The knee being a weight bearing joint is subject to an enormous amount of stress. With each foot strike the impact force that travels from the foot all the way to the head is dissipated at the knee. It is the main shock absorber joint of the body. The mere act of walking puts a loading force on the knee joint that is equivalent to three times that of the body weight. Jogging, one of the most favored types of exercise increases this force to four times that of walking. Over time, the cumulative effect results into the wear and tear of the joint. Inside the joint are cartilages that line the ends of the bone. A cartilage acts as a cushion that absorbs shock during walking. It is smooth to ensure easy movement. As the cartilage of the knee breaks down, pain sets in, and the knee becomes stiff. As the disease progresses, the knee becomes unstable. At times, the pain becomes so unbearable that the simple act of walking, climbing stairs, or just getting up from a chair becomes an ordeal. These occur when the cartilage becomes totally worn off. When this happens, a knee replacement may be your only option to walking pain free again.
So what is knee replacement? Knee replacement is removing the damaged cartilage and bone of the knee and replacing it with an artificial joint in the form of prosthesis. The prosthesis may be made up of Titanium alloy, Cobalt alloy, Zirconium alloy, and a high molecular weight polyethylene plastic. The prosthesis becomes the new knee and thus prevents the bone from rubbing against each other. This corrects leg deformity, relieves pain, and improves function. Because of these, total knee replacement has become one of the most common and most successful orthopedic procedures. Fig. 1.
How long does the procedure last? Knee replacement usually takes approximately two hours. After the procedure, you are brought to the Postoperative Acute Care Unit for your recovery from the anesthetics.
What kind of anesthetics is used? You will be placed on epidural anesthesia. This is a type of regional anesthesia wherein you would be numb from the waist down. This is usually coupled with intravenous sedation.
What do I expect after the surgery? When you wake up after your surgery, you will notice that you will be wearing Anti-thrombotic stockings and possibly ‘leg squeezers’. These two devices prevent blood clots from forming in your leg. That afternoon, your physical therapy begins. The physical therapist will come in twice a day for your exercises. Your therapist will help you learn to walk using a walker. For the next couple of days, you will notice that you will be able to walk farther and farther as you begin to regain balance and strength from the therapy.
How long do I stay in the hospital? Depending on how fast you recover, you will be admitted for approximately 3-4 days barring any complications.
What are the possible complications of a total knee replacement? Like any type of surgery, infection is a possible complication. Anytime you cut the skin, the body’s natural barrier from the environment, you risk the chance of getting an infection. However, the risk can significantly be brought down by giving antibiotics just before the surgery. Good technique and a clean air environment such as a laminar flow in the Operating Theater can decrease this risk further. Deep vein thrombosis (DVT) or blood clot in the veins of the leg, is also a possible complication. Having DVT runs the risk of developing pulmonary embolism. A pulmonary embolism or PE occurs when the blood clot in the leg breaks off and lodges in the pulmonary artery of the lung. PE is a potentially fatal condition. To decrease the risk of DVT and PE, a prevention program has been instituted. This includes the use of anti-thrombotic stockings, leg squeezers in the form of sequential compression device, exercises to move the legs, and if indicated, blood thinners. Other less common possible complications are fractures of the bone during preparation or insertion of the prosthesis, nerve damage, heart attack, stroke, or complications arising from chronic illnesses. Although uncommon, they can prolong full recovery.
How do I know if I am a candidate for a knee replacement? When the pain limits your participation in the activities you love to do, or have hindered you from performing your daily activities, or you have begun experiencing pain at rest or at night, you may benefit from a knee replacement. Ask our Joint Replacement experts if knee replacement is for you.
At the Arthritis and Joint Replacement section, we have created a Total Knee Replacement Pathway to enhance clinical outcomes and decrease complication rates.