Introduction to musculoskeletal disorders
Isabel L. Nunes, Faculty of Science and Technology, Universidade Nova de Lisboa
- 1 Introduction
- 2 Definition
- 3 Prevalence of MSDs
- 4 Groups at risk
- 5 Work-related MSDs risk factors
- 6 Types of work related musculoskeletal disorders
- 7 References
- 8 Links for further readings
Work-related musculoskeletal disorders (MSDs) cover a broad range of health problems associated with repetitive and strenuous work. These health problems range from discomfort, minor aches and pains, to more serious medical conditions which can lead to permanent disability. Every year millions of European workers are affected by MSDs. The most well-known MSDs are low back pain and work-related upper limb disorders. The first is mainly associated with manual handling while the main risk factors for the latter are associated with task repetition and awkward work postures. Nowadays lower limb work-related MSDs are also been recognized as disorders that may be associated with occupational activity.
Work-related MSDs associated with repetitive and strenuous working conditions continue to represent one of the biggest occupational problems in companies. Despite the variety of efforts to control them, including engineering design changes, organizational modifications and working methods training programs, work-related musculoskeletal disorders account for a huge amount of human suffering and to companies and to healthcare systems .
The term work-related MSDs refers to health problems affecting the muscles, tendons, ligaments, cartilage, the vascular system, nerves or other soft tissues and joints of the musculoskeletal system. They are caused or aggravated primarily by work itself and they can affect the upper limb extremities, the neck and shoulders, the lower back area, and the lower limbs.
Prevalence of MSDs
Effects on health
The main work-related health problem affecting European workers is work-related MSDs. Across Europe it is estimated that 44 million workers have MSDSs which are caused by their work . These disorders are widespread in all activity sectors, but [Agriculture|agriculture]] and construction are the two most affected sectors. Therefore, MSDs are a central concern in Europe, given the increasingly large number of workers involved. According to data from the Sixth European Working Conditions Survey (conducted in 35 countries: EU28 plus Albania, Macedonia, Montenegro, Norway, Serbia, Turkey and Switzerland) almost half of European workers suffer from work-related MSDs. 44.7% of the workers reported backache and 44.4% muscular pains in shoulders, neck and/or upper/lower limbs. This means that about 75-80 million workers reported suffering from work-related MSDs in Europe. Within the EU, backache seems to be the most prevalent work-related health problem, closely followed by neck and upper limb problems. Variability among EU Member States’ self reported backache levels are high, ranging from a maximum of 59% in France, to a minimum of 28% in Hungary.
Similar findings arise from the Labour Force Survey (2013). 60% of the respondents with work-related health problems identified musculoskeletal problems as their most serious work-related health problem and 15.9% identified stress, depression or anxiety as their most serious health problem. It is important to note that the survey only addresses the most serious problem experienced. Respondents may also suffer from other problems (seen as of lesser importance) so these figures should not be regarded as indicative of the total experiencing such problems at all.
According to earlier statistics, bone, joint or muscle problems that mainly affect the back occur more often than upper limb and lower limb disorders . Problems affecting the lower limbs are more severe and workers with problems of the hips, legs or feet more often experience longstanding sick leave (figure 1).
Figure 1 – Sickness absence due to different types of musculoskeletal problems in employed persons in the EU 27 in the past 12 months (%) (Labour Force Survey 2007)
Among the recognized occupational diseases, the highest occurrence is found for the diagnostic group of musculoskeletal problems (figure 2). When looking into the list of recognized diseases more specifically, the diseases that are most prominently registered are Carpal tunnel syndrome and Diseases due to overstraining of the muscular and tendonous insertions .
Figure 2 - Contribution of five important diseases to the recognized occupational diseases in europe (%), (European Occupational Diseases Statistics, EODS, 2001 -2007)
Other factors contributing to the relevance of the subject are the economic consequences resulting from the work-related MSDs’s high prevalence and the suffering they cause, often leading to permanent, partial or total disability of the worker. The economic consequences are twofold: for employers, MSDs reduce company efficiency due to loss of productivity; and they increase societal costs, namely worker compensation, medical and administrative costs. In some EU Member States 40% of the costs of workers’ compensation are caused by MSDs, reaching up to 1.6% of the gross domestic product (GDP) of the country itself . In general, the cost to the EU each year in lost productivity and sickness absences is estimated at 2% of the GDP .
