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HomeHealthThe Impact of Work Environment on Knee Health: Insights from Singapore

The Impact of Work Environment on Knee Health: Insights from Singapore


Identifying the hazardous activities and modifying the work conditions so as to reduce exposure are important steps in prevention. Studies throughout the world have reported an elevated risk of knee disorders in occupations that involve heavy loading of the knee joint. While heavy lifting and frequent stair climbing are frequently cited as causes of knee osteoarthritis, a better understanding of the specific activities that lead to knee injury is needed for developing effective prevention strategies.

Knee disorders have become a significant cause of disability in most industrialized and developing countries. They not only affect the elderly and the obese, but also increasingly the young and active. While some knee injuries, such as those resulting from an accident, are not preventable, many disorders develop over time and can be prevented or minimized with the aid of interventions.

Factors Influencing Knee Health

Another factor at work is squatting, which has been shown to cause an increase in the rate of radiographic changes of osteoarthritis in the knees, particularly in the tibiofemoral compartment. Heavy lifting has a similar effect and has been associated with an increased risk of symptomatic osteoarthritis in the same compartments.

Some jobs and leisure activities require people to be in constant positions or to carry out the same activity for a long time. For example, it has been shown that prolonged kneeling is associated with an increased risk of osteoarthritis in the knee. Kneeling for 1-32 hours per week has a two-fold increased risk, and >32 hours per week has a six-fold increased risk!

Knee health can be influenced by multiple factors, and one significant factor is the work environment. Repeated kneeling, squatting, heavy lifting, climbing stairs or ladders, and working while standing on hard surfaces can all contribute to the wearing out of knee cartilage. Cartilage is a firm, rubbery tissue that acts as a cushion between the bones in the knees.

Physical Demands of Work

Occupational tasks, such as heavy lifting and prolonged periods of standing, have long been believed to be associated with an increased risk of knee OA. In a recent systematic review, concluded that there was limited evidence for occupational risk factors in the development of knee OA and called for more research in this area. This conclusion is somewhat surprising, given that the relationship between occupational risk factors and hand OA is well established. In contrast to hand OA, knee OA has received relatively little attention in occupational health research. While it is clear that knee injuries (e.g., ligament ruptures) often lead to OA in later life, there is still debate as to whether specific occupational activities increase the risk of developing knee OA in the absence of traumatic injury. One problem in assessing how work affects knee health is the difficulty in isolating occupational factors from those of recreational or sporting activities, which may also impact knee joint health. Despite these challenges, it is still important to identify occupational risk factors for knee OA, as this knowledge could lead to the development of prevention strategies and early interventions for individuals at high risk.

Ergonomics and Workplace Design

According to the findings from interviews conducted at PT. Astra Honda Motor, workers stated that the current workplace design demands them to work more with less time and less energy, resulting in excessive changes in the work process. This indicates that the conditions are bad working conditions and are not good for the health of the knees. These findings are similar to those in the Hyodo unhealthy work, where more energy is required and repetitive tasks can lead to early weariness and decreased job performance capacity.

Workplace design is influenced by the working conditions that need to be suitable for the work process in terms of quality and quantity. Good and bad workplace conditions differ in the physical and mechanical aspects. Good working conditions allow workers to perform their work with ease and less energy, while bad working conditions require more energy and often leave workers feeling tired after work. Excess energy used contrary to the recommended amount can lead to early weariness, decreased job performance capacity, risky behavior during work, and increased risk of injury.

Occupational Hazards and Knee Injuries

Occupational hazards and injuries can come from a traumatic incident or from cumulative wear and tear over time. They occur at a higher rate for many blue-collar jobs, where employees are more likely to put their bodies at risk during the normal activities of the job. In particular, those who do manual labor which requires heavy lifting, prolonged standing, repetitive bending or squatting are at a higher risk for knee injuries. One such example would be floor layers, who have a 75% lifetime risk of developing symptoms in their knees. The high rate of injuries in this profession led to a study done in Sweden to determine the primary causes of disability in floor layers over time. They found a direct link between symptoms and degenerative changes in the patella tendon and knee osteoarthritis to years of kneeling down on one or both knees when installing flooring materials. This study shows that knee injuries are not purely isolated incidents and can severely impact an individual’s quality of life and ability to work if not properly addressed. An injury at work can also complicate the matter of receiving compensation and benefits in regard to medical costs and time off from work. A study on advanced occupational knee osteoarthritis and disability in the construction industry showed that a variety of barriers exist in the worker’s compensation system and that obtaining compensation or finding less demanding work may prove to be very difficult.

