Total Knee Replacement Surgery
If you are considering knee surgery, the following information can help you to better understand the procedure and implants.
Your knees work hard during your daily routine, and arthritis or a knee injury can make it difficult for you to perform normal tasks. If your injury or arthritis is severe, you may begin to experience pain even 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 you and your doctor decide that a total knee replacement is right for you, the following information will help you understand 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, the prosthesis is made up of four parts, or components. The tibial component has two elements and replaces the top of the shin bone or tibia. This component is made up of a metal tray attached directly to the bone, with 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.
The Procedure:
Before you begin surgery, you’ll receive medication to help you relax, and the anesthesiologist will talk with you about the medications that will be used. In the operating room, you will be under full anesthesia.
Once you are anesthesized, the surgeon will begin by making an incision in your leg to allow access to the knee joint. The joint is then exposed, and the surgeon will 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 the prosthesis can fit exactly. Once the femur is cut, then the tibia is cut, using another jig for proper alignment of the knee prosthesis. The undersurface of the patella is then removed.
Then the prosthesis is placed. This begins with the femoral prosthesis, which is cemented in place with a special bone cement. Next, the metal tray is attached to the top of the tibia, and the plastic spacer is attached to the metal tray. This will provide the weight-bearing surface of the femur. If this component should wear out later 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.
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’ll continue your home exercise program and go to outpatient physical therapy, where you will work on an advanced strengthening program and activities such as stationary cycling, walking, and aquatic therapy.
Your long-term rehabilitation goals include a range of motion from 100 to 120 degrees of knee flexion, mild or no pain with walking or other functional activities, and independence in all activities of daily living.