Whole-body vibration-related health disorders in occupational medicine--an international comparison

Vibration Rather than Microgravity Affects Bone Metabolism in Adult Zebrafish Scale Model

Gravity and mechanical forces cause important alterations in the human skeletal system, as demonstrated by space flights. Innovative animal models like zebrafish embryos and medaka have been introduced to study bone response in ground-based microgravity simulators. We used, for the first time, adult zebrafish in simulated microgravity, with a random positioning machine (RPM) to study bone remodeling in the scales. To evaluate the effects of microgravity on bone remodeling in adult bone tissue, we exposed adult zebrafish to microgravity for 14 days using RPM and we evaluated bone remodeling on explanted scales. Our data highlight bone resorption in scales in simulated microgravity fish but also in the fish exposed, in normal gravity, to the vibrations produced by the RPM. The osteoclast activation in both rotating and non-rotating samples suggest that prolonged vibrations exposure leads to bone resorption in the scales tissue. Stress levels in these fish were normal, as demonstrated by blood cortisol quantification. In conclusion, vibrational mechanical stress induced bone resorption in adult fish scales. Moreover, adult fish as an animal model for microgravity studies remains controversial since fish usually live in weightless conditions because of the buoyant force from water and do not constantly need to support their bodies against gravity.

Occupational exposure to whole-body vibration and neck pain in the Swedish general population

The primary aim of this study was to determine if occupational exposure to whole-body vibration (WBV) was associated with reporting neck pain. A cross-sectional study was conducted on a sample of the general population living in northern Sweden, aged 24-76 years. Data was retrieved through a digital survey that collected subjectively reported information on exposure to WBV and biomechanical exposures as well as neck pain. The study included 5,017 participants (response rate 44%). Neck pain was reported by 269 men (11.8%) and 536 women (20.2%). There was a statistically significant association between reporting occupational exposure to WBV half the time or more (adjusted OR 1.91; 95% CI 1.22-3.00) and reporting neck pain. In gender-stratified analyses, the same pattern was observed in men, while there were too few women to determine any association. We conclude that occupational exposure to whole-body vibration was associated with neck pain in men.Practitioner summary: This cross-sectional, survey-based study investigated associations between self-reported occupational whole-body vibration and neck pain. It showed significant associations between frequent exposure to whole-body vibration and neck pain among men but not women. In occupational health care settings, whole-body vibration could be considered as a possible risk factor for neck pain.

Beyond physiology: Acute effects of side-alternating whole-body vibration on well-being, flexibility, balance, and cognition using a light and portable platform A randomized controlled trial

A good body-balance helps to prevent slips, trips and falls. New body-balance interventions must be explored, because effective methods to implement daily training are sparse. The purpose of the current study was to investigate acute effects of side-alternating whole-body vibration (SS-WBV) training on musculoskeletal well-being, flexibility, body balance, and cognition. In this randomized controlled trial, participants were randomly allocated into a verum (8.5 Hz, SS-WBV, N = 28) or sham (6 Hz, SS-WBV, N = 27) condition. The training consisted of three SS-WBV series that lasted one-minute each with two one-minute breaks in between. During the SS-WBV series, participants stood in the middle of the platform with slightly bent knees. During the breaks in between, participants could loosen up. Flexibility (modified fingertip-to-floor method), balance (modified Star Excursion Balance Test), and cognitive interference (Stroop Color Word Test) were tested before and after the exercise. Also, musculoskeletal well-being, muscle relaxation, sense of flexibility, sense of balance, and surefootedness were assessed in a questionnaire before and after the exercise. Musculoskeletal well-being was significantly increased only after verum. Also, muscle relaxation was significantly higher only after verum. The Flexibility-Test showed significant improvement after both conditions. Accordingly, sense of flexibility was significantly increased after both conditions. The Balance-Test showed significant improvement after verum, and after sham. Accordingly, increased sense of balance was significant after both conditions. However, surefootedness was significantly higher only after verum. The Stroop-Test showed significant improvement only after verum. The current study shows that one SS-WBV training session increases musculoskeletal well-being, flexibility, body balance and cognition. The abundance of improvements on a light and portable platform has great influence on the practicability of training in daily life, aiming to prevent slip trips and falls at work.

