Total Knee Replacement
When pain can no longer be tolerated or treated effectively, surgery to replace the knee may be the logical next step. More than 500,000 such procedures are performed annually in the United States, a figure that is expected to grow significantly with the aging population.
Total knee replacement is one of the most common surgical procedures performed at Virginia Mason, with outcomes that exceed national standards. It is not uncommon for patients to have both knees replaced at the same time (bilateral total knee replacement), a procedure that is done on a regular basis by orthopedic surgeons at Virginia Mason.
Candidates for a total knee replacement are usually middle age or older, and have managed their pain with:
- Limitation of activities
- Weight loss
- Or any of these factors in combination for years or even decades
Other candidates may experience a sudden onset of pain in the knee and limitation of movement.
The Total Knee Replacement Implant
A total knee replacement implant usually consists of two parts made of chrome cobalt, titanium alloy and polyethylene plastic. The cobalt-chrome component is attached to the end of the thigh bone (femur) and a titanium alloy base plate is attached to the end of the leg bone (tibia). A polyethylene plastic "articulating" surface is then positioned between them. A polyethylene plastic "button" is attached to the undersurface of the knee cap (patella). The knee implant comes in many different sizes to fit every knee. It weighs about the same as the natural surfaces removed.
The Surgical Procedure: Total Knee Replacement
The goal of a total knee replacement is to eliminate pain and restore the natural movement of the knee. A knee replacement is a major surgical procedure performed in the operating room. You will be instructed on pre-surgical preparations prior to the date of your operation.
Before surgery, you will be given an anesthetic. The type of anesthesia will be determined by you, your surgeon and the anesthesiologist. New pain management techniques have been a major advancement in total knee replacement surgery. Most patients receive spinal anesthesia and a special thigh nerve catheter. The spinal anesthesia will block any sensation in the lower part of your body so that you will not feel anything during surgery. The catheter dramatically reduces pain after surgery. In addition to the spinal anesthesia, you will be sedated to a sleeping state for the duration of the procedure and wake up in the recovery room.
During the operation, a "cuff" or tourniquet will be placed around your upper thigh and it will be inflated to eliminate bleeding during surgery. Your surgeon will then make an incision along the front of your knee, which will be anywhere from four to eight inches in length. The size of the leg and the flexibility of the tissues determine the length of the incision. Your surgeon will then shift the kneecap and its tendons to the side and examine the surfaces of the joint. The damaged surfaces are shaved off. In a total knee replacement these would be all of the joint surfaces including the undersurface of the knee cap. Your surgeon will also create a narrow channel in the middle of the leg bone (tibia) to receive the stem portion of the metal implant.
Once the arthritic surfaces of the joint have been removed, a highly polished cobalt-chrome resurfacing component is secured to the end of the femur and a titanium alloy base plate and stem to the top of the tibia. A plastic polyethylene component is then secured on top of the tibial base plate. A polyethylene plastic button is placed on the undersurface of the knee cap. Each component is secured to its respective bone surfaces with a strong bone cement. The alignment and thickness of the components restores the normal straightness to the knee and re-establishes the normal tension on the ligaments. As a result, the length of the joint is returned to normal. Because the materials are hard surfaces instead of the natural soft surfaces, patients may at times notice the tapping of the artificial surfaces together.
Before your surgeon finishes, one or two drains may be inserted near the knee to help remove any accumulating fluids. The drains are removed one to two days later. The total time of your surgery may be one to two hours.
Bilateral Total Knee Replacement
If you are having a total knee replacement of your other knee, these same procedures will be performed sequentially by your surgeon or even simultaneously, with a different surgeon and team working on your other knee.
The Virginia Mason Difference in Anesthesiology
Total joint replacement can be one of the most painful surgeries when traditional methods of pain control are used. At Virginia Mason, however, physicians are using new approaches. For knee replacement surgery, this includes a continuous nerve block technique called the "Adductor Canal Catheter" that not only reduces pain, but also maintains muscle strength in the leg, which is critical to recovery.
The ability of Virginia Mason anesthesiologists to keep joint replacement patients comfortable is evident in patient satisfaction scores for pain control in the 99th percentile.
What to Expect After Total Knee Replacement Surgery
Following surgery, you will be taken to a recovery room where your vital signs will be monitored. Once you have recovered, you will be moved to a regular hospital room. More than 70 percent of patients are comfortable and functional and leave the hospital on the second day after surgery. Some patients go home the day after surgery. Those having bilateral total knee replacements may be in the hospital a little longer.
Inpatient Physical Therapy
On the same day as your surgery, a physical therapist will help you sit up in bed and show you how to perform light exercises. You may even stand and walk a short distance with a cane or walker on this first day. (If you have had a bilateral knee replacement you may stand on the second day after surgery.) Each day you are in the hospital, and several times a day, the physical therapist will work with you and help you walk a little bit farther. Your road to recovery begins with these simple exercises that will eventually help you regain strength and functional use of your knee.
Outpatient Physical Therapy
Prior to joint replacement surgery, many patients attend a physical therapy orientation in Virginia Mason's Department of Physical Medicine and Rehabilitation or the Sports Medicine clinic. The orientation provides patients with helpful information, including safety recommendations (rearranging frequently used items for easier reach), assistive devices, such as a front-wheeled walker and joint-specific exercises.
Your surgeon or physical therapist will talk to you in more detail about exercises to do at home after surgery, either on your own or with the help of a physical therapist. Rehabilitation services also are available through Virginia Mason's Department of Physical Medicine and Rehabilitation and the Sports Medicine clinic.
Much of the success of your surgery will depend upon completion of these exercises to help you regain strength and mobility in your knee. Your rehabilitation may take 12 weeks. The key is to go slowly and perform only the exercises prescribed for you.
Virginia Mason's Peer Partners is a unique program of support for hospitalized patients. Volunteers who have been through similar situations visit with patients and their families to answer questions and assist with non-medical concerns. Peer Partners can also help caregivers understand how to best provide care and support when a patient returns home.
Risks of Total Knee Replacement Surgery
All precautions to ensure patient safety are taken prior to every operation at Virginia Mason. However, as with any surgery, some risks remain.
One is the risk of the implant loosening over time. In a recent study, the risk of loosening at five years was found to be 1 percent and at 12 years was 3 percent. Your surgeon will talk to you in more detail about the risks associated with your surgery.
Many patients ask how long the implant will last. The answer must take into account several factors, including:
- Patient age
- Physical condition
- Body weight
- Activity level
Because these devices are made with durable materials that provide a secure fit, a total knee implant is expected to last between 20 to 30 years.
Questions About Total Knee Replacement Surgery?
To schedule a consultation with an orthopedic surgeon about total knee replacements, call (206) 341-3000.