Musculoskeletal disorders in farmers and farm workers

All-terrain vehicle use in agriculture: exposure to whole body vibration and mechanical shock

Whole body vibration (WBV) and mechanical shock were measured in 12 New Zealand farmers during their daily use of all-terrain vehicles (ATVs). As per the International Organization for Standardization (ISO) guidelines for WBV exposure, frequencies between 0 and 100Hz were recorded via a seat-pad tri-axial accelerometer during 20min of ATV use. The farmers were also surveyed to estimate seasonal variation in daily ATV usage as well as 7-day and 12-month prevalence of spinal pain. Frequency-weighted vibration exposure and total riding time were calculated to determine the daily vibration dose value (VDV). The daily VDV of 16.6m/s(1.75) was in excess of the 9.1m/s(1.75) action limit set by ISO guidelines suggesting an increased risk of low back injury from such exposure. However, the mean shock factor R, representing cumulative adverse health effects, was 0.31 indicating that these farmers were not exposed to excessive doses of mechanical shock. Extrapolation of daily VDV data to estimated seasonal variations of farmers in ATV riding time demonstrated that all participants would exceed the ISO recommended maximum permissible limits during the spring lambing season, as compared to lower exposures calculated for summer, autumn and winter. Low back pain was the most commonly reported complaint for both 7 day (50%) and 12 month prevalence (67%), followed by the neck (17% and 42%) and the upper back (17% and 25%) respectively. The results demonstrate high levels of vibration exposure within New Zealand farmers and practical recommendations are needed to reduce their exposure to WBV.

Medically reported work-related ill-health in the UK agricultural sector

BACKGROUND

Self-reported work-related ill-health (WRI) statistics suggest that agricultural workers in the UK are at an increased risk of musculoskeletal disorders (MSD), skin and respiratory disease. However, there is little comprehensive medically reported information on WRI in the UK agricultural sector.

METHODS

Cases of WRI within the UK from 2002 to 2008, as reported to The Health and Occupation Reporting (THOR) network by occupational physicians, clinical specialists and general practitioners, were analysed. Directly standardized incidence rate ratios (SRRs) for the agricultural sector versus all other sectors were calculated for dermatological, musculoskeletal, respiratory and psychological illness, using as the standard population the UK working population as estimated from the Labour Force Survey.

RESULTS

During 2002-08, 471 cases within the agricultural sector were reported to THOR (2% of all cases). Based on reports by clinical specialists, male agricultural workers aged <65 years had significantly raised SRRs for MSD (2.3, 95% CI 1.6-3.3), allergic alveolitis (32, 95% CI 19-51), asthma (1.9, 95% CI 1.2-3.0) and skin neoplasia (7.9, 95% CI 5.8-10.9) and a significantly reduced SRR for asbestos-related respiratory disease (0.4, 95% CI 0.2-0.7). Reports of mental ill-health in agricultural workers were low.

CONCLUSIONS

These medically reported incidence data provide information on WRI in the UK agricultural sector. Consistent with other sources, there are increased risks for asthma, allergic alveolitis and MSD and a reduced risk for mental ill-health. The raised incidence of skin cancer requires confirmation and further comparison with reliable estimates of the incidence in the UK workforce.

Neck pain combined with arm pain among professional drivers of forest machines and the association with whole-body vibration exposure

The purpose of this study was to investigate the existence of neck pain and arm pain among professional forest machine drivers and to find out if pain were related to their whole-body vibration (WBV) exposure. A self-administered questionnaire was sent to 529 forest machine drivers in northern Sweden and the response was 63%. Two pain groups were formed; 1) neck pain; 2) neck pain combined with arm pain. From WBV exposure data (recent measurements made according to ISO 2631-1, available information from reports) and from the self-administered questionnaire, 14 various WBV exposure/dose measures were calculated for each driver. The prevalence of neck pain reported both for the previous 12 months and for the previous 7 d was 34% and more than half of them reported neck pain combined with pain in one or both arms. Analysis showed no significant association between neck pain and high WBV exposure; however, cases with neck pain more often experienced shocks and jolts in the vehicle as uncomfortable. There was no significant association between the 14 WBV measures and type of neck pain (neck pain vs. neck pain combined with arm pain). It seems as if characteristics of WBV exposure can explain neither existence nor the type of neck pain amongst professional drivers of forest machines. The logging industry is important for several industrialised countries. Drivers of forest machines frequently report neuromusculoskeletal pain from the neck. The type of neck pain is important for the decision of treatment modality and may be associated with exposure characteristics at work.

