it is important to detect them and act at an early stage.
The most common WRULDs are:
- Neck: Tension Neck Syndrome, Cervical Spine Syndrome;
- Shoulder: Shoulder Tendonitis, Shoulder Bursitis, Thoracic Outlet Syndrome;
- Elbow: Epicondylitis, Olecranon Bursitis, Radial Tunnel Syndrome, Cubital Tunnel Syndrome;
- Wrist/Hand: De Quervain Disease, Tenosynovitis Wrist / Hand, Synovial Cyst, Trigger Finger, Carpal Tunnel Syndrome, Guyon’s Canal Syndrome, Hand-Arm Syndrome, Hypothenar Hammer Syndrome.
Upper limb disorders are common in the general population. Data from (national) studies report a prevalence of 5 to 10% for non-specific complaints of strain that interferes with day-to-day activities, but rates could be as high as 22 to 40% in specific working populations. For instance, for carpal tunnel syndrome studies have found prevalence rates of 7 to 14,5% . However disease labels and case definitions vary considerably between studies which might, in part, explain the differences between prevalence rates .
According to results from the sixth European Working Conditions Survey (EWCS) approximately three out of every five workers in the EU-28 reported MSD complaints in 2015. These self-reported complaints are MSD in general and not only work-related MSD. The most common MSDs are backache (43%) but upper limb disorders come in second place (41%). Muscular pains in lower limbs are reported less often (29 % in 2015). Women are more likely to report upper limb disorders and the percentages increase with the age of the workers. More than 1 out of 2 female workers aged 55 or older report an upper limb disorder (figure 1). Upper limb disorders are mostly reported by workers in Agriculture, Forestry and Fishing (56%), Construction (54%) and Mining and Quarrying (51%). In sectors such as Finances and Insurance activities, Arts, Entertainment and Recreation and Education, the number of workers reporting upper limb disorders are smaller (around 30%) (figure 2).
The true extent of costs due to work-related MSDs across EU Member States is difficult to assess and compare because of differences in organisation of insurance systems, the lack of standardised assessment criteria and the fact that little is known on the validity of reported data. Certain studies estimated the cost of WRULD at 0.5-2% of Gross National Product (GNP). Data from France (Caisse primaire d’assurance maladie (CPAM) of the Loire Region) provides information on the costs of different types of upper limb disorders. These data show that the average cost to companies is €12,780 for a carpal tunnel-related MSD, €52,759 for a rotator cuff tendinitis-related MSD and €18,220 for an epicondylitis-related MSD. These estimations do not include the days of sick leave for the affected worker, which for carpal tunnel are approximately 151 days, for rotator cuff tendinitis 298 days and for epicondylitis 195 days .
Upper limb disorders are frequently attributed to work although the evidence that occupational factors are important in the development of these conditions is limited. Review studies found only limited or no evidence to support the causal relationship .
An EU-OSHA report (2019) analysed which physical, organisational and/or psychosocial risk factors are significantly related to the prevalence of three different types of MSD complaints (back, upper limbs and lower limbs) based on the data from the EWCS (2015). The results with regard of upper limb disorders are summarised in table 1 .
Table 1 - Associations between self-reported MSDs and physical, organisational and psychosocial risk factors
|Associations between self-reported WRULDs and||Significant relationship identified||No significant relationship identified|
|Physical risk factors||- Vibrations from hand tools - Working in tiring or painful positions - Carrying or moving heavy loads - Repetitive hand or arm movements - Being exposed to low temperatures||- Lifting or moving people - Working with computers, laptops, etc. - Sitting|
|Organisational and psychosocial risk factors||- Anxiety - Overall fatigue - Sleeping problems - Mental well-being - At work subjected to: verbal abuse threats physical violence - Employee voice - Job gives the feeling of work well done - Take a break when you wish - Fairly treated at workplace - Job requires hiding of feelings - Work-related stress - Working at very high speed||- At work subjected to: bullying/harassment unwanted sexual attention - Pace of work dependent on: direct demands from customers, etc.; direct control by management - Feeling energised - Knowing what is expected at work - Able to choose or change order of tasks|
Table 1 shows that upper limb disorders can be associated with a variety of workplace and work characteristics (physical load, work environment, work organisation and psychosocial factors). Also individual factors such as health status, age and gender have an impact .