MSDs is a major cause of sick leave. In total 61% of the persons that report a work-related MSD went on sick leave. About 35% reported sick leave for less than one month and 26% reported sick leave for at least one month. This means that about 60% of all short term (< 1 month) and long term (at least 1 month) sickness absence in the EU27 due to work-related health problems can be attributed to musculoskeletal problems (Labour Force Survey 2007, ). Most persons with low back pain recover quickly and without residual functional loss, irrespective of treatment. Overall, 60 to 70% recovers by 6 weeks, and 80 to 90% by 12 weeks. Recovery after 12 weeks is slow and uncertain. Although the majority of the persons with low back pain will have recovered after several weeks, recurrence frequently occurs. The recurrence rate ranges from 20% to 44% within one year in the working population. Lifetime recurrence ranges up to 85% . These consequences of low back pain and MSDs in general on organisations and companies explain why MSDs are considered an OSH issue of major concern according to the ESENER survey. In about 80% of the organisations MSDs are considered of moderate to major concern. Only "Accidents" have a higher ranking than MSDs .
It is long recognized that work may adversely affect health. Almost three centuries ago (in 1717) the Italian physician Bernardino Ramazzini, father of occupational medicine acknowledged the relationship between work and certain disorders of the musculoskeletal system due to the performance of sudden and irregular movements and the adoption of awkward postures. Due to this fact some disorders assumed names related with the professions where they mainly occurred. Therefor a variety of terms for MSDs can be found that directly refer to jobs and professions, for instance “carpenter’s elbow”, “seamstress’ wrist” or “bricklayer’s shoulder” .
Prevalence of risk factors for MSDs
The Fifth European Working Conditions Survey (EWCS), carried out between January and June of 2010, covered 34 countries – EU27, Norway, Croatia, the former Yugoslav Republic of Macedonia, Turkey, Albania, Montenegro and Kosovo and involved almost 44,000 workers. One important conclusion drawn from the study was that European workers remain as exposed to physical hazards as they did 20 years ago (the First EWCS was carried out in 1991). For instance, one third of the workers (33%) carry heavy loads at least a quarter of their working time, while almost one in four (23%) are exposed to vibration. As Figure 3 shows nearly half of all workers (46%) work in tiring or painful postures for at least a quarter of the time, and repetitive hand or arm movements (63%) are a feature of work for more Europeans today than it was 10 years ago . Notice that the data in Figure 3 refers to those who said they experienced these hazards at least a quarter of their working time. It can be concluded that the known risk factors for MSDs are not declining in the work places.
Although not shown in the figure, data from the most recent EWCS (2015) shows a remarkably similar pattern with the proportions reporting exposure to the various hazards virtually unchanged. Thus, 33% still report carrying heavy loads (at least a quarter of their working time); 20.6% report exposure to hand-arm vibration; 46.6% report working in tiring postures and 63% report carrying out repetitive hand or arm movements.
Figure 3 - Exposure to physical risks over time (% exposed quarter of the time or more), EU27 (%)
Groups at risk
Due to high exposure to physical risk factors MSD are particularly prevalent among workers from the following sectors: agriculture, construction, transport and road safety, and communication, manufacturing, hotels and restaurants, health and social work and mining.
Recent findings suggest that the impact on the prevalence of MSDs is not related to the industry sector but to the actual content of the job. When controlling for the actual content of the job, no significant differences emerge among industries .
Women have been reported as having a higher incidence of MSDs . However, there is no evidence that gender per se is a significant factor for the development of MSDs. The analysis of MSDs records shows that most disorders can be explained based on job characteristics. Men jobs appear to generate mainly 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). For instance, regarding lower limbs the type of job can explain some gender differences in the type and frequency of disorders:
- men in construction are mostly affected by knee problems;
- women are significantly exposed to prolonged standing and walking (e.g. in the retail sector, the hotel and catering sector, cleaning work, education or in health care) reporting more problems in hips, legs and feet. Other possible causes for the higher incidence of MSDs among women are: domestic work; hormonal cycles; pregnancy or use of the contraceptive pill .
Aging can lead to an increase of MSDs prevalence, due to a reduction in body resistance. Therefore, MSDs can become more prevalent worldwide as the population ages throughout the world. All racial groups are affected.
The Health and Safety Executive (HSE, UK) noted that “new employees, particularly young workers and those returning to work from a holiday, sickness or injury, may need to be introduced to a slower rate of production than the existing ‘workforce’, followed by a gradual increase in pace. This works best, for example, by only working for a limited time per day at production speed, increasing as appropriate. Introducing newcomers at a slower pace enables them to develop good work practices before having to concentrate on working fast, and helps them to assimilate training more effectively. Ideally, early training should be done ‘off-line’.”.
The strong correlation between the incidence of MSDs and working conditions is well known, particularly considering the physical risk factors associated with jobs (e.g., awkward postures, high repetition, force exertion, static work, cold or vibration . Work intensification, stress and other psychosocial factors also seem to be factors that increasingly contribute to the onset of those disorders.
