Musculoskeletal symptoms among young male workers and associations with exposure to hand-arm vibration and ergonomic stressors

Risk factors for surgically treated cervical spondylosis in male construction workers: a 20-year prospective study

BACKGROUND CONTEXT

Degenerative changes due to cervical spondylosis (CS) can detrimentally affect work ability and quality of life yet understanding of how physical exposure affects disease progression is limited.

PURPOSE

To assess the associations between occupational physical exposures and occurrence of surgically treated cervical spondylosis (ST-CS) and early exit from the labor market via disability pension.

STUDY DESIGN/SETTING

Prospective register study with 20 years follow-up period.

PATIENT SAMPLE

Swedish construction workers participating in a national health surveillance project conducted between 1971 and 1993.

OUTCOME MEASURES

Surgically treated cervical spondylosis (ST-CS) and early labor market exit at a minimum rate of 25% time on disability pension.

METHODS

Associations between occupational physical exposures (job exposure matrix) and subsequent ST-CS (National Hospital in-patient register) and early labor market exit via disability pension (Swedish Social Insurance Agency register) were assessed in a cohort of male construction workers (n=237,699).

RESULTS

A total of 1381 ST-CS cases were present and a 20 years incidence rate of 35.1 cases per 100,000 person years (95% confidence interval (CI) 33.2-36.9). Increased relative risk (RR) for ST-CS was found for workers exposed to non-neutral (RR 1.40, 95% CI 1.15-1.69), and awkward neck postures (1.52, 1.19-1.95), working with the hands above shoulder height (1.30, 1.06-1.60), and high upper extremity loading (1.35, 1.15-1.59). Increased risk was also present for workers who reported frequent neck (3.06, 2.18-4.30) and upper back (3.84, 2.57-5.73) pain in the 12 months prior to survey. Among workers with elevated arm exposure, higher risk was seen in those who also had more frequent neck pain. ST-CS cases took early retirement more often (41.3%) and at a younger age (53 years) than the total study cohort (14.8% and 56 years of age, respectively).

CONCLUSIONS

Occupational exposure to non-neutral neck postures, work with hands above shoulders and high loads born through the upper extremities increased the risk for ST-CS and early retirement due to disability. Decreasing postural and load exposure is salient for primary, secondary, and tertiary prevention of CS. Neck pain was shown to be a prognostic factor for ST-CS, which stresses the importance of acting early and taking preventative action to reduce workplace exposure, and the need for systematic medical check-ups within primary or occupational care to mitigate disease progression and early labour market exit due to disability.

Adverse health manifestations in the hands of vibration exposed carpenters - a cross sectional study

BACKGROUND

Despite EU regulatory standards, many workers suffer injury as a result of working with hand-held vibrating tools. Our aim of this study was to confirm whether carpenters, a highly exposed group, suffer more injuries to their hands than painters, a group assumed to be less exposed to vibration.

METHODS

193 carpenters (participation rate 100%) and 72 painters (participation rate 67%), all men, answered a questionnaire and underwent a clinical examination to identify manifestations of neural and vascular origin in the hands. Neurosensory affection was defined as having at least one symptom in the fingers/hands (impaired perception of touch, warmth, or cold, impaired dexterity, increased sensation of cold, numbness or tingling, or pain in the fingers/hands when cold) and at least one clinical finding (impaired perception of touch, warmth, cold, vibration, or two-point discrimination). Logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

Neurosensory affection was fulfilled for 31% of the carpenters and 17% of the painters, age-adjusted OR 3.3 (CI 1.6-7.0). Among carpenters with neurosensory affection 18% reported interference with daily life activities, the most common symptoms being increased sensation of cold, numbness and pain in the fingers/hands when cold, the most common clinical findings were impaired perception of touch and vibration. Neurosensory affection was found in 12% of young carpenters (≤ 30 years old). No difference was found in the prevalence of white fingers between carpenters and painters.

