What Is a Knee Replacement?
If your knee is severely damaged by arthritis or injury, it may be difficult to perform simple activities, and you may even begin to feel pain even at rest. If medications, changing your activity level, and using walking supports are not helpful, you may want to consider knee replacement surgery.
Knee replacement surgery, also known as arthroplasty, repairs your knee’s damaged and worn surfaces to try and relieve your pain, correct your leg deformity, and help you resume normal activities.
An important factor in deciding whether to have knee replacement surgery is understanding what the procedure can and can’t do. More than 90 percent of individuals who undergo knee replacement experience a dramatic reduction of knee pain and a significant improvement in the ability to perform everyday activities of daily living. But total knee replacement won’t make you a super-athlete or allow you to do more than you could before you developed arthritis. Following surgery, you will be advised to avoid some types of activity, including jogging and high-impact sports, for the rest of your life.
Causes
Knees wear out for various reasons, including inflammation from arthritis, injury, or simple wear and tear. Previous injury and obesity are other known causes.
Arthritis, which can run in families, is the most common cause of chronic knee pain and disability. Most knee arthritis is due to a lifetime of wear and tear. Nobody knows why some people get severe arthritis while others don’t or why one knee in the same person gets arthritis while the other does not. Previous injury and obesity are other known causes of arthritis.
The most common forms are osteoarthritis, rheumatoid arthritis, and traumatic arthritis.
Osteoarthritis usually occurs after age 50 and often in individuals with a family history of arthritis. The cartilage that cushions the bones of the knee softens and wears away. The bones rub against one another, causing knee pain and stiffness.
Rheumatoid arthritis is a disease in which the knee’s membrane becomes thickened and inflamed, producing too much fluid that overfills the joint space. This chronic inflammation can damage the cartilage and eventually cause cartilage loss, pain, and stiffness.
Traumatic arthritis can follow a serious knee injury. A knee fracture or severe tears of the knee’s ligaments may damage the articular cartilage over time, causing knee pain and limiting knee function.
Symptoms
Typical symptoms include:
- Severe knee pain that limits your everyday activities.
- Difficulty going up or down stairs, walking distances, or getting up from low seats.
- Moderate or severe knee pain while resting, either day or night.
- Swelling, stiffness, or a feeling of looseness.
- Failure to obtain pain relief from non-steroidal anti-inflammatory drugs. These medications, including aspirin and ibuprofen, often are most effective in the early stages of arthritis. Their effectiveness in controlling knee pain varies greatly from person to person.
- Inability to tolerate or complications from pain medications.
- Failure to substantially improve with other treatments such as cortisone injections, physical therapy, or other surgeries.
Diagnosis
If you are experiencing any of the above symptoms, please consult an orthopedic specialist. An evaluation consists of several components:
- A medical history to gather information about your general health, the extent of your knee pain, and your ability to function.
- A physical examination to assess your knee motion, stability, strength, and overall leg alignment.
- X-rays to determine the extent of damage and deformity in your knee.
- Occasionally, blood tests, Magnetic Resonance Imaging (MRI), or a bone scan may be needed to determine the condition of your knee's bone and soft tissues.
Treatment
The first steps in treating knee arthritis are activity modification, regular exercise programs, and weight loss. The muscles around the knee protect it during activity; however, every step puts your body weight several times through your knee. Improved strength and decreased body weight will prolong the life of your knee. Soft knee braces and shoe modifications can sometimes help, as can medications like Tylenol® or anti-inflammatories (NSAIDs) and some dietary supplements. You may need to use a cane or walker.
The next step is injections. Steroids may be used to decrease inflammation, or a lubricant may be used to improve the function of the knee. They can be repeated from time to time if they help.
Surgery is the final step in treating knee arthritis if the above steps have failed and the pain is limiting your lifestyle and activities. A knee replacement can help eliminate most of the pain from arthritis. Surgical options include knee arthroscopy (although this is rarely used just for arthritis), partial knee replacement, and total knee replacement.
Total knee replacement involves an 8-inch to 10-inch incision down the center of the knee to replace lost cartilage with metal and plastic. The goal of knee replacement is to provide a pain-free knee that allows relatively normal activities and lasts for as long as possible. Using the current techniques, 90 percent to 95 percent of knee replacements should last 15 years or longer.
Minimally invasive knee replacement attempts to accomplish all this through an incision that is only 4 inches to 6 inches long, which means that potentially, there will be less damage to the tissue around the knee. Benefits with a smaller incision may also include a shorter hospital stay, a shorter recovery, and a better-looking scar.
Research Continues
Advocates of minimally invasive knee replacement are working to address concerns about the accurate positioning of the knee replacement by combining small-incision surgery with computer-guided instruments. The potential benefits, risks, and costs are not yet established.
Reproduced with permission Fischer S., (interim ed): Your Orthopaedic Connection. Rosemont, Illinois. Copyright American Academy of Orthopaedic Surgeons.