Self-reported back pain among farm women in southeast Louisiana

This cross-sectional survey details the incidence and predictors of self-reported back pain among farm women from southeastern Louisiana. The sample was obtained from a preexisting data set of a cross-sectional randomized sample of farm women who participated in the Louisiana Farm Family Injury Prevention and Health Initiative research project. The Haddon Injury Model was used as the conceptual framework. Approximately one fourth of the women in the sample reported back pain in the past year. The major findings from logistic regression analysis were that women reported back pain if they were hauling animals to market and had physical health conditions. Implications for nursing practice include assessing the risk of back pain among farm women and providing client education that includes the importance of compliance with recommended health screenings for early detection and treatment of physical health conditions associated with back pain.

Prevalence and changes in chronic diseases among South Korean farmers: 1998 to 2005

Background

Epidemiologic studies have suggested a unique pattern of disease among farmers in Western countries, but limited information is available about the magnitude of disease prevalence and their changes over time in Asian farmers. The aim of this study was to compare the prevalence and changes in chronic diseases among farmers with those of other occupational groups in South Korea.

Methods

Using data from three consecutive cross-sectional national surveys: the Korean National Health and Nutrition Examination Survey 1998 (n = 39,060), 2001 (n = 37,769), and 2005 (n = 34,145), we calculated age and gender-standardized prevalence of chronic diseases by the direct method and compared the prevalence changes from 1998 to 2005.

Results

Female farmers had significantly higher chronic disease prevalence than other occupational groups in all three surveys. Arthritis was the most prevalent chronic disease among farmers for both men and women. Compared with other populations, farmers demonstrated a higher prevalence of arthritis and intervertebral disc disorders. Farmers showed higher prevalence changes for intervertebral disc disorders than other occupational workers.

Conclusion

Our findings support that South Korean farmers have a distinct pattern of diseases prevalence from other populations. More detailed studies investigating the risk of musculoskeletal diseases and intensive intervention efforts to reduce the prevalence these diseases, particularly among female farmers, are required.

Self-Reported Back Pain among Farm Women in Southeast Louisiana

This cross-sectional survey details the incidence and predictors of self-reported back pain among farm women from southeastern Louisiana. The sample was obtained from a preexisting data set of a cross-sectional randomized sample of farm women who participated in the Louisiana Farm Family Injury Prevention and Health Initiative research project. The Haddon Injury Model was used as the conceptual framework. Approximately one fourth of the women in the sample reported back pain in the past year. The major findings from logistic regression analysis were that women reported back pain if they were hauling animals to market and had physical health conditions. Implications for nursing practice include assessing the risk of back pain among farm women and providing client education that includes the importance of compliance with recommended health screenings for early detection and treatment of physical health conditions associated with back pain.

Ache, Pain, and Discomfort

The main purpose of the study was to investigate the prevalence of perceived symptoms of musculoskeletal disorders (MSD) among workers on large-scale dairy and pig farms in Sweden (herd size more than 300 cows and 450 sows) and to identify potential risk factors in the development of MSD. A study based on questionnaires was carried out among 42 workers on 10 large dairy farms and among 37 workers on 10 large pig farms in Southern Sweden during the autumn of 2002. Most importantly, the study showed that 86% of the dairy workers and 78% of the pig workers reported some kind of MSD during a period of 12 months prior to the study. The most frequently reported MSD among both the dairy and the pig workers were in the "upper extremities" (52% and 62%, respectively) especially in the shoulders and in "the back" (60% and 57%, respectively) especially in the lower back. Furthermore, being of short stature, doing repetitive work, working in awkward positions and being exposed to dust were significant risk factors in having MSD among the workers in this study. Thus, working with many cows and sows on large-scale farms in Sweden can be considered as a high risk job with regard to MSD.

Ethnic, racial, and gender variations in health among farm operators in the United States

PURPOSE

The purpose of this study was to collect baseline prevalence data on the health problems faced by minority, white, and female farm operators.

METHODS

An occupational health survey of farm operators was conducted by the U.S. Department of Agriculture, National Agricultural Statistics Service between February and August 2000. A stratified random sample of farm operators from 50 U.S. states based on the 1997 Census of Agriculture was selected for telephone interview. Interviews were primarily conducted using a computer assisted telephone instrument system.