Strategies for Promoting Knee Health in the Workplace

The company employed a physiotherapist as a consultant to teach alternative methods to its employees. For example, the act of scrubbing a floor on one’s hands and knees was replaced by using a long-handled brush or a floor cleaning machine. The consultant also provided valuable information about early symptom recognition of knee damage and specified what should be done in response to different types of pain. This was followed by a question and answer session which encouraged active participation by employees. This initiative served to empower employees with knowledge and increased their vigilance about knee health during work.

The purpose of training and education is to increase employee awareness about knee injuries and preventive strategies. This is an essential starting point for reducing knee injury prevalence as many workers underestimate the capacity for knee damage in even some of the most mundane work tasks. At the cleaning company, a training and education session involved showing employees what equipment and work methods contributed to knee damage and pain.

In the process of reducing the prevalence of knee injuries at work, the most logical stepping-stone is to implement strategies to improve the work environment and to promote knee health. Given that the prevalence of work-related knee pain Singapore is 25%, such initiatives will be of great importance in numerous industries. We have gone on to outline two case studies to demonstrate what these initiatives will entail in practice. The first is a cleaning company and the second is a pharmaceutical company.

Training and Education

Training and education are one of the strategies to promote knee health at the workplace. However, there is a lack of information on the kind of training that is effective for preventing knee injuries. Promotion of knee health should be incorporated into general health and safety training conducted by the company. For specific targeting of at-risk workers, the training should cover issues related to specific job tasks as it has been shown that job-related factors are strong predictors of the development of knee OA and knee pain, especially in crouching and kneeling, squatting, and heavy lifting tasks. Those with crouch-heavy jobs should be educated about the effects of high tibiofemoral load and meniscal extrusion and the resulting increased risk of knee OA. Trade workers should be taught to recognize symptoms of overuse and the importance of early treatment to prevent further joint damage. Material should be in the form of print or multimedia as a study found that a significant predictor of perceived severity of knee OA was exposure to and belief in the credibility of health information. An education program was also recommended by office workers to increase understanding of knee injury risk and prevention strategies to incorporate changes into behavioral habits at work.

Implementing Ergonomic Solutions

According to The Free Dictionary, the study of ergonomics looks at the ‘fit’ between people and the things they do and use – in this case, the workers and their work tools. It is pertinent to the adjusting of the work environment to the worker for the prevention of bodily stress, strain and discomfort, and in the case of this study, knee injury. A key to this is ensuring that the work is conducted within the workers’ ‘comfort zone’ where stress and strain are minimized due to the work being within the worker’s physical limits. If the work is beyond the worker’s limits, it is necessary to reduce the work demands by using various ergonomic tools and in some cases change the work process. The most technically demanding and time-consuming stage in changing the work environment is redesigning the work process, and in this study, it is the maintenance workers who would receive the greatest benefits from a change in the work process. This is seen in the change in the method of removing weeds on traffic islands. The conventional method using a hand tool requires one to kneel on one knee while supporting one’s weight with the other leg. This increases the likelihood of knee injury or exacerbating an existing knee condition. An alternative method using a custom-built cart eliminates the need to kneel and thus reduces stress on the knees.

Injury Prevention Programs

Injury prevention programs can be implemented as a one-step solution or can be structured into various components. The most successful prevention programs are likely to be multifaceted and integrated with other health and safety initiatives and related to the organization’s goals. Program success is often realized in terms of reduced incidence of injuries and workers’ compensation costs. To estimate the effectiveness of any intervention, it is necessary to compare pre-intervention and post-intervention injury incidence and/or work exposures. If a reduction in injuries is observed, it is likely that the program has been effective. However, it should be noted that a lack of change in injury incidence could be a lack of program effect or an erroneous program focus on a low injury rate. Any changes in the work environment or work process resulting from program activities may increase the need to modify the program, program components, or focus. This indicates that injury prevention should be an ongoing, evolving process. High-quality research should be done to continuously evaluate the effectiveness of program components. At a fundamental level, prevention programs need to identify and mitigate injury risk factors. This can be done by targeting specific high-risk jobs, tasks, or work environments. In the realm of prevention, it is more effective to focus on avoiding injuries rather than trying to promote quick recovery from injury. This ties in with the concepts of positive health and negative health. Positive health is the state of complete physical, mental, and social well-being, and negative health is the absence of illness or injury. The WHO (World Health Organization) defined health as being a state of positive well-being and not just the absence of disease. Although it is common to equate positive health to enhanced productivity by avoiding injury, an alternative pathway is to link safety to health and thus health promotion to safety. This can be achieved by using worksite health promotion (WHP) to change employees’ attitudes and behavior towards the promotion of their own health and safety. This concept will fit well into injury prevention program activities.

