Assessing the Influence of Antivibration Glove on Digital Vascular Responses to Acute Hand‐arm Vibration

Prevalence of carpal tunnel syndrome symptoms among neurosurgical spine surgeons

Background

Neurosurgeons, particularly spine surgeons, have high exposure to vibrations via electric or pneumatic drills and repetitive motion. Although no data exist for the prevalence of carpal tunnel syndrome (CTS) among these surgeons, anecdotal evidence suggests the rate of symptoms is higher than in the general population.

Methods

An anonymous questionnaire was developed to assess demographics, practice patterns, presence of CTS symptoms, and treatment (time off, bracing, medication, injections, surgery). The survey was sent via anonymous email link to members of the AANS/CNS Joint Section on Disorders of the Spine and Peripheral Nerve.

Results

101 members responded: 44 reported at least one symptom related to CTS (43.6%). There was no statistically significant relationship between overall or spine case volume, the number of cases performed annually/daily, and CTS symptoms. Respondents working in non-teaching settings were significantly more likely to have CTS symptoms than academic teaching institutions (50.0% v. 45.0%; p = 0.0112).

Conclusions

Our survey demonstrated CTS to be more prevalent in spine neurosurgeons (43.6%) than in the general population (1-5%). The lack of significant association between most practice-based metrics and CTS symptoms may indicate that respondents have a minimum case volume that exceeds the amount of vibration exposure/repetitive motion to develop symptoms. The significantly increased prevalence of CTS among neurosurgeons at non-teaching institutions suggests that residents provide operative assistance offsetting the vibration exposure/repetitive motion by attendings. Further research may determine the root cause for the high prevalence of CTS in spine neurosurgeons and devise methods for reducing vibration exposure.

Problems related to measuring the transmissibility of anti-vibration gloves. Possible efficacy for impact tools used in mining and quarrying activities

AbstractThis commentary takes into account some of the most relevant studies investigating the transmissibility of anti-vibration (AV) gloves. AV gloves are almost useless at the palm level in the low frequencies (less than 31.5 Hz), while they generally start to have an appreciable reduction of the vibration over 400 Hz. In their use with impact tools, having a low dominant vibration frequency usually between 25-60 Hz for chipping hammers and drills, and less than 30 Hz for pneumatic breakers, the average transmissibility reduction at the palm level is 13% (min 2% - max 26%) when used with hammers, and 1% (increment of 4% and reduction of 6%) when used with breakers. The transmissibility at the finger level, especially in the low frequencies, is almost nothing or produces an increase of the vibration. Other problems related to the increase of the applied force and the reduction of dexterity are reported.

Development of a finger adapter method for testing and evaluating vibration-reducing gloves and materials

The objective of this study was to develop a convenient and reliable adapter method for testing and evaluating vibration-reducing (VR) gloves and VR materials at the fingers. The general requirements and technical specifications for the design of the new adapter were based on our previous studies of hand-held adapters for vibration measurement and a conceptual model of the fingers-adapter-glove-handle system developed in this study. Two thicknesses (2 mm and 3 mm) of the adapter beam were fabricated using a 3-D printer. Each adapter is a thin beam equipped with a miniature tri-axial accelerometer (1.1 g) mounted at its center, with a total weight ≤ 2.2 g. To measure glove vibration transmissibility, the adapter is held with two gloved fingers; a finger is positioned on each side of the accelerometer. Each end of the adapter beam is slotted between the glove material and the finger. A series of experiments was conducted to evaluate this two-fingers-held adapter method by measuring the transmissibility of typical VR gloves and a sample VR material. The experimental results indicate that the major resonant frequency of the lightweight adapter on the VR material (≥800 Hz) is much higher than the resonant frequencies of the gloved fingers grasping a cylindrical handle (≤300 Hz). The experimental results were repeatable across the test treatments. The basic characteristics of the measured glove vibration transmissibility are consistent with the theoretical predictions based on the biodynamics of the gloved fingers-hand-arm system. The results suggest that VR glove fingers can effectively reduce only high-frequency vibration, and VR effectiveness can be increased by reducing the finger contact force. This study also demonstrated that the finger adapter method can be combined with the palm adapter method prescribed in the standardized glove test, which can double the test efficiency without substantially increasing the expense of the test.

Tool-specific performance of vibration-reducing gloves for attenuating fingers-transmitted vibration

BACKGROUND

Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration-reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined.

OBJECTIVE

The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmitted vibrations in three orthogonal directions (3D) from powered hand tools.

METHODS

A transfer function method was used to estimate the tool-specific effectiveness of four typical VR gloves. The transfer functions of the VR glove fingers in three directions were either measured in this study or during a previous study using a 3D laser vibrometer. More than seventy vibration spectra of various tools or machines were used in the estimations.

