The Arthritic Knee
Osteoarthritis, better known as degenerative arthritis, is the second leading cause of disability in the U.S. behind heart disease. The knee is the most common joint to be affected largely due to our recent surge in excess body weight, the high frequency of knee injuries and our extended longevity. These factors often lead to wear and deterioration of the articular cartilage, that smooth coconut-like, slippery surface that caps the end of bones at joints. An old or unbalanced tire that loses its tread is a useful analogy.
An aching, stiff, sometimes swollen knee after activity, prolonged standing or sitting that worsens over time and begins later in life (after age 50) is usually osteoarthritis. At times these symptoms linger for years or they can increase quickly over several months and require medical attention. Regular x-rays usually suffice in diagnosing moderate or advanced knee arthritis.
Fortunately treatment options are available and usually begin with reducing stress to the knee with lifestyle changes such as weight loss and non-weight bearing exercise (biking, swimming, exercise machines) to maintain leg strength. Anti-inflammatory medicines such as aspirin, Motrin or Aleve, which are inexpensive over-the-counter pills, and Tylenol, a non-narcotic pain reliever, are effective in reducing symptoms and should be the initial treatment. Glucosamine is a supplement that in theory supplies cartilage with essential ingredients but its efficiency is questionable.
If anti-inflammatory medicines are not effective then Cortisone, a very potent anti-inflammatory medicine, can be injected by a physician into the knee joint every four to six months to help reduce symptoms secondary to cartilage wear. Another option that might be considered is hyaluronic acid, a long protein molecule in synovial fluid that protects, nourishes and lubricates articular cartilage. The quality of synovial fluid in arthritic joints is poor, similar to old oil in your car engine. An “oil change” has been available for over ten years for arthritic knees. This is known as “Synvisc” and is comprised of hyaluronic acid extracted from the crowns of chickens and placed in a syringe that is injected weekly for three weeks into the moderately arthritic knee. It is healthy for the remaining cartilage and in most cases provides some symptom relief for about a year.
When knee pain becomes disabling, the final solution is replacement surgery. Over the past forty years this technology has evolved to provide one of the most successful operations in orthopaedics with over 500,000 performed each year in the U.S. The remaining cartilage and some bone are trimmed from the joint surfaces with precise instruments and replaced with high-grade metal and plastic. The new designs restore knee motion, strength and stability that allow patients to eventually return to almost any activity (including hiking, skiing, biking and tennis) with minimal residual symptoms. Ninety-eight percent of patients are satisfied with the outcome, although about a third will still have some long term mild pain and limitations. The implants are very durable; at fifteen years almost ninety percent will still be functioning well.
Some patients have arthritis in only one side of the knee. A partial prosthesis is available that replaces only the defective side, leaving all good cartilage intact. This is done through a small incision with a much faster and easier recovery than a total knee replacement. Ultimately most patients are not even aware they have an implant.
Another recent development that eases surgical recovery after a knee replacement is nerve blocks. Anesthesiologists at BMH have perfected numbing the two major nerves to the knee, eliminating most post-operative pain for the first day or two. Patients have a much easier time after surgery avoiding heavy narcotics, moving faster and getting home or to rehab in just two or three days.
If you develop an arthritic knee, you will eventually come under the care of an orthopaedic surgeon. Every arthritic knee is unique; therefore, treatment options selected by you and your orthopedist may vary somewhat from what I have presented.
Jon Thatcher, MD, is a board-certified orthopaedic surgeon with Southern Vermont Orthopaedic & Sports Medicine.