Hand-arm vibration syndrome (HAVS) and musculoskeletal symptoms in the neck and the upper limbs in professional drivers of terrain vehicles--a cross sectional study

Near-wall hemodynamic parameters of finger arteries altered by hand-transmitted vibration

BACKGROUND

Sustained exposure to high-level hand-transmitted vibrations may result in angioneurotic disorders, which partly originate from vibration-altered hemodynamics in the finger arteries when repeating these disturbances throughout working life. Hence, the aim of this study is to assess the most relevant hemodynamic descriptors in the digital arteries, determine the relationship between the latter and vibration features, and gain better understanding of the physiological mechanisms involved.

METHODS

An experimental setup, mainly comprised of an ultra-high frequency ultrasound scanner and a vibration shaker, was used to image the digital proper volar arteries of the forefinger. Raw ultrasound data were post-processed by custom-made numerical routines to supply a pulsatile fluid mechanics model for computing the hemodynamic descriptors. Twenty-four healthy volunteers participated in the measurement campaign. Classical statistical methods were then applied to the dataset and also the wavelet transform for calculating the signal power in the frequency bands matching cardiac, respiratory, myogenic and neurogenic activities.

RESULTS

The artery diameter, the wall shear stress - WSS - and the WSS temporal gradient - WSSTG - were found to be the most relevant descriptors. Vibration-induced WSS was divided by three compared to its basal value whatever the vibration frequency and it was proportional to log2 of the acceleration level. Marked increases in WSSTG when stopping vibration might also lead to adverse health effects. Vibration caused a drop in WSS power for the frequency band associated with the neurogenic activity of the sympathetic nervous system.

CONCLUSION

This study may pave the way for a new framework to prevent vibration-induced vascular risk.

Evaluation of the bio-dynamic response of the hand-arm system and hand-tool designs - A brief review

Hand-operated tools transmit a high magnitude of vibration exposure to the hand-arm system that causes occupational diseases. The health effects caused in various countries for the past years due to usage of hand tools are necessary to identify the occupational disorders. Researchers have conducted various studies on biological effects, hand-transmitted vibration exposure and biodynamic responses throughout the years. This article goes over each of these studies in detail, as well as identifying areas where more research is needed. The majority of studies deal with the following topics: general guidelines for hand-transmitted vibrations; assessment techniques of vibration exposure; hand-tool evaluation methods; influence of hand-tool design to overcome the biomechanical effects; and finite element modelling for quantifying vibration exposure. In response to this, understanding the biodynamic behaviour of the hand-arm system is useful for better ergonomic intervention in hand tools to reduce fatigue and increase comfort.

Vibration from Electric Hand-Held Harvesters for Olives

Olive harvesting is the most expensive cultivation operation in areas where full mechanization is not possible due to structural conditions such as low tree density, old trees, irregular spacing, and terraced fields, which are very frequent in many small Italian farms. Under these conditions the use of hand-held vibrating harvesters is quite wide spread, because they are capable of approximately three times the productivity of workers using manual harvesting methods. Unfortunately, the use of these machines exposes the operators to hand-arm vibration risk and acceleration values are affected by several factors, including harvester kinematics, rod material and geometry, and load conditions. In this study several models of electrical portable harvesters, obtained by combining six harvester heads and four rods (one telescopic), were tested under idling and load conditions, measuring acceleration values on the rod, near the hand positions. Assuming the use of the machinery for 4 h per day, the result is a level of daily vibration exposure A(8) for the most exposed hand ranging from about 11 to 40 m/s2, much higher than the daily exposure limit value of 5 m/s2 stated by the European Directive 2002/44/EC. With the same harvester head, reduction in vibration may be achieved by using carbon fiber rods rather than aluminum ones or by increasing the rod diameter. The most significant reduction is achievable by designing harvester heads whose kinematics inherently incorporate oscillation compensation.

A Supernumerary Soft Robotic Limb for Reducing Hand-Arm Vibration Syndromes Risks

The most common causes of the risk of work-related musculoskeletal disorders (WMSD) have been identified as joint overloading, bad postures, and vibrations. In the last two decades, various solutions ranging from human-robot collaborative systems to robotic exoskeletons have been proposed to mitigate them. More recently, a new approach has been proposed with a high potential in this direction: the supernumerary robotic limbs SRLs are additional robotic body parts (e.g., fingers, legs, and arms) that can be worn by the workers, augmenting their natural ability and reducing the risks of injuries. These systems are generally proposed in the literature for their potentiality of augmenting the user's ability, but here we would like to explore this kind of technology as a new generation of (personal) protective equipment. A supernumerary robotic upper limb, for example, allows for indirectly interacting with hazardous objects like chemical products or vibrating tools. In particular, in this work, we present a supernumerary robotic limbs system to reduce the vibration transmitted along the arms and minimize the load on the upper limb joints. For this purpose, an off-the-shelf wearable gravity compensation system is integrated with a soft robotic hand and a custom damping wrist, designed starting from theoretical considerations on a mass-spring-damper model. The real efficacy of the system was experimentally tested within a simulated industrial work environment, where seven subjects performed a drilling task on two different materials. Experimental analysis was conducted according to the ISO-5349. Results showed a reduction from 40 to 60% of vibration transmission with respect to the traditional hand drilling using the presented SRL system without compromising the time performance.