RESULTS

Population prevalences were calculated for 7137 farm operators. Prevalences were greatest for musculoskeletal discomfort, followed by respiratory problems, hearing loss, and hypertension. Generally, Latino and Asian American operators had lower prevalences for health problems than white non-Latino and white operators, respectively. African-American operators had greater prevalences for hypertension, and osteoarthritis, but lower prevalences for hearing loss, skin problems, heart problems, and cancer than white operators. American Indian or Alaska Native operators had higher prevalences for musculoskeletal problems, skin problems, and hypertension.

CONCLUSIONS

Prevalences for the different ethnicity and race groups are not the same. Studies that combine racial and ethnic groups, or study only white and non-Latino farm operators may overestimate or underestimate the prevalence of health conditions in the entire farm operator population.

The impact of operating heavy equipment vehicles on lower back disorders

Literature reviews examining the relationship between heavy equipment vehicle (HEV) operation and the development of musculoskeletal disorders have generally been qualitative in nature and have not employed an evidence-based assessment procedure. This research determines the extent to which whole-body vibration/shock and working postures are associated with lower back and neck disorders among HEV operators, while accounting for individual (i.e. age, gender, prior history of back or neck disorders) and occupational (i.e. material handling, climatic conditions, psychosocial factors) confounders. Published articles were obtained from a search of electronic databases and from bibliographies in the identified articles. A critical appraisal of these articles was conducted using an epidemiological appraisal instrument (Genaidy et al. 2007). The meta-analysis was conducted using statistical techniques employing fixed-effect and random-effect models. Eighteen articles reporting observational studies satisfied the inclusion criteria adopted for this research. The methodological qualities of the published studies ranged from marginal to average. The meta-relative risk was found to be 2.21, indicating that operators exposed to driving HEVs are at more than twice the risk of developing lower back pain in comparison to those not exposed to driving HEVs. Therefore, it seems possible that there is a causal relationship between working as a HEV operator and development of lower back disorders. Prospective cohort studies are urgently needed to confirm the outcomes of this evidence-based methodology (based in part on the meta-analysis) and the biological plausibility should be further explored. The reported findings point to a need for improved ergonomic design of HEVs.

Individual and occupational risk factors for knee osteoarthritis - study protocol of a case control study

Background

Knee osteoarthritis (OA) is one of the frequent and functionally impairing disorders of the musculoskeletal system. In the literature, a number of occupational risk factors are discussed as being related to the development and progress of knee joint diseases, e.g. working in kneeling or squatting posture, lifting and carrying of heavy weights. The importance of the single risk factors and the possibility of prevention are currently under discussion. Besides the occupational factors, a number of individual risk factors are important, too. The distinction between work-related factors and individual factors is crucial in assessing the risk and in deriving preventive measures in occupational health. In existing studies, the occupational stress is determined mainly by surveys in employees and/or by making assumptions about individual occupations. Direct evaluation of occupational exposure has been performed only exceptionally.

The aim of the research project ArGon is the assessment of different occupational factors in relation to individual factors (e.g. constitutional factors, leisure time activities, sports), which might influence the development and/or progression of knee (OA). The project is designed as a case control study.

Methods/Design

To raise valid data about the physical stress associated with occupational and leisure time activities, patients with and without knee OA are questioned by means of a standardised questionnaire and an interview. The required sample size was estimated to 800 cases and an equal number of controls. The degree and localisation of the knee cartilage or joint damages in the cases are documented on the basis of radiological, arthroscopic and/or operative findings in a patient record. Furthermore, occupational exposure is analysed at selected workplaces. To evaluate the answers provided in the questionnaire, work analysis is performed.

Discussion

In this research project, specific information on the correlation of occupational and individual factors on the one hand and the current state of knee OA on the other will be analysed in order to describe preventive measures. In addition, information regarding a better evaluation of various forms of physical stress in different occupations will be available. This might lead to more effective prevention strategies.

