Impact of Load on Craniovertebral Angle in Construction Workers: A Correlational Study

Background

A construction worker is a trader, a worker (traditionally considered a non-qualified trader), or a specialist working in the physical construction of a building. Among the most common construction traders are carpenters, electricians, heavy machinery operators, iron workers, laborers, masons, plasterers, plumbers, pipefitters, sheet metal workers, steel fixing workers and welders.¹ Construction employees had around 1 million jobs in 2010, of which only 59% were taken up by workers.

Construction workers work on all types of construction sites, performing a wide variety of jobs from very straightforward jobs to highly challenging and dangerous jobs. While certain roles require some training and experience, most jobs typically require little expertise and can be learned quickly. This sector employs a significant number of skilled, semiskilled, and unskilled employees due to its high demand.¹ The workforce working in the construction industry face a number of challenges at work since then.

Among these occupations, construction workers experience a large number of serious injuries and is one of the most dangerous sectors. The International labor organization (ILO) reports that at least 108 thousand workers are killed on site every year, accounting for around 30% of all workers. Risk among construction workers is 3 to 6 times higher when compared to other workers in the developing countries.^{2, 3}

The challenges faced by construction workers in India include loss of equal wages. They are not paid a minimum wage. Furthermore, their working time and hours are not regulated. They don’t get paid for working overtime. They operate under dangerous conditions. The working conditions and facilities at the working site are far from satisfactory. Apart from these, there are no leisure facilities. There is no supply of drinking water, toilets, canteens, etc. They are forced to live in slums where there are no proper living conditions. The surroundings are absolutely unhygienic. There is no adequate sanitation, portable water, electricity, toilet, drinking water, leisure and environmental factors such as high temperatures and humidity.⁴ Moreover construction workers have no social security benefits and labour rights.⁵

Women workers along with men are equally employed in this field, in particular for non-qualified jobs such as sundry and manual work. They work at various building and project sites that are extremely hazardous in nature and thus face a range of issues and challenges.6 Their main challenges are health, work-life balance, safety, wage discrimination, abuse, and above all, is the working condition.⁷ There are numerous constitutional and legal provisions on the safety of women, particularly in the unorganised sector; they suffer from various disadvantages in terms of their working lives as well as their homes.⁸ The benefits of labour laws have not been covered in case of women workers in many areas, especially, health, maternity and social security. India’s construction workforce is estimated as 30 million people, and about half of them are women.^9,10

Musculoskeletal Disorders (MSD) are injuries and disorders that affect the movement or the musculoskeletal system (i.e. muscles, tendons, ligaments, nerves, discs, blood vessels, and supporting structures of the upper and lower limbs, neck and lower back); they can be induced, precipitated or aggravated by sudden exertion or prolonged exposure to physical stress such as high strength, repetitiveness etc. (Niosh, 2015) Popular names for MSD are repetitive motion injury, repetitive stress injury, and overuse injury. Job-related musculoskeletal disorder occur when the mechanical workload is greater than the functional ability of our body.¹¹ The occurrence of work-related non-traumatic soft tissue injuries to the spine, back, and upper extremities is approximately 6.2 per 100 full time employees in the construction industry^12,13. In construction workers, MSDs are the major cause of productivity loss at job, functional impairment, and permanent disability. However, workers in different construction jobs are at a risk of developing different job-related MSDs primarily due to different biomechanical risk factors^4,14

Musculoskeletal disorders (MSDs) result in deteriorating health and work capacity, increased absenteeism, reduced productivity at work, impairment at work, increased maintaining costs and low morale.¹⁵ Construction workers are at a higher risk of experiencing musculoskeletal symptoms related to work when compared to workers in other professions. Work-related musculoskeletal symptoms are not only one of the biggest occupational health issues in the world; they are also known as an economic burden on the society.¹⁶ Multiple costs, both direct and indirect costs derive from this occupational disorder and contribute to musculoskeletal symptoms. these symptoms typically occur in many areas of the human body including neck, upper limbs, lower limbs and back. Exhaustion and discomfort are the most common early signs of work-related musculoskeletal symptoms. Sprains/strains, lower back pain, neck/toes and knee injuries are the typical MSDs in construction industry.

