Hand-arm Vibration Syndrome in Farmers and its Correlation with Degenerative Triangular Fibrocartilage Complex Injury.

CONTEXT: Hand-arm vibration syndrome (HAVS) is an occupational disease that affects workers who are exposed to vibrations. Farmers are prone to various musculoskeletal and cumulative trauma disorders. These occur owing to overuse, degeneration, and excess physical efforts along with whole-body vibrations- owing to the use of farming equipment such as tractors and harvesters. AIMS: Aims of the study were to find out the prevalence of various symptoms of HAVS among farmers using tractors, harvesters, etc., and to find out the correlation of triangular fibrocartilage complex (TFCC) injury with HAVS. SUBJECTS AND METHODS: A prevalence study was conducted among farmers. Farmers were selected by random sampling method and were asked to fill-up a HAVS surveillance questionnaire. The handgrip strength was recorded with a hand dynamometer. Assessment of carpal tunnel syndrome was done, and correlation of HAVS with TFCC injury was assessed.
RESULTS: Data from 100 farmers was obtained and analyzed. The musculoskeletal symptoms of HAVS, more specifically pain was prevalent (n = 65), followed by sensorineural symptoms (n = 70), and the vascular symptoms were less common (n = 43). HAVS accounts for a prevalence of 64% with 39% of farmers having TFCC injury along with HAVS (P value = <0.0001).
CONCLUSIONS: These findings reported in the study provide a better understanding of the impact and extent of HAVS in farmers. There is a significant prevalence of HAVS with mild symptoms of vascular component, mild to moderate symptoms of sensorineural component, and significant involvement of the musculoskeletal component. In addition, TFCC injury is correlated with HAVS. Copyright:

INTRODUCTION

Farming is an occupation that requires great efforts; thus, the physical conditions of farming make farmers highly susceptible to various musculoskeletal disorders, upper limb disorders, cumulative trauma disorders, etc.[1] As the world is advancing, new machinery is designed to decrease the workload of farmers, which may affect their physical condition owing to its nature of performance and repetitive use.

Hand-arm vibration syndrome (HAVS) is an occupational disease that occurs due to consistent use of vibrating tools or equipments which affects workers who are exposed to whole-body vibrations (WBVs) along with hand-transmitted vibrations (HTVs).[12] Triangular fibrocartilage complex (TFCC) injury is a consequence of both acute traumatic injury and degeneration secondary to repetitive loading of the involved extremities.[3]

High-frequency vibration is first absorbed by the distal-most parts of the body namely fingers and hand, giving rise to the vascular and sensorineural symptoms of HAVS,[45] whereas the vibration of lower frequencies is likely to be transmitted to the arms and shoulders and may be associated with the musculoskeletal abnormalities in hand and arm leading to pain and partial loss of functions of the hand.[4]

The risk of HAVS and the symptoms of the condition that appear among farm workers is unclear.[1]

Symptoms of HAVS can be seen in Indian farmers as they make use of appreciable force while working in the fields and carry out activities such as lifting, digging, and shoveling and also are exposed to WBV and HTV owing to the use of the machinery such as tractors and harvesters.[1]

In addition, owing to the usage of tractors and other machinery, farmers are subjected to complex and varied vibration conditions (ranging frequency of vibration to 1–9 Hz) with multi-axis translation and rotational vibration inputs to different parts of the body leading to disorders when used with improper ergonomics.[6]

HAVS has three components namely vascular, sensorineural, and musculoskeletal.[4]

The three different components of HAVS might exist and progress independently.[7] Carpal tunnel syndrome (CTS) can also be associated with HAVS and can coexist with HAVS, or HAVS can manifest individually.[48]

The exposure of vibration causes many structures to alter their physiology.[4910] Symptoms occur owing to direct vibration-induced damage to the soft tissues, or they may occur secondary to local nerve damage.[411]

HAVS results in loss of dexterity in hand, which may impair everyday activities, and potentially increases the risk of occupational accidents.[2] It may also lead to disability and poor quality of life.[12] HAVS is also linked to reduced daily functioning,[4] lower levels of well-being,[1314] and psychological stress.[4]

To diagnose the symptoms of HAVS, Stockholm workshop scale is been widely used.[151617] A full workup is necessary to exclusively diagnose HAVS; however, the special tests or particular assessment of HAVS is unclear and needs to be designed accordingly.