CONCLUSIONS

Carpenters showed more symptoms and clinical findings of neurosensory affection than painters, probably due to vibration exposure. Also young carpenters showed signs of neurosensory affection, which indicates that under current conditions workers at these companies are not protected against injury. This underlines the importance of reducing exposure to vibration and conducting regular medical check-ups to detect early signs of neural and vascular manifestations indicating hand-arm vibration injuries. Special attention should be given to symptoms of increased sensation of cold, pain in the fingers when cold, and numbness, as these were the most common initiating ones, and should be addressed as early as possible in the preventive sentinel process. It is also important to test clinically for small- and large-fibre neuropathy, as the individual may be unaware of any pathology.

Musculoskeletal complications of hand-arm vibration syndrome among tyre shop workers in Kelantan, Malaysia

Objectives. Exposure to hand-arm vibration (HAV) is associated with hand-arm vascular syndrome (HAVS), which is characterized by musculoskeletal complications. However, evidence on this matter has been inconclusive. Therefore, this study aimed to determine and compare the prevalence of musculoskeletal complications of HAVS between a high-exposure (≥5 m·s^-2) group and a low-moderate-exposure (<5 m·s^-2) group and to explore the factors associated with the musculoskeletal complications of HAVS among tyre shop workers in Kelantan, Malaysia. Methods. A cross-sectional study involving 200 tyre shop workers was carried out. HAV was measured by a vibration meter. The workers were divided into two exposure groups - according to their 8-h time-weighted average, A(8), of vibration exposure - and compared. Results. Almost half of the workers reported musculoskeletal complications of the upper limbs and neck. Only the lifetime vibration dose (LVD) was significantly associated with the development of musculoskeletal complications. Conclusion. The high-exposure group had a higher prevalence of musculoskeletal complications. Only the LVD was significantly associated with complications. However, all factors of the work system, such as ergonomics, handgrip force and posture, might contribute to the development of musculoskeletal complications of HAVS and should be included in assessments.

Occupational Safety and Health Among Young Workers in the Nordic Countries: A Systematic Literature Review

This review aimed to identify risk factors for occupational accidents and illnesses among young workers in the Nordic countries and to attain knowledge on specific vulnerable groups within the young working force that may need special attention. We conducted a systematic review from 1994 to 2014 using five online databases. Of the 12,528 retrieved articles, 54 met the review criteria and were quality assessed, in which data were extracted focusing on identifying occupational safety, health risk factors, and vulnerable groups among the young workers. The review shows that mechanical factors such as heavy lifting, psychosocial factors such as low control over work pace, and organizational factors such as safety climate are all associated with increased injury risk for young Nordic workers. Results show that exposures to chemical substances were associated with skin reactions, e.g., hand eczema. Heavy lifting and awkward postures were risk factors for low back pain, and high job demands were risk factors for mental health outcomes. The review identified young unskilled workers including school drop-out workers as particularly vulnerable groups when it comes to occupational accidents. In addition, apprentices and young skilled workers were found to be vulnerable to work-related illnesses. It is essential to avoid stereotyping young Nordic workers into one group using only age as a factor, as young workers are a heterogeneous group and their vulnerabilities to occupational safety and health risks are contextual. Politicians, researchers, and practitioners should account for this complexity in the education, training and organization of work, and workplace health and safety culture.

The incremental effect of psychosocial workplace factors on the development of neck and shoulder disorders: a systematic review of longitudinal studies

BACKGROUND

To systematically analyse evidence on the incremental effect of work-related psychosocial risk factors on the development of neck and shoulder disorders, as reported in longitudinal studies.

METHODS

A systematic literature search was conducted in three data bases (MEDLINE, EMBASE, and PsychINFO) until May 2009. The quality assessment leading to a methodological quality score of the included studies was conducted by two independent reviewers using a standardised checklist. Criteria for the evaluation of evidence were established. Heterogeneity analyses were conducted.

RESULTS

Altogether 18 prospective longitudinal studies were included in the analysis. Potential psychosocial risk factors were mainly based on the job demand control (support) model by Karasek (1998). Study results were too heterogeneous to deduce pooled risk estimates. But the weight of evidence was strong for an incremental effect of job demands, job control, social support, and job strain, on the development of neck and/or shoulder disorders.