Work characteristics, such as hard manual work and repetitive monotonous motions, are factors of significance contributing to occupational disability.¹⁹ Heavy physical labour, in particular lifting and static loading of muscles and uncomfortable working positions contribute to MSD in construction workers.²⁰

The International labor organization reports that the cost of work-related injuries and accidents amount to 4 % of the world’s gross domestic product. According to the National Research Council and the Institute of Medicine, the overall cost of recorded work-related MSDs is as high as US Dollars 45–54 billion.²¹ Compelling evidence indicate that the construction industry offers an atmosphere that raises the vulnerability of employees to work-related MSD (WMSD).²²

In India, fatal injury rate for the construction industry is higher than the national average in the unorganized market. It is one of the most dangerous and accidentprone occupations recorded by the International Labor Organization (ILO, 2011).²³ Internationally, 17% of all work-related deaths are in the construction sector (ILO, 2011). Survey by Indian Labor Organization (ILO, 2009) found that 165 out of every 1000 employees are injured in the construction sector. Health risks in the construction industry can be divided into mechanical and non-mechanical hazards. Mechanical hazards include accidental impact problems, scrap metal penetration and sharp objects and crushing. Non-mechanical risks are a primary cause of workplace diseases and physical problems.^5,24 Previous pain in these areas of the body is the greatest indicator of pain in future years in the lower back, spine, elbows, upper arm or wrist. There are three main ergonomic risk factors: high recurrence of activities, intense exercise and repeated or prolonged uncomfortable postures. Risk factors include bad work practices, bad general health habits, poor rest, poor nutrition, fitness and hydration.

There is a major effect on the neck when carrying overhead load leading to changes in the neck posture.⁹ Working above the level of head, working with the arms extended above head level is normal in some activities such as setting up electricity or ventilation channels in the ceiling, or painting the ceiling. When operating with arms extended upwards the small muscles of the shoulder have to do extra work to support the weight of the arms. The load is particularly high if the worker also keeps the tool or load in the hand away from the shoulder.²⁶ In order to see the work being performed, the worker also needs to turn the neck sideways stretching the neck. Many of these construction workers report working with a forward head position and neck flexion, resulting in neck disorders and neck pain¹³. Neck and shoulder conditions affect 26.3% of men and 32.1% of women, among the Taiwanese construction workers.^{9 , 14}

Construction workers are members of a low socioeconomic group. They are not aware of the demerits of bearing heavy weight on their head. They normally bear cement bags/sacks, bricks, ballasts of at least 15 to 20 kg in weight. Full cement bags weigh between 36 to 45 kg. Standard weight concrete blocks, weigh approximately 16 kg and construction workers are involved in lifting, gripping, carrying, pulling or moving these and that affects their neck posture. Common neck disorders associated with work activities involving forceful arm exertions include degenerative disc disorders such as disc herniation or cervical spondylosis, and in some cases more severe muscle disorders such as tension neck syndrome.9 This contributes to constant pressure on the craniovertebral angle^15,16,17

Normal cervical lordosis is a curve in the cervical spine, the area of spine that includes neck vertebrae. This curve helps to stabilize the head and spine. In a healthy spine, the cervical lordosis appears like a large C, with the C pointing to the back of the neck. Numerous studies examined the moment generating capacity of the neck and reported strength values for different cervical postures in men, women, and different age groups. Prolonged, static postures are normal and are reported to cause discomfort both during non-neutral and neutral neck postures.²⁷

Neck posture has a strong correlation with neck musculoskeletal disorders (MSDs) in the occupational settings. This muscle movement induces an increase in spinal load by compressing the cervical joints¹⁹. Studies have shown that subjects with head, neck, and shoulder pain are more likely to have a lower craniovertebral (CV) angle that suggests greater forward head posture (FHP) when compared to those asymptomatic.¹⁷ FHP is distinguished by both the upper cervical extension and lower cervical flexion. These changes in the cervical region can lead to musculoskeletal dysfunction such as an upper crossed syndrome caused by poor head position over a long period of time. In addition, patients with FHP usually complain of pain in the neck and shoulder pain.

Electronic Head Posture Instrument (EHPI) for calculating the angle of CV is a measuring scale accurate to one decimal place, and the electronic sensor reads the angle automatically. EHPI has high intrarater (0.91– 0.93) and interrater reliability (0.92–0.93) for both normal subjects and those with neck pain. It was found that the craniovertebral angle significantly decreased during load bearing, indicating that head also plays a role to counterbalance load.

Symptoms of work-related musculoskeletal condition begin early in construction workers and can lead to further disability. This research would help to assess changes in craniovertebral angle to avoid cord compression and biomechanical changes in neck of construction workers. There is also a need to educate and raise awareness about the risk of injury due to heavy loads in this group of people and appropriate steps should be taken to pursue early medical attention and care for musculoskeletal disorders before they become chronic. The primary objective of this study was to evaluate the relationship between load and craniovertebral angle in the construction workers.

