Osteoarthritis
Osteoarthritis is a common problem for many people after middle age. Osteoarthritis is sometimes referred to as degenerative, 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. There is still some confusion about where the pain in osteoarthritis actually comes from. 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).
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. If the diagnosis is still unclear, 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.
Non-Surgical Treatment
Treatment is directed at decreasing the symptoms of the condition, and slowing the progression of the disease. OA of the knee is a condition many people face. But thanks to continued advances in medicine, there are now many treatment options available. Recent information now shows that the condition may be maintained, and in some cases may even improve. The first goal is to reduce pain in the knee. Your physician may prescribe acetaminophen (Tylenol), a mild analgesic, as an excellent first-line pain reliever in this problem. Some people may also get relief of pain with anti-inflammatory medication, such as ibuprofen and aspirin. In either case, medications should be used in combination with physical therapy.
If the symptoms continue, a cortisone injection may be used to bring the inflammation under better control and ease your pain. Cortisone is a very powerful anti-inflammatory medication, but does have secondary effects that limit its usefulness in the treatment of osteoarthritis. Repeated injections increase the risk of developing a knee joint infection, called septic arthritis. Most physicians use cortisone sparingly, and avoid multiple injections unless the joint is already in the end stages of degeneration where the next step is an artificial knee replacement.
Recently, a new type of injectable medication has become available in the US. Hyaluronic acid preparations have been used in Europe and Canada for several years and seem to be beneficial in decreasing the symptoms in knees that have mild to moderate osteoarthritis changes. The medication requires 3 injections given over a two week period. The medication seems to reduce symptoms in many patients for 6-8 months.
Limit pain: Your physical therapist has several tools, or modalities, to help control the acute symptoms caused by osteoarthritis of the knee. Sources of heat, like a moist hot pack, ultrasound, or diathermy, can help reduce discomfort by stimulating blood flow and overriding pain sensation. Joint mobilization may be chosen for its ability to provide nutrition and lubrication to the joint surfaces. It is also helpful for overriding the transmission of pain to the brain. Another helpful treatment to reduce pain is transcutaneous nerve stimulation (TENS for short), which uses a mild electrical impulse to block pain. Certain topical ointments (such as Capsaicin) can also help limit pain.
Increase range of motion: By improving knee movement, you may find that pain symptoms ease. Another benefit of gaining more motion is that it keeps the joint surfaces healthy. And finally, it helps prepare your knee for higher levels of activity. Range of motion can be gained with a pool exercise program, gentle stretching by your therapist, or with the use of a stationary bike.
Increase strength: In the early stages, strengthening may be done using isometric exercise. These are exercises in which the muscles contract, but the joint stays in one position. Isometrics help restore strength while protecting you from further pain and irritation. As your muscles gain strength, you may notice less pain in the knee while feeling a sense of ease with walking and doing general activities.
Muscular control: Sometimes the knee gets an extra jolt when you accidentally miss a stair or when you stub your toe. Untrained leg muscles are slow to respond in protecting the knee joint, and these jolting forces do more damage to the softer bone under the cartilage. A trained muscle will generate force quickly. Conditioning exercises help knee muscles generate forces more quickly, acting as shock absorbers in protecting the knee joint.
Walking aids: A cane or walker may be suggested by your physical therapist. Using a walking aid can take some of the stress off the joint, protecting it from undue stress and strain.
Shock absorption: A good pair of shoes will help reduce shock. Also, if you choose walking as your primary exercise, choose a walking surface like cinder or grass. Avoid cemented or other hard surfaces. If you find that increasing your walking speed irritates your knee, limit your speed. Other exercises that prevent high impact shock include stationary biking and swimming.
Alignment: When the knee is not properly aligned, extra pressure may develop on one side of the knee joint. In these cases, a special shoe insert, or orthotic, with a heel wedge can help relieve pressure and pain. Sometimes an osteoarthritis knee brace may be chosen. These braces are designed to unload the pressure, whether on the inside or outside of the knee joint.
Sugical Treatment
Arthroscopy
Arthroscopy is sometimes useful in the treatment of osteoarthritis of the knee. 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 which are badly worn may be roughened with a burr to promote the growth of new cartilage – a fibrocartilage material that is similar to 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 – 2 years.
Proximal Tibial Osteotomy
Osteoarthritis usually affects the inside half (medial compartment) of the knee more often than the outside (lateral compartment). This can lead to the lower extremity becoming slightly bowlegged. The result is that there is more pressure on the medial joint surfaces, which leads to more pain and faster degeneration. In some cases, realigning the angles in the lower extremity can result in shifting the weight-bearing line to the lateral compartment of the knee. This, presumably, places the majority of the weight-bearing force into a healthier compartment. The result is to reduce the pain and delay the progression of the degeneration of the medial compartment. This procedure is not always successful, and generally will reduce your pain, but not eliminate it altogether. The advantage to this approach is that very active people still have their own knee joint, and once the bone heals there are no restrictions to activity level.
The proximal tibial osteotomy it is thought buys some time before ultimately needing to perform a total knee replacement. The operation probably lasts for 5-7 years if successful.
Total Knee Replacement
The ultimate solution for osteoarthritis of the knee is to replace the joint surfaces with an artificial knee joint. The decision to proceed with a total knee replacement is usually only considered in people over the age of 60, (although younger patients sometimes require the surgery simply because no other acceptable solution is available to treat their condition). The main reason that orthopedic surgeons are reluctant to perform the surgery on younger individuals, is that the younger the patient, the more likely the artificial joint will fail during the patient’s lifetime. Replacing the knee again, a process called a revision, is much harder, has more potential complications and is less likely to be successful.