What is Osteoarthritis?
Osteoarthritis is the most common form of arthritis. It affects approximately 70 to 80% of the population over the age of 50 and in fact about one third of white adults from North America and Northern Europe between the age of 25 and 74 show signs of the disease on X-rays in at least one extremity joint (hands, feet, knees or hips). In total, more than 35 million Americans are affected with the disease and it is the leading cause of disability in the elderly.
Traditionally the disease has been thought of as a degenerative process of the articular cartilage covering the ends of the bones that form joint surfaces. We are beginning to consider the condition as a group of overlapping processes that are both mechanical and biological in nature.
Normally, the cartilage serves to cushion and protect the bones of the joint as they absorb mechanical loads and allow for low friction movement as the bones articulate over one another. Healthy joints are able to withstand great pressures due to the elasticity of the cartilage as a result of its ability to hold water within a molecular matrix. In osteoarthritis, however there is an alteration in the normal tissue building and breakdown processes that are present in the cartilage and the underlying bone.
What are the Causes and Symptoms of Osteoarthritis?
The exact cause of osteoarthritis is unknown but there are several factors that precipitate the tissue changes that cause the disease. The changes may be initiated by trauma in combination with metabolic and genetic factors. The effect ranges from molecular to biomechanical and results in a breakdown of the protective cartilage down to the underlying subchondral bone. On X-ray we see an eburnation (thickening) and a buildup of calcium on the surface of the bone forming bone spurs or osteophytes.
The result is experienced primarily as joint pain with decreases in range of motion and in some cases local inflammation in the involved area that is tender to the touch. The pain tends to be mild to moderate and comes on slowly. It is usually made worse with activity of the involved joint and subsides with rest. There can be pain at rest in severe cases. The inflammation appears to affect the synovial membrane that encloses the joint space. At least in animal studies it has been found that the amount of inflammation corresponds with the degree of cartilage loss.
It has been found that certain cellular messenger proteins called cytokines are suspected to play a role in the formation in the disease. These proteins are known to be involved in immunity and in the inflammatory process. Two in particular tend to be elevated in the synovial fluid and cartilage of joints affected by the disease. They tend to initiate cartilage destruction and inflammation of tissues. As the cartilage breaks down it becomes thinner and there is a thickening of the bone surface leading to the formation of bone spurs.
What are the Risk Factors for Ostoearthritis?
Although it is difficult to pin down the exact cause of the disease, certain risk factors have been determined to be associated with the condition. Prevalence rates vary as to the joints involved but in general the most significant determinant of osteoarthritis is the advancement of age at least until the seventh decade. It is known that women are at a higher risk than men, especially after the onset of menopause. Obesity is especially correlated with osteoarthritis of the knee and to some extent the hip joint. This is probably at least in part due to the increased mechanical stress caused by the added weight.
European studies have looked at occupational and athletic factors that may increase risk for the disease. For example, osteoarthritis of the knees has a higher incidence in jobs where there is a significant amount of kneeling, squatting and climbing stairs. There is a higher incidence hip involvement associated with jobs requiring heavy lifting and farming. Although there is an increased risk of osteoarthritis in the joints of the lower limbs of athletes, joggers do not appear to be at risk unless there is altered biomechanical function of the joints involved.
What is the Prevention and Treatment for Osteoarthritis?
There is no conventional curative treatment for osteoarthritis as management of the disease is largely directed at controlling the pain and inflammation associated with the condition. Muscles play a significant role in protecting and supporting the joints of the body and for that reason exercise is important in the management of osteoarthritis. It has been demonstrated in patients with knee osteoarthritis that joint function was improved and pain reduced after undergoing an exercise/ strengthening program involving the quadriceps muscles of the thigh. Weight reduction was also found to be helpful in reducing the pain and impaired function associated with knee osteoarthritis. Orthopedic supports may also be effective in supporting the involved body parts.
Non-steroidal anti-inflammatory drugs (NSAIDS) are commonly prescribed for osteoarthritis but usually have adverse side effects. Research from the United States and Europe has consistently demonstrated the effectiveness of two naturally occurring substances called glucosamine sulfate and chondroitin sulfate. They have not only been effective in decreasing pain and arresting the progression of the disease but also in reversing the condition. They are rarely associated with any side effects. Other nutrients that may prove to be useful in controlling the disease include MSM (methylsulfonylmethane), silicon, calcium, magnesium, and Boswellia seratta.
1). Adderly, Brenda “The Promise of Arthritis Relief, Naturally.” Better Nutrition. March 2000
2). Brier, Steven R. Primary Care Orthopedics. St. Louis: Mosby, Inc., 1999
3). Creamer, Paul. “Osteoarthritis.” Lancet. August 16, 1997