Effects of stochastic resonance whole-body vibration on sensorimotor function in elderly individuals-A systematic review

Introduction

Due to demographic changes, falls are increasingly becoming a focus of health care. It is known that within six months after a fall, two thirds of fallers will fall again. Therefore, therapeutic procedures to improve balance that are simple and can be performed in a short time are needed. Stochastic resonance whole-body vibration (SR-WBV) may be such a procedure.

Method

An electronic search to assess the effectiveness of SR-WBV on balance in the elderly was conducted using databases that included CINAHL Cochrane, PEDro, and PubMed. Included studies were assessed using the Collaboration Risk of Bias Tool by two independent reviewers.

Results

Nine studies showing moderate methodological quality were included. Treatment parameters were heterogeneous. Vibration frequency ranged from 1 to 12 Hz. Six studies found statistically significant improvements of balance from baseline to post measurement after SR-WBV interventions. One article found clinical relevance of the improvement in total time of the "Expanded Time to Get Up and Go Test".

Discussion

Physiological adaptations after balance training are specific and may explain some of the observed heterogeneity. Two out of nine studies assessed reactive balance and both indicated statistically significant improvements after SR-WBV. Therefore, SR-WBV represents a reactive balance training.

A Review of Bioinspired Vibration Control Technology

Due to huge demand in engineering, vibration control technology and related studies have always been at the frontiers of research. Although traditional vibration control methods are stable and reliable, they have obvious shortcomings. Through evolution and natural selection, certain body-parts of animals in the natural world have been cleverly constructed and well designed. This provides a steady stream of inspiration for the design of vibration control equipment. The prime objective of this review is to highlight recent advances in the bionic design of vibration control devices. Current bionic vibration control devices were classified, and their bionic principles were briefly described. One kind was the bionic device based on the brain structure of the woodpecker, which is mostly used to reduce vibration at high frequencies. Another kind of bionic device was based on animal leg structure and showed outstanding performance in low frequency vibration reduction. Finally, we briefly listed the problems that need to be solved in current bionic vibration control technology and gave recommendations for future research direction.

Spatiotemporal gait parameter changes due to exposure to vertical whole-body vibration

BACKGROUND

Vertical whole-body vibration (vWBV) during work, recreation, and transportation can have detrimental effects on physical and mental health. Studies have shown that lateral vibration at low frequencies (<3 Hz) can result in changes to spatiotemporal gait parameters. There are few studies which explore spatiotemporal gait changes due to vertical vibration at higher frequencies (> 3 Hz). This study seeks to assess the effect of vWBV on spatiotemporal gait parameters at a greater range of frequencies (≤ 30 Hz).

METHODS

Stride Frequency (SF), Stride Length (SL), and Center of Pressure velocity (CoPv) was measured in seven male subjects (23 ± 4 years, 1.79 ± 0.05 m, 73.9 ± 9.7 kg) during In-Place Walking and nine male subjects (29 ± 7 years, 1.78 ± 0.07 m, 77.8 ± 9.9 kg; mean ± SD) during Treadmill Walking while exposed to vWBV. Load cells measured ground reaction forces during In-Place Walking and sensorized insoles acquired under-foot pressure during Treadmill Walking. Statistical tests included a one-way repeated-measures ANOVA, post-hoc two way paired T-tests, statistical power (1-β), correlation (R²), and effect size (Cohen's d).

RESULTS

While statistical significance was not found for changes in SF, SL, or Mean CoPv, small to large effects were found in all measured spatiotemporal parameters of both setups. During Treadmill Walking, vWBV was correlated with a decrease in SF (R² = 0.925), an increase in SL (R² = 0.908), and an increase in Mean CoPv (R² = 0.921) and Max CoPv (R² = 0.952) with a significant increase (p < 0.0083) in Max CoPv at frequencies of 8 Hz and higher.