SUBJECTS AND METHODS

A prevalence study was conducted among the local farmers in and around the area to find the prevalence of HAVS and its correlation with TFCC injury. Ethical approval was granted by the Institutional Ethical Clearance Committee. Working farmers between age group of 40 and 70 years were selected by random sampling method. Male subjects working in the fields for more than 5 years and those using machineries in the field such as tractors, harvesters, JCB, etc., were included in the study. Approximately, 100–125 male farmers were selected on the basis of inclusion and exclusion criteria and were requested to participate in the study out of which around 100 farmers consented to fill-up the HAVS surveillance questionnaire and were assessed for TFCC injury and CTS using special tests such as TFFC grind test and Allen's test, respectively. In addition, the handgrip strength was checked using a handheld dynamometer. Subjects with major surgeries affecting their general health, subjects who only used manual methods of farming, subjects with unstable health parameters, and subjects involved as a worker in any other factory or industrial setup were excluded from the study.

Biostatistical analysis was done with the help of statistician, and results were obtained using appropriate biostatistical tools.

RESULTS

The average age of farmers was 53.54 ± 10.09. To rule out CTS in Indian farmers along with HAVS, Allen's test was performed. The test was negative in 57 (57%) participants and positive in 43 (43%) of participants. In addition, to rule out degenerative TFCC injury, TFCC grind test was performed and the test was positive in 56 (56%) participants and negative in 44 (44%) of participants. HAVS was ruled out by the Stockholm workshop scale.

Interpretation of grading done by Stockholm workshop scale

Tables 1A and 1B show the grading of symptoms of HAVS in the population studied.

Table 1A

For vascular component

Stage	Grade	Clinical description	Population affected	Percentage of affected population
0V		No attacks	58	58.00%
1V	Mild	Occasional attacks affecting only the tips of one or more fingers	42	42.00%
2V	Moderate	Occasional attacks affecting the distal and middle (rarely also proximal) phalanges of one or more fingers	0	0%
3V	Severe	Frequent attacks affecting all phalanges of most fingers	0	0%
4V	Very severe	As in stage 3V with tropic changes in the finger tips	0	0%

Table 1B

For sensorineural component

Stage	Clinical description	Population affected	Percentage of affected population
0SN	Vibration exposure but no symptoms	30	30.00%
1SN	Intermittent numbness with or without tingling	67	67.00%
2SN	Intermittent or persistent numbness, reduced sensory perception	2	02.00%
3SN	Intermittent or persistent numbness, reduced tactile discrimination, and/or manipulative dexterity	1	01.00%

Table 1A presents the grading of vascular component of HAVS, which ranges from 0V to 4V, among which 58% of the population had no attacks of vibration white finger (VWF) on exposure to cold and 42% of the population had mild symptoms with occasional attacks affecting only the tips of one or more fingers.

Table 1B presents the grading of a sensorineural component of HAVS, which ranges from 0SN to 3SN, among which 67% of population presented with symptoms of intermittent numbness with or without tingling and 30% of the population had vibration exposure but no symptoms.

The percentage of upper extremity pain (including shoulder, arm, forearm, and hand) perceived by the population was also studied. Approximately, 58% working farmers experience pain in their upper extremities, and about 42% of the working population was asymptomatic.

Distribution of handgrip strength among farmers was also seen. Data show that the handgrip strength of 74% of the population was between 0 and 20 kg (including both right and left hand). The data show that the prevalence of HAVS with all symptoms including mild vascular symptoms, sensorineural symptoms, and pain is 38% and the prevalence of HAVS including only sensorineural symptoms and pain is 26%, collectively comprising 64% of prevalence rate.