The causes of work-related MSDs are multifactorial and there are numerous work-related risk factors for the various types of MSDs. Several risk factors including physical and mechanical factors, organisational and psychosocial factors, and individual and personal factors may contribute to the genesis of MSDs. Workers are generally exposed to several factors at the same time and the interaction of these effects are often unknown  .
Work-related MSDs refer to injuries developed over time that are caused by a combination of risk factors that act simultaneously on a joint or body region, in a synergistic effect. Until now the biological pathogenesis associated with the development of the majority of the work-related MSDs is unknown. Several models have been proposed to explain the biological mechanisms. Usually three sets of factors are considered :
- Physical factors (e.g., sustained or awkward postures, repetition of the same movements, forceful exertions, hand-arm vibration, all-body vibration, mechanical compression, and cold);
- Psychosocial factors (e.g., work pace, autonomy, monotony, work/rest cycle, task demands, social support from colleagues and management and job uncertainty); and
- Individual factors (e.g., age, gender, professional activities, sport activities, domestic activities, recreational activities, alcohol/tobacco consumption and, previous work-related MSDs).
Most of the factors can occur both at work and in leisure time activities. Thus, it is important to include all the relevant activities performed both at work and outside work when of a specific employee developing MSDs in a particular working environment.
As referred before, risk factors act simultaneously on a worker joint or body region in a synergistic effect. To manage the risk factors it is advisable and important to take into account this interaction rather than focus on a single risk factor.
Because of high individual variability it is impossible to estimate the probability of developing work-related MSDs at individual level. As physicians usually say “There are no diseases, but patients.”
As mentioned before, most of the recorded work related MSD affect the lower back, neck, shoulders and upper limbs. MSD affect less often the lower limbs. It is important to recognise however that not all MSDs are caused by work, although work may provoke symptoms and the problem may prevent a person from working, or make it more difficult. For example, a recent study found that age, gender and BMI made a bigger proportional contribution to developing carpal tunnel syndrom (CTS) than work-related factors.
Work-related Upper Limb Disorders (WRULDs) 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. EU-OSHA has produced a series of reports about upper limb and neck work-related MSDs, see for instance . Also very useful information about MSDs prevention can be found in the two following reports  and .
However the designation of WRULDs in international literature is not consensual. In addition to MSDs, other terms are sometimes used referring to similar symptoms and health problems. Examples are: - cervicobrachial syndrome, occupational cervicobrachial disorders; - occupational overuse syndrome; - repetitive strain injury, repetitive stress injury, repetitive motion injuries; - cumulative trauma disorders; - upper limb disorders, upper extremity musculoskeletal disorders, upper limb pain syndromes. 
Despite all the available knowledge some uncertainty remains about the level of exposure to risk factors that triggers MSDs. In addition there is significant variability of individual response to the risk factors exposure.
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.
Low back work-related MSDs include spinal disc problems, muscle and soft tissue injuries. These disorders are mainly associated with physical work, manual handling and vehicle driving activities, where lifting, twisting, bending, static postures, and whole body vibration are present.
Until now little attention has been given to the epidemiology of work-related lower limb MSDs. However, lower limb MSDs is a problem in many workplaces and they tend to be related with conditions in other areas of the body. Lower Limb Disorders affect the hips, knees and legs and usually happen because of overuse. Acute injury caused by a violent impact or extreme force is less common. Workers working over a long period in a standing or kneeling position are most at risk. The most common risk factors at work are: - repetitive kneeling and/or squatting; - fixed postures such as standing for more than two hours without a break; - frequent jumping from a height.  
Despite the lack of attention given to this type of work-related MSDs they deserve significant concern, since they often give up high degrees of immobility and thereby can substantially degrade the quality of life. Lower limb work-related MSDs that have been reported in occupational populations are:
- Hip/thigh conditions: Osteoarthritis (most frequent), Piriformis Syndrome, Trochanteritis, Hamstring strains, Sacroiliac Joint Pain;
- Knee/lower leg: Osteoarthritis, Bursitis, Beat Knee/Hyperkeratosis, Meniscal Lesions, Patellofemoral Pain Syndrome, Pre-patellar Tendonitis, Shin Splints, Infra-patellar Tendonitis, Stress Fractures;
- Ankle/foot: Achilles Tendonitis, Blisters, Foot Corns, Halux Valgus (Bunions), Hammer Toes, Pes Traverse Planus, Plantar Fasciitis, Sprained Ankle, Stress fractures, Varicose veins, Venous disorders .
