In total knee replacement surgery, your damaged knee joint is replaced with an artificial joint. A joint is made of two or more bones, some cartilage and supportive ligaments, and the muscles that control the movement of the joint. Normally, cartilage covers the ends of the bones to help them slide smoothly on each other. If your cartilage is worn down from overuse (osteoarthritis) or is diseased, movement at the joint can be very painful. Removing the areas of the joint that are causing pain and replacing them with artificial parts will reduce or eliminate the pain you feel.
Total joint replacements are designed to help you walk and do routine daily activities without pain. They are not designed for and will not hold up to the stresses of vigorous athletic activity.
The artificial parts that are used for knee replacement surgery are together called a "prosthesis" and are usually made of three parts:
- The lower part of the prosthesis replaces the top part of your lower leg bone (tibia). This part is often in two sections and is made of a metal plate with a plastic surface on top. Sometimes the surgeon will select a prosthesis that is made only of polypropylene (plastic).
- The upper part of the prosthesis replaces the bottom part of your thigh bone (femur). This part of the prosthesis is made of metal.
- The knee cap (patella) part of the prosthesis replaces the under surface of your knee cap. This part is also made of plastic.
There are two ways that the prosthesis can be attached to your bone:
- A cemented prosthesis uses a special type of cement to hold the pieces of your artificial joint in place.
- A different method of fixation is to use an uncemented prosthesis that is made of a material that is "porous". This means the material has tiny holes in it that your bone can grow into. Your doctor will decide which of these two methods is best for your surgery.
Your orthopaedic surgeon may suggest that you have a visit with your family doctor to prepare for your upcoming surgery. Your doctor may recommend that you begin to practice the exercises that you will need to do after surgery to help with your recovery. In addition, you should practice the best ways to use a walker or crutches.
Work with your doctor to think ahead about your rehabilitation time after surgery; you may need to have some additional help at home for a few weeks. Your doctor may have you take some antibiotic medications before and after your surgery to help reduce the risk of infection.
Before your surgery day, your doctor may suggest that you donate some of your own blood so that it will be available if your body needs it during surgery. You can donate blood up to 5 weeks before your operation.
You should not have any skin infections or irritations on your leg at the time of surgery. Call you surgeon prior to the surgery if any of these problems occur. You should wash your leg with soap before going to the surgical center for your procedure.
The complication rate following total knee replacement is low. Serious complications occur in fewer than 2% of patients. Talk with your doctor before surgery about the risks of knee replacement surgery. Some of the risks include the possibility of infection, loosening of the prosthesis attachment to your bone, prosthetic breakage, and joint stiffness. Any of these complications can limit or prolong your recovery.
The development of a deep vein thrombosis, or blood clot, is the most common serious complication with joint replacement surgery. This occurs most frequently in your calves. The clot may extend into the thighs or pelvis. If a portion of the blood clot breaks loose, it may travel in your veins up your lungs and get caught there. This can block blood flow in the lungs. This is called a pulmonary embolism and can be dangerous. To prevent this, you doctor may put you on a blood thinning medication that will prevent those clots from forming. You can also wear stockings on your legs that will help the circulation in your legs. While in the hospital you may be given compression stockings to help decrease the risk of DVT.
The Day of your Surgery
You will probably need to be at the surgery center or hospital a couple of hours before your surgery. The nurses may give you an intravenous (IV) line so you can receive fluids and medications. You will be given anesthesia that will numb the knee area through the surgery.
During the Surgery
After the anesthesia takes effect, the doctors will make an incision over the knee and will replace areas of your joint with the prosthesis pieces. The orthopaedic surgeon uses instruments that measure the precise angle of the prosthesis surfaces so the angle of the knee joint will be correct. After the joint is replaced, the doctor will close the incision with sutures or staples.
After your surgery, you will have intravenous (IV) medications for about a day to help reduce the risk of infection, to help prevent blood clots, and to help control pain. Most patients do have some pain following surgery while their muscles and tissues heal. You will probably stay in the hospital less than one week.
Once you are out of the hospital, you will need to walk with crutches, a cane or a walker for three to four weeks to allow your tissues to heal from the surgery. Your doctor will help you get involved in some physical therapy to help move your recovery process along by regaining motion and strength around your joint.
Most knee replacement patients are fully recovered in three to six months. Starting an exercise program will help with the recovery process. Talk with your orthopaedic surgeon about the best exercise program to help your recovery process. Swimming and walking are exercises that will put minimal stress on your knees and will help you regain strength and improve your overall health. You probably will be advised against doing activities (such as running and tennis) that put a lot of stress on your knees.