Ground Reaction Forces during Human Locomotion on Railroad Ballast

Locomotion over ballast surfaces provides a unique situation for investigating the biomechanics of gait. Although much research has focused on level and sloped walking on a smooth, firm surface in order to understand the common kinematic and kinetic variables associated with human locomotion, the literature currently provides few if any discussions regarding the dynamics of locomotion on surfaces that are either rocky or uneven. The purpose of this study was to investigate a method for using force plates to measure the ground reaction forces (GRFs) during gait on ballast. Ballast is a construction aggregate of unsymmetrical rock used in industry for the purpose of forming track bed on which railway ties are laid or in yards where railroad cars are stored. It is used to facilitate the drainage of water and to create even running surfaces. To construct the experimental ballast surfaces, 31.75-mm (1¼-in.) marble ballast at depths of approximately 63.5 mm (2.5 in.) or 101.6 mm (4 in.) were spread over a carpeted vinyl tile walkway specially designed for gait studies. GRF magnitudes and time histories from a force plate were collected under normal smooth surface and under both ballast surface conditions for five subjects. GRF magnitudes and time histories during smooth surface walking were similar to GRF magnitudes and time histories from the two ballast surface conditions. The data presented here demonstrate the feasibility of using a force plate system to expand the scope of biomechanical analyses of locomotion on ballast surfaces.

Understanding the ergonomic risk for musculoskeletal disorders in the United States agricultural sector

INTRODUCTION

Farming is a very large industry in the United States. Understanding the risks for injuries and more specifically musculoskeletal disorders in this industry poses a challenge for health officials.

METHODS

A review was conducted of the existing peer-reviewed publications prior to December 2006 about injuries and musculoskeletal disorders for farmers and farm workers. The aim was to review existing knowledge concerning: (1) the prevalence, types, and causes of farm-related injuries, paying particular attention to musculoskeletal disorders and the special populations within the agricultural sector, and (2) interventions that have been developed to reduce risk factors associated with farm-related injuries.

RESULTS

Farmers and farm workers experience high rates of low back, shoulder, and upper extremity disorders. Musculoskeletal disorders may disproportionately affect farm youth and migrant workers due to the types of farm tasks performed. There is an urgent need for improved and validated interventions to reduce exposures and to improve the health of farmers and farm workers.

DISCUSSION

Future farm-related musculoskeletal disorder research should emphasize: (1) better identification of exposures for special populations, (2) development of interventions for diverse farm populations, and (3) identification of additional exposures for musculoskeletal disorders. Inadequate understanding of musculoskeletal disorders in farming impedes efforts to prevent this common and important type of occupational injuries on farms.

Public health perspective--how to improve the musculoskeletal health of the population

Musculoskeletal disorders are the most common cause of long-term sick leave in several western countries and individuals with chronic musculoskeletal pain score very low on health status measurements. Musculoskeletal health is multidimensional and is best understood from a biopsychosocial perspective. Body structure and function interacts with personal and environmental factors, affecting the ability to perform activities and participate in society. Interventions aimed at the whole population must attend to the underlying causes of musculoskeletal disorders and promote a healthy lifestyle. Safe environments and activities could reduce the risk of traumatic events and also make participation possible for those with a disability. Public beliefs about musculoskeletal symptoms and consequences need to be changed in order to minimise fear and avoidance, which, together with other psychosocial factors, could lead to chronicity. Public awareness and identification of those at risk for the development of musculoskeletal problems could lead to early and properly timed management.

Prevalence and physical determinants of low back pain in a rural Chinese population

STUDY DESIGN

This was a community-based cross-sectional study that is part of an ongoing study of genetics and osteoporosis.

OBJECTIVES

To estimate the 1-year self-reported prevalence of low back pain (LBP); and to assess the association between physical exposures (occupation, physical stress, and vibration) and LBP in a rural Chinese population. This study also explored how these associations change when individuals with LBP report additional pains in other parts of the body.

SUMMARY OF BACKGROUND DATA

Little is known about the prevalence and determinants of LBP in rural developing populations, even though approximately half of the world's population, mostly from the developing world, is engaged in agriculture, a known strenuous activity.

METHODS

Families with at least three participating siblings residing in the surrounding rural region of Anqing city, Anhui Province, China, were invited to participate in the study through public announcements and direct invitations by village physicians. A questionnaire including demographics, physical exposures, and musculoskeletal pain was administered to 13,965 men and women (age, 25-64 years). Generalized estimating equations were used to estimate LBP prevalence and examine associations between LBP and physical exposures.

RESULTS

The 1-year prevalence of LBP was 64%. Twenty-five percent reported no pain at any body site. Women had higher prevalence of LBP than men across all age groups. Being a farmer, reporting moderate or heavy physical stress, and having had former or current exposures to vibration were positively associated with LBP (P < 0.05). Physical exposures were also associated with cases of LBP combined with other musculoskeletal pains, and generally, the more pains individuals reported, the more likely it was that they were farmers and were exposed to vibration.

CONCLUSION

A high prevalence of LBP and LBP with additional musculoskeletal pain existed in this rural Chinese sample. We found evidence of a link between physical exposures and LBP, and LBP with additional musculoskeletal pain. Further understanding of the characteristics and risk factors of LBP in rural developing areas is needed.

Severe back pain among farmworker high school students from Starr County, Texas: baseline results

PURPOSE

This cohort study is among the first to estimate the prevalence of and examine potential risk factors for severe back pain (resulting in medical care, 4+ hours of time lost, or pain lasting 1+ weeks) among adolescent farmworkers. These youth often perform tasks requiring bent/stooped postures and heavy lifting.

METHODS

Of 2536 students who participated (response rate across the three public high schools, 61.2% to 83.9%), 410 students were farmworkers (largely Hispanic and migrant). Students completed a self-administered Web-based survey including farm work/nonfarm work and back-pain items relating to a 9-month period.

RESULTS

The prevalence of severe back pain was 15.7% among farmworkers and 12.4% among nonworkers. The prevalence increased to 19.1% among farm workers (n = 131) who also did nonfarm work. A multiple logistic regression for farmworkers showed that significantly increased adjusted odds ratios for severe back pain were female sex (4.59); prior accident/back injury (9.04); feeling tense, stressed, or anxious sometimes/often (4.11); lifting/carrying heavy objects not at work (2.98); current tobacco use (2.79); 6+ years involved in migrant farm work (5.02); working with/around knives (3.87); and working on corn crops (3.40).

CONCLUSIONS

Areas for further research include ergonomic exposure assessments and examining the effects of doing farm work and nonfarm work simultaneously.

Osteoarthritis of the knee and hip and activity: a systematic international review and synthesis (OASIS)

The goal of this study was to determine which activities in four domains, daily life, exercises, sports and occupational activities, should be recommended, in favor or against, for the patient suffering from knee or hip OA.

METHODS

Scientific literature was searched in Medline, Embase and Cochrane databases for articles in French or English, reporting original data. The articles were evaluated with standardized epidemiological criteria. Seventy-two articles were retained. Recommendations were graded according to the level of scientific evidence (A high, B moderate, C clinical consensus) and were formulated for primary care.

CONCLUSIONS AND RECOMMENDATIONS

For activity of daily life (ADL), the OASIS group states with a moderate level of scientific evidence, that ADL are a risk factor for knee OA and that risk increases with intensity and duration of activity. The group concludes that healthy subjects as well as OA patients in general can pursue a high level of physical activity, provided the activity is not painful and does not predispose to trauma (grade B). Radiographic or clinical OA is not a contraindication to promoting activity in patients who have a sedentary lifestyle (grade C). For exercises and other structured activities pursued with a goal of health improvement, the group states with a high level of scientific evidence that they have a favourable effect on pain and function in the sedentary knee OA patient. The OASIS group recommends the practice of exercises and other structured activities for the sedentary patient with knee OA (grade A). Static exercises are not favored over dynamic exercises, availability, preference and tolerance being the criteria for the choice of an exercise (grade A). As results deteriorate when exercises are stopped, they should be performed at a frequency of between one and three times per week (grade B). Professional assistance can be useful in improving initial compliance and perseverance (grade B). There is no scientific argument to support halting exercise in case of an OA flare-up (grade C). For sports and recreational activity, the group states with a high degree of scientific evidence, that these activities are a risk factor for knee and hip OA and that the risk correlates with intensity and duration of exposure. The group also states, with a high degree of scientific evidence, that the risk of OA associated with sport is lesser than that associated with a history of trauma and overweight. No firm conclusion could be drawn about the possible protective role of sports such as cycling, swimming or golf. The OASIS group recommends that athletes should be informed that joint trauma is a greater risk factor than the practice of sport (Grade A). The high level athlete should be informed that the risk of OA is associated with the duration and intensity of exposure (Grade B). The OA patient can continue to engage regularly in recreational sports as long as the activity does not cause pain (Grade C). The OA patient who practices a sport at risk for joint trauma should be encouraged to change sport (Grade C). For occupational activity, the OASIS group states with a high level of scientific evidence that there is a relationship between occupational activity and OA of the knee and hip. The precise nature of biomechanical stresses leading to OA remains unclear but factors such as high loads on the joint, unnatural body position, heavy lifting, climbing and jumping may contribute to knee and hip OA. The group recommends that taking an occupational history should always be part of managing the OA patient (Grade B). In the knee or hip OA patient, work-related activity that produces or maintains pain should be avoided (Grade B). Physicians should be alerted by the early knee and hip signs and symptoms in workers exposed to stresses that are known or supposed to favour knee or hip OA (Grade C).

