Work Related Musculoskeletal Disorders in Defence Personnel Involved in Heavy Engineering Maintenance

Background: Work-related Musculoskeletal disorder (WMSDs) are multifactorial occupational disorders, having high morbidity and economic cost. Heavy engineering maintenance personnel involved in manual material handling, physical load with awkward posture poses high risk of WMSDs. Objectives: This study investigates the prevalence of work-related Musculoskeletal disorder (WMSD) among Indian defence personnel involved in heavy engineering maintenance work. Setting and Design: A cross-sectional survey was conducted with participant consents. Materials and Methods : 379 defence personnel involved in heavy engineering maintenance task were assessed for WMSDs, using NMQ. The effect of risk factors such as age, working hours, BMI, smoking and type of job on WMSDs was analysed. Statistical Analysis: Data analysis was done using using logistic regression with SPSS version 14. Results : 67.54 % personnel (N=379) reported WMSDs with total of 704 WMSDs. 51.45% reported multiple WMSDs and 16.09% had single WMSDs. Highest WMSDs were reported in low back (44.85%), followed by knee (28.23%), elbow/forearm (15.83%), ankle/foot (22.95%), shoulder (18.46%), upper back (18.46%), neck (15.83%) and wrist/fingers (12.92%). Long working hours (p=0. 000; OR=1.83, 1.58-2.12) and smoking habits (p=0.000; OR=5.52, 3.43-8.48) are significantly correlated with WMSDs. Automobile me chanics (p=.045; OR=2.64, 95% CI=1.04-6.72) and welders (p= 0.034; OR =2.32, 95% CI = 1.21 – 4.36) are at higher risk of WMSDs. Conclusion: There is a high prevalence of WMSDs among Indian defence mechanics. It is suggested that ergonomics training is required for maintenance workers. The detrimental effect of smoking is also noted with the prevalence of WMSDs. material handling, excessive load, repetitive task, work pressure, wrong postures causing WMSDs 10


Introduction
MSDs are multifactorial disorders, which cause damage to muscles, ligaments, cartilages, tendons, soft tissues and nerves 1 . MSDs are characterized by varying severity of pain, restricted range of motion and limitation of functions 2 . Maintenance and repair jobs pose a high risk of MSDs, due to heavy physical work or manual material handling, awkward posture and high job demand 3 . MSDs that are occupational health hazards are termed as work related musculoskeletal disorders.
Work Related Musculoskeletal Disorders (WMSDs) have high morbidity and economic costs 4 . WMSDs negatively affects the workers' health, thereby lowers productivity, increases absenteeism and work day loss and is associated with substantial financial cost 5 . The economic cost of workrelated injury and illness was estimated to be 4% of the GDP of developing countries 6 . In the case of developed countries, indirect cost for MSDs amounts to 40% of total annual costs of accidents 7 . Unfortunately, WMSDs are under reported in developing countries and indirect cost of occupational musculoskeletal disorder (non-fatal) in 2007 was 1.5 and 1.1 billion dollars, respectively due to lack of standardized statistics recording and notification system 8 .
Defence forces are equipment intensive and have a large number of personnel employed for maintenance and repair of heavy engineering system 9 . These personnel provide close support to combat units and most equipment are maintained and repaired in-situ, under field conditions with bare minimum infrastructure. This entails risk factors such as manual material handling, excessive load, repetitive task, work pressure, wrong postures causing WMSDs 10 .
Musculoskeletal injuries and disorders are main reason for morbidity and temporary disability in military population 11,12 . Health clinic visit rates are approximately equal for injuries and illness in military environment but the morbidity associated with injuries is over five times greater than that associated with illness 13,14 . MSDs are second highest reason for premature discharge from military services 15 . Combat environment and geographical topography are responsible for MSDs in US military 16 . Large number of musculoskeletal injuries is seen in defence services, but studies identifying the cause and risk factors of these musculoskeletal injuries/disorders are sparse 17 . The literature so far lacks any insight about the WMSDs in defence personnel, involved in maintenance and repair operation along with combat duties.
This highlights the significant role of defence personnel involved in maintenance and repair operation.

Objective
The study aims to investigate the prevalence of WMSDs in defence personnel involved in maintenance and repair operation.