SIGNIFICANCE

Study results demonstrated that vWBV influences spatiotemporal gait parameters at frequencies greater than previously studied.

Deleterious effects of whole-body vibration on the spine: A review of in vivo, ex vivo, and in vitro models

Occupational exposure to whole-body vibration is associated with the development of musculoskeletal, neurological, and other ailments. Low back pain and other spine disorders are prevalent among those exposed to whole-body vibration in occupational and military settings. Although standards for limiting exposure to whole-body vibration have been in place for decades, there is a lack of understanding of whole-body vibration-associated risks among safety and healthcare professionals. Consequently, disorders associated with whole-body vibration exposure remain prevalent in the workforce and military. The relationship between whole-body vibration and low back pain in humans has been established largely through cohort studies, for which vibration inputs that lead to symptoms are rarely, if ever, quantified. This gap in knowledge highlights the need for the development of relevant in vivo, ex vivo, and in vitro models to study such pathologies. The parameters of vibrational stimuli (eg, frequency and direction) play critical roles in such pathologies, but the specific cause-and-effect relationships between whole-body vibration and spinal pathologies remain mostly unknown. This paper provides a summary of whole-body vibration parameters; reviews in vivo, ex vivo, and in vitro models for spinal pathologies resulting from whole-body vibration; and offers suggestions to address the gaps in translating injury biomechanics data to inform clinical practice.

Transmission of whole body vibration - Comparison of three vibration platforms in healthy subjects

The potential of whole body vibration (WBV) to maintain or enhance musculoskeletal strength during ageing is of increasing interest, with both low and high magnitude WBV having been shown to maintain or increase bone mineral density (BMD) at the lumbar spine and femoral neck. The aim of this study was to determine how a range of side alternating and vertical WBV platforms deliver vibration stimuli up through the human body. Motion capture data were collected for 6 healthy adult participants whilst standing on the Galileo 900, Powerplate Pro 5 and Juvent 100 WBV platforms. The side alternating Galileo 900 WBV platform delivered WBV at 5-30 Hz and amplitudes of 0-5 mm. The Powerplate Pro 5 vertical WBV platform delivered WBV at 25 and 30 Hz and amplitude settings of 'Low' and 'High'. The Juvent 1000 vertical WBV platform delivered a stimulus at a frequency between 32 and 37 Hz and amplitude 10 fold lower than either the Galileo or Powerplate, resulting in accelerations of 0.3 g. Motion capture data were recorded using an 8 camera Vicon Nexus system with 21 reflective markers placed at anatomical landmarks between the toe and the forehead. Vibration was expressed as vertical RMS accelerations along the z-axis which were calculated as the square root of the mean of the squared acceleration values in g. The Juvent 1000 did not deliver detectable vertical RMS accelerations above the knees. In contrast, the Powerplate Pro 5 and Galileo 900 delivered vertical RMS accelerations sufficiently to reach the femoral neck and lumbar spine. The maximum vertical RMS accelerations at the anterior superior iliac spine (ASIS) were 1.00 g ±0.30 and 0.85 g ±0.49 for the Powerplate and Galileo respectively. For similar accelerations at the ASIS, the Galileo achieved greater accelerations within the lower limbs, whilst the Powerplate recorded higher accelerations in the thoracic spine at T10. The Powerplate Pro 5 and Galileo 900 deliver vertical RMS accelerations sufficiently to reach the femoral neck and lumbar spine, whereas the Juvent 1000 did not deliver detectable vertical RMS accelerations above the knee. The side alternating Galileo 900 showed greater attenuation of the input accelerations than the vertical vibrations of the Powerplate Pro 5. The platforms differ markedly in the transmission of vibration with strong influences of frequency and amplitude. Researchers need to take account of the differences in transmission between platforms when designing and comparing trials of whole body vibration.

Preventive action with a population of excavator drivers exposed to whole-body vibration

BACKGROUND:

Whole-body vibration is a major cause of lower back pain among employees, and the medical and preventive care teams of occupational health departments are often confronted with lower back pain problems among machine operators.

