In Europe, work-related musculoskeletal disorders (MSDs) represent a substantial economic burden to society and are one of the major causes of health-related productivity loss. Besides having obvious consequences for the individual, work-related health problems bring substantial costs for employers. Until now, limited attention has been paid to work related lower limb MSDs. Nevertheless, among workers lower limb MSDs are one of the three most reported types of MSD (after backache and muscular pain in the upper limbs). 29% of the workers reported muscular pain in the lower limbs in 2015. Lower limb MSDs are a problem in many workplaces and the problem increases over the years.
The main risk factors for work-related lower limb disorders include squatting, kneeling, pushing foot pedals, walking, climbing stairs or ladders, heavy lifting, frequently jumping from a height, prolonged standing and prolonged sitting. The last two risk factors mentioned are underestimated.Lower limb disorders affect the hips, knees, feet and legs and usually occur due to overstrain. Workers working over a prolonged period in a standing or kneeling position are most at risk because of kneeling and/or squatting and fixed postures, such as prolonged standing or sitting without a break. The risk factors for lower limb disorders are not specific to any of the sites of the lower extremities and they also tend to be associated with disorders in other regions of the body such as the upper limb and torso.
Mechanisms in developing MSDs
The origin of most musculoskeletal disorders (MSDs) lies in a mismatch between the external load and the capacity of the human body to resist biomechanical and physiological strain. Excessive force can trigger different pathophysiological processes depending on the tissues affected. It is the magnitude, duration and frequency of the load as well as the time for recovery that determines the physiological effect. In general, a mismatch between load and capacity can lead to physiological responses in tissues, such as inflammation, irritated muscles, damaged tendons, destroyed cartilage of the joints and disturbances in the function of the nerve. Both acute and overuse injuries may be suffered by workers, although overuse injuries tend to be more common.
Effects of prolonged standing
Prolonged standing means: standing on the job at a spot for > 1 hour continuously and/or more than 4 hours a day. If these guidelines are exceeded, measures are needed to prevent MSDs.
When prolonged standing occurs, this decreases the circulation of blood and reduces the nutrient supply to muscles, thus allowing muscular fatigue to set in. The consequences regarding lower limbs may be:
- Fatigued legs include increased tendency to fall by slipping and tripping, and a higher risk for developing lower back pain.
- Insufficient blood flow may lead to discomfort / fatigue and pain in neck and shoulders.
- Insufficient blood flow can lead to circulatory problems in the legs and lead to pain, varicose, and swelling of the legs.
- Development of venous disorders of the lower limbs and discomfort at the ankle/foot. Eventually, discomfort may lead to ankle/foot complaints.
- Due to prolonged standing, the blood in the legs and the venous tension increases. This may lead to cardiovascular problems, such as varicose veins.
- Immobilization of the joints (spine, hip, knees and feet) may occur and lead to degenerative damage of the joints and pain as a consequence.
When the duration of prolonged standing increases, the risk of musculoskeletal complaints also increases.
It is important to understand that there is an important difference between prolonged standing and dynamic standing. Prolonged standing means standing still on exactly the same spot. Dynamic standing means there is a possibility to move about on approximately one square meter. Between these two ways of standing there is a difference in mechanic load of musculoskeletal structures, and there is a substantial physiological difference. Besides a difference in mechanic load of musculoskeletal structures there is a substantial physiological difference. When a worker moves about on just one square meter, the blood flow propulsion mechanisms can work perfectly. An approach to move about ones workstation in a dynamic fashion even if the available space is limited can therefore be part of a prevention approach.
Effects of prolonged sitting
Until now, no specific relationship has been established between prolonged sitting and MSD complaints in lower limbs. One review found contradictory evidence of a link, concluding that there was plausible, but limited evidence to support prolonged sitting as a risk factor, particularly for knee and ankle injuries, and prolonged sitting or sitting in an awkward posture for hip pain. However, given the clear association of lower limb disorders with prolonged standing, sitting is suggested as a preventive measure. Musculoskeletal health effects related to prolonged static sitting that do occur are low back pain and neck- shoulder complaints. Therefore, prolonged sitting should be avoided.
Psychosocial risk factors
Factors potentially contributing to the development of MSDs include some psychosocial and organisational factors in the workplace. Low satisfaction with social relationships at work, lack of control over work, feeling exhausted after work and work content are the psychosocial risk factors most likely to impact on lower limb disorders.
Workers at risk
Types of tasks and jobs at risk
- Any job that includes prolonged standing for more than 1 hours continuously or more than 4 hours a day.
- Workers in occupations that include tasks which specifically strain the lower limbs, such as, fire fighters, farmers, construction workers, forestry workers, miners, carpet and floor layers and tillers, athletes and military (combatant) personnel.
