The cartilage that lines our joints is an amazing tis-sue. When healthy, this cartilage known as articular cartilage or hyaline cartilage, provides a relatively soft, durable surface, with less friction than ice. It al-lows us to bear weight and move our joints smoothly without pain, usually for a lifetime.
Arthritis is a generic term that implies a thinning, or loss of this specialized cartilage tissue. When arthri-tis develops and the cartilage cap within the joint is lost, the bone that was supporting the cartilage is ex-posed and it experiences stresses it was not designed to handle. These "bone on bone" changes create a spiral of increased force on the bone, progressive loss of mo-tion, increasing deformity and pain.
The arthritis problem arises in part because, unlike many tissues, cartilage has a very limited ability to heal once damaged. In contrast, if you break a bone, the body undergoes a stepwise repair process and within a certain time period the fractured ends of the bone knit back together. Once the healing process is complete, the bone is as strong as it was before it broke. Unfortunately, this is not the case with carti-lage. There are many factors that contribute to carti-lage's poor capacity to heal itself after injury. In a nut-shell, it is due to the lack of blood supply and the fact that the cells that produce cartilage are imbedded within a complex tissue matrix and cannot "move" to the site of injury.
Arthritis can have many causes: medical conditions that cause repeated inflammation like gout or rheuma-toid arthritis, trauma to the joint such as a fracture or bruise, infection within the joint, etc. The most com-mon cause of arthritis is "osteoarthritis." This is con-sidered a "wear and tear" process and occurs more commonly with age. Osteoarthritis is common, affect-ing over a quarter of the adult population and can be quite debilitating.
People often ask the questions: 'Will exercise cause arthritis? Can osteoarthritis be prevented? What are the options if I have arthritis? So, does exercise cause arthritis?' No, probably not.
It seems logical that a layer of cartilage, like a set of tires, will wear out over time and the more mileage, or harder the tires are driven, the sooner it will occur. There is some truth to this thinking. As we age the cells that maintain healthy cartilage become less effi-cient, certain waste products accumulate within the joint, and minor cartilage injuries add up over time. All of this results in thinning of the joint surface. How-ever, this is not entirely the case with cartilage.
Cartilage is living tissue, and like other tissues, it generally responds to stress by getting stronger. Body-builders work their muscles, resulting in stronger, more-efficient muscles. Cross-country skiers aerobi-cally work their heart muscles and their hearts be-comes stronger and use oxygen more effectively.
Cartilage is similar. It responds to increased use by increasing the amount of materials that make a healthy joint, and becomes more efficient in clearing waste products. The muscles and tissue around the joint becomes stronger and better able to support and protect the joint.
Numerous studies have shown that exercise is bene-ficial, results in better joint strength and flexibility, and does not cause the cartilage to wear out more quickly. In fact, studies suggest that people who exer-cise regularly often have less arthritis than people who are sedentary.
Most of the studies supporting improving joint health with exercise are done in people doing moderate exercise. The jury is still out on how prolonged, repeti-tive, long-term, high-impact activities, like ultra mara-thon running, will affect cartilage. People in certain occupations, heavy laborers for instance, seem to have an increased risk of developing arthritis. But with proper form, avoiding injury, and fortunate genetics, it may turn out that prolonged high-impact exercise is not detrimental to cartilage health either.
Can osteoarthritis be prevented? Maybe. There are clearly things you should avoid to decrease your chance of getting arthritis.
Avoid injury. Again, because cartilage is a living tis-sue, it has a strength and tolerance limit. Just as too much stress can tear a ligament or tendon, too much pressure or force on cartilage will cause it to break down as well. This can occur as a result of a one-time event (a fracture into the joint) or from a chronic over-load state that exceeds the capacity for the cartilage to renew itself. This type of chronic overload could be seen with obesity, angular bone deformities, etc. Be-cause cartilage has such a limited ability to heal after injury, it is difficult, even with modern medicine, to restore the cartilage to its previous level of function once significant injury occurs. So to avoid arthritis, it is best to avoid injury to the cartilage.
Don't smoke. Smoking is detrimental to cartilage.
Eat well. Healthy cartilage depends on the proper nutrients.
Genetics. Some things are out of our control. Carti-lage, like all of our tissues, is a unique combination of many structures and chemicals based on our DNA. One person's cartilage is inherently more or less dura-ble that another's. This is not an excuse, but some peo-ple will develop arthritis despite doing "everything right."
What are options if you have arthritis?
Choose low-impact activities, physical therapy, weight loss, use of a cane, bracing and medications. All can decrease the pain and disability that accompanies arthritis.
If severe arthritis develops, joint replacement may be a good option. With modern techniques and im-plants, a replaced joint may last more than 20 to 30 years and usually allows a return to many athletic ac-tivities.
If you are thinking about joint replacement, con-sider getting it done locally. We have an excellent hos-pital, with experienced physicians, nurses and thera-pists who can provide state-of-the-art care.
Dr. Daniel B. Judd is board-certified in orthopaedic surgery and orthopaedic sports medicine. He treats pa-tients at St. Luke's Clinic-Sun Valley Sports Medicine in Ketchum.