OBJECTIVES:

The objectives of this research are to determine the number of excavator drivers exposed to whole-body vibration levels above 0.5m/s², identify other exposure factors that may contribute to back pain, and propose corrective measures.

METHODS:

Vibration measurements were carried out on individual excavator drivers while they were observed carrying out working tasks, after which prevention advice is given. Factors which determine vibration levels are logged on to a database.

RESULTS:

The multivariate analysis of several determining factors shows vibration exposure levels vary depending on the varied work tasks being carried out.

CONCLUSION:

This study identifies exposed employees among excavator operators. For each workstation, the determining factors that could explain the high exposures to vibrations are identified. This work shows the important role of tasks on exposure levels. A better adaptation of the tools used to carry out work tasks would allow a decrease in the vibration level of this type of machine.

Preliminary comparison of vibration measurement accuracy between a low cost, portable acceleration measurement unit and a gold-standard accelerometer system

Characterization of Whole-Body Vibration (WBV) exposure is important for the development and evaluation of mitigation strategies for occupational WBV. However, barriers associated with cost and complexity limit widespread use of current gold-standard accelerometer (GSA) measurement systems. Small, simple, low cost Acceleration Measurement Unit (AMU) devices with built-in batteries and memory potentially allow for more efficient collection of WBV data, but the measurement accuracy of these devices need to be evaluated. Using known acceleration inputs generated by an accelerometer calibrator and field collected vibration profiles simulating real-world vibration exposures, the measurements of an AMU device and GSA system were compared. Analysis of accelerometer calibrator data showed no significant difference in weighted acceleration (A_w) measurements between the systems (mean difference -0.001 m/s², p = 0.95). In field collected vibration profile testing, differences in A_w measurements were small (0.06 m/s², 4.6%). These results suggest the AMU evaluated in this study may be acceptable for measuring occupational WBV.

Musculoskeletal diseases among French military high-speed boat pilots

In 2016, the French Navy acquired a new high-speed boat, called ECUME. It exposes crewmembers to significant Whole Body Vibrations. This work explores the musculoskeletal diseases among this population. We conducted a retrospective declarative epidemiologic study using anonymous questionnaires. Eighty-four sailors were included. Fifty-six (66.7%) report acute traumas during a nautical raid during the 12 months study period. Sixty (71.4%) report chronic pains, which they associate with their nautical activity. Among them, only 16 (26.7%) have consulted a doctor, but 32 (53.3%) report consuming medication, including 18 through selfmedication. More than half rely to alternatives medicine, especially osteopathy. The traumatic risk of ECUME riding is obvious. Many crewmembers minimize their symptoms, and consult rarely a physician. They give preference to selfmedication and alternative medicines.

An enhanced whole-body vibration emission index for railway vehicles

Whole-body vibration (WBV) is a concept that is gaining importance in the railway sector. Occupational disorders, such as back pain and sciatica, frequently cause sick leave and have resulted in lawsuits against employers. Railway operators require a clear procedure for specification and purchase of certified rail vehicles that evaluate the vehicle from the point of view of the effect of WBV. However, a review of current standards and studies shows no clear and simple method for defining a vibration emission value, such as that defined in EN 1032 for mobile machinery. This study proposes a systematic and robust railway driver-related vibration index and describes the methodology for its determination. The proposed index, based on current WBV standards, is robust and allows comparisons between vehicles. For index validation, we used experimental results as well as results from a neural network using the cabin floor data. Practitioner summary: A new vibration emission index is proposed for the certification of railway vehicles, using whole-body vibration, based on current standards. It could be used as a criterion when purchasing a vehicle and as a design specification for manufacturers, thereby improving the ergonomics of drivers' working environment. Abbreviations: EAV: exposure action value; RMS: root mean square; VDV: vibration dose value; VEI: vibration emission index; VTV: vibration total value; WBV: whole-body vibration.