- Tasks where workers stand in one place for long periods (over 1 hour without getting away from the workstation and over 4 hours a day), such as hairdressers and barbers, assembly line workers, industrial workers, sales workers, cashiers, nursing and health care workers.
- Jobs where workers have to kneel or squat. The risks are found to be higher when kneeling/squatting is sustained for at least half an hour, or it occurs intermittently (on two or more occasions) for more than 2 hours a day, such as in construction work, service work, floor and carpet laying and tilling, metal industries, shipbuilding, turbine manufacturing, aircraft manufacturing.
- Jobs that include long walking distances (>two miles a day), such as the work of: postal workers, nurses, garbage collectors, order pickers, security guards.
- Climbing steps and/or ladders - a risk factor for the development of hip and knee MSDs. Studies suggest that these risks are high when the activity occurs more than 30 times a day or 10 times in an hour, or when more than 30 flights of steps/rungs of ladder are traversed at a single time.
- Lifting loads, particularly those weighing more than 20 kilograms - indicated in several studies as a risk factor for hip and knee MSDs, although this is more the case for males than females.
- Drivers - at risk when they drive long hours at a time (over 4 hours) and because of jumping down from vehicles from a height greater than 1 meter from the ground1. By jumping out, the body has to absorb the impact of the landing. This adds up to absorbing five times the body weight due to the fall speed. The lower back, knees and ankles are at risk of damage.
- Any job that includes prolonged sitting for more than 2 hours continuously or more than 5 hours a day, however this concerns other types of health effects rather than lower limb MSDs.
Specific groups at risk
- Experience: Inexperienced workers’ are more at risk in the early years of their employment (0-5 years). Many years of working is a risk for experienced workers, where cumulative exposure to lower limb hazards across working life is likely to play a role.
- Gender: There is no evidence that gender per se is a significant factor for the development of lower limb MSDs, except that men and women are highly segregated into different types of work where they are exposed to different hazards. Likewise, regarding lower limb MSDs the type of job can explain some gender differences in the type and frequency of disorders. Women are more often employed in occupations where prolonged static standing occurs, such as assembly line work, hairdresser and nurse. When men have to stand to work this is more likely to involve walking than static standing, such as warehouse work. Women are therefore more likely to suffer from leg and foot complaints. Men are more employed as carpet layers, for example, where knee disorders are prevalent. Men are also more likely to climb ladders as part of their work, or as lorry drivers where they may harm themselves by jumping down from their vehicles, both of which are associated with knee injuries.
- Educational level: Workers with a lower educational level and migrant workers are more at risk because they tend to perform higher risk jobs (e.g. production lines, cleaning jobs, harvesting in agricultural jobs).
Lower Limb MSDs at work affect the hips, knees and legs and usually occur because of overstrain. Workers may report lower limb pain, tenderness or stiffness of joints, being unable to straighten or bend those joints. Tenderness, aches and pains, stiffness, weakness, tingling, numbness, cramp and swelling to the muscles of the lower limbs are symptoms that suggest overstrain or an underlying condition. In most cases no specific type of MSD is identified.
Scientific evidence indicates that there are several recognised diseases of the lower limb, which can be work-related such as: hip and knee osteoarthritis; knee bursitis, meniscal lesions/tears; stress fracture/reaction injury and varicose veins of the lower legs.
Examples of specific conditions
Lower limb disorders for which there is evidence linking them to work include:
- Osteoarthritis: Osteoarthritis is the most common type of arthritis and causes stiffness of the joints as their cartilage coating becomes damaged or worn. Osteoarthritis is most common in the back, knees and hips. In cases of hip osteoarthritis, symptoms often start with the appearance of pain in the groin area since the hip joint is located below the groin, Hip osteoarthritis is a particular risk for farmers. Knee osteoarthritis is a risk for miners, floor layers and cleaners and being overweight increases the risk.
- Knee bursitis: Knee bursitis causes painful, swollen or tender knees and is caused by repetitive or extended periods of kneeling or activities that strain the knees. It is common in people who spend long periods of time kneeling, for example, carpet fitters, concrete finishers and roofers. It is also known as housemaid’s knee because housemaids historically spent long periods of time on their knees scrubbing floors. Beat knee or hyperkeratosis is the thickening of the skin over the knee due to pressure. It is an acute and extreme form of bursitis and is common among those regularly involved in knee-straining activities, such as kneeling and squatting.
- Meniscal lesions/ tear damage: If the knee is bent or twisted while bearing a load, the force may cause meniscal lesions or damage to occur. Overstrain trauma, for example repetitive squatting or kneeling, can also cause meniscus injury or damage.
