There are several ways to treat the pain caused by arthritis. One way is total knee replacement surgery. The decision to have total knee replacementsurgery should be made very carefully after consulting your doctor and learning as much as you can about the knee joint, arthritis, and the surgery.
In total knee replacement surgery, the bone surfaces and cartilage that have been damaged by arthritis are removed and replaced with artificial surfaces made of metal and a plastic material. We call these artificial surfaces “implants”, or “prostheses”.
During Total Knee Replacement
The patient is first taken into the operating room and given anaesthesia. After the anaesthesia has taken effect, the skin around the knee is thoroughly scrubbed with an antiseptic liquid. The knee is flexed about 90 degrees and the lower portion of the leg, including the foot, is placed in a special device to securely hold it in place during the surgery. Usually a tourniquet is then applied to the upper portion of the leg to help slow the flow of blood during the surgery. An incision of appropriate size is then made.
Removing the Damaged Bone Surfaces
The damaged bone surfaces and cartilage are then removed by the surgeon. Precision instruments and guides are used to help make sure the cuts are made at the correct angles so the bones will align properly after the new surfaces (implants) are attached.
Small amounts of the bone surface are removed from the front, end, and back of the femur. This shapes the bone so the implants will fit properly. The amount of bone that is removed depends on the amount of bone that has been damaged by the arthritis.
A small portion of the top surface of the tibia is also removed, making the end of the bone flat.
The back surface of the patella (kneecap) is also removed.
Attaching the Implants
An implant is attached to each of the three bones. These implants are designed so that the knee joint will move in a way that is very similar to the way the joint moved when it was healthy. The implants are attached using a special kind of cement for bones.
The implant that fits over the end of the femur is made of metal. Its surface is rounded and very smooth, covering the front and back of the bone as well as the end.
The implant that fits over the top of the tibia usually consists of two parts. A metal baseplate fits over the part of the bone that was cut flat. A durable plastic articular surface is then attached to the baseplate to serve as a spacer between the baseplate and the metal implant that covers the end of the femur.
The implant that covers the back of the patella is also made of a durable plastic.
Artificial knee implants come in many designs. Some designs may have pegs, requiring small holes to be drilled into the bone after the damaged surfaces have been removed. Others may have central stems. In addition, some designs may allow screws to be used on the lower implant to provide added attachment security. The surgeon will choose the implant design that best meets the patient’s needs.
Closing the Wound
If necessary, the surgeon may adjust the ligaments that surround the knee to achieve the best possible knee function.
When all of the implants are in place and the ligaments are properly adjusted, the surgeon sews the layers of tissue back into their proper position. A plastic tube may be inserted into the wound to allow liquids to drain from the site during the first few hours after surgery. The edges of the skin are then sewn together, and the knee is wrapped in a sterile bandage. The patient is then taken to the recovery room.
What Happens After the Total Knee Replacement
When you are back in your hospital room, you will begin in a rehabilitation program designed specially for you. This program will help you regain strength, balance, and get you back to the activities you enjoy. It may include a machine, called a continuous passive motion machine, that automatically moves your leg.
Your physical therapist will help you perform appropriate exercises. About 24 hours after surgery, you will probably be asked to stand. Within the next 24 hours, you will begin to walk a few steps with the help of a walker.
You will be discharged as soon as our surgeon determines that you have recovered sufficiently. You can expect to stay in the hospital for about three days after your surgery. Your bandages and sutures will usually be removed before you leave the hospital.
At home, you will need to continue your exercises. Your physical therapist will instruct you about proper home care, and may continue to work with you.
Within six weeks after surgery, most patients are able to walk with a cane. You will probably feel well enough to drive a car within seven to eight weeks after surgery.
In most cases, successful total knee replacement will relieve your pain and stiffness, and allow you to resume many of your normal daily activities.