Pregnancy disorders in female workers at the industrial area of Sidoarjo, Indonesia

Background: The number of female workers in Indonesia has increased and female workers have been discovered to be very vulnerable to several hazards and health problems in the workplace environment linked to their menstrual cycle and pregnancy. Therefore, this study was conducted to analyze risk factors associated with pregnancy disorders in female workers. Design and Methods: The research was conducted through the use of a cross-sectional design with 307 female workers using simple random sampling. Furthermore, a descriptive analysis was conducted to describe the conditions of the respondents during pregnancy to childbirth process. Results: The results showed 45% of respondents had pregnancy disorders, 16% had miscarriages, and despite the fact most of the prenatal care processes was assisted by doctors or midwives, 2.6% of the respondents consulted Traditional Birth Attendants, who were also recorded and was found to account for 2.9% of the deliveries. Moreover, the risk factors associated with pregnancy disorders include vibrations (P=0.004), irritants (P=0.002) and repetitive works (P=0.009). Conclusions: It is recommended that companies should provide maternal and child health protection and control for any risk associated with female workers.

Occupational risk factors for musculoskeletal disorders among railroad maintenance-of-way workers

BACKGROUND

Our objective was to examine occupational risk factors for musculoskeletal disorders of the neck, back, and knee among railroad maintenance-of-way (MOW) workers.

METHODS

Four thousand eight-hundred sixteen active, retired, and disabled members of the Brotherhood of Maintenance of Way Employes Division (BMWED) completed a survey. We computed adjusted prevalence ratios (aPRs) using Poisson regression for neck, back, and knee musculoskeletal symptoms by work exposures, adjusted for age, region, race/ethnicity, smoking, and potential second job and spare time vehicle vibration exposure.

RESULTS

Among active male BMWED members, we found associations between use of high-vibration vehicles and neck pain (aPR = 1.47, 95% confidence interval (CI): 1.07-2.03) and knee pain (aPR = 1.38, 95% CI: 1.04-1.82) for more than 1.9 years (vs 0) of full-time equivalent use; but not back pain. Back pain radiating below the knee (sciatica indicator) was associated with high-vibration vehicle use greater than 0.4 and less than 1.9 years (aPR = 1.58, 95% CI: 1.15-2.18). We also found significant associations between often or always lifting, pushing, pulling, or bending on the job (vs seldom or never) and neck pain (aPR = 2.43, 95% CI: 1.20-4.90), back pain (aPR = 1.94, 95% CI: 1.24-3.03), the sciatica indicator (aPR = 5.18, 95% CI: 1.28-20.95), and knee pain (aPR = 2.84, 95% CI: 1.47-5.51), along with positive gradients in the outcome by exposure time.

CONCLUSIONS

Biomechanical work exposures, including force and nonneutral postures, were associated with neck, lower back, and knee pain. Whole-body vibration, as measured by the duration of use of high-vibration vehicles, was associated with neck pain, knee pain, and sciatica. Prevention programs should address occupational risk factors for musculoskeletal disorders among MOW workers.

Occupational Exposure on Board Fishing Vessels: Risk Assessments of Biomechanical Overload, Noise and Vibrations among Worker on Fishing Vessels in Southern Italy

Sea fishing is one of the sectors with the highest risk of illness and work-related accidents. The purpose of the study is to evaluate the exposure of fishing workers to three major risks: biomechanical overload, noise, and whole-body vibrations. We used common methods and measurement tools in the field: observational video analysis, questionnaires, and direct measurement. Noise and vibrations levels were measured aboard five boats belonging to the main fishing communities of Southern Italy. The random sample consisted of 310 workers, of whom 108 agreed to complete a questionnaire to collect data on the perception of occupational risk and self-perception of health conditions. We found that fishermen had a high prevalence of osteoarticular pathologies (42%) and that the biomechanical overload risk is mainly related to handling manual loads. Furthermore, the results indicate that the levels of weekly noise exposure exceed the exposure limit value of 87 decibel A (dBA) for fishing workers, and that the most noisiest area is the engine room. Exposure levels to whole-body vibrations were below <0.5 m/s2. Knowledge on occupational hazards and health effects in the fisheries sector should be used to develop ship technology, raise awareness of the correct use of personal protective equipment, and improve health surveillance of these workers.

