Decision to Have Surgery
People often wonder when and why they should have their knee replaced. This is an individualized question that depends upon a person’s activity level and functional needs. Many people with arthritis live with pain that prevents them from participating in activities that they love; others are so debilitated that they have difficult putting on their shoes and socks. Total knee replacement offers a solution to the problem of arthritis and is performed with the goal of pain relief and resumption of activity. After a rehabilitation from a successful total knee replacement, a patient can expect to have at least as much motion as prior to surgery, without pain. According to a study presented at the American Academy of Orthopaedic Surgeons, total knee replacement dramatically improves a patient’s quality of life and significantly reduces his/her long-term treatment costs. This study found that not only was a total knee replacement cost-effective when compared with non-operative management, it also provided more function and a better quality of life.
A total knee replacement is considered a major operation, and the decision to undergo total knee replacement is not a trivial one. People usually decide to undergo surgery when they feel they can no longer live with the pain of their arthritis.
The Prosthetic Implant
The implant for a total knee replacement is composed of 4 parts: the tibial and femoral components, a plastic insert, and the patella. The tibial and femoral components are made out of metal, usually cobalt-chrome, and are used to cap the ends of the femur and tibia after the arthritic bone is removed. The plastic insert is made out of ultra high molecular weight polyethylene (UHMWPE) and fits into the tibial component, such that the highly polished surface of the femur glides against the plastic. The patella component is also made of UHMWPE, and glides against the front of the femoral component. All together, the components weigh about 1 to 2 lbs. They are generally fixed to the bone with cement.
The total knee replacement is performed in an operating room with a special laminar airflow system, which helps reduce the chance of infection. Your surgeon will be wearing a "spacesuit", also designed to reduce the chance of infection. The entire surgical team will consist of your surgeon, two to three assistants, and a scrub nurse.
The anesthesia for a total knee replacement is given through an epidural catheter, which is a small tube inserted into the back. This is the same type of anesthesia given to women in labor. You will be made numb from the waist down so that you will not feel anything. The catheter stays in for 1-2 days after the surgery to help with your post-operative pain control. During the course of the operation, you can be as awake or as sleepy as you want to be. In addition to the epidural block, another nerve block in the leg may be used, or local anesthetic may be given inside the knee at the end of the procedure, to aid in postoperative pain control.
After the epidural block is administered, a tourniquet, or cuff, will be placed around your thigh. The tourniquet will be inflated during surgery to help reduce the loss of blood. The incision for a total knee replacement is made along the front of your knee. The incision will measure anywhere from 4 to 10 inches depending upon your anatomy.
The arthritic surfaces of the femur, tibia, and patella are exposed and removed with power instruments. In so doing, deformities of the knee are corrected, and the knee will appear straighter after surgery. The bone is prepared to receive the artificial knee joint, and then the prosthesis is inserted. Staples and/or dissolvable sutures are used to close the skin.
The entire operation will take from 1 to 2 hours. Afterwards, you will be brought to the recovery room, where your blood work and vital signs will be checked. Most patients can be brought to a regular room within a few hours; others will need to stay overnight in the recovery room, as determined by your surgeon and anesthesiologist. Patients generally stay in the hospital for 2-3 days following total knee replacement surgery.