The knee joint is formed where your thighbone (femur) meets the shinbone (tibia). The thighbone is rounded on the end which rests on the flat surface formed on the end of the shinbone. A smooth cushion of articular cartilage covers the end of each bone and is lubricated by fluid produced by the joint lining, allowing the bones to move against each other easily and without pain. When the joint does not work as it should, you experience decreased mobility and pain.
The causes for joint replacement are arthritis, osteonecrosis and injury.
- Arthritis, the wearing away of the cartilage of a joint, can be caused by aging, injury or disease. As the bones rub together without the cushion of the cartilage, pain and further deterioration can occur.
- Osteonecrosis occurs when the blood supply for the femur is decreased, causing part of the bone to die and break down under weight bearing. The result is a very painful joint.
- A sports or work-related injury to the ligaments or cartilage in the knee can cause abnormal wearing of the articular cartilage. Once this articular cartilage wears out, a knee replacement is often needed.
You would be considered for total knee replacement if you have pain every day and a lot of pain at night; your pain limits your work, play or daily activities; or your knee "gives way" often.
The surgery is performed under general anesthesia by an orthopedic surgeon. The surgery usually takes 2 to 3 hours. During this time, the surgeon replaces a layer of bone on the end of the femur with a layer of metal. The end of the tibia is replaced with a flat, metal tray-like device on which a strong plastic "wafer" sits. Following surgery, you will be in the recovery room for another hour or two, then taken to a room in the hospital.
Knee replacement is scheduled weeks in advance, so you should consider making changes during this time that could maximize your recovery. Talk to your surgeon about your diet, exercise, weight and medicines. If you have any health changes, such as an infection, report them to your doctor as soon as possible. Finally, you should use this time to get plenty of rest.
You can also use the time prior to surgery to prepare for your return home. After surgery, any sitting areas you use should allow your hips to remain higher than your knees, because that will make it easier for you to get up. Before you have your surgery, check to make sure these areas allow you to use proper form. Examples of areas to "test" are your favorite chair, the side of the bed, the sofa, the toilet and the seats in your car. If any of these spots prevent proper form as described above, use a firm pillow to raise the level of your hips. Special aids can also be purchased, such as a raised toilet seat. If your bedroom is located upstairs, you may want to consider making a temporary room downstairs until you are able to go up and down the stairs easily.
The average length of stay in the hospital is five days. During this recovery time, you will work with physical and occupational therapists to help you prepare for your return home. Before you go home, the hospital staff will teach you how to get in and out of bed and a chair, walk with crutches or a walker, get in and out of the shower and go up and down steps. All of these activities will be taught using precautions to protect your new joint. You will also be advised on the medicines you will be taking, special supplies you will need and how to use them, how to care for your incision and what exercises you should do during your recovery at home. Make sure to ask any questions you may have - your recovery is important!