Neurocritical care of high-risk infants during inter-hospital transport

The centralisation of neonatal intensive care in recent years has improved mortality, particularly of extremely preterm infants, but similar improvements in morbidity, such as neurodevelopmental impairment, have not been seen. Integral to the success of centralisation are specialised neonatal transport teams who provide intensive care prior to and during retrieval of high-risk neonates when in-utero transfer has not been possible. Neonatal retrieval aims to stabilise the clinical condition and then transfer the neonate during a high-risk period for patient. Transport introduces the hazards of noise and vibration; acceleration and deceleration forces; additional handling and temperature fluctuations. The transport team must stabilise the infant fully prior to transport as when on the move they are limited by space and movement to effectively attend to clinical deterioration. Inborn infants have better neurodevelopmental outcome compared with the outborn and aetiology of this seems to be multifactorial with the impact of transport itself during critical illness, remaining unclear. To improve the neurological outcomes for transported infants, it seems imperative to integrate the advancing intensive care neuromonitoring tools into the transport milieu. This review examines current inter-hospital transport neuromonitoring and how new modalities might be applied to the neurocritical care delivered by specialist transport teams.

Work-relatedness of lumbosacral radiculopathy syndrome: Review and dose-response meta-analysis

OBJECTIVE

Clinicians need to know whether lumbosacral radiculopathy syndrome (LRS) can be attributed to work. This review describes what work-related risk factors are associated with LRS.

METHODS

A systematic review was performed in PubMed and Embase. Inclusion criteria were that LRS was diagnosed by a clinician and workers exposed to work-related risk factors were compared to workers less or not exposed. A quality assessment and a meta-analysis were performed, including a dose-response analysis.

RESULTS

The search resulted in 7,350 references and 24 studies that fulfilled the inclusion criteria: 19 studies were rated as having a high risk of bias and 5 as having a low risk of bias. The median number of LRS patients per study were 209 (interquartile range 124-504) and the total number of participants was 10,142. The meta-analysis revealed significant associations with heavy physically demanding work (odds ratio [OR] 2.03, 95% confidence interval [CI] 1.48-2.79), bending or twisting of the trunk (OR 2.43, 95% CI 1.67-3.55), and lifting and carrying in combination with bending or twisting of the trunk (OR 2.84, 95% CI 2.18-3.69). No significant associations were found for professional driving (OR 1.46, 95% CI 0.90-2.35) or sitting (OR 1.08, 95% CI 0.49-2.38). A dose-response relation was present per 5 years of exposure for bending (OR 1.12, 95% CI 1.04-1.20), lifting (OR 1.08, 95% CI 1.02-1.14) and the combination of bending and lifting (OR 1.14, 95% CI 1.01-1.29).

CONCLUSIONS

Moderate to high-quality evidence is available that LRS can be classified as a work-related disease depending on the level of exposure to bending of the trunk or lifting and carrying. Professional driving and sitting were not significantly associated with LRS.

Anatomical Parameters of the Acetabulum in Heavy Vehicle Operators

It has been suggested that long-term exposure by heavy vehicle operators to whole-body vibration (WBV) may be related to an increased risk of pathological changes in the anatomical parameters of the hip. The aim of this study was to explore the difference in anatomical parameters of acetabulum in drivers of heavy vehicles (experimental group; n=60) and subjects who have not been exposed to WBV (control group; n=60). The anteroposterior radiographic view of the hips was used to measure the following parameters: the vertical centre edge (VCE), the ‘horizontal toit externe’ angle (HTE), the neck shaft angle (NSA) and the acetabular depth (AD). Compared with the control group, the mean VCE angle values and AD were signifi cantly lower, while the average HTE and NSA values were signifi cantly higher in the experimental group. This study supports the hypothesis that exposure to whole-body vibration during operation of a vehicle causes an increased risk of acetabular dysplasia.

