A total knee replacement (a.k.a total knee arthroplasty) is a surgical procedure in which parts of the knee joint are replaced with artificial parts (prostheses).
The knee joint functions as a hinge joint between the thigh bone (femur) and leg bone (tibia). The surfaces where these bones meet can become worn out over time which can cause pain and swelling.
Approximately 700,000 knee replacements are performed annually in the U.S., and most studies demonstrate that 80-90% of total knee replacements will last between 15 and 20 years.
Total Knee Replacement
REASONS FOR A KNEE REPLACEMENT
Total knee replacement in one option to decrease pain and improve function to an arthritic knee. The most common reason people undergo knee replacement surgery is that they have failed all other conservative treatments.
The goal of a knee replacement is to reduce pain, maximize knee function, and improve quality of life. There is no age minimum or limit, but most patients have significant pain and/or disability prior to considering the procedure
Because the replacement parts can wear out over time, we generally recommend you delay the surgery until it is absolutely necessary.
Weight loss - The knee sees about four pounds of pressure for each pound of body weight, so reduced pain can be seen with even a small amount of weight loss (eg. 10 to 15 lbs).
Exercise/Physical therapy - Strengthening the muscles around the knee help take pressure off of the knee joint. Motion of the joint helps to keep it from getting stiff.
Medications - These include anti-inflammatory medications such as acetaminophen (Tylenol), ibuprofen (Advil), and naproxen (Naprosyn). It is important that patients discuss this option with their primary care provider to be sure the risk of side effects is low.
Knee bracing or shoe inserts - Both of these may help better align the leg/knee which distributes the weight more evenly within the joint.
Arthroscopy - A minimally-invasive procedure through small incisions that can address certain types of damage.
Osteotomy - A procedure in which the leg bone is cut and realigned to shift the weight from the damaged part of the knee to the healthy or less damaged side. Usually reserved for "younger" patients with arthritis localized to one side of the knee.
Partial knee replacement - This involves replacing only one part of the knee joint. There is some debate as to whether a partial or total knee replacement is better, so the risks and benefits of both should be considered.
THE KNEE REPLACEMENT PROCEDURE
The surgery involves replacing the knee with artificial parts (prostheses). In general, the patient is completely asleep for surgery (general anesthesia). A nerve block injection can be administered by the anesthesiologist right before surgery to help control the pain after surgery.
After surgery, the patient will be in the recovery room for 2 to 3 hours for monitoring then sent up to the inpatient floor. Most people stay two nights in the hospital after surgery.
Blood clots in the legs are a common concern after knee replacement surgery. To reduce the risk, certain practices are common, including: early mobilization with a physical therapist, exercises in bed, blood thinning medication, and inflatable boots around your legs.
Infection is another major concern, and patients receive antibiotics before, during, and for 24 hours after surgery. Factors that can increase your risk for infection include: poor diet, obesity, smoking, and uncontrolled diabetes.
It is common to begin physical therapy the day of or one day after surgery while you are in the hospital. After leaving the hospital, some patient will receive physical therapy in home or at a clinic while others may require a little more time in a rehabilitation facility.
It is important to avoid overworking or straining the knee during the recovery process. Think "slow and steady." After several months of rehabilitation, you will be able to have a more active lifestyle.
High-impact activities such as running and contact sports are not recommended after surgery, but you should be able to participate in walking, bicycling, and swimming activities.
Blood clots - Having a knee replacement increases the risk of a blood clot forming in a vein (a.k.a "DVT"). Symptoms of a DVT clot include leg pain and swelling.
Infection - Infection following a knee replacement is a relatively uncommon but serious complication. Symptoms may include fever, chills, pain in the knee that gets worse suddenly, redness, or swelling. Superficial infection may be treatable with antibiotics, but deep infections usually require removal of the joint implants. A new artificial knee can then be placed again once the infection has been treated.
Stiffness - Despite compliance with physical therapy, a patient's knee may occasionally get stiff and not straighten or bend all the way. They may require a return to the operating room where knee tissue can be stretched under anesthesia.
Early failure - Reasons a knee may not last the usual 15-20 years include: infection, loosening of the implants, fracture of the bone around the implant, and knee instability. If these occur, revision surgery is usually necessary.
Peroneal nerve injury - The most common neurologic complication after a knee replacement. It results in numbness, tingling, and a foot drop. Certain knees are more at risk than others.