Knee Injuries: Osteoarthritis
Osteoarthritis is a common problem for many people. Osteoarthritis is sometimes referred to as "degenerative joint disease," or wear-and-tear arthritis. The main problem in osteoarthritis is degeneration of the articular cartilage that covers the joint. This results in areas of the joint where bone rubs against bone. Bone spurs may form around the joint as the body's response. Osteoarthritis may result from an injury to the knee earlier in life. Fractures involving the joint surfaces, instability from ligament tears, and meniscal injuries can all cause abnormal wear and tear of the knee joint. Not all cases of osteoarthritis are related to prior injury, however. Research has shown that some people are prone to develop osteoarthritis, and this tendency may be genetic. Osteoarthritis develops slowly over several years. The symptoms of osteoarthritis are mainly pain, swelling, and stiffening of the knee. The pain of osteoarthritis is usually worse after activity. Early in the course of the disease, you may notice that your knee does fairly well while walking, then after sitting for several minutes the knee becomes stiff and painful. As the condition progresses, pain can interfere with even simple daily activities. In the late stages, the pain can be continuous and even affect sleep patterns. This pain probably does not come from the covering of the joint, the articular cartilage, because this tissue does not have a nerve supply. Sources of pain may be due to:
- Inflammation in the lining of the joint, called the synovium
- Small fractures in the bone under the cartilage, the subchondral bone
- Pressure from blood in the area
- Stretching of nerve endings over a bone spur (osteophyte)
- Degenerative tears in the meniscus cartilage
- Loose bone chips in the joint
The diagnosis of osteoarthritis can usually be made on the basis of the initial history and examination. X-Rays are very helpful in the diagnosis and may be the only special test required in the majority of cases. In some cases of early osteoarthritis, the X-rays may not show changes typical of osteoarthritis. It is not always clear where the pain is coming from. Knee pain from osteoarthritis may be confused with other common causes of knee pain such as a torn meniscus or kneecap problems. Sometimes, an MRI scan may be ordered to look at the knee more closely. An MRI scan is a special radiological test where magnetic waves are used to create pictures that look like slices of the knee. The MRI scan shows more than the bones of the knee. It can show the ligaments, articular cartilage, and menisci as well. The MRI scan is painless, and requires no needles or dye to be injected.
If the diagnosis is still unclear, or the patient does not respond to non-operative treatment, arthroscopy may be necessary to actually look inside the knee and see if the joint surfaces are beginning to develop changes from wear and tear. Arthroscopy is a surgical procedure where a small fiberoptic television camera is inserted into the knee joint through a very small incision. The surgeon can then move the camera around inside the joint while watching the pictures on a TV screen. The structures inside the joint can be evaluated with small surgical instruments to see if there is any damage. Looking directly at the articular cartilage surfaces of the knee is the most accurate way of determining how advanced the osteoarthritis is. Arthroscopy also allows the surgeon to debride the knee joint. Debridement essentially consists of cleaning out the joint of all debris and loose fragments. During the debridement any loose fragments of cartilage are removed and the knee is washed with a saline (salt) solution. The areas of the knee joint that are badly worn may be roughened with a burr to promote the growth of new cartilage – a fibrocartilage material that is similar scar tissue. Debridement of the knee using the arthroscope is not 100% successful. If successful, it usually affords temporary relief of symptoms for somewhere between 6 months - 3 years.
Here are some long-term solutions to help manage osteoarthritis of the knee:
- Control pain and inflammation. Aspirin, Advil, and Aleve are available over-the-counter. Prescription strength anti-inflammatory medicine is also available.
- Glucosamine and chondroitin are medications that may provide pain relief in osteoarthritis.
- Reduce shock by using a walking aid (cane), wearing good shoes, choosing soft surfaces, and keeping the leg muscles conditioned for unexpected stresses.
- Exercise daily to maintain range of motion, strength, and cardiovascular fitness.
- Take precautions with daily activities to avoid stressing the knee.
- Avoid activities in your fitness and recreational pursuits that cause high impact loads to the knee such as walking, jogging, hiking, and stair-stepper machines.
- Substitute impact activities with low impact activities such as stationary cycle, swimming, cross-country ski machine, rowing machine, or elliptical machine.
- Follow a regular exercise program 2 to 3 times a week to stretch and strengthen the muscles around the knee.