New regression model for predicting hand-arm vibration (HAV) of Malaysian Army (MA) three-tonne truck steering wheels

OBJECTIVE

The objective of this study was to present a new method for determination of hand-arm vibration (HAV) in Malaysian Army (MA) three-tonne truck steering wheels based on changes in vehicle speed using regression model and the statistical analysis method known as Integrated Kurtosis-Based Algorithm for Z-Notch Filter Technique Vibro (I-kaz Vibro).

METHODOLOGY

The test was conducted for two different road conditions, tarmac and dirt roads. HAV exposure was measured using a Brüel & Kjær Type 3649 vibration analyzer, which is capable of recording HAV exposures from steering wheels. The data was analyzed using I-kaz Vibro to determine the HAV values in relation to varying speeds of a truck and to determine the degree of data scattering for HAV data signals.

RESULTS

Based on the results obtained, HAV experienced by drivers can be determined using the daily vibration exposure A(8), I-kaz Vibro coefficient (Ƶ(v)(∞)), and the I-kaz Vibro display. The I-kaz Vibro displays also showed greater scatterings, indicating that the values of Ƶ(v)(∞) and A(8) were increasing. Prediction of HAV exposure was done using the developed regression model and graphical representations of Ƶ(v)(∞). The results of the regression model showed that Ƶ(v)(∞) increased when the vehicle speed and HAV exposure increased.

DISCUSSION

For model validation, predicted and measured noise exposures were compared, and high coefficient of correlation (R(2)) values were obtained, indicating that good agreement was obtained between them. By using the developed regression model, we can easily predict HAV exposure from steering wheels for HAV exposure monitoring.

Musculoskeletal injuries in auto racing: a retrospective study of 137 drivers

BACKGROUND AND PURPOSE

The effect of continuous exposure of a driver's bones and muscles to vibration and G forces to years of automobile racing and the effect on overall health have not yet been examined in detail. The goal of this study was to investigate via questionnaire the musculoskeletal injuries and influencing parameters in 130 amateur and 7 professional race car drivers.

MATERIALS AND METHODS

A questionnaire, translated in English and German, was used to investigate the parameters that influence the racing performance and the character of resulting injuries.

RESULTS

This investigation involved 137 drivers (133 men and 4 women) with a mean age of 42 years (standard deviation = 15). Approximately half of the drivers had < 10 years of experience in auto racing (49%). The drivers mainly complained about pains in the lumbar (n = 36; 26%), shoulder (n = 27; 20%), and neck regions (n = 25; 18%). The driver's posture and the comfort of the seat were statistically significant for causing lower back and upper legs pains. The race duration was relevant to neck and shoulder discomfort.

CONCLUSION

The high incidence of musculoskeletal injuries in race car driving indicates the need for further improvements. Elimination of driver complaints about pain in the spine and upper extremities can be achieved through technical development, as already accomplished in Formula One racing.

A prospective cohort study of neck and shoulder pain in professional drivers

In a three-year follow-up study, the occurrence of neck and shoulder pain (NSP) in terms of frequency, duration and intensity was investigated in a population of 537 male professional drivers. Over the follow-up period, the cumulative incidences for neck and shoulder pain were 31.9% and 21.4%, respectively. After adjustment for potential confounders, a measure of cumulative whole-body vibration exposure was significantly associated with all NSP outcomes. Lifting loads and work with hands above shoulder level were significantly related to shoulder outcomes, while driving with trunk bent or twisted was associated with neck pain. Limited job decision, low social support and job dissatisfaction were significant predictors of neck outcomes. Psychological distress was associated with all NSP outcomes. The findings of this cohort study suggest that NSP outcomes are of multifactorial origin in driving occupations.

PRACTITIONER SUMMARY

This prospective cohort study highlighted the multifactorial nature of neck and shoulder pain (NSP) outcomes in a population of professional drivers. Cumulative whole-body vibration exposure, physical load factors and adverse psychosocial environment at the workplace, as well as individual-related psychological distress, were significant predictors of the occurrence of NSP in the professional drivers.

