• What is osteoarthritis?
• What is the cause of osteoarthritis?
• Should osteoarthritis be an occupational concern?
• What are some things a workplace can do?

What is osteoarthritis?

Osteoarthritis, also known as osteoarthrosis or, more commonly, degenerative joint disease, is a disorder that affects the joints. At the joint, the surfaces of the bones are lined with tissue called cartilage. Cartilage provides a smooth surface for movements. Sometimes, the cartilage between bones softens, and some of its fibres separate. The normally smooth cartilage becomes pitted and frayed, and whole segments of cartilage may be lost. Bony outgrowths form which interfere with the movement of nearby tendons and joints. These changes make movement of the joint more difficult and very painful and are signs of degenerative joint disease or osteoarthritis.

Osteoarthritis is the most common form of arthritis. In Canada, it affects about 10% of the adult population. Osteoarthritis most commonly affects joints such as the knees, hands (finger and thumb joints), neck, lower back, and hips.

What is the cause of osteoarthritis?

The cause of degenerative joint disease is not known. Some researchers claim that one cause of degenerative joint disease is mechanical overstrain or stress, such as rapid, repetitive movements and the use of force in extreme positions that could result in joint trauma. Another theory is that mechanical overload breaks the cartilage. However, many researchers do not agree with these theories of mechanical origin. They suggest that some factors, including mechanical stress, may activate the release of certain substances that destroy the cartilage. In any event, these are causes that could happen in the workplace or through non-work activities.

Should osteoarthritis be an occupational concern?

The relation between degenerative joint disease and work is not clear. Other, non-work related risk factors are implicated; for example, age, gender, heredity factors, obesity, and bone and joint disorders - congenital (present at birth) or developmental (occurred while the bones were growing). Other risk factors that may or may not be work-related are any previous inflammatory joint disease and injury to joints.

Most likely, joint degeneration develops from a combination of hereditary, constitutional and environmental causes. Occupational stress factors such as carrying heavy loads can cause changes such as joint degeneration. Awkward postures, extreme movements and injuries can start symptoms or make existing symptoms worse in workers who already have degenerative joint disease. Whatever the causes, time may be a factor. It is not a common disease in people under 40. On the other hand, about 80% of people over 75 years of age have osteoarthritis. The age group between 40-50 years old is the part of the population that has the highest diagnosis rate for osteoarthritis. Loss of joint function from this disorder is a major cause of long-term work disability.

What are some things a workplace can do?

Proper body mechanics should be used in all daily activities -- including at work -- to reduce joint stress, and decrease pain when ever possible.

Good ergonomic principles can help, such as:

• Picking up books or files with straight fingers or between palms rather than grasping with bent fingers.
• Locating work directly in front of you, not to one side. Avoid twisting movements by centering your body to your work.
• Using the strongest joints available for the activity (e.g., lift with your leg muscles, not your back). Roll objects rather than lift them, or use a trolley.
• Avoiding tasks that tight grasp and pressure along the thumb side of the hand such as picking up parts or materials.
• Avoiding prolonged standing or sitting positions to minimize muscle stiffness, pain and fatigue.

Other options may be to provide tools or facilities that will help accommodate employees, including:

• Reducing muscle effort and increasing strength by using tools with built-up handles - for example: scissors, and utensils.
• Installing a raised toilet seat to make it easier and safer to stand up.
• Planning for alternate tasks or breaks so that there can be a change in body position.
• Discussing options for flexible work schedules and tasks with your employer to allow you to plan for changes in function that come with arthritis.

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Document last updated on August 17, 2010

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