The correlation of HAVS and TFCC among farmers was studied, and it was observed that HAVS accounts for a prevalence rate of 64% with 39% of farmers having TFCC injury along with HAVS (P value = <0.0001).

DISCUSSION

This study was conducted among farmers to find the prevalence of HAVS in farmers. HAVS is an occupational disease that may affect workers who are exposed to HTV or to WBV provided the occupation involves use of upper extremities.

Previous studies state that in industries such as construction, mining, forestry, foundry work, automobile assembly, and metal working trades, HAVS is commonly seen.[4] In a study conducted among the UK farm workers, it was found that they are exposed to HTV and in turn are prone to HAVS. In these workers, there was a moderately high risk of cold-induced finger blanching and sensorineural symptoms, and the prevalence ratios were found out to be 1.2–2.6 in comparison with unexposed occupations.[1] It was interesting to find more about HAVS through this study. This study did show some variations owing to geographical and environmental variations.

There are three components of HAVS namely vascular, sensorineural, and musculoskeletal.

The symptoms of a vascular component include episodic finger blanching, cold intolerance, and VWF, which is a type of secondary Raynaud's phenomenon and the most established symptom for the diagnosis of HAVS.[181920] This occurs because of local endothelial damage caused by repetitive mechanical trauma, although small and oxidative stress formed in the hand. This, in turn, leads to peripheral vasoconstriction by activation of the sympathetic nervous system.[4] However, these symptoms may be associated with atmospheric conditions and geographical distribution of the population. These symptoms may be seen less in tropical areas owing to temperature variations.

The symptoms of the sensorineural component include paraesthesia or altered sensations, tingling, and numbness experienced in the hands of the workers.[1819] This may occur as vibration forces combined with mechanical stress predispose to damage the nerve fibers of the fingers.

The symptoms musculoskeletal component, include pain and weakness in the upper extremities [21] leading to reduced grip strength.[3] Hand is the most distal-most part of the body and thus absorbs high-frequency vibrations and transmits it to arms and shoulders leading to pain and impairment of the function of upper extremities.

The objectives of the study were fulfilled; the prevalence of various symptoms of HAVS including grip strength among farmers who use machinery adjunct to their manual labor was recorded and the correlation of TFCC injury with HAVS owing to degeneration, repetitive trauma, and overuse was established.

This study shows that among 100 farmers 64 of them had symptoms of HAVS although mild and not severe. Among these 64 farmers, 26 of them had no vascular symptoms and 38 of them had all symptoms seen in HAVS including mild vascular symptoms and mild-moderate sensorineural symptoms along with pain and reduced grip strength. Thus, this study shows that 43% of population had mild vascular symptoms and 67%–70% of population had mild to moderate sensorineural symptoms with 65% of population having symptoms of pain and 74% of population having reduced grip strength of both right and left hands, below 20 kg, whereas normal handgrip strength for mean age is 35–40 kg.

Therefore, mild HAVS is prevalent in farmers with a percentage of 64 in every 100 farmers.

Allen's test was carried out to find out the associated CTS with HAVS. It was found that among 100 farmers, 43 of them had CTS and it was either associated with HAVS or manifested individually. In majority of cases, it was associated with HAVS.

TFCC grind test was carried out to rule out TFCC injury in farmers. It was found that among 100 farmers, 44 of them had TFCC injury, and among these 44 farmers, 39 of them had HAVS along with TFFC injury owing to mechanical trauma and degeneration.

This accounts for a prevalence rate of 64% with 39% of farmers having TFCC injury along with HAVS, which states that TFCC injury is associated with HAVS with correlation coefficient (r) = 0.5809 and P value = <0.0001.

CONCLUSIONS

These findings reported in the study provide a better understanding of the impact and extent of HAVS in farmers. There is a significant prevalence of HAVS with mild symptoms of vascular component, mild to moderate symptoms of sensorineural component, and significant involvement of the musculoskeletal component. In addition, TFCC injury is correlated with HAVS.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.