Knee Replacement
There are many conditions that result in degeneration of the knee joint. Osteoarthritis is the most common cause for patients who have knee replacement surgery. Osteoarthritis is commonly referred to as "wear and tear arthritis". Osteoarthritis can occur with no previous injury to the knee joint - the knee simply "wears out". Some people may have a genetic tendency that increases their chances of developing osteoarthritis. Fractures of the knee, torn cartilage, and torn ligaments can cause the knee joint to function abnormally. This abnormal function can lead to excessive wear and tear of the joint many years after the injury - just like an out-of-balance tire can wear out too soon.
Image source: http://www.jointreplacement.com/xq/ASP.default/mn.local/pg.cat/joint_id.6/ cat_id.8/joint_nm.Knee/local_id.32/qx/default.htm
Frequently Asked Questions (FAQ’s)
The information presented below is only for informational purposes. Your surgeon will talk to you about details regarding your specific procedure.
What are some signs or symptoms that I may need a knee replacement?
There are numerous symptoms why you may need a knee replaced. They are:
- Severe knee pain that limits your everyday activities, including walking, going up and down stairs, and getting in and out of chairs. You may find it hard to walk more than a few blocks without significant pain and you may need to use a cane or walker.
- Moderate or severe knee pain while resting, either day or night.
- Chronic knee inflammation and swelling that doesn’t improve with rest or medications.
- Knee deformity, a bowing in or out of your knee.
- Knee stiffness, inability to bend and straighten your knee.
- Failure to obtain pain relief from non-steroidal anti-inflammatory drugs. These medications, including aspirin and ibuprofen, often are most effective in the early stages of arthritis. Their effectiveness in controlling knee pain varies greatly from person to person. These drugs may become less effective for patients with severe arthritis.
- Inability to tolerate or complications from pain medications.
- Failure to substantially improve with other treatments such as cortisone injections, physical therapy, or other surgeries.
What can I expect during my surgical evaluation?
The orthopedic evaluation consists of several components:
- A medical history, in which your orthopedic surgeon gathers information about your general health and asks you about the extent of your knee pain and your ability to function.
- A physical examination to assess your knee motion, stability, and strength and overall leg alignment.
- X-rays to determine the extent of damage and deformity in your knee.
- Occasionally blood tests, an MRI (Magnetic Resonance Imaging) or a bone scan may be needed to determine the condition of the bone and soft tissues of your knee.
Your orthopedic surgeon will review the results of your evaluation with you and discuss whether total knee replacement would be the best method to relieve your pain and improve your function. Other treatment options including medications, injections, physical therapy, or other types of surgery also will be discussed and considered.
Your orthopedic surgeon also will explain the potential risks and complications of total knee replacement, including those related to the surgery itself and those that can occur over time after your surgery.
What are the different types of artificial knee joints (prosthesis)?
There are two main types of artificial knee replacements:
- Cemented Prosthesis
- Uncemented Prosthesis
Both types are widely used. In many cases, a combination of the two types is used. The kneecap, or patellar, portion of the prosthesis is usually cemented into place. The choice to use a cemented or uncemented prosthesis is usually made by the surgeon based on your age and lifestyle.
Each prosthesis has four parts:
- The tibial component replaces the end of the tibia. The tibia is commonly called the shinbone.
- The femoral component replaces the end of the femur, the groove where the kneecap slides. The femur is commonly called the thighbone. It is the largest bone in the body.
- The patellar component replaces the surface on bottom of the patella. The "top" of the kneecap is the part you can feel through your skin. The "bottom" is the on the other side, and slides up and down in the femoral groove whenever you bend or straighten your leg.
The femoral component is made of metal. The tibial component is usually made of two parts - a metal tray that is fitted directly onto the bone, and a plastic spacer that provides a bearing surface. The plastic used is very tough and very slick - so slick and tough that you could ice skate on a sheet of the plastic without much damage to the plastic. A cemented prosthesis is held in place using an epoxy type cement that attaches the metal to the bone. An uncemented prosthesis has a fine mesh of holes on the surface that allows the bone to grow into the mesh and attaches the prosthesis to the bone.
What anesthesia is used during knee replacement surgery?
You will most likely be admitted to the hospital on the day of your surgery. After admission, you will be evaluated by a member of the anesthesia team. The most common types of anesthesia are general anesthesia, in which you are asleep throughout the procedure, and spinal or epidural anesthesia, in which you are awake but your legs are anesthetized. The anesthesia team with your input will determine which type of anesthesia will be best for you.
What is the actual Knee Replacement procedure like?
The procedure itself takes about two hours. Your orthopedic surgeon will remove the damaged cartilage and bone and then position the new metal and plastic joint surfaces to restore the alignment and function of your knee. After surgery, you will be moved to the recovery room, where you will remain for one to two hours while your recovery from anesthesia is monitored. After you awaken, you will be taken to your hospital room.
What can I expect during my hospital stay?
You will most likely stay in the hospital for several days. After surgery, you will feel some pain, but medication will be given to you to make you feel as comfortable as possible. Walking and knee movement are important to your recovery and will begin immediately after your surgery. Your orthopedic surgeon may prescribe one or more measures to prevent blood clots and decrease leg swelling, such as special support hose, inflatable leg coverings (compression boots), and blood thinners.
To restore movement in your knee and leg, your surgeon may use a knee support that slowly moves your knee while you are in bed. The device, called a continuous passive motion (CPM) machine, decreases leg swelling by elevating your leg and improves your venous circulation by moving the muscles of your leg. Foot and ankle movement is encouraged immediately following surgery to also increase blood flow in your leg muscles to help prevent leg swelling and blood clots. Most patients begin exercising their knee the day after surgery. A physical therapist will teach you specific exercises to strengthen your leg and restore knee movement to allow walking and other normal daily activities soon after your surgery.
What are common complications that arise as a result of Knee Replacement Surgery?
The complication rate following total knee replacement is low. Serious complications, such as a knee joint infection, occur in less than 2 percent of patients. Major medical complications, such as heart attack or stroke occur even less frequently. Chronic illnesses may increase the potential for complications. Although uncommon, when these complications occur they can prolong or limit your full recovery. Blood clots in the leg veins are the most common complication of knee replacement surgery. Your orthopedic surgeon will outline a prevention program, which may include periodic elevation of your legs, lower leg exercises to increase circulation, support stockings, and medication to thin your blood.
What will my recovery be like?
The success of your surgery also will depend on how well you follow your orthopedic surgeon’s instructions at home during the first few weeks after surgery.
Wound Care You will have stitches or staples running along your wound or a suture beneath your skin on the front of your knee. The stitches or staples will be removed several weeks after surgery. A suture beneath your skin will not require removal. Avoid soaking the wound in water until the wound has thoroughly sealed and dried. A bandage may be placed over the wound to prevent irritation from clothing or support stockings.
Diet Some loss of appetite is common for several weeks after surgery. A balanced diet, often with an iron supplement, is important to promote proper tissue healing and restore muscle strength.
Activity Exercise is a critical component of home care, particularly during the first few weeks after surgery. You should be able to resume most normal activities of daily living within three to six weeks following surgery. Some pain with activity and at night is common for several weeks after surgery. Your activity program should include:
- A graduated walking program to slowly increase your mobility, initially in your home and later outside.
- Resuming other normal household activities, such as sitting and standing and walking up and down stairs.
- Specific exercises several times a day to restore movement and strengthen your knee. You probably will be able to perform the exercises without help, but you may have a physical therapist help you at home or in a therapy center the first few weeks after surgery.
Driving usually begins when your knee bends sufficiently so you can enter and sit comfortably in your car and when your muscle control provides adequate reaction time for braking and acceleration. Most individuals resume driving about four to six weeks after surgery.
Download a brochure from Depuy Orthopedics about Knee Replacement