Child labor in Ghana cocoa production: focus upon agricultural tasks, ergonomic exposures, and associated injuries and illnesses

OBJECTIVES

The goal of this study was to determine the occupational hazards experienced by children harvesting cocoa in western Ghana in order to design a vocational literacy life skills curriculum and radio social messaging campaign with a safety component to decrease hazardous work exposures in child agricultural work.

METHODS

An observational analysis was conducted of children aged 9 through 17 based upon personal interviews of agricultural workers, focus groups, and direct observation of work practices and activities. Job site analysis incorporated task mapping, job hazard review, and a review of equipment and use of protective gear.

RESULTS

Children and young people aged 9 through 17 are exposed to hazardous occupational exposures including strenuous work, sharp tools, and pesticides. Lack of training in proper safety practices and inadequate personal protective equipment were commonly noted. Injuries and illnesses included musculoskeletal disorders, sprains, strains, lacerations to the head, fractures, eye injuries, rashes, and coughing.

CONCLUSION

Children working in cocoa harvesting are exposed to physical and chemical hazards without proper training or personal protective equipment. Unless safety interventions occur, there are potential long-term adverse health consequences.

Primary osteoarthritis of hip, knee, and hand in relation to occupational exposure

AIM

To identify occupations with excess prevalence of osteoarthritis of the knee, hip, and hand in a nationwide survey and to compare occupations with and without excess prevalence with regard to biomechanical stresses and severity of osteoarthritis.

METHODS

Patients presenting with osteoarthritis of the knee, hip, or hand were recruited throughout France by their treating physician who collected information on history, including age at onset, occupation, and occupational stresses to joints. Severity was assessed using joint specific functional status questionnaires: Lequesne for the hip and knee and Dreiser for the hand. The distribution of osteoarthritis patients by occupation was compared with the distribution of occupations in all workers in France to obtain prevalence rate ratios.

RESULTS

Occupations with the greatest prevalence rate ratio were female cleaners (6.2; 95% CI 4.6 to 8.0), women in the clothing industry (5.0; 95% CI 3.9 to 6.3), male masons and other construction workers (2.9; 95% CI 2.6 to 3.3), and agriculture male and female workers (2.8; 95% CI 2.5 to 3.2). A twofold greater prevalence rate was observed within certain occupations between self-employed and salaried workers. Early onset of osteoarthritis was seen in the more heavy labour jobs with almost 40% of patients reporting their first symptoms before the age of 50.

CONCLUSION

The early onset and severity of osteoarthritis in certain occupations warrants an urgent need for occupation specific studies for the development and evaluation of preventive strategies in this leading cause of disability in Western countries.

Chronic disease risk in central New York dairy farmers: results from a large health survey 1989-1999

BACKGROUND

The agricultural workplace presents a variety of health and safety hazards; it is unknown whether farm work may be a risk factor for certain chronic diseases.

METHODS

The health survey data from a large rural population in central New York were used from two studies (1989, 1999) to assess both 1999 prevalence and 10-year incidence of self-reported diabetes, heart disease, hypercholesterolemia, and hypertension among farm (predominantly dairy) and non-farm residents. The 1999 asthma prevalence was also assessed.

RESULTS

Multiple logistic regression models for 1999 prevalence found statistically significant protective effects of farming for hypertension (OR=0.83, P=0.0105) and hypercholesterolemia (OR=0.853, P=0.0522). Non-significant results were seen for heart disease (OR=0.67, P=0.128) and diabetes (OR=0.856, P=0.1358). The model for 1999 asthma prevalence showed a significantly elevated risk for farming (OR=1.542, P=0.0004). Logistic models created for the 10-year incidence of hypertension, hypercholesterolemia, diabetes, and heart disease did not show a significant effect for farming.

CONCLUSIONS

The protective effect of farming observed for the 1999 prevalence of hypertension and hypercholesterolemia was not seen for the 10-year incidence of these diseases.

Static load repetition is a risk factor in the development of lumbar cumulative musculoskeletal disorder

STUDY DESIGN

In vivo feline model subjected to variable number of repetitions of a short static lumbar flexion followed by an equally long rest period.