Materials and Methods
This cross-sectional study focuses on defence personnel involved in heavy engineering repair and maintenance operation. These defence personnel work as automobile mechanics, crane operators, welders and hydraulic system mechanics. A survey research was done at seven different geographic locations from three different terrains in India: (i) Plains and coastal region (ii) High Altitude and Hilly (North-Eastern region) (iii) Semi-desert (North-Western region).
A total of 423 defence personnel involved in variety of maintenance tasks were enrolled for the study, after an informed consent. 379 personnel correctly responded, making a response rate of 89.5%. 44 personnel were excluded due to incomplete information. They were divided into two groups, based on their experience. Group 1 (G1) -personnel having minimum 15 year of service and did more of supervision, guiding and coordination of maintenance task (n= 120). The Group 2 (G2) -personnel with less than 15 year of service and were involved in executing maintenance and repair task (n=303).
Respondents filled a self-reported questionnaire, having Part A as personal information and Part B as Nordic Musculoskeletal Questionnaire (NMQ). After a thorough briefing, All respondents were asked to answer the occurrence of musculoskeletal symptom, experienced by them during last 12 months in various body parts (neck, shoulder, forearm/ elbow, wrist, upper back, low back, knee and foot/ankle). The presence of MSDs was defined as ache, pains or discomfort in any of the eight body regions marked in body-chart ( Figure 1). The symptoms of headaches, chest and abdominal pain were excluded, as they could be related to systemic illness.
The case definition of musculoskeletal symptoms is taken similar to National Institute of Occupational Safety and Health (NIOSH) (2) and is (i) the subject who felt musculoskeletal symptom in last 12 months in any of the body parts (ii) the symptoms that lasted for more than seven days at a stretch or it was felt for more than once in a month. MSDs due to non-occupational causes such as motor accident or sports activities were excluded from the study. To avoid the recall bias, the MSDs were restricted to past one year. The period of investigation was from 14 Mar 2016 to 3 Oct 2018. This study was approved for ethical consideration of Research Involving Human Research Subject, by NMIMS ethical committee.
The descriptive statistical analysis of data of 379 respondents was carried out to understand the distribution of demographic details including age, BMI, employment duration, working hours, smoking, job content, body parts affected and MSD prevalence. The variables under the      Table 2). Multiple WMSDs are higher than single WMSDs. Among all job title, personnel suffering from multiple WMSDs are much higher than personnel suffering with single WMSDs. Welder reported highest prevalence of single as well as multiple WMSDs.   (Table 4).

Results
Four models (M1 to M4) were derived to find out the significant risk factors of WMSDs through logistic regression. We found that the prevalence of WMSDs were significantly affected by daily working hours (OR = 1.83, 95% CI = 1.58-2.12) and smoking (OR = 5.52, 95% CI = 3.43 -8.48).