Modal Damping Ratio and Optimal Elastic Moduli of Human Body Segments for Anthropometric Vibratory Model of Standing Subjects

The present study aims to accurately estimate inertial, physical, and dynamic parameters of human body vibratory model consistent with physical structure of the human body that also replicates its dynamic response. A 13 degree-of-freedom (DOF) lumped parameter model for standing person subjected to support excitation is established. Model parameters are determined from anthropometric measurements, uniform mass density, elastic modulus of individual body segments, and modal damping ratios. Elastic moduli of ellipsoidal body segments are initially estimated by comparing stiffness of spring elements, calculated from a detailed scheme, and values available in literature for same. These values are further optimized by minimizing difference between theoretically calculated platform-to-head transmissibility ratio (TR) and experimental measurements. Modal damping ratios are estimated from experimental transmissibility response using two dominant peaks in the frequency range of 0–25 Hz. From comparison between dynamic response determined form modal analysis and experimental results, a set of elastic moduli for different segments of human body and a novel scheme to determine modal damping ratios from TR plots, are established. Acceptable match between transmissibility values calculated from the vibratory model and experimental measurements for 50th percentile U.S. male, except at very low frequencies, establishes the human body model developed. Also, reasonable agreement obtained between theoretical response curve and experimental response envelop for average Indian male, affirms the technique used for constructing vibratory model of a standing person. Present work attempts to develop effective technique for constructing subject specific damped vibratory model based on its physical measurements.

Construction of a web-based questionnaire for longitudinal investigation of work exposure, musculoskeletal pain and performance impairments in high-performance marine craft populations

OBJECTIVE

High-performance marine craft personnel (HPMCP) are regularly exposed to vibration and repeated shock (VRS) levels exceeding maximum limitations stated by international legislation. Whereas such exposure reportedly is detrimental to health and performance, the epidemiological data necessary to link these adverse effects causally to VRS are not available in the scientific literature, and no suitable tools for acquiring such data exist. This study therefore constructed a questionnaire for longitudinal investigations in HPMCP.

METHODS

A consensus panel defined content domains, identified relevant items and outlined a questionnaire. The relevance and simplicity of the questionnaire's content were then systematically assessed by expert raters in three consecutive stages, each followed by revisions. An item-level content validity index (I-CVI) was computed as the proportion of experts rating an item as relevant and simple, and a scale-level content validity index (S-CVI/Ave) as the average I-CVI across items. The thresholds for acceptable content validity were 0.78 and 0.90, respectively. Finally, a dynamic web version of the questionnaire was constructed and pilot tested over a 1-month period during a marine exercise in a study population sample of eight subjects, while accelerometers simultaneously quantified VRS exposure.

RESULTS

Content domains were defined as work exposure, musculoskeletal pain and human performance, and items were selected to reflect these constructs. Ratings from nine experts yielded S-CVI/Ave of 0.97 and 1.00 for relevance and simplicity, respectively, and the pilot test suggested that responses were sensitive to change in acceleration and that the questionnaire, following some adjustments, was feasible for its intended purpose.

CONCLUSIONS

A dynamic web-based questionnaire for longitudinal survey of key variables in HPMCP was constructed. Expert ratings supported that the questionnaire content is relevant, simple and sufficiently comprehensive, and the pilot test suggested that the questionnaire is feasible for longitudinal measurements in the study population.

ISSLS Prize Winner: Vibration Really Does Disrupt the Disc: A Microanatomical Investigation

STUDY DESIGN

Microstructural investigation of vibration-induced disruption of the flexed lumbar disc.

OBJECTIVE

The aim of the study was to explore micro-level structural damage in motion segments subjected to vibration at subcritical peak loads.

SUMMARY OF BACKGROUND DATA

Epidemiological evidence suggests that cumulative whole body vibration may damage the disc and thus play an important role in low back pain. In vitro investigations have produced herniations via cyclic loading (and cyclic with added vibrations as an exacerbating exposure), but offered only limited microstructural analysis.