RESULTS

When assessed based on frequency-weighted acceleration, the gloves provided little vibration reduction. In some cases, the gloves amplified the vibration by more than 10%, especially the neoprene glove. However, the neoprene glove did the best when the assessment was based on unweighted acceleration. The neoprene glove was able to reduce the vibration by 10% or more of the unweighted vibration for 27 out of the 79 tools. If the dominant vibration of a tool handle or workpiece was in the shear direction relative to the fingers, as observed in the operation of needle scalers, hammer chisels, and bucking bars, the gloves did not reduce the vibration but increased it.

CONCLUSIONS

This study confirmed that the effectiveness for reducing vibration varied with the gloves and the vibration reduction of each glove depended on tool, vibration direction to the fingers, and finger location. VR gloves, including certified anti-vibration gloves do not provide much vibration reduction when judged based on frequency-weighted acceleration. However, some of the VR gloves can provide more than 10% reduction of the unweighted vibration for some tools or workpieces. Tools and gloves can be matched for better effectiveness for protecting the fingers.

The Efficacy of Anti-vibration Gloves

Anyone seeking to control the risks from vibration transmitted to the hands and arms may contemplate the use of anti-vibration gloves. To make an informed decision about any type of personal protective equipment, it is necessary to have performance data that allow the degree of protection to be estimated. The information provided with an anti-vibration glove may not be easy to understand without some background knowledge of how gloves are tested and does not provide any clear route for estimating likely protection. Some of the factors that influence the potential efficacy of an anti-vibration glove include how risks from hand-arm vibration exposure are assessed, how the standard test for a glove is carried out, the frequency range and direction of the vibration for which protection is sought, how much hand contact force or pressure is applied and the physical limitations due to glove material and construction. This paper reviews some of the background issues that are useful for potential purchasers of anti-vibration gloves. Ultimately, anti-vibration gloves cannot be relied on to provide sufficient and consistent protection to the wearer and before their use is contemplated all other available means of vibration control ought first to be implemented.

Anti-vibration gloves?

For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered.

The effects of vibration-reducing gloves on finger vibration

Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed.

RELEVANCE TO INDUSTRY

Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understanding of the glove effects on finger vibration and provided useful information on the effectiveness of typical VR gloves at reducing the vibration transmitted to the fingers. The new results and knowledge can be used to help select appropriate gloves for the operations of powered hand tools, to help perform risk assessment of the vibration exposure, and to help design better VR gloves.

Vibration-reducing gloves: transmissibility at the palm of the hand in three orthogonal directions

Vibration-reducing (VR) gloves are commonly used as a means to help control exposures to hand-transmitted vibrations generated by powered hand tools. The objective of this study was to characterise the vibration transmissibility spectra and frequency-weighted vibration transmissibility of VR gloves at the palm of the hand in three orthogonal directions. Seven adult males participated in the evaluation of seven glove models using a three-dimensional hand-arm vibration test system. Three levels of hand coupling force were applied in the experiment. This study found that, in general, VR gloves are most effective at reducing vibrations transmitted to the palm along the forearm direction. Gloves that are found to be superior at reducing vibrations in the forearm direction may not be more effective in the other directions when compared with other VR gloves. This casts doubts on the validity of the standardised glove screening test. Practitioner Summary: This study used human subjects to measure three-dimensional vibration transmissibility of vibration-reducing gloves at the palm and identified their vibration attenuation characteristics. This study found the gloves to be most effective at reducing vibrations along the forearm direction. These gloves did not effectively attenuate vibration along the handle axial direction.

Vibrotactile perception at glabrous and nonglabrous skin of fingers: repeatability of measurements and changes induced by acute vibration exposure

OBJECTIVES

We sought to determine the within-session and between-session repeatability of vibrotactile perception threshold (VPT) measurements and the response patterns in VPT induced by acute exposure to short-term vibration from grasping a vibrating handle, at both glabrous and nonglabrous skin of fingers.

METHODS

Baseline VPT was recorded twice at glabrous and nonglabrous side of fingers in the right hand of eight healthy volunteers. Then, the subjects were exposed to three exposure conditions (vibration at 31.5 Hz and 250 Hz, and no vibration), from gripping a vertical handle by the right hand, conducted on 3 different days at an interval of 1-3 wk. After exposure, the subjects released the hand and further VPT measurements at each location were made.

RESULTS

Compared to the nonglabrous side, VPT measurements at the glabrous side demonstrated better within-session and between-session repeatability with lower coefficient of repeatability and higher intraclass correlation coefficient. After exposure, a significant increase in VPT was noted under both 31.5 Hz and 250 Hz (p<0.05-0.001) exposure conditions in the glabrous finger. In the nonglabrous finger, a pronounced increase in VPT was revealed under 250 Hz exposure condition (p=0.05).

CONCLUSIONS

While measuring VPT at glabrous and/or nonglabrous fingers, the importance of the site of measurement should be considered; the repeatability for such measurements appears to be better at the glabrous site. At high frequency, vibrotactile perception appears to be affected in both glabrous and nonglabrous skin from acute vibration exposure.