CONCLUSION

While we found evidence for an incremental effect of different psychosocial work factors (in addition to the effect of physical job factors), these results have to be interpreted carefully in order to support the notion that psychological factors can have an independent causal influence on the development of musculoskeletal disorders. Nevertheless, our findings are important for the development of preventive strategies, as they stress the need for preventive approaches that tackle both physical and psychosocial factors. Future research is warranted to consolidate and strengthen the results of this review.

Psychosocial work stressors as antecedents of musculoskeletal problems: a systematic review and meta-analysis of stability-adjusted longitudinal studies

Although the relationship between psychosocial workplace conditions and musculoskeletal problems has been extensively studied, the causal impact of psychosocial workplace factors in the development of musculoskeletal problems remains unclear. The purpose of the present study was to conduct a systematic review of baseline-adjusted prospective longitudinal studies estimating the lagged effect of psychosocial risk factors on musculoskeletal problems in industrialized work settings. A literature review was conducted by searching the MEDLINE, EMBASE, and PsychINFO databases dated until August 2009. The authors classified studies into categories of psychological work stressors and musculoskeletal problems. Available effect sizes were converted to odds ratios (OR). ORs were then pooled for each stressor-problem relationship using a random-effects model. Additionally, the possibility of publication bias was assessed with the Duval and Tweedie nonparametric "trim and fill" procedure. In total, 50 primary studies fulfilled inclusion criteria. Within these studies at least five effect sizes were available for 23 of the 45 possible psychosocial work stress-musculoskeletal problems relationships, leaving 9 psychosocial variables and four musculoskeletal problem areas for analyses. Of these 23 relationships, pooled OR estimates were positive and significant ranging from 1.15 to 1.66 with the largest pooled OR estimating the relationship between highly monotonous work and lower back pain. The lagged effect of low social support on lower limb problems was the only effect size for which the statistical test for bias was significant. Most psychosocial stressors had small but significant lagged effects on the development of musculoskeletal problems. Thus, organizational interventions to minimize these stressors may be promising in reducing one risk factor for the development of employee musculoskeletal problems.

Longitudinal evidence for the association between work-related physical exposures and neck and/or shoulder complaints: a systematic review

BACKGROUND

Most existing reviews focus on evidence for the association between neck and/or shoulder complaints and physical exposures at the workplace gathered from cross-sectional studies. In comparison, this review summarizes existing evidence from longitudinal studies only.

METHODS

A systematic literature research was conducted in Medline and EMBASE (1975-2009), and all studies were scanned by at least two researchers according to strict inclusion criteria. Levels of evidence were assigned according to the number of studies reporting similar findings, and according to the methodological quality of the included studies.

RESULTS

Altogether 21 longitudinal studies (19 high-quality studies) met the inclusion criteria and were included in this review. In comparison with former reviews, we found strong evidence for an association between shoulder complaints and manual material handling (MMH) (range between Odds Ratio (OR) 1.4 and 4.9), vibration (range between OR 1.6 and OR 2.5), trunk flexion or rotation (range between OR 1.8 and OR 5.1), and working with hands above shoulder level (range between OR 1.1 and OR 1.8). Apart from that, the included studies confirmed existing knowledge on the association between physical exposures at the workplace and neck and/or shoulder complaints.

CONCLUSIONS

This analysis of longitudinal studies allowed for new evidence with regard to four cause-effect chains between physical exposures at work and the development of shoulder, neck and neck/shoulder complaints. As outcome variables varied greatly among the included studies, harmonization in studies on musculoskeletal research is desirable.

Variability in hand-arm vibration during grinding operations

BACKGROUND

Measurements of exposure to vibrations from hand-held tools are often conducted on a single occasion. However, repeated measurements may be crucial for estimating the actual dose with good precision. In addition, knowledge of determinants of exposure could be used to improve working conditions. The aim of this study was to assess hand-arm vibration (HAV) exposure during different grinding operations, in order to obtain estimates of the variance components and to evaluate the effect of work postures.