METHODS

Twenty-nine healthy mature ovine lumbar motion segments flexed 7° and subjected to vibration loading (1300 ± 500 N) in a sinusoidal waveform at 5 Hz to simulate moderately severe physiologic exposure. Discs were tested either in the range of 20,000 to 48,000 cycles (medium dose) or 70,000 to 120,000 cycles (high dose). Damaged discs were analyzed microstructurally.

RESULTS

There was no large drop in displacement over the duration of both vibration doses indicating an absence of catastrophic failure in all tests. The tested discs experienced internal damage that included delamination and disruption to the inner and mid-annular layers as well as diffuse tracking of nucleus material, and involved both the posterior and anterior regions. Less frequent tearing between the inner disc and endplate was also observed. Annular distortions also progressed into a more severe form of damage, which included intralamellar tearing and buckling and obvious strain distortion around the bridging elements within the annular wall.

CONCLUSION

Vibration loading causes delamination and disruption of the inner and mid-annular layers and limited diffuse tracking of nucleus material. These subtle levels of disruption could play a significant role in initiating the degenerative cascade via micro-level disruption leading to cell death and altered nutrient pathways.

LEVEL OF EVIDENCE

5.

Apparent mass matrix of standing subjects exposed to multi-axial whole-body vibration

This paper describes the experimental characterisation of the apparent mass matrix of eight male subjects in standing position and the identification of nonlinearities under both mono-axial and dual-axis whole-body vibration. The nonlinear behaviour of the response was studied using the conditioned response techniques considering models of increasing complexity. Results showed that the cross-axis terms are comparable to the diagonal terms. The contribution of the nonlinear effects are minor and can be endorsed to the change of modal parameters during the tests. The nonlinearity generated by the vibration magnitude is more evident in the subject response, since magnitude-dependent effects in the population are overlaid by the scatter in the subjects' biometric data. The biodynamic response is influenced by the addition of a secondary vibration axis and, in case of dual-axis vibrations, the overall magnitude has a marginal contribution. Practitioner Summary: We have measured both the diagonal and cross-axis elements of the apparent mass matrix. The effect of nonlinearities and the simultaneous presence of vibration along two axes are smaller than the inter-subject variability.

Patient-reported side effects immediately after chiropractic scoliosis treatment: a cross-sectional survey utilizing a practice-based research network

Background

Concern exists regarding the potential for chiropractic treatment to cause adverse effects in individuals with scoliosis. The aim of this paper is to present the self-reported responses of 189 scoliosis patients over 3198 unique visits, collected over one calendar year from nine chiropractic clinics, regarding how they felt and the side effects they experienced immediately after chiropractic treatment.

Methods

Thirty six private chiropractic clinics specializing in the treatment of scoliosis were asked to participate in a prospective study regarding the side-effects of the chiropractic treatment of scoliosis; 9 agreed to participate. A response form was provided to each scoliosis patient at the end of their clinic visit, and consisted of two questions: “How do you feel after your treatment today?” and “Did you experience any side-effects as a result of your treatment today?”

Results

One hundred eighty nine informed consent forms were collected and 3198 response forms were collected, suggesting an average of 17 visits per patient. Patients reported feeling worse post-treatment after 5.0 % of the visits. The incidence of side-effects was 29.7 %. Muscle soreness accounted for 35.2 % of all side effects. 99.9 % of all side effects were classified as mild. Six moderate side-effects (sprains/strains) were reported out of 3,198 visits. There were no reported cases of severe side effects.

Conclusion

Mild side effects were common, although the frequency was slightly lower than the average for chiropractic interventions. The rate of moderate side effects reported was one per 533 visits involving the care of 189 scoliosis patients surveyed from 9 chiropractic offices over a timeframe of one calendar year. No serious adverse events occurred that required medical attention, hospital stays, or surgical intervention. Based upon this preliminary data, side effects reported by scoliosis patients immediately after chiropractic treatment appear to be relatively common but generally benign.