Osteoarthritis in the Knee
What is Osteoarthritis?
Arthritis is the nation’s number one chronic disease and affects more than 41 million Americans. The most common form of arthritis, called osteoarthritis, affects 1 in every 3 people by the time they reach age 30 and nearly everyone by the time they are 60. About half the people with arthritis don’t have symptoms and only a small group have arthritis to the point of severe pain or becoming disabled. The main 3 types of arthritis are osteoarthritis (OA), rheumatoid arthritis, and gout.
Osteoarthritis is a common problem for many people once they reach middle age. Osteoarthritis is also called degenerative arthritis, or wear-and-tear arthritis. Osteoarthritis in the knee can result from an injury to the knee earlier in life. Bone fractures in joint surfaces, instability of the knee from ligament tears, and injuries to the menisci can all cause abnormal wear-and-tear of the knee joint. Not all osteoarthritis in the knee is related to a prior knee injury. Research shows that genetics can make someone prone to developing osteoarthritis.
The main issue in osteoarthritis is the gradual wearing away of the articular cartilage that covers the ends of the bones in a joint. This degeneration results in areas where bone rubs against bone. The body may respond to this rubbing by forming bone spurs around the joint. The process results in discomfort, pain, stiffness, grating and sometimes deformity. The pain usually occurs with movement and goes away with rest. Some people have pain when they resume activity after a period of rest. Pain can be worse at the end of the day.
Causes of Osteoarthritis in the Knee
The factors that contribute to osteoarthritis include heredity, being overweight, and repetitive stress injuries. The causes of osteoarthritis in the knee joint are many:
• Improperly repaired meniscal tear
• Removal of the meniscus
• A bone fracture
• Bowlegs or knock knees
• Abnormal development of the hip
• Being immobilized for a long time
• Abnormal overuse of the joint
• Chronic inflammation or infection
• Rheumatoid arthritis can also cause osteoarthritis
• Diabetes and Hypothyroidism can make you susceptible to osteoarthritis
It used to be thought that activities such as jogging or physical activity caused osteoarthritis, but it’s now believed that this is not true. Learn more about knee anatomy and function.
Symptoms – What Does Knee Osteoarthritis Feel Like?
Osteoarthritis develops slowly over many years. The main symptoms of osteoarthritis are pain, swelling, and stiffening of the knee. The pain of osteoarthritis is usually worse after activity. Early in the development of osteoarthritis in the knee, you may notice your knee does fairly well when you’re walking, but after sitting for several minutes your knee gets stiff and painful. As osteoarthritis progresses, the pain can interfere with even simple daily activities. In the late stages of osteoarthritis, you can have pain almost all the time which can affect your sleep.
Warning signs of arthritis include:
• persistent pain and stiffness when you first wake up or at the end of the day
• pain, tenderness or swelling in the knee
• you can’t move the knee normally
• you keep having episodes of pain and stiffness in the knee
• if you have the above symptoms for more than 6 weeks
How is Osteoarthritis of the Knee Diagnosed?
Diagnosing arthritis early can prevent permanent damage. It is not always easy to diagnose and can take several weeks or months to get a definitive diagnosis. Osteoarthritis is usually diagnosed by taking a history and doing a physical examination of the knee. XRays or are very helpful in the diagnosis along with other test such as an arthrogram, needle aspiration of joint fluid, or blood tests. Xrays can show narrowing of the space between the bones, the formation of bone spurs, and cysts.
How is Osteoarthritis of the Knee Treated?
Osteoarthritis is a condition which progresses slowly over a period of many years. Osteoarthritis cannot be cured it can only be treated. Treatment is directed at reducing your symptoms and slowing down the progress. 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 your condition may be maintained, and in some cases it may even improve.
The first goal is to reduce pain in the knee. Your doctor can prescribe acetominophen, a mild analgesic, as an excellent first try to relieve pain. Some people get relief of pain with anti-inflammatory medication or NSAIDS (Advil, ibuprophen). Medications should be used in addition to physical therapy.
Knee pain does not come from the thin covering of the joint, the hyaline cartilage, as this tissue doesn’t have a nerve supply. Pain can come from:
- inflammation in the lining of the joint, called the synovium
- small fractures in the bone under the cartilage, the subchondral bone
- pressure from blood or fluids that collect in the knee
- stretching of nerve endings over bone spurs (osteophytes)
If your pain symptoms continue, cortisone may be injected to control inflammation and ease pain. Cortisone is a very powerful anti-inflammatory that has side effects that limit its usefulness in treating osteoarthritis. The major drawback of intra-articular cortisone injections is that it may actually speed up the degeneration process if its used several times. Most doctors use cortisone sparingly, and won’t inject the joint more than once unless it is already in the end stages of degeneration.
Treatment for Sudden Flare Ups:
Limit pain: Your physical therapist has several ways to help control the sudden symptoms caused by osteoarthritis of the knee. Using heat, like a moist hot pack, ultrasound, or diathermy, can stimulate the blood flow and help reduce pain. Moving the Joint can bring nutrition and lubrication to the joint surfaces and is helpful for blocking 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 nonprescription topical ointments (Capsaicin) can also help reduce pain.
Increase range-of-motion: Improving the movement in your knee may ease pain symptoms. Another benefit of knee motion is that it keeps the joint surfaces healthier. And finally, movement helps prepare your knee for more strenuous activities. Range-of-motion can be gained by exercising in a pool or hot tub, gentle stretching by your or your therapist, or riding 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 accidently miss a stair or when you stub your toe. Untrained leg muscles are slow to respond and protect the knee joint. These jolting forces do further damage to the softer bone underneath the cartilage. Conditioning exercises can train your knee muscles to generate force more quickly and act as shock absorber to protect the knee joint.
Walking aids: Your physical therapist my give you a cane or walker to take some of the stress off the knee, protecting it from undo stress and strain.
Shock absorbers: Well made shoes that fit well can help reduce shock. Also, if you choose walking as your primary exercise, walk on surfaces like cinder (found on running tracks) or grass. Avoid cement, asphalt or other hard surfaces. Slow down if increasing your walking speed irritates your knee. Other exercises that prevent shock to your knee include riding a stationary bike and swimming.
Alignment: When the bones of the knee are not properly aligned, extra pressure can be placed on one side of the knee. If this happens, a special shoe orthotic with a heel wedge can relieve pressure and pain. Sometimes wearing a knee brace for made for osteoarthritis can help—the brace is designed to “unload” the pressure on either the inside or outside of the knee joint.
Daily activities: Helpful hints to reduce strain on your knee:
- Avoid standing for longer than 10 minutes; sit on a high stool or rest often.
- Limit stair climbing; take the elvator, escalator, or ramp.
- Don’t stoop and squat; keep everyday items at waist level, or use a reacher.
- Park your car close to where you’re going.
- Raise beds, chairs, and toilets when possible.
Daily exercise: Your joint surfaces can stay healthier by consistently working your leg through a full range of motion and using safe, load-bearing exercises. Use exercise to keep the hip, knee, and ankle muscles strong. Avoid pain by working in a pain-free arc of movement, limiting walking speeds, and overstressing the knee. In the presence of pain, use static, isometric exercise.
General fitness: The Surgeon General recommends that everyone get 30 minutes of moderate activity a day for as many as seven days a week. Along with reducing the risk of heart disease, lowering stress, managing body weight, and prolonging life, a general fitness program can also help you in managing OA of the knee. Before undertaking such a program, consult your physician. Moderate activity can include walking, swimming, stationary biking, or low impact aerobics.
Exercise progression: Your exercise program will be advanced cautiously to inlcude strengthening, balance, endurance, and functional activities. Your program will address key muscle groups of the buttock and hips, thigh, and calf. Several exercise choices can further stabilize and control the knee. Finally, a select group of exercises can be used to simulate day-to-day activities like raising up on your toes or standing from a raised stool. Specific exercises may then be chosen to simulate work or hobby demands.
Long Term Management
Long-term ways to help manage osteoarthritis of the knee:
- Control pain and inflammation.
- Reduce shock by using a walking aid, wearing good shoes, choosing soft surfaces, and keeping the leg muscles in shape for unexpected stresses.
- Exercise daily to keep up range of motion and strength in your knee.
- Wear a shoe orthotic with a heel wedge for better alignment.
- When doing daily activities take precautions to avoid stress on your knee.
There are braces that can reduce the pressure on the side of the knee that is most affected. These braces are designed mainly for the more common condition of early wear and tear in the medial compartment of the knee. A brace may ease your pain and is worth trying.
Arthroscopy is sometimes useful in the treatment of osteoarthritis of the knee. Looking directly at the articular cartilage surfaces is the most accurate way of find out how advanced the osteoarthritis is. Arthroscopy allows the surgeon to clean out (debride) the knee joint of all debris and loose fragments. During debridement any loose fragments of cartilage are removed and the knee is washed with a saline solution. The badly worn areas of the knee joint may be roughened with a burr to promote the growth of fibrocartilage that is cartilage similar scar tissue. Debridement of the knee using an arthroscope is not 100% successful. When it works, it usually gives relief of symptoms for 6 months to 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, or in medical terms, a genu varum deformity. The result is that the weight bearing line of the lower extremity moves more medially (towards the medial compartment of the knee). (It’s really all in the physics/biomechanics of the situation.) The result is that more pressure on the medial joint surfaces, which leads to more pain and faster degeneration.
In some cases, re-alligning 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.
The procedure to reallign the angles of the lower extremity is called a Proximal Tibial Osteotomy. In this procedure a wedge of bone is removed from the lateral side of the upper tibia. This converts the extremity from being bow-legged to knock-kneed. 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 in the best of circumstances is probably only temporary. It is thought that this operation buys some timebefore ultimately needing to do a total knee replacement. The operation probably lasts for 5-7 years if successful.
Total Knee Replacement
The final solution for osteoarthritis of the knee is to replace the joint surfaces with an artificial knee joint. The decision to go ahead with a total knee replacement is usually considered in people over the age of 60, (although younger patients sometimes need knee replacement when there is no other acceptable solution available to treat their condition).
The main reason that orthopedic surgeons are reluctant to do a knee replacement on younger people is that the younger the patient, the more likely the artificial joint will fail. Replacing a failed artificial knee is much harder and more likely to fail.
Artificial knee joints last about 10-15 years in an elderly person. Younger patients are more active and put more stress on the artificial joint that can lead to loosening and early failure. Also, younger patients are more likely to outlive an artificial joint and will probably need a knee joint revision at a later age. For these reasons an orthopedic surgeons don’t like to recommend a knee replacement in young patients.
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