METHODS

Ten experienced operators used two compressed air-driven angle grinders of the same make in a simulated work task at a workplace. One part of the study consisted of using a grinder while assuming two different working postures: at a standard work bench (low) and on a wall with arms elevated and the work area adjusted to each operator's height (high). The workers repeated the task three times. In another part of the study, investigating the wheel wear, for each grinder, the operators used two new grinding wheels and with each wheel the operator performed two consecutive 1-min grinding tasks. Both grinding tasks were conducted on weld puddles of mild steel on a piece of mild steel. Measurements were taken according to ISO-standard 5349 [the equivalent hand-arm-weighted acceleration (m s(-2)) averaged over 1 min]. Mixed- and random-effects models were used to investigate the influence of the fixed variables and to estimate variance components.

RESULTS

The equivalent hand-arm-weighted acceleration assessed when the task was performed on the bench and at the wall was 3.2 and 3.3 m s(-2), respectively. In the mixed-effects model, work posture was not a significant variable. The variables 'operator' and 'grinder' together explained only 12% of the exposure variability and 'grinding wheel' explained 47%; the residual variability of 41% remained unexplained. When the effect of grinding wheel wear was investigated in the random-effects model, 37% of the variability was associated with the wheel while minimal variability was associated with the operator or the grinder and 37% was unexplained. The interaction effect of grinder and operator explained 18% of the variability. In the wheel wear test, the equivalent hand-arm-weighted accelerations for Grinder 1 during the first and second grinding minutes were 3.4 and 2.9 m s(-2), respectively, and for Grinder 2, they were 3.1 and 2.9 m s(-2), respectively. For Grinder 1, the equivalent hand-arm-weighted acceleration during the first grinding minute was significantly higher (P = 0.04) than during the second minute.

CONCLUSIONS

Work posture during grinding operations does not appear to affect the level of HAV. Grinding wheels explained much of the variability in this study, but almost 40% of the variance remained unexplained. The considerable variability in the equivalent hand-arm-weighted acceleration has an impact on the risk assessment at both the group and the individual level.

Neuropathic pain-like alterations in muscle nociceptor function associated with vibration-induced muscle pain

We recently developed a rodent model of the painful muscle disorders induced by occupational exposure to vibration. In the present study we used this model to evaluate the function of sensory neurons innervating the vibration-exposed gastrocnemius muscle. Activity of 74 vibration-exposed and 40 control nociceptors, with mechanical receptive fields in the gastrocnemius muscle, were recorded. In vibration-exposed rats ∼15% of nociceptors demonstrated an intense and long-lasting barrage of action potentials in response to sustained suprathreshold mechanical stimulation (average of 2635 action potentials with frequency of ∼44Hz during a 1min suprathreshold stimulus) much greater than that has been reported to be produced even by potent inflammatory mediators. While these high-firing nociceptors had lower mechanical thresholds than the remaining nociceptors, exposure to vibration had no effect on conduction velocity and did not induce spontaneous activity. Hyperactivity was not observed in any of 19 neurons from vibration-exposed rats pretreated with intrathecal antisense for the IL-6 receptor subunit gp130. Since vibration can injure peripheral nerves and IL-6 has been implicated in painful peripheral neuropathies, we suggest that the dramatic change in sensory neuron function and development of muscles pain, induced by exposure to vibration, reflects a neuropathic muscle pain syndrome.

Mechanisms mediating vibration-induced chronic musculoskeletal pain analyzed in the rat