However, although these may occur in specific occupational groups (for example Piriformis Syndrome and Trochanteritis have been reported amongst dental personnel; and hamstring strains amongst athletes) the extent to which these have been generally shown to be caused by work is unclear and there are many non-work related factors that can contribute, possibly making the major contribution.
The non-specific work related MSD are musculoskeletal disorders that have less well-defined symptoms, i.e. the symptoms tend to be diffuse and non-anatomical, spread over many areas: nerves, tendons and other anatomical structures. The symptoms involve pain (which becomes worse with activity), discomfort, numbness and tingling without evidence of any discrete pathological condition.
Table 2 synthesizes the most relevant MSDs described above and groups them by body part and anatomical structure affected.
Table 2: Most relevant MSD by body part and affected anatomical structure
- Nunes, I. L., 'FAST ERGO_X – a tool for ergonomic auditing and work-related musculoskeletal disorders prevention', WORK: A Journal of Prevention, Assessment, & Rehabilitation, 34, 2009, pp.133-148
- Fit for work – Infographic. Key facts on MSDs, Retrieved 22 May 2015 from 
- Eurostat - Health and safety at work in Europe (1999-2007) – A statistical portrait, Inna Šteinbuka, Anne Clemenceau, Bart De Norre, August 2010. Available at: 
- EU-OSHA – European Agency for Safety and Health at Work, Work-related musculoskeletal disorders: Back to work report, 2007. Available at: 
- EU-OSHA - European Survey of Enterprises on New and Emerging Risks. Managing safety and health at work, 2010, Retrieved 27 February 2015 from 
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- EUROFOUND – European Foundation for the Improvement of Living and Working Conditions, "Fifth European Working Conditions survey - 2010", 2012. Available at: 
- EUROFOUND - Health and well-being at work: A report based on the fifth European Working Conditions Survey, 2012. Available at: 
- EU-OSHA – European Agency for Safety and Health at Work, New risks and trends in the safety and health of women at work, 2013. Available at: 
- HSE – Health and Safety Executive, Upper limb disorders in the workplace, 2002. Available at: 
- PEROSH - Sustainable workplaces of the future – European Research Challenges for occupational safety and health. Multifactorial genesis of work-related Musculoskeletal disorders (MSDs), 2012. Available at: 
- INRS – Dossier Troubles musculosquelettiqes (TMS). Retrieved 20 May 2015 from: 
- Violante FS, Farioli A, Graziosi F, Marinelli F, Curti S, Armstrong TJ, Mattioli S, Bonfiglioli R. (2016) Carpal tunnel syndrome and manual work: the OCTOPUS cohort, results of a ten-year longitudinal study. Scand J Work Environ Health. 2016; 42(4): 280–290. doi:10.5271/sjweh.3566
- EU-OSHA – European Agency for Safety and Health at Work, Work-related neck and upper limb musculoskeletal disorders, 1999. Available at: 
- EU-OSHA – European Agency for Safety and Health at Work, Safety and Health at Work. European Good Practice Awards, 2007. Prevention of work-related MSDs in practice, 2007. Available at: 
- EU-OSHA – European Agency for Safety and Health at Work, Work-related musculoskeletal disorders: Prevention report, 2008. Available at: 
- Nunes, I. L., Modelo de Sistema Pericial Difuso para Apoio à Análise Ergonómica de Postos de Trabalho [Fuzzy Expert System Model to Support Workstation Ergonomic Analysis], Dep Eng Mecânica e Industrial, Universidade Nova de Lisboa, Lisbon, Portugal, 2003
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- HSE - Health and Safety Executive, Lower Limb disorders. Retrieved 22 May 2015 from 
- HSE – Health and Safety Executive, Lower limb MSDs. Scoping work to help inform advice and research planning, RR706 Research Report, 2009. Available at: 
- Ring, D., Kadzielski, J., Malhotra, L., Lee, S.-G. P. & Jupiter, J. B., 'Psychological Factors Associated with Idiopathic Arm Pain', The Journal of Bone and Joint Surgery (American), 87, 2005, pp. 374-80.
Links for further readings
EU-OSHA - European Agency for Safety and Health at Work, Current and emerging occupational safety and health (OSH) issues in the healthcare sector, including home and community care, Available at: 
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, OSH in figures: Work-related musculoskeletal disorders in the EU - Facts and figures, 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, E-fact 44 - Checklist for the prevention of manual handling risks, Available at: 
EU-OSHA - European Agency for Safety and Health at Work, E-fact 43 - Checklist for preventing WRULDs, Available at: 
EU-OSHA - European Agency for Safety and Health at Work, E-fact 42 - Checklist for prevention of lower limb disorders, Available at: 
EU-OSHA – European Agency for Safety and Health at work, Work-related musculoskeletal disorders: prevention report, 2008, Available at: