Work Related Musculoskeletal Disorders
Physical Factors in Work Place and Ergonomics
Prof. Dr. Selma KARABEYWork-related musculoskeletal disorders (WMSDs) are a group of painful disorders of muscles, tendons, and nerves. low back pain, neck pain carpal tunnel syndrome, tendonitis, thoracic outlet syndrome, tension neck syndrome, WMSDs are very difficult to define within traditional disease classifications. These disorders have received many names, such as:
Repetitive motion injuries. Repetitive strain injuries. Cumulative trauma disorders. Occupational cervicobrachial disorders. Overuse syndrome. Regional musculoskeletal disorders. Soft tissue disorders.MSDs are the single largest category of work-related illness, representing a third or more of all registered occupational diseases in the United States, the Nordic countries, and Japan.MSDs occur in certain industries and occupations with rates up to three or four times higher than the overall frequency.
4What are the risk factors for WMSDs?WMSDs arise from arm and hand movements such as bending, straightening, gripping, holding, twisting, clenching and reaching.These common movements are not particularly harmful in the ordinary activities of daily life. WMSDs are associated with work patterns that include:
Fixed or constrained body positions. Continual repetition of movements. Force concentrated on small parts of the body, such as the hand or wrist. A pace of work that does not allow sufficient recovery between movements.
Generally, none of these factors acts separately to cause WMSD. WMSDs commonly occur as a result of a combination and interaction among them.Bending (kvrmak, bkmek) straightening (dzeltmek, dorultmak), gripping (skma, kavrama), holding(tutmak,kaldrmak), twisting (burma,dndrme), clenching (skmak,perinlemek) and reaching (uzatmak,uzanmak)Heat, cold and vibration also contribute to the development of WMSD.5 High-risk sectors include nursing facilities;air transportation; mining; food processing;leather tanning; and heavy and light manufacturing(vehicles, furniture, appliances, electrical and electronic products, textiles, apparel and shoes)
Numerous risk factors including occupational, individual and social factors may be involved in the development of MSDs. The workrelated risk factors include physical demands such as handling heavy loads, repetitive movements, forceful exertion, vibration, and maintaining awkward postures. The effects of these factors depend on their duration, frequency, and intensity. Each of these physical demands may also contribute to the aggravation or recurrence of MSDs. Factors related to work organization (schedule, work pace, work environment, psychosocial, etc.) may influence physical work demands and may also be risk factors for MSDs. Individual factors (age, height, health status, level of physical fitness, etc.) may also contribute. However, exposure to a specific risk factor does not necessarily result in the development of an MSD, and the full range of factors must be taken into account when attempting to establish the cause of these disorders. For example, A particularly forceful exertion, performed in a poor posture, may be sufficient to cause a musculoskeletal problem, even if the rate of repetition is low.Conversely, a movement that does not require much force, performed in an acceptable posture, can become harmful if it is repeated thousandsof times. (Simoneau et al., 1996).6Upper extremity musculoskeletal disorders are also highly prevalent in manual-intensive occupations, such asclerical work, postal service, cleaning, industrial inspectionand packaging.
Back and lower limb disorders occur disproportionately among truck drivers, Warehouse workers, airplane baggage handlers, Construction trades, nurses, nursing aides and other patient-care workers,operators of cranes and other large vehicles
A series of motions performed every few seconds with little variation may produce fatigue and muscle-tendon strain.If adequate recovery time is not allowed for these effects to diminish, or if the motions also involve awkward postures or forceful exertions, the risk of actual tissue damage and other musculoskeleteal problems will probably increase.A task cycle time of less than 30 sec has been considered as repetitive. Estimates vary as to repetition rates that may pose a hazard, because other factors, such as force and posture, also affect these determinations.One proposal for defining high risk repetition rates for different body parts is shhown in the chart in Tray 6-B9
Cumulative and repetitive motion injuries, also described as musculoskeletal disorders (MSDs), occur when the body reacts to strenuous motion (i.e., bending, climbing, crawling, reaching, twisting), overexertion, or repetitive motion. MSD injuries include sprains (burkma), strains (incinme), tears (yrtlma,kopma), back pain, soreness (ar), carpal tunnel syndrome, hernia, and musculoskeletal system and connective diseases. MSD cases are more severe than the average nonfatal workplace injury or illness, typically involving an average of 2 additional days away from work.5 In 2007, the median number of days away from work for all workplace injuries was 7 days; for MSD injuries, the median was 9 days. In addition to MSD injuries as defi ned above, musculoskeletal workplace injuries include fractures, bruises/contusions (ezilme-berelenme), and amputations.Although the rate of nonfatal occupational injuries and illnesses has decreased over the past 15 years, the relative percentage of MSD cases fl uctuatedwithin a narrow range of 30% to 34% from 1992 to 2006. In 2007, the ratio dropped below 30% for the first time (29%).10
The distribution of MSD injuries by type of injury has remained essentially constant over the past six years, as has the distribution between males (62%-6 Slightly more than one-half (56%) of all sprain, strain, and tear injuries resulting in days away from work in 2007 were classified as an MSD injury. Although sprains, strains and tears represent about 40% of total workplace injuries and illnesses involving days away from work, they represent three-fourths (75.3%) of all MSD injuries. Back pain, carpal tunnel syndrome, tendinitis, soreness and pain (other than back pain), and a range of other conditions comprise the remaining MSD injuries.11 Low back pain
The best predictor of low back pain is a history of low back pain.First episodes occur among persons in the age range 20-39 years.But the proportion of the population is relatively uniform across the working years.It is seen more frequently among males than females in Western countriesBut in surveys in the general population, males and females are affected with equal frequency.Persons in lower social classes are more likely to report low back pain than those in higher classes,Probably because of their tendency to have jobs requiring heavy physical labour.Worldwide at least 37 percent of low back pain has been attributed to occupational factors (Punnett et al.2005)The prevalence of low back pain is also high in low income areas of the world.
In a community based study in rural China , the percentage having low back pain during the course of a year was 65 per cent (Barrero et al. 2006) It was 61 per cent for tannery workers in India (ry et al. 1997)56 per cent in steel industry in South Africa (Van Vuuren et al. 2005)36 per cent in an urban population in Turkey (Gilgil et al. 2005)
Lifting objects of 25 Ib or more Lifting of heavy objects while bending and twisting the bodyHolding heavy objects from the body while liftingFailing to bend the knees while lifting.Driving motor vehicles either on or of the jobExposure to whole-body vibration increase the risk for the low back pain
Sitting in combination with other exposures such as whole body vibration and awkward posture increases the risk for low back pain Cigarette smoking has been found in many studies to be associated with low back painPsychological attributes such as low social support in the workplace and low job satisfaction may increase risk.
Many risk factors in middle and low income countries are similar to those high income countries.In rural China, having been a farmer , reporting moderate or heavy physical stress andBeing exposed to vibration were associated with low back pain (Barrero et al.2006)In urban Turkey, cigarette smoking was related to the occurrence of low back pain. (Gilgil et al. 2005) Estimating the global burden of