While occupational exposure to vibration is a common cause of acute and chronic musculoskeletal pain, eliminating exposure produces limited symptomatic improvement, and reexposure precipitates rapid recurrence or exacerbation. To evaluate mechanisms underlying these pain syndromes, we have developed a model in the rat, in which exposure to vibration (60-80Hz) induces, in skeletal muscle, both acute mechanical hyperalgesia as well as long-term changes characterized by enhanced hyperalgesia to a proinflammatory cytokine or reexposure to vibration. Exposure of a hind limb to vibration-produced mechanical hyperalgesia measured in the gastrocnemius muscle of the exposed hind limb, which persisted for approximately 2 weeks. When nociceptive thresholds had returned to baseline, exposure to a proinflammatory cytokine or reexposure to vibration produced markedly prolonged hyperalgesia. The chronic prolongation of vibration- and cytokine-hyperalgesia was prevented by spinal intrathecal injection of oligodeoxynucleotide (ODN) antisense to protein kinase Cepsilon, a second messenger in nociceptors implicated in the induction and maintenance of chronic pain. Vibration-induced hyperalgesia was inhibited by spinal intrathecal administration of ODN antisense to receptors for the type-1 tumor necrosis factor-alpha (TNFalpha) receptor. Finally, in TNFalpha-pretreated muscle, subsequent vibration-induced hyperalgesia was markedly prolonged.

PERSPECTIVE

These studies establish a model of vibration-induced acute and chronic musculoskeletal pain, and identify the proinflammatory cytokine TNFalpha and the second messenger protein kinase Cepsilon as targets against which therapies might be directed to prevent and/or treat this common and very debilitating chronic pain syndrome.

The Influence of Education and Exercise on Neck Pain

Neck pain is a significant contributor to worldwide disability and poses a considerable financial burden to its stakeholders. The prognosis for chronic neck pain is generally poor, and the associated disability seems to be more persistent than low back pain. It has been suggested that the goals of a rehabilitation program are to maximize return to function, limit progression of degenerative changes, and prevent further injury. The variety of treatment options can make it difficult for clinicians to agree on the most effective treatment intervention. This article reviews noninvasive treatment considerations for patients with neck pain. Exercise-based interventions, including aerobic conditioning, stretching, and strengthening, are addressed. Moreover, concepts related to education are covered, including the effects of posture and ergonomic counseling.

Dose-response relationship between exposure to hand-arm vibration and health effects among metalworkers

OBJECTIVES

The aim of this study was to explore the relationship of exposure to hand-arm vibration (HAV) and vascular, sensorineural and musculoskeletal symptoms and symptoms of carpal tunnel syndrome (CTS) in a population of Finnish metalworkers.

METHODS

A questionnaire on HAV exposure and symptoms was sent to 530 metalworkers. Those who reported finger blanching, numbness or tingling of the fingers or symptoms of CTS were invited to further examinations (n = 133). Their cumulative lifelong exposure to HAV, the level of current exposure and the history of use of tools causing impulse vibration were evaluated. The association of different symptoms with the HAV exposure was assessed with logistic regression analyses adjusted for age and smoking. The vibration perception thresholds (VPTs) were tested according to ISO 13091-1:2001.

RESULTS

The cumulative exposure index varied between 0 and 115,000 m(2) years d s(-4), the mean being 20,591 m(2) years d s(-4). The average of current daily vibration exposure was 1.6 m s(-2) and 39% of the participants had a history of exposure to impulse vibration. Of the respondents, 49% reported white fingers, 66% neurosensory symptoms, 56% symptoms of CTS and 75% musculoskeletal symptoms. The cumulative exposure index was associated with symptoms of white fingers [odds ratio (OR) 2.4-4.5], with symptoms of CTS (OR 4.6-6.1), with neurosensory symptoms (OR 5.7-17.3) and with musculoskeletal symptoms (OR 4.7-5.4). The risk of all these symptoms increased as the cumulative vibration dose increased. The history of exposure to impulse vibration had a significant effect on the occurrence of neurosensory symptoms (P = 0.024). The current exposure to HAV correlated significantly with all of the above-mentioned symptoms. The results of the VPT test were associated with the level of cumulative exposure to HAV.

CONCLUSIONS

There seems to be a dose-response relationship between the cumulative lifetime vibration dose of the HAV and finger blanching, sensorineural symptoms, symptoms of CTS and musculoskeletal symptoms of upper limbs and neck in the group of metalworkers of the study. The risk for neurosensory symptoms was the most significantly related to exposure to HAV and also to impulse vibration. Further studies are needed to confirm the present results also in other occupational groups taking into account the possible synergistic effect of workload as well.