Discussion
In this study, we investigated the prevalence of Work-Related Musculoskeletal Disorders (WMSDs) and their association with type of job in heavy engineering maintenance work force of Indian defence. We found that large numbers of personnel suffer with WMSDs, but this is not reflected in their medical records or defence hospital data. Aches and pain during working are taken as acceptable norms or usual part of life by these personnel. There is lack of awareness about prevention, treatment and ergonomic care. They also hesitate in repetitively reporting the discomforts and pains frequently, as it may be taken as sign of excuse from the work.
67.54% of respondents reported WMSDs with total of 704 WMSDs in 379 respondents. This is because 51.45% of respondents reported multiple WMSDs and 16.09% had single WMSDs. Low back WMSDs was high among all job titles (44.85%) of heavy engineering. High Prevalence of low back WMSDs is also reported by Torp et al., (1996) in car mechanics and   28 in Norwegian Royal navy 18,19 . They have very high physical and cognitive demands, both as soldier and technicians respectively. The strategic machine/equipment may not be designed ergonomically for its maintainability, which force personnel to work in awkward posture for long time. Also, it is not always possible to take out defected machinery part out of the heavy machinery or  vehicle and it must be repaired in situ, allowing very limited space to access them. We have observed them working in squat, semi squat, back flexed to complete range in standing position, kneeling positions and even lying under the vehicle with their hand raised above shoulders. These factors such as dual role, high physical and cognitive demand, awkward posture, long working-hours predispose them to high risk of WMSDs [20][21][22][23] . Welders reported Wrist/finger WMSDs they are exposed to hand transmitted vibration, while using heavy drilling equipment or pneumatically operated cutting tools. Similar results were reported for steel maintenance workers 20 , and for machine operators using vibratory drilling tools 7 mm displacement amplitude 24,25 .
Automobile mechanics too had high number of all type of WMSDs with maximum affection in low back. They were found to have never ending repair work lined up. Repair work in night-time, in-situ work and work underneath the vehicle/ equipment poses issues of inadequate illumination, which is reported risk factor for WMSDs 11,26 . While repairs, Hydraulic system mechanics perform repair and maintenance of weapon systems which includes heavy barrels, hydraulic cylinders and cradle system. It requires lifting, holding and carrying heavy components, application of excessive force for twisting and turning of levers. Resultantly, they suffer more from low back, elbow/forearm and ankle/foot WMSDs.
Crane operators reported high percentage of ankle/foot, elbow/forearm, and shoulder WMSDs 27,28 . They frequently get engaged in recovering heavy vehicle from accidental site, many a time in hilly terrain. Their task involves frequent mounting and dismounting from crane, lifting fixing heavy chain, D shape blocks & shackles to objects. Manually heavy material handling has been very well identified as cause of WMSDs in manual material handlers 30 .
Across all Job titles, multiple WMSDs were higher. Smokers and overweight personnel reported more multiple WMSDs. Similar findings were reported by Vieira, Kumar, and Narayan (2008) genetic disposition, personal traits and habits. Not all risk factors can be controlled. Preventative programs frequently focus on workload, organizational and psychophysical issues.
Smoking, no-exercise, and overweight generally receive less attention. This study assessed the association between smoking, no-exercise, and overweight and low back disorder in welders and nurses. A retrospective epidemiological study and a questionnaire survey were conducted. The records of injuries were examined and 111 workers (64 welders and 47 nurses in welders. They observed smoking, and overweight as increased risk of low back disorder 29 . Morken T et al., (2000) and Knapik et al., (2004) also reported positive correlation between smoking and MSDs in Aluminium industry workers and combat recruits 13,31 . Though smoking has effects on the immune system that has long-term consequences for tissue healing even after smoking cessation 32 , it is a modifiable risk factors that if addressed can reduce the prevalence of MSDs 33 .
Defence maintenance personnel, who worked more than 8 hour/day had more WMSDs. This is probably because their average daily working hours are much higher than normal industrial norms (ILO 1930, Convention 1 and 30) which is 8 hours/day 34 . Defence personnel officially are otherwise on duty for any emergent requirement, except during leaves. In addition to their professional jobs, they perform physical training, other administrative and security related tasks in rotation as per schedule. They work in shift and provide round the clock support to combat troops for any maintenance related tasks. M. Bovenzi & N. Stacchini (2002)fork-lift truck drivers, and 46 crane operators. The vector sum of the frequency-weighted r.m.s. acceleration of vibration measured on the seatpan of port vehicles and machines averaged 0·90 m/s 2 for fork-lift trucks, 0·48 m/s 2 for straddle carriers, 0·53 m/s 2 for mobile cranes, and 0·22 m/s 2 for overhead cranes. The 12-month prevalence of low back symptoms (LBP, sciatic pain, treated LBP, sick leave due to LBP) too had reported 'increase exposure to work' as low back pain risk in 245 machine operators involved in maintenance operation 35 . Long working hours is the proven risk factor of occupational injuries among automobile and maintenance worker 36 .

Conclusion
This study revealed high prevalence of WMSDs among heavy engineering maintenance personnel of Indian defence forces. Specifically, Low back, knees, ankle/foot and elbow/forearm were most affected areas. Moreover, this study revealed more presence of multiple WMSDs, with high BMI, long working hours, smoking and four different job trades (automobile mechanics, welders, crane operators and hydraulic system mechanics) as risk factors. The ergonomic risk factors in terms of workload, work pressure, awkward posture, in appropriate workspace, long working hours, shift duties, tough terrain and poor illumination might lead to many WMSDs in these personnel.

Relevance of Study
This is the first study to link WMSDs in defence forces and maintenance workers, especially in Indian scenario. Up till now, the focus was on combat forces and recruits, mainly highlighting training methods, uniforms, shoes, or reducing organisational stress [37][38][39] . The results of this study will be applicable for community of heavy engineering maintenance workforce for their WMSDs.

Recommendations
Authorities should install the measures for screening of WMSDs and their work-related ergonomic risk factors to prevent WMSDs. Initiatives and intervention to control these risks is advocated by early recognition and appropriate treatment. Reporting of WMSDs to be institutionalized for further analysis and plan for prevention measures.

Limitation of Study
The findings of this study are limited to assessment of risk factors without direct measurement of postural assessment (through video recording) with constraints of non-applicability of industrial law to defence maintenance personnel. Even 12-month recall period used by us would have likely caused recall bias to some extent as 40 reported that longer recall period can cause recall bias, if injuries are less severe.