Worksite Wellness Initiatives

Other programs like the smoking cessation have indirect benefits to knee health but would generally promote better overall health for the employee. All these programs should show long term benefits to knee health as it reduces obesity rates and creates a workforce more aware of health and its effects. This would reduce the prevalence of knee issues mentioned in the introduction.

Weight loss challenges were a common program among SIA and SMRT staff. They cited the high prevalence of obesity in Singapore and related it to knee osteoarthritis. It was mentioned that many employees are overweight and do not consider the long term effects on joint health. Weight loss challenges had been quite successful with employee buy in and visible weight loss in some cases. SIA had a comprehensive weight management and fitness & diet program which were held yearly featuring professional trainers from a local gym. The fitness and diet programs are aimed at teaching employees good exercise and diet habits. These programs usually have a small number of committed participants who are willing to make lifestyle changes. One SIA employee with a desk job and noted weight gain had positive results from such a program. At the end of the 3 month program he lost 7kg and felt that the dietary advice given would help him maintain a healthier lifestyle. This employee had a past knee injury which had hindered his regular exercise due to repetitive strain from running sports. Such programs would benefit him and others with pre-existing knee conditions who are unable to participate in high impact sports.

Eight companies agreed to participate in the interviews regarding their programs. These companies were from a good mix of industries with 3 from manufacturing, 2 from service sectors, 2 from office jobs and 1 in healthcare. The largest contingent was health promotion programs as this has been a main focus of many wellness programs today. Health promotion programs are aimed at helping employees act on health risk factors. These may take the form of weight loss challenges, smoking cessation programs, or dietary change programs just to name a few.

Unlike the other three strategies, worksite wellness initiatives primarily target employees’ health through activities or programs initiated by the employer. They are getting increasing attention as a means to maintain employee health and wellness. While these programs were not implemented with knee health in mind, many of the programs have components that may benefit knee health. This section will present the types of worksite wellness initiatives offered by various companies in this study. The Wellness Councils of America (WELCOA) categorizes wellness programs into 7 key areas, and the initiatives will be presented using these categories (Health Promotion, Health Protection, Health Culture, Occupational Health and Safety, Mental Health, Environmental Health, and Human Resources). This is a very useful framework to evaluate the types of programs available to the employees.

Case Studies and Success Stories

Occupational situations were recorded for a 41-year-old male with a 55kg body weight in a study carried out in the Rehabilitation Centre, Tan Tock Seng Hospital (TTSH) to explore the effect of work environment on knee health. This man was in the army as a commando for 20 years and is currently a full-time undergraduate. The army training school provided him with the first stage of injury on his left knee 24 years ago. He twisted his knee on the sand during a training session and the original pain subsided after a series of acupuncture treatments. But the injury recurred a year later when he was doing his parachute jump training. Subsequent years of wear and tear on the knee from the nature of his job worsened the knee condition. Needless to mention all the jumps, running, climbing up and down the slopes, and prolonged field camp activities; they caused frequent giving way and mild swelling on his left knee. The aggravated knee condition forced him to downgrade to a clerk job and finally he was discharged from the army on medical grounds 3 years ago. His knee condition improved after he had stopped all strenuous army activities, but there were still episodic giving way and occasional mild pain at the end of the day. Currently, he is working as a part-time tutor while still pursuing his degree. This change of job and work environment has somewhat relieved his knee problem, but there were no significant changes due to his naturally degenerated knee condition from the years of abuse. This person was referred from the polyclinic and had an MRI of the left knee done. He was diagnosed to have a complex tear of the medial meniscus and the presence of degenerative disease on the same side. A decision was made for an arthroscopy procedure to mend the tear. This case is a clear demonstration of a knee injury caused by the hazardous nature of the army environment with a source of ideal history comparison. His current job will serve as a contrasting phase, which is an important factor in the study methodology.

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