Total Knee Replacement Surgery

If you are considering total knee replacement surgery, the following information might help you understand the procedure and implants better.

Your knees work hard during your daily routine, and arthritis of the knee or a knee injury can make it hard for you to perform normal tasks. If your injury or arthritis is severe, you may begin to experience pain when you are sitting down or trying to sleep.

Sometimes a total knee replacement is the only option for reducing pain and restoring a normal activity level. If your and your doctor decide a total knee replacement is right for you, the following information will give you an understanding about what to expect.

A total knee replacement involves cutting away the damaged bone of the knee joint and replacing it with a prosthesis, which prevents the bones from rubbing together and provides a smooth knee joint.

Implant Components

In the total knee replacement procedure, each prosthesis is made up of four parts. The tibial component has two elements and replaces the top of the shin bone (tibia). This prosthesis is made up of a metal tray attached directly to the bone and a plastic spacer that provides the bearing surface.

The femoral component replaces the bottom of the thigh bone (femur). This component also replaces the groove where the patella (kneecap) sits.

The patellar component replaces the surface of the kneecap, which rubs against the femur. The kneecap protects the joint, and the resurfaced patellar button slides smoothly on the front of the joint.

The Procedure

Before you are taken to the operating room, you will be given medication to help you relax and the anesthesiologist will talk with you about the medications he will use. In the operating room, he will place you under full anesthesia.

Once you are "under", the surgeon will begin by making an incision in your leg to allow access to the knee joint. He will then expose the joint and place a cutting jig - a template - on the end of the thigh bone. This template allows the surgeon to cut the bone precisely so that the prosthesis fits exactly. Once it is cut, then the shin bone is cut using another template for proper alignment of the knee prosthesis. The undersurface of the kneecap is then removed.

Now it is time to place the prosthesis. The surgeon cements the thigh bone part in place using a special bone cement. Next, he attaches the metal tray to the top of the shin bone. This will provide the weight-bearing surface of the femur. The plastic spacer is then attached to the metal tray. If this component should wear out and the rest of the artificial knee is sound, it can be replaced. This is known as a revision. Next, the surgeon cements the patellar button in place behind the kneecap. Finally, the surgeon closes the incision, puts in a drain, and applies the post-operative bandaging.

Returning Home

You will be discharged when you can get out of bed on your own and walk with a walker or crutches, walk up and down three steps, bend your knee 90 degrees, and straighten your knee.

At home, you should begin walking with a cane as tolerated. Keep your incision clean and dry and watch closely for any signs of infection.

You will continue your home exercise program and go to outpatient physical therapy, where you will work on an advanced strengthening program and such programs as stationary cycling, walking, and aquatic therapy.

Your long-term rehabilitation goals are a range of motion from 100-120 degrees of knee flexion, mild or no pain with walking or other functional activities, and independence in all activities of daily living.