As the joint starts to wear out, the surface of the joint becomes irregular, and the muscle wastes away due to pain and disuse. Stiffness occurs due to inflammation and pain associated with movement.
In the earlier stages of osteoarthritis, rehabilitation may provide significant benefit. Rehabilitation for arthritis focuses on range of motion to the joint and strengthening the muscles around the joint. Exercises that are particularly beneficial are bicycling and swimming. Bicycling at high revolution and low resistance acts to lubricate the joint and smooth the joint surfaces as they rub together. At least 20 minutes a day on a stationary bicycle is recommended. Swimming allows exercise without bearing weight on the involved joint and is an excellent way to maintain muscle strength around the joint without causing irritation. Daily stretching is useful to maintain range of motion.
Use of ice is often helpful when the joint is particularly swollen or painful. Ice acts to decrease inflammation and swelling in the joint and acts as an analgesic by slowing nerve conduction in the pain fibers around the joint. Topical treatments may provide temporary relief as well. These are typically one of a variety of skin irritants such as menthol or caspacin (pepper!). These agents act to irritate and thus warm the skin around the painful joint. Relief occurs due to the warmth as well as the over stimulation of the local sensory nerves which temporarily distracts and overrides the pain fibers. Elastic braces or ace bandages provide some relief due to the added sense of stability and warmth. The pressure from the brace may also help to limit swelling.
The mainstay of medication treatment for degenerative arthritis is antiinflammatory medicine. The most commonly used category of these are called non steroidal antiinflammatory drugs (NSAID). This is to differentiate them from steroid antiinflammatory drugs which are very powerful, but have more side effects. The antiinflammatory drugs work to stop the natural chemical mediators of inflammation in the body. The uneven surfaces caused by degeneration of the joint cause an inflammatory reaction in the joint. NSAID limit this secondary inflammation but do not affect the degeneration of the joint. They also act to relieve pain. The most common side effect is gastrointestinal upset.
There are currently several new methods for trying to protect and enhance cartilage function, either through injection or orally. The exact efficacy of these treatments is still being debated in the scientific community, but they are still being used extensively.
Hyaluronic Acid: Hyaluronic acid is a type of molecule that occurs naturally in the joint and is important in the structure and function of cartilage. It is a type of sugar (glycosaminoglycan) that acts as the backbone on which other important cartilage molecules (proteoglycans) aggregate. These aggregates combine with proteins (collagen) to make up the spongy resilient cartilage surface. Hyaluronic acid has recently been approved by the FDA for injection into the joint. It is thought to act by providing additional lubrication, controlling permeability of the lining of the joint (synovium) and possibly by promoting further cartilage proteoglycan synthesis and function. Between 3 and 5 injections are given into the knee over a 1-2 week period. The majority of patients experience some relief of pain that can last between 6-12 months. The relief is temporary, however, and repeat injections or other treatments are often necessary.
Glucosamine is one of the building blocks (aminomonosacharide) of the large sugar molecules that make up cartilage tissue. The body normally produces glucosamine from glucose, a basic nutritional sugar. Taking supplemental glucosamine provides the body with a ‘prefab’ ready source of this important cartilage building block, enhancing the joints ability to produce new cartilage tissue. Glucosamine may also have a mild antiinflammatory effect. The recommended dose is at least 1 gram daily, and there are no known side effects. The medication is obtainable without a prescription. It may take 2-3 months before the effects are detectable, so be patient!
Chondroitin Sulfate is another type of molecule that contributes to the structure of cartilage. It is important in the binding of the spongy sugar aggregates to the structural protein framework which comprises cartilage. It is also thought to help inhibit some of the harmful enzymes that break down cartilage. A typical dose of chondroitin sulfate is 1000 mg/day. There are no known side effects.
Cortisone is a type of steroid that is used for its powerful antiinflammatory properties. Cortisone is extremely effective and safe when used properly and in moderation. It is not intended for repeated use, however, due to its ability to cause degeneration of tissue over time. A single cortisone injection will often give relief of pain and swelling for 6 months to a year. Cortisone is often used for end stage arthritis in order to buy time until a joint replacement surgery becomes necessary.
In Office Joint Debridement (Arthroscopy)
Much of the pain of arthritis comes from the small particles of debris in the joint which cause swelling and inflammation. Tremendous relief can often be obtained from simply washing out the joint (debridement). We have successfully performed these joint ‘clean outs ‘ in the office setting using local anesthesia in numerous patients. The procedure takes under an hour and patients leave the office with band aid dressings and walking without the need for crutches. Pain relief averages 1-3 years.
Regrowing New Cartilage
If the knee cartilage has started to wear out in a localized spot, but the remainder of the catilage is still intact, there are several modern techniques available to attempt to resurface the damaged area. These techniques are not effective once extensive wear or full blown arthritis has set in.
With this procedure, puncture holes are made surgically in the bone beneath the damaged cartilage in order to create bleeding and clot formation. Once a clot fills in the area of cartilage defect, over time the clot tissue will be transformed into a type of scar cartilage (fibrocartilage). This tissue acts as a patch, like spackling an area of chipped paint. The new tissue does not have the mechanical integrity of normal cartilage, however, and will often degenerate in 3-5 years. After surgery weight bearing is avoided for 4-6 weeks to allow the clot to mature, and a passive motion machine is used 6 hours/day to stimulate healing. Full healing takes approximately 6 months.
This relatively new procedure replaces a localized area of damaged cartilage with a plug of cartilage and bone from a donor site in the same knee. Sort of like a hair transplant. This technique seems to be an option for small localized defects especially those smaller than 1 or 1.5 centimeters. Since this procedure is new there are still some unanswered questions about its long term effectiveness and about the possible detrimental effects on the donor site.
One of the most exciting new techniques for the treatment of cartilage surface damage is the ability to clone the patients own cartilage and reimplant the cells back into the joint. This technique involves taking a small sample of cartilage from the joint, extracting the cartilage cells and growing new cells in the laboratory using cell culture techniques. These cells are then reimplanted into the damaged area of the joint and kept in place with a patch of periostium, the skin-like lining of the adjacent bone. After surgery the leg is kept non weight bearing for 4-6 weeks and a continuous passive motion machine is used for 2 weeks to stimulate cartilage growth. Full recovery takes 6 months-1 year. Up to ten year data is currently available on this technique with 80-90% of patients achieving good-excellent results.
Knee Joint Replacement
When all other methods of treatment for arthritis have failed, joint replacement is recommended.
Total Knee Replacement
A total, or complete, knee replacement is when all the arthritic surfaces of the joint are surgically removed and replaced with a metal surface and a plastic spacer. This procedure is highly effective and is still the recommended treatment for advanced arthritis of the knee. The surgery takes 1-2 hours. Full weight bearing is allowed as tolerated the day after surgery. Full recovery takes 3-6 months. The average knee replacement can be expected to last 10-15 years.
When only one portion of the joint is arthritic, it is often possible to replace only that portion of the joint and leave the remaining structures intact. This is called a unicondylar arthroplasty. The advantage is that less bone is removed, the ligaments and one meniscus is preserved and the joint feels more ‘normal’ after surgery. Post surgical recovery is also speedier. If this replacement ever wears outs, a total knee replacement can always be done at a later date.
The UniSpacer is a small, metallic kidney-shaped insert that is intended to restore stability and normal alignment for patients whose arthritis is primarily located on the inside half of the knee. It also provides a smooth surface for the bonews to glide over when cartilage has been worn away by arthritis. The UniSpacer conforms to the natural bone structure and stays in place without bone cememt or screws. Implantation of the UniSpacer does not requre bone cuts. The UniSpacer comes in a wide range of sizes to conform as closely as possible to the weight and size of each patient.
Osteoarthritis Injuries – The Future
A new technique is currently under investigation in Norway that injects a polymer into the arthritic knee. The polymer then hardens slowly as it conforms to the contour of the joint and acts as a new spacer. Human trials have just begun and this technique is not approved for use in the United States at this time. It is not clear what will happen to this polymer over time or what the long term consequences may be.
Several centers are working experimentally to develop a method for inserting cartilage cells into the joint embedded in a gel-like absorbable matrix. This is currently only being done in animal models.