The Causes of Osteoarthritis
Learn Which Risk Factors You Can Control
-- By Becky Hand, Licensed & Registered Dietitian & Nicole Nichols, Health Educator
Osteoarthritis, the most common form of arthritis, is a major health problem affecting an estimated 21 million adults in the United States alone. Osteoarthritis begins with the breakdown of joint cartilage which results in pain, stiffness, swelling and tenderness. The joints of the fingers, spine, hips and knees, are most often affected, but osteoarthritis can also affect the shoulders, elbows, wrists and ankles.
Although the exact cause of osteoarthritis is not known, some experts believe that joint damage occurs as a response to physical stress (such as injury or repetitive movement). This wear and tear can erode the cartilage, which serves to cushion the ends of the bones in a joint and helps the joint move smoothly and easily. As the cartilage breaks down, the ends of the bones thicken and the joint may lose its normal shape. Eventually, the ends of the bones begin to rub together causing pain and tenderness. The damaged joint tissue can cause the release of substances called "prostaglandins," which further contribute to the pain and swelling associated with osteoarthritis.
There are two main categories of risks that can contribute to osteoarthritis—those that you can't change, and those that you can.<pagebreak>
Uncontrollable Risk Factors
These variables are out of your control. Although you can't do anything to change them, it's important to know whether you fall into any of these higher-risk categories.
Your age. Osteoarthritis usually occurs in older people (although it can afflict young adults who experience joint injuries). Almost all people over 65 show some signs of developing osteoarthritis, and by age 70, nearly every person will have this condition. However, symptoms of osteoarthritis commonly begin between the ages of 30 and 40.
- Your gender. Before age 45, osteoarthritis occurs more often in men, but after age 45, osteoarthritis is more common in women.
- Your race. Caucasians and African Americans have an overall higher risk of developing osteoarthritis than other racial and ethnic groups.
- Your family history. You are more likely to develop osteoarthritis if one or both of your parents had the condition. Research suggests that defective genes, which cause deterioration of the joint, can be passed down from parent to child.
- Your health history. Certain diseases, such as rheumatoid arthritis, change the structure of the cartilage and therefore increase the risk for osteoarthritis.
- Your previous injuries. Joint injuries or overuse, whether from physical labor, sports, or repetitive injury, can increase the risk for developing osteoarthritis. Even a single injury to a joint can result in the development of osteoarthritis many years later.
- Your joint alignment. Joints that move or fit together incorrectly are more likely to develop osteoarthritis.
Controllable Risk Factors
- Your weight. Did you know that every time you take a step, the force on your knees and hips equals two to three times your body weight? Climbing down steps will increase the pressure on your knees and hips by six-fold—that's 900 pounds of pressure for a person who weights just 150 pounds. Your risk of developing osteoarthritis generally increases with the amount of weight that your joints have to bear. Once osteoarthritis has developed, being overweight exacerbates the condition. Your SparkDiet can help you lose the extra pounds safely and permanently.
- Your activity level. You are more likely to develop osteoarthritis if you are physically inactive or physically overactive. A lack of exercise weakens muscles and bones, decreasing flexibility and support at the joints, which eventually leads to pain and stiffness. At the same time, over-exercising can also be harmful to the joints. Stick with moderate exercise to strengthen the joints, decrease pain and improve range of motion. Read Managing Arthritis with Exercise to get started.
- Your strength level. If the muscles surrounding your joints are weak (the thigh muscles above the knee, for example), then you are more prone to developing osteoarthritis in those joints. Strength training can help you build muscle, which strengthens your joints and provides protection against osteoarthritis. If you already have osteoarthritis, a physical therapist can assess your muscle strength, flexibility and joint stability and recommend different exercises for you.
- Your diet. A diet low in omega-3 fatty acids (the good-for-you fats, from foods like flaxseeds, pumpkin seeds, hempseeds, and salmon) and high in unhealthy fats (corn, safflower and cottonseed oils, fatty meats, high-fat dairy products, saturated fat and trans fats) may contribute to your risk of developing osteoarthritis. Healthy omega-3's reduce joint inflammation while unhealthy fats can increase it. Read Foods that Fight Osteoarthritis for more information.