Materials and Methods

A simple random sampling design was adopted to sample 200 construction workers in and around Bangalore. The study duration was 6 months. Workers irrespective of gender and between 20 and 40 years of age, working for >5 years, 5-6 hours duration in a day, carrying an overhead load of approximately 20 kg per day (pilot study was done) were recruited. Patients with a history of surgery, recent fractures, spinal fractures, spinal deformities, and torticollis were excluded.

Subjects complying with the inclusion and exclusion criteria were recruited. Subjects were informed about the study and written consent was obtained. Baseline and demographic data such as height, weight, age, gender, BMI, duration of working hours, experience in years and weight carrying capacity was determined. Posture of was examined to rule out any deformities that might confound the study results.

The craniovertebral angle was measured. The angle was measured using an electronic head posture system (Figure 1). It consists of three components: electronic angle detector, a transparent plastic base and a camera tripod stand (Figure 2). The angle finder was placed on a translucent plastic base and placed on a tripod stand.

Subjects were advised to wear clothing that would expose their neck and the upper thoracic spine. They were also instructed to remove their socks and shoes and stand in a relaxed position, with eyes facing straight ahead and weight distribution on both sides. The spinous process of C7 was palpated and an adhesive pin was mounted on it. A further adhesive pin was mounted on the tragus of the left ear.

The participants were then instructed to stand in front of the electronic head posture tool facing his left/right shoulder. He/she was then instructed to flex and stretch the head three times and then rest it in a relaxed position. Photograph was taken from a distance of 0.5 m until the line on the transparent plastic base was  aligned with the pin markers (Figure 3).

A virtual line was drawn between the two pin markers on the images from the midpoints of the tragus to the C7. The EHPI was adjusted until the two lines of the indicator were aligned with the markers. The angle finder reading reflects the angle of CV. The narrower the angle of the CV, the longer the translation of the anterior head and greater the load, and vice versa.

Out of 200 subjects, 11.5% were women (23) and 88.5% were men (177). The mean age of the sample was 30 years and ranging between 20 and 40 years. The unpaired t-test was carried out to compare the baseline characteristics between gender. The mean load carrying capacity (kg) was significantly higher among male construction workers (47.23±5.30) when compared to female construction workers (40.22±6.82, p<0.05). The mean CV angle in male construction workers (42.21±4.41) was slightly lower than mean CV angle in female construction workers (46.09±4.50, p<0.05). However, other baseline characteristics were not significant.

The results of the correlation between baseline characteristics and CV angle between construction workers are presented in Table 2. The Karl Pearson method was used and we observed a negative correlation between load (kg) and CV angle (r= -0.049NS) in male construction workers and in female construction workers (r=-0.089 NS). However, the association between load (kg) and CV angle was significant (p<0.05) regardless of the gender. The above data suggests that load and CV angle are inversely related to each other.

Table 3 provides a compares mean CV angle across duration (hour), experience (year) and load (kg) categories. The mean CV angle score was found to be decrease with rise in load (kg). One-Way ANOVA was applied, and was significant (p<0.05).

Discussion

The main objective of the study was to determine the impact of load on CV angle in construction workers. The EHPI was used for the assessment of head posture and the impact of load on craniovertebral angle in construction workers. Measurements using EHPI were made in 200 construction workers engaged in overhead activities such as lifting bricks and an average weight of 20 kgs per day. The weight of male construction workers was found to be higher than that of female workers. The mean load score (kg) 47.23±5.30 was significantly higher among male construction workers when compared to female construction workers (40.22±6.82). The male workers lift a considerable amount of weight and the average weight approaches the normal limit of 20 kg. Anderson et al. who found a major impact of load on the sagittal vertebrae at T9 and T12 levels. The carriage of shoulder height load resulted in greater postural variance than the carriage at a lower height. It has also been observed that there is rising inclination of the trunk and a raising head on the trunk extension with increasing load on the back.

The mean CV angle in male construction workers (42.21±4.41) was slightly lower than the mean CV angle in female construction workers (46.09±4.50) due to their biological, physical and strength disparities. Chris ho ting et al measured forward head posture through CV angle to assess the relationship between head posture and severity and disability of patients with neck pain. A substantial difference between CV angle of females and that of males was observed throughout the study.