There are several occupational risk factors resulting in high mechanical loads on the neck, shoulder and upper limbs.
- Force exertion: sustained or excessive force results in heavy mechanical loads on the neck, shoulders and upper limbs: handling objects, using tools, fast movements or excessive force generated by the muscles of the body, local force and stress from items coming into contact with parts of the upper limbs. Force is the amount of effort required to perform a task or a job. It depends on someone's posture and the number of exertions performed. As a higher force is exerted, the stress on the body is higher. Different manipulating actions on a tool are examples of activities that require exerting force or muscle effort (e.g. digital gripping is more demanding than palm gripping). Not only is the intensity of effort harmful but also its duration.
- Repetitive movements are especially hazardous when they involve the same joints and muscle groups over and over again and whenever the same movement is done too often, too quickly and for too long. Analysing the repetitiveness of a task involves the steps or cycles it takes. Work involving repetitive movements is very tiring because the worker cannot fully recover in the short periods of time between movements. If the work activity continues in spite of the fatigue, injuries can occur. The cycle duration is significant if less than 30 seconds or if the repetitive movements account for 50% of work time (e.g. repetitive tasks: nailing a deck, screwing drywall, and tying rebar).
- Working posture – poor posture – uncomfortable working posture: any body position can cause discomfort and fatigue if it is maintained for long periods of time, but certain tasks can make workers use unnatural standing positions. Uncomfortable working posture or awkward postures represent unnatural positions, deviated from “neutral positions", in which joints are held or moved away from the body's natural position. The closer the joint is to its end of range of motion, the greater the stress placed on the soft tissues of that joint, such as muscles, nerves, and tendons. When muscles are contracted, the body is subjected to a greater mechanical effort. Joint positions of the upper limb, when working outside comfort angle, increase the possibility of WRULDs, regardless of effort intensity or degree of repetition.
- Contact pressure – any external pressure that is applied to soft tissues (e.g. holding tools where handles press into parts of the hand or arm; sharp edges of tools, machines or furniture that press into the fleshy tissues) can cause distortion and injury.
- Poor workspace layout, poor design of tools and machinery can result in adopting stressful working postures and applying force;
- Temperature of the workplace affects the body muscles: excessive heat increases overall fatigue and produces sweat which makes it hard to hold tools, requiring more force; excessive cold can make the hands feel numb, making it hard to grip and requiring more force; every movement and position involving more effort are more likely to develop work-related neck and upper limb disorders (WRULDs).
- Poor lighting can create glare or shadows that may require workers to adopt awkward positions to see clearly what they are doing;
- High levels of noise may cause the body to tense in static body postures resulting a more rapid onset of fatigue;
- Vibration can cause damage to nerves and blood tissues as well as other soft tissues. Hand-arm vibrations cause tingling and numbness, or loss of sensibility, requiring a higher clamping force and awkward body positions because vibration hand tools are harder to control.
The risk of injury increases when two or more WRULDs risk factors are combined in one job; moreover, task duration in each shift plus the number of working days the task is performed, determine the risk level.
Prevalence of physical risk factors
With regard of the prevalence of physical risk factors (physical load and work environment factors) data based on the EWCS show a slightly downward trend (table 2). However, the percentages of workers who report that are exposed to 1 or more physical risk factor for a least a quarter of the time remains high. For instance, more than 60% of the workers report an exposure to repetitive hand/arm movements.
Table 2: Percentage of workers reporting that they are exposed to different physical risk factors at their work at least a quarter of the time, EU-28, 2005, 2010 and 2015
|Carrying or moving heavy loads||35||34||32|
|Painful or tiring positions||46||47||43|
|Repetitive hand or arm movements||62||64||61|
|Working with computers, laptops, smartphones||47||53||58|
Organisational and psychosocial factors
Organisational as well as psychosocial factors impact WRULDs. These include 
- working under time pressure and deadlines;
- lack of work breaks;
- lack of social support received by colleagues, supervisors or management;
- high work demands and low work demands;
- poor job design, no task variation;
- job insecurity, temporary work and piecework: less skilled manual workers at the lower end of the labour market are most affected;
- low status work: low-paid, unskilled, paced and repetitive work.
These risk factors do not only lead to stress, but can increase the risk of MSDs because stress related changes in the body such as increased muscle tension could make workers more susceptible to MSDs. Psychosocial risk factors may affect workers’ psychological response to work and workplace conditions or may change their behaviour .
MSDs result from an imbalance between biomechanical demands and the worker functional abilities. When demands are lower than individual capacities, the probability of developing MSDs is small, the risk is minimal. When demands are higher, the muscle-joint structures are overstrained and there is a risk of MSDs .
Individual variability refers to: muscle strength, psychomotor skills. Consequently, such differences can be: the ability to perform repetitive gestures or fine finger movements or performing movements for a long time. The workers’ different body dimensions can lead to poor postures when working at a shared workstation. Other individual characteristics are health status, previous diseases, level of training, etc.
Women report more WRULDs than men (see also figure 1). However, there is no evidence that gender per se is a significant factor for the development of MSDs . Job characteristics differ between men and women. Men are more often employed in jobs with a higher exposure to physical risk factors, while typical women tasks involve a combination of physical factors (e.g. prolonged standing and sitting, forced postures, jobs involving moving people and repetitive work) and psychosocial factors (e.g. time pressure). As reported in some studies undertaken in working populations, women have a higher risk of WRULDs than men, but the study failed to quantify this association because of the occurrence of an interaction between gender and physical demand of the task in the final multivariate model. The gender difference could also be linked to differences in exposure to constraints at work or at home, household work, childcare .
Age represents a susceptibility factor, because the functional capacity of soft tissues, resistance to stress, muscle strength decrease with age . Furthermore:
- accumulation of years of exposure to occupational demands;
- recent changes in work organisation which have led to atypical career paths, precarious working conditions and instability of a job; in such conditions when more factors are involved, it is difficult to relate age, workplace and the risk of MSDs;
- new employees may need time to acquire skills/pace of work.
The prevention of work-related upper limb disorders (WRULDs) is not only an economic, social and moral need, but also an employer’s obligation within the occupational risk assessment.
The preventive approach is a complex one and it should include:
- detection of the work tasks with MSDs risk (e.g. using checklists)
- ergonomic analysis of these work situations, work stations, activity, work environment and operators’ complaints (using also the questionnaires method);
- assessment of: biomechanical (e.g. using checklists assessing the physical workload), organisational and psychosocial MSDs risks.
An example of a checklist is the EU-OSHA checklist on the prevention of WRULDs. The checklist also provides preventive actions .
- drawing up ergonomic solutions to eliminate/decrease the assessed risk factors:
- ergonomic design of work tools;
- product design;
- ergonomic layout of the workstations;
- job design
- ergonomic layout of the physical work environment;
- ergonomic organisation of the activity: alternation of repetitive and non-repetitive tasks (e.g. with demands on other muscle groups), short and frequent breaks, short time rotation in different workplaces, job enrichment, settle adjusting periods when changing production/after an absence, elimination of the performance bonuses;
- training and education (for example, at individual level - physical exercises to prevent and reduce the impact of WRULDs);
- monitoring the employees’ health state the early detection of any signs and symptoms and the corrective measures before the effects become irreversible. As if the specific MSDs can be more easily diagnosed (and therefore monitored), it is also important that non-specific musculoskeletal disorders to be considered in health monitoring and surveillance system.
The WRULDs prevention needs a global managerial approach which takes into account not only the prevention of new diseases, but also the MSDs affected employees’ permanence in jobs, readjustment and re-integration.
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