Total knee replacement treats painful knees by eliminating bone-on-bone contact and replacing painful arthritic surfaces with highly polished metal and plastic. Smooth caps are permanently secured to the ends of the knee bones to allow the joint to glide comfortably.
The remaining normal bone, ligaments, and muscle are preserved. The operation generally takes an hour. In the end, a virtually pain-free gliding surface is restored.
Recovery today occurs much more quickly. Progress in postoperative recuperation is credited to several technical changes in the surgery. Most obvious to patients is a major reduction in the skin incision. Depending on the size of the patient and the patient's knee, Saint John’s surgeons can shrink the length of the incision by up to a third or a half of the traditional incision length. Below the skin, well-established dissection techniques and miniaturized instrumentation have been modified to reduce muscle and tendon trauma.
Rather than cutting the muscle and tendon in half, surgeons now preserve the muscle by pushing it to the side. The muscle starts working again right after surgery, and the patient starts walking the same day.
Clearly, not cutting the muscle has a direct and immediate benefit. Clinical studies demonstrate not only a faster return of muscle function, but also a lasting improvement in range of motion.
Currently, most healthy patients will leave the hospital in two to three days with only a cane. The vast majority will be independent enough to go directly home.
Total Knee Replacement Surgery
If you are considering knee surgery the following total knee replacement 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 experience pain when you’re 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.
This “new joint” 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 or 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 or femur.
This component also replaces the groove where the patella, or kneecap, sits.
The patellar component replaces the surface of the knee cap, which rubs against the femur.
The patella protects the joint, and the resurfaced patellar button will slide smoothly on the front of the joint.
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The Procedure
Before you are taken to the operating room you’ll be given medication to help you relax, and the anesthesiologist will talk with you about the medications he’ll be using. In the operating room, you will be placed 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’ll then expose the joint and place a cutting jig or template on the end of the femur, or thigh bone.
This jig allows the surgeon to cut the bone precisely so that the prosthesis fits exactly. Once the femur is cut, the tibia is cut using another jig for proper alignment of the knee prosthesis. The undersurface of the patella is then removed.
Now it’s time to place the prosthesis. This begins with the femoral prosthesis, which is cemented in place using a special bone cement. Next the metal tray is attached to the top of the tibia. This will provide the weight-bearing surface of the femur. The plastic spacer is then attached to the metal tray. This will provide the weight-bearing surface of the femur. If this component should wear out while the rest of the artificial knee is sound, it can be replaced. This is known as a “revision.”
Next the patellar button is cemented in place behind the knee cap. Finally, the incision is closed, a drain is put in, and the post-operative bandaging is applied.