This shows that increase in load had an impact on the CV angle, resulting in a smaller CV angle. Rajanna et al. showed that most women workers (98.6%) engage in building construction activities in study areas. In another study conducted by Guo et al.11, it was reported that neck and shoulder disorders affect 23.6% of male and 32.1% of female among Taiwanese construction workers, which supported the selection criteria for female subjects in this study. In girls, the prevalence of neck pain increases with age, and in this study normal healthy individuals were selected. A relationship between head posture and severity and disability in patients with neck pain was observed. Also, a positive and significant relationship between pain intensity and superficial muscle activity was seen. The other baseline characteristics such as age, weight, height, BMI, duration and experience did not have any significant difference on the CV angle when compared between men and women.

The load was negatively correlated in male and female workers and in general subjects. It was found to be not significant in males and females but it was found to be of significant importance as applied to the total subjects of 200 workers, as the load increases the CV angle will decrease and vice versa.

The correlation between age and craniovertebral angle showed negative correlation (men, r=-0.070, women, r=-0.015) and was not significant. With increase in age, CV angle decreased and vice versa.

The correlation between weight and CV angle was negative for men (r=-0.067) and positive in women (r=0.033). The association between height and CV angle was negative in men (r=-0.097) and positive correlation in women (r=0.189). BMI of both male (r=-0.019) and female (r=-0.043) workers showed a weak negative association and was not significant. Duration when correlated with CV angle showed positive correlation in males (r=0.051) and a negative correlation (r=-0.085) in females. Experience when correlated with CV angle showed negative correlation in males (r=-0.056) and positive correlation in females (r=0.074).

Ariens et al reported that neck pain correlated with the cervical ROM and decreased with shorter period of overhead work. Overhead work increases tension and tightness around the neck and shoulder muscles. Lee et al suggested that there is correlation between cervical range of motion and flexion relaxation ratio. They also reported that there was significant reduction in cervical ROM and flexion relaxation ratio as the weight of bag being carried increases and that the reduction in range of motion and neuromyological changes in the neck reduced cervical flexion relaxation ratio. This study showed that overhead work was associated with high risk leading to musculoskeletal disorders.

When CV angle was compared across various baseline characteristics a one-way analysis of variance was applied to evaluate the importance of load over CV angle and the f ratio was found to be significant. This study indicates that there is a high influence of load on the CV angle. Increased load leads to decrease in CV angle and therefore leading to biomechanical changes in the neck. Altered biomechanics during lifting can cause increased joint stress and a rise in the probability of injury. Heavy lifting can cause trauma or soft tissue tears. This can lead to hemorrhage, edema, inflammatory reactions and subsequent tissue degeneration. An injury may lead to scar tissue formation which can change the biomechanics and strain all associated structures leading to biomechanical complications such as loss of cervical lordosis, cord compression, disc prolapse and other musculoskeletal anomalies.

A number of studies have reported that subjects with a forward head posture are vulnerable to neck disorder or irregular neck stress. Findings of the present study have shown that EPHI is valid when assessing the position of head and neck. It is an easy and convenient tool to assess head posture. Patients with a smaller CV angle are vulnerable to increased pain severity and neck disability. The present study reports that there is a significant correlation between load (kg) and CV angle in construction workers. 

Limitations

The CV angle was measured regardless of whether or not the staff had neck pain. The presence/absence of pain may have affected the CV angle and needs to be addressed.

The average weight carried was around 20 kgs, but the exact amount of load that was carried on a day generally exceeds the regular load that could have affected the CV angle.

Age and experience were not homogeneous and may have had an impact on the study.

Recommendations

Construction workers are at a higher risk of developing neck disorders, so attention must be paid to construction workers and adequate ergonomic steps (regular checkups, adequate leave days, training and education of workers, regulated working hours, regular breaks, protective equipment, weight of overhead load) should be adopted at the work site.

More research should be carried out to evaluate the sensitivity and precision of the electronic head posture instrument in the assessment of CV angle and range of motion.

The EHPI can be used to calculate the angle of overhead activity carrying large number of loads on an annual basis to assess its effectiveness.

Conclusions

To avoid problems and to prevent MSDs, the amount of overhead load must be minimised. Many musculoskeletal issues can be avoided by improving the workplace environmental quality, minimizing exposure to external loads acting on the body, improving job procedures, coordinating work, educating and training workers on the identification of ergonomic hazards and teaching problem solving skills to find suitable solutions.

Health promotion and campaigning are required to raise awareness and educate staff on health hazards (workrelated accidents and illnesses) due to inadequate use of protective equipment. This will help to raise employee and industry awareness on the high impact due to load on the cervical region.

Conflict of Interest

Authors declare that there is no conflict of interest.