- Stress fracture/stress reaction injuries: Stress fractures and reaction injuries are the result of repeated micro-injuries to bone, typically found in those who regularly undertake marching or stamping of the feet. They are more common in people undergoing military training and in athletes, particularly long-distance runners.
- Varicose veins: Varicose veins are any dilated subcutaneous veins of the leg. Workers may complain of feelings of heaviness and pain, a sensation of swelling of the legs, nighttime calf cramps and restless legs. These complaints can increase during the day, especially after prolonged standing. Those who are pregnant or overweight are at increased risk of developing varicose veins. Varicose risk also increases in old age.
What employers can do
Lower limb MSDs are a major cause of sickness absence accounting for, on average, 25 days' absence per incident. By managing the risks, you can reduce the number of people taking sickness absence and also the average length of each absence.
- Determine, as part of your risk assessment, what the physical load of specific tasks is. Use the checklist for prevention of lower limb disorders as a first step of your risk assessment.
- Reduce the requirement for load-bearing where there is likely to be pressure on the joints
- Workplace redesign/modification interventions can help prevent and control lower limb MSDs in the workplace, particularly when the worker is thereby encouraged to adopt optimal work postures and to exert reduced levels of tasks forces. A good workplace design starts with determining whether the work must be carried out standing or sitting. Furthermore, the work and the health design guidelines must be taken into account.
- Providing mechanical aids, e.g. for manual handling and repetitive tasks;
- Providing adjustable height equipment, e.g. tables. This helps avoid awkward postures when working, important for avoiding work-related MSDs in general, not just lower limb disorders.
- Using staff rotation to lessen the time spent carrying out 'risky' tasks;
- Make sure your workers take regular breaks and encourage them to take micro breaks.
- Providing seating, where possible, rather than squatting or kneeling and to avoid long periods standing.
- Provide personal protective equipment such as:
- Anti-fatigue matting. There is some evidence that anti-fatigue matting may be effective in reducing the risks from prolonged standing. However, the use of mats in the workplace requires careful consideration because of the increased risk from slips and trips.
- Shock absorbing insoles and modified shoes: there is limited evidence that using these aids reduces the risk. The positive effects are mainly in respect of injuries from vertical impact loads.
- Knee pads – if correctly selected for the type of work and correctly used – can be useful for protection against bursitis when kneeling on hard surfaces. Although they do not reduce the risk of extreme knee inflexion.
- Introduce new working methods which require the workers to move instead of standing or sitting.
- Create a dynamic workplace where sitting less and moving more is the norm. Equally, it is important to avoid prolonged static standing. The Beupstanding toolkit is designed to raise awareness about prolonged standing and sitting.
- Introduce worksite exercise interventions .
- Create an environment and culture that supports physical activity, healthy eating and a healthier weight and encourage the behavioural change of workers.
- Stimulate participation in sport and leisure activities to avoid inactivity.
- Train workers in safe work methods, e.g. not jumping out of lorry cabs. Encourage workers to report any symptoms early. Involve workers in hazard identification and implementing measures to reduce risks.
What workers should be aware of (symptoms)
If you think you may be suffering from a lower limb disorder that may be caused or aggravated by your work, there are things you can do to help yourself and assist your employer in helping you.
What to look for
The symptoms you should be particularly aware of are:
- Stiffness, pain
- Increase of local temperature and swelling
- Restricted joint movement
What the worker can do
- Report symptoms to your employer early. It is important that you report any symptoms as soon as possible because help could be available and early intervention often prevents further damage. By reporting symptoms early, your employer can assess whether there is a problem and may want to observe your job. Other workers may be experiencing similar problems and, unless you tell someone, the problem may not be realised.
- Pay attention to your working posture and adjust your working environment so that your work becomes less demanding.
- Change posture and take breaks, even if very short, as often as possible.
- Ask for medical assistance. If your workplace does not have access to this type of support, you should see your doctor to explain your symptoms and the type of work that you do. Although they may or may not be able to diagnose your condition, they can provide some help and advice or may refer you to a specialist health professional – especially if some form of clinical intervention is required.
- At your workplace adaptations may be needed, for example to your working station, the tools/equipment you use or the way your work is organised. A usually starting point is to look at possibilities for alternating sitting, standing and look at possibilities to work with a stool where standing is needed. To work in a dynamic and not static way is usually a very good idea.
- These changes may be permanent and apply to a group of workers, or could be temporary and specific to you as an individual when dealing with a current problem or recovering from your symptoms. Another option is to rotate (heavy load) tasks and types of work between workers.
- Improve your lifestyle. Healthier people are more resistant to the possible health effects of work.
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