Risk factors for musculoskeletal disorders development: hand-arm tasks, repetitive work
Viorica Petreanu and Aurelia-Mihaela Seracin, National Research - Development for Health and Safety, Romania
- 1 Introduction
- 2 Work-related neck and upper limb disorders
- 3 Risk factors for work-related neck and upper limb disorders
- 4 Exposure to risk factors
- 5 Prevention
- 6 References
- 7 Links for future reading
The aim of this article is to present the risk factors in hand-arm tasks leading to neck and upper limb musculoskeletal disorders (MSDs) [[:Category:Musculoskeletal disorders|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.
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) 2015, 44.6% of workers (employees or self-employed) reported problems with backache in the previous 12 months, while 44.4% cited problems with muscular pains in the shoulders, neck and/or upper limbs. The Labour Force Survey (LFS) 2007 demonstrates that back problems are the most self-reported work-related health problems. Upper limb disorders are more self-reported than lower limb disorders (table 1). Furthermore, the LFS reveals that employed men and women differed with respect to the type of work-related health problem that was considered to be the most serious health problem. Men more often had back problems than women. Women however reported far more frequently upper limb disorders as the most serious work-related health problem . Both data sources, EWCS and LFS, rely on self-reported health problems, which makes it difficult to estimate the true extent of the problem. Individuals experiencing musculoskeletal disorders tend to experience, and so report, their work as physically demanding and as a consequence surveys that rely on self-reporting may over-estimate the occupational contribution to these disorders .
According to 2013 LFS data, 60.1% of those questioned reported a musculoskeletal disorder in the preceding 12 months 'caused or made worse by' their work.
Table 1 - Type of work-related health problem indicated as the most serious among persons with a work-related health problem in the EU27 (%)
|Type of work-related health problem:||Persons that work, or worked previously (%)||Persons that work (%)|
|Bone, joint or muscle problem which mainly affects|
|Neck, shoulders, arms or hands||18.8||20.1|
|Hips, legs or feet||12.6||11.3|
Figure 1 – Relative occurrence* of the type of work-related health problem indicated as most serious health problem in the past 12 months in employed persons (EU27) (LFS 2007)
a value of ‘0’ means that the type of work-related health problem was least often reported, whereas a value of ‘1’ reflects that the type of work- related health problem was most often reported.
The true extent of work-related MSDs’ costs across Member States is difficult to assess and compare. “This can be due to the difference 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) .
The European Risk Observatory Report (2010)  showed that a high proportion of days lost in the Member States of the European Union is due to MSDs and absences are often longer. Data from the UK show that workers affect by WRULDs took on average 15.9 days off work. The total estimated number of working days lost in 2013/14 due to WRULDs was 3.2 million .
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   . However, the causes of work-related neck and upper limb disorders (WRULDs) are multifactorial and include workplace and work characteristics (physical load, work environment, work organisation and psychosocial) as well as individual factors . The acknowledged risk factors related to various types of MSDs include physical, organisational, psychosocial and individual factors.
Workplace and work characteristics
There are several relevant occupational risk factors resulting in high mechanical loads on the neck, shoulder and upper limbs. Factors seldom occur separately; there is a combination of factors of different intensities and frequencies specific for each work task.
- Hand 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.
- 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 behavior  .
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.
Gender 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, job 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 .
- 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.
Exposure to risk factors
Concerning the exposure to risk factors related with the development of MSDs in upper limbs, the European Survey on Working Conditions showed that, in 2010, 63.5% of workers in the EU-27 reported repetitive hand or arm movements .
The prevalence of risk factors related to MSDs is emphasized by the percentage of workers carrying or moving heavy loads, working in painful/tiring positions and reporting repetitive hand/arm movements, all of them at least 25% of the time.
Table 2: The prevalence of risk factors related to MSDs in percentage of workers (in 2010)
|Carrying or moving heavy loads||33.5||32.8|
|Painful or tiring positions||46.4||46.4|
|Repetitive hand or arm movements||63.5||64.2|
The prevention of work-related neck and upper limb disorders (WRULDs) risks 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:
- work tools ergonomic design;
- product design;
- ergonomic layout of the work stations;
- manufacturing organisation;
- 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 cure WRULDs);
- monitoring the employees’ health state the precocious 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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Links for future reading
EU-OSHA - European Agency for Safety and Health at Work, New risks and trends in the safety and health of women at work, Available at:  EU-OSHA - European Agency for Safety and Health at Work, The human-machine interface as an emerging risk, Available at:  EU-OSHA - European Agency for Safety and Health at Work, E-fact 45 - Checklist for preventing bad working postures, Available at:  EU-OSHA – European Agency for Safety and Health at work, Work-related musculoskeletal disorders: prevention report, 2008, Available at: 
EWCO – European Working Conditions Observatory, Managing musculoskeletal disorders, Oct. 2007. Available at: 
HSE - Upper limb disorders in the workplace, 2002, Available at: