Here, we present a summary of information on the topic of knee replacement. This information is not meant as a substitute for advice, diagnosis, and treatment by a healthcare specialist.

Knee Overview

Total Knee Replacement
Replacing the diseased and painful joint surfaces of the knee with metal and plastic components shaped to allow continued motion of the knee is a procedure known as Total Knee Replacement and may be recommended and undertaken by an orthopaedic surgeon. In this procedure, the surgeon will typically remove the damaged surfaces of all three bones (the femur, the tibia, and the patella) using special, precision instruments. Following this removal, the replacement surfaces are then fixed into place.

The replacements consist of:

• Knee Femoral Component - a rounded metal component that closely resembles the curve of your natural bone which replaces the surface of the femur.
• Polyethylene Articulating Surface - a smooth plastic component made of ultra-high-molecular-weight polyethylene plastic that serves as the cartilage.
• Stemmed Tibial Plate - a smooth metal component that replaces the surface of the tibia and holds the Polyethylene Articulating Surface.
• Patella Component - an implant made of the same polythylene plastic which may replace the undersurface of the kneecap.

Preparing for Surgery
Once the decision has been made to pursue a knee replacement, the patient will need to complete a series of tasks in order to properly prepare for the surgery.

• A physical exam by your primary care physician may be requested in order to confirm your general health and ability to undergo the surgery.
• An exercise program and/or weight loss regime may be initiated to improve your weight and physical condition.
• Smokers will need to discuss their habit with their physician as smoking increases certain risks in relation to surgery.
• Arrange to complete any dental work that may be in progress to avoid infections from the mouth from entering the bloodstream and therefore entering the new joint.
• As you are likely to need blood during the surgery, your surgeon will arrange for your blood bank to have that transfusion available. Alternatively, your surgeon may advise you to donate one or two units of blood ahead of time for this purpose.

The Surgery
Necessary medications and fluids will be administered to the patient through an I.V. during the surgery. The patient is taken to the operating room and given anesthesia. Once the anesthesia takes effect, a special solution is used to scrub and sterilize the knee area.

Depending on the individual circumstances for the patient and techniques used, the surgery will take approximately one to three hours. In the standard technique, a long incision over the knee exposes the joint through detachment of part of the quadriceps muscle (in fact the vastus medialis) from the kneecap. With the bones fully visible to the surgeon, the surgeon uses special, precision guides and instruments to remove the damaged surfaces and shape the ends of the bones to accept the implants.

With the surfaces prepared, the implants are then secured to the bones. To achieve the best possible knee function, it might also be necessary to adjust the ligaments that surround the knee. The surgeon will then close the incision when he is satisfied with the fit and function of the implants. For the fluids that naturally develop at the surgical site, a special drain may be inserted into the wound site for drainage. A sterile bandage is then applied to the surgery site.

The patient will be sent to the recovery room following the completion of the surgery. There, they will slowly regain consciousness as the anesthesia wears off. The nurse accompanying the patient will instruct the patient to cough or breathe deeply to help clear the lungs. Pain medication will be administered and a foam wedge or pillows will be placed between the legs to help hold the joint in place. When the patient has regained full consciousness, they are taken to their hospital room. The knee will be swollen and tender for a few days following the surgery.

Following Surgery
Patients begin a rehabilitation program in their hospital room following their surgery. The muscles around the new knee need to be strengthened and the patient needs to gain range of motion in the knee. The rehabilitation program will be tailored specifically for the individual. It may include use of a rehabilitation machine, called a continuous passive motion machine, which uses automation to move the knee up and down to help reduce stiffness.

Patients are usually instructed to stand about 24 hours following their surgery. Then, within 24 hours, a physical therapist will begin to start a walking regiment with the patient, helping them to walk a few steps at a time with the aid of a walker. Prior to dismissal from the hospital, an occupational therapist will spend time with the patient instructing them on the ideal maneuvering to ensure proper use of the new knee in the performance of daily tasks at home. For instance, the therapist will give instructions on how to go to the bathroom, how to dress, how to sit or stand, how to maneuver stairs, how to pick up objects, and many other typical home situations.

Discharge from the hospital typically takes place three to four days following the surgery...depending on the patient's speed of recovery. Some patients are referred to a rehabilitation facility or department if their condition warrants further rehab and instruction. Usually, the bandages and sutures are removed before the patient leaves the hospital. When the patient has returned home, they should continue to take their prescribed medications and perform their rehab exercises as instructed by their surgeon and physical therapist. A physical therapist will instruct the patient about proper home care, and may continue to work with them in the home environment. Some patients require the use of the passive motion machine in their homes following dismissal. Hospital staff will arrange for this use, if necessary. The most effective means of recovery are walking, remaining active, and performing the required home exercises.

After this surgery, any future dental work requires an antibiotic before the dental work can be done.

Activity Resumption
Most patients are able to walk with a cane within six weeks following surgery. Within seven to eight weeks after surgery, patients usually feel well enough to drive a car.

For the majority of cases, successful joint replacement surgery relieves the pain and stiffness experienced prior to the operation. Resumption of many of the patient's normal daily activities is to be expected. However, some activities will be restricted. Contact sports or activities that put extreme stress on the joint are to be avoided. While the artificial joint can be replaced, the second implant is rarely as effective as the first replacement. So maximizing the wear of the original replacement is paramount.

Artificial Knee Endurance
The period of time that the artificial knee will remain intact and functional depends on many factors and varies for each patient. Some of the factors include:

• the patient's physical condition
• the patient's activity level
• the patient's weight
• the accuracy of the implant placement
• the endurance of the materials in the artificial joint

Artificial joints are not as strong and durable as the patient's original, healthy joint; and there is no guarantee that the new joint will endure to the end of the patient's life.

Knee joint replacement surgery today is a typical, safe, successful procedure. Compared to the pain and immobility experienced prior to the surgery, most patients enjoy relief from pain and improved range of motion. With this new mobility and pain ease, some patients may have a tendency to overdo their physical activity. The new synthetic joint will provide a smooth joint movement. The fluid in the joint, the synovial fluid, will lubricate the joint, just as it did in the natural joint. Some wear will occur over time in the synthetic joint depending on the use of the joint. Extremely stressful activities and the stress from heavier patients will cause the joint to wear more quickly and reduce the service life of the artificial joint. Should the joint components become loose or undergo wear on the plastic portions of the implant, the necessity of revision surgery to replace the worn components, or all of the components may become apparent. Your surgeon can discuss this potential with you taking into account your particular clinical circumstances, the type of implants used, and your post-surgical lifestyle.

Following your surgery, you should become informed by your surgeon about the following situations which may affect the longevity and success of your knee replacement:

• maintaining your general physical condition
• adjusting your activity level
• maintaining your ideal weight
• avoiding repetitive heavy lifting
• avoiding excessive stair climbing
• avoiding high impact sports such as jogging, downhill skiing, and high impact aerobics
• consulting your physician before beginning a new sport or activity
• being smart about everyday movements
• avoiding physical activities involving quick starting and stopping motions, twisting or impact stresses
• avoiding excessive bending when weight bearing, like climbing steep stairs
• not lifting or pushing heavy objects
• not kneeling
• avoiding low seating surfaces and chairs.

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