OBJECTIVES

The purpose of this study was to determine the influence of the number of repetitions as a risk factor in promoting a cumulative low back disorder in the feline model.

SUMMARY OF BACKGROUND DATA

Epidemiologic data point out that the increased number of repetitions of static lumbar loading is a major risk factor in the development of cumulative low back disorder. Biomechanical and physiologic confirmation of the epidemiology is lacking. Recent work demonstrated that repetitive static loading results in accumulation of creep in the lumbar viscoelastic tissues, resulting in a neuromuscular disorder consisting of spasms during loading and hyperexcitability of lumbar muscles during following rest. It was also shown that the load magnitude is a major risk factor. It is hypothesized that increased number of repetitions of static load periods result in increased severity of the resulting neuromuscular disorder.

METHODS

Static lumbar flexion of 10 minutes duration followed by 10 minutes rest was repeated three times in one experimental group, six times in the second, and nine times in the third group. In all groups, the creep developing in the lumbar viscoelastic tissues as well as the reflexive EMG from the multifidus were monitored during the flexion/rest periods and throughout a 7-hour recovery period after the repetitions.

RESULTS

Creep developed and accumulated during each of the flexion/rest periods in the three experimental protocols, with larger residual creep at the end of the nine repetitions. A residual creep was still present at the end of the 7 hours of recovery allowed in each of the three groups. During the flexion/rest sessions, EMG spasms were present, and the presence of an initial hyperexcitability was detected during the 7 hours of recovery in all the preparations. The presence of a delayed hyperexcitability was revealed only in the group subjected to nine flexion/rest periods, while it was not observed in the groups subjected to three and six flexion/rest repetitions. The statistical analysis (post hoc Fisher test) performed on the normalized integrated EMG and displacement data during the recovery phase showed a significant difference between the nine repetitions group and the other two groups (P < 0.0001). The two-way ANOVA analysis revealed a significant effect of time (P < 0.005) and number of repetitions (P < 0.0001) on all considered parameters.

CONCLUSIONS

It was concluded that a cumulative neuromuscular disorder develops because of repetition of static lumbar flexion, and the severity of the disorder provoked is magnified by the number of repetitions. Despite the highly favorable 1:1 work-to-rest ratio and the 7-hour post loading rest period, a full recovery of creep was not obtained in this study.

Psychosocial Factors and Low Back Pain, Consultations, and Sick Leave Among Farmers and Rural Referents: A Population-Based Study

Farmers have more low back pain (LBP) than nonfarmers. In a previous report, we found that differences between farmers and nonfarmers in physical work exposure did not explain the LBP differences. In this report, we tested the hypothesis that psychosocial factors might explain the differences in LBP reporting, medical consultation, and sick leave. A cross-sectional population-based survey of 1,013 middle-aged farmers and 769 matched referents was performed. Data on LBP, consultations, and sick leave during lifetime was obtained along with information on psychosocial, social network, and lifestyle variables. Several of the psychosocial variables were associated with LBP but the difference in LBP prevalence between farmers and nonfarmers could be explained only marginally. Farmers and self-employed referents tended to have lower odds of sick leave because of LBP than employed referents after adjustment for psychosocial factors.

Osteoarthritis in the hip and whole-body vibration in heavy vehicles

BACKGROUND

Farmers have an increased risk of osteoarthritis in the hip, but the mechanism is not known. It has been suggested that the driving of tractors and jumping up and down from the tractor cabin is of importance. In this study, we test the hypothesis that driving vehicles with high levels of whole-body vibration (WBV) is associated with an increased risk of osteoarthritis in the hip.

METHODS

This is a cohort study of male operators of heavy vehicles working in the construction industry. They participated in a national health control program. The incidence rate for joint replacement in the hip was found in the Swedish Hospital Discharge Register for 1987 to 1998 and compared with the incidence in reference groups. Their exposure to WBV was estimated from their job titles. The rates were adjusted to body mass index (BMI) and smoking habits and compared to referents participating in the same health control program.

RESULTS

Drivers exposed to WBV had not an increased risk of joint replacement due to osteoarthritis in the hip (RR = 0.82; 95% CI 0.51-1.24).

CONCLUSIONS

This study does not support the hypothesis that exposure to WBV during operating a vehicle cause an increased risk of osteoarthritis in the hip.