Specific features of vibration-induced disorders

AIM

Assessment of the specific clinical manifestations of hand-arm vibration syndrome (HAVS) or whole-body vibration syndrome (WBVS).

PATIENTS AND METHODS

Seventy-six patients (34 with HAVS and 33 with WBVS) were examined analysing the data from their medical history, clinical examinations and autonomic nervous system study, capillaroscopy, distal Doppler ultrasound study, vibrotactile sense, roentgenography, and electromyography.

RESULTS

HAVS manifests mainly in the upper limbs as microcirculatory disturbances: RR 2.59; 95% CI (1.64-4.10), Raynaud's syndrome: RR 16.50; 95% CI (2.33-117.04), increased vascular resistance in the digital arteries of the hands: RR 9.71; 95% CI (3.28-28.75); distal autonomic neuropathy of the upper limbs: RR 15.04; 95% CI (3.91-57.88); sensory polyneuropathy predominantly of the upper limbs: RR 21.00; 95% CI (3.01-146.57); median neuropathy: RR 14.56; 95% CI (2.04-104.06); cervical spondylosis with/without osteochondrosis: RR 2.09; 95% CI (1.33-3.28). In patients with WBVS we observed predominantly degenerative changes of the lumbar spine segment: RR 2.49; 95% CI (1.55-3.99); lumbosacral radicular symptoms: RR 8.53; 95% CI (3.73-19.52).

CONCLUSION

Dose-dependant, microcirculatory, peripheral vascular, peripheral nerve and musculoskeletal disorders of the upper limbs were found in HAVS and musculoskeletal and peripheral nerve injuries of the spine and the lower limbs were found in WBVS.

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.

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.

Changes in EMG activity in the upper trapezius muscle due to local vibration exposure

Exposure to vibration is suggested as a risk factor for developing neck and shoulder disorders in working life. Mechanical vibration applied to a muscle belly or a tendon can elicit a reflex muscle contraction, also called tonic vibration reflex, but the mechanisms behind how vibration could cause musculoskeletal disorders has not yet been described. One suggestion has been that the vibration causes muscular fatigue. This study investigates whether vibration exposure changes the development of muscular fatigue in the trapezius muscle. Thirty-seven volunteers (men and women) performed a sub-maximal isometric shoulder elevation for 3 min. This was repeated four times, two times with induced vibration and two times without. Muscle activity was measured before and after each 3-min period to look at changes in the electromyography parameters. The result showed a significantly smaller mean frequency decrease when performing the shoulder elevation with vibration (-2.51 Hz) compared to without vibration (-4.04 Hz). There was also a slightly higher increase in the root mean square when exposed to vibration (5.7% of maximal voluntary contraction) compared to without (3.8% of maximal voluntary contraction); however, this was not statistically significant. The results of the present study indicate that short-time exposure to vibration has no negative acute effects on the fatiguing of upper trapezius muscle.

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

OBJECTIVE

The overall aim of this study was to explore the association between incident musculoskeletal symptoms in the neck and upper limbs and exposure to hand-arm vibration and ergonomic stressors.

METHODS

The study has a prospective design and data at baseline and follow-up was assessed by self-administered questionnaires. The study population consisted of students that had graduated from vocational high schools in 2001-2003 in northern and western Sweden and a total of 586 men responded to both the baseline and follow-up questionnaires. The mean age was 20.7 (range 19-27) years, and the exposure information included questions regarding hand-arm vibration, postural stress, computer work, mental stress and perception of muscular tension. Musculoskeletal symptoms in the neck and upper limbs were assessed at baseline and at follow-up.

RESULTS

Men who reported their daily vibration exposure duration (work and leisure) as more than 1 h at baseline had an increased risk of neck pain in the preceding 7 days at follow-up, when adjusting for all the other exposure variables (PR 3.29, 95% CI 1.02-14.9). Men with a calculated 8-h weighted vibration exposure level [A(8)] above 1.7 m/s(2) had an increased risk of developing neck pain in both the unadjusted and adjusted analyses compared to those with an exposure level below 0.5 m/s(2).

CONCLUSION

Men who reported their daily vibration exposure duration (work and leisure) to be more than 1 h at baseline had an increased risk of neck pain for the preceding 7 days at follow-up. An increased prevalence of neck pain was also observed in individuals with a calculated 8-h frequency weighted vibration exposure level above 1.7 m/s(2) (calculated from data assessed at follow-up) compared to those with an exposure level below 0.5 m/s(2). The increased risks remained when adjusting for postural and mental stress; however the results could still be confounded by other ergonomic and physical load factors not adjusted for in the analyses.