A Total Knee Replacement (TKR) or Total Knee Arthroplasty is a surgery that replaces an arthritic knee joint with artificial metal or plastic replacement parts called the ‘prostheses’.
The procedure is usually recommended for older patients who suffer from pain and loss of function from arthritis and have failed results from other conservative methods of therapy.
The typical knee replacement replaces the ends of the femur (thigh bone) and tibia (shin bone) with plastic inserted between them and usually the patella (knee cap).
Other causes include
In an Arthritic Knee
The combinations of these factors make the arthritic knee stiff and limit activities due to pain or fatigue.
The diagnosis of osteoarthritis is made on history, physical examination & X-rays.
There is no blood test to diagnose Osteoarthritis (wear & tear arthritis).
The decision to proceed with TKR surgery is a cooperative one between you, your surgeon, family and your local doctor.
The benefits following surgery are relief of symptoms of arthritis. These include
Prior to surgery you will usually have tried some conservative treatments such as simple analgesics, weight loss, anti-inflammatory medications, injections, modification of your activities, canes, or physical therapy.
Once these have failed it is time to consider surgery. Most patients who have TKR are between 55 to 80 years, but each patient is assessed individually.
Each knee is individual and knee replacements take this into account by having different sizes for your knee. If there is more than the usual amount of bone loss, sometimes extra pieces of metal or bone are added.
Surgery is performed under sterile conditions in the operating room under spinal or general anesthesia. You will be on your back and a tourniquet applied to your upper thigh to reduce blood loss. Surgery takes approximately two hours.
The surgeon cuts down to the bone to expose the bones of the knee joint.
The damaged portions of the femur and tibia are then cut at the appropriate angles using specialized jigs. Trial components are then inserted to check the accuracy of these cuts and determine the thickness of plastic required to place in between these two components. The patella (knee cap) will be resurfaced.
The real components are then inserted with cement and the knee is again checked to make sure things are working properly. The knee is then carefully closed and drains usually inserted, and the knee dressed and bandaged.
In anticipation of your surgery please review the links below for some helpful exercises to improve your surgical outcome.
When you wake, you will be in the recovery room with intravenous drips in your arm and a number of other monitors to check your vital observations.
Once stable, you will be taken to the surgical floor. Most patients will walk the same day of surgery. Physical Therapy will be continued throughout the hospital stay.
To avoid lung congestion, it is important to breathe deeply and cough up any phlegm you may have. You will also have a device called an Incentive Spirometer to assist with deep breathing.
Your Orthopaedic Surgeon will use one or more measures to minimize blood clots in your legs, such as inflatable leg coverings and possibly compression stockings. Most patients will be started on Aspirin 81 mg take twice daily for 6 weeks after surgery to prevent blood clots. Some patients may be required to use another blood thinner if they are at a higher risk for blood clots.
A lot of the long term results of knee replacements depend on how much work you put into it following your operation.
Usually, you will remain in the hospital for 1-2 nights. You will need physical therapy on your knee following surgery.
You will be discharged on a walker or crutches for 10-14 days, and usually progress to a cane for 10 days.
Sutures are removed at 14 days and you will go home with a waterproof bandage.
Bending your knee is variable, but by 2 weeks should bend to 90 degrees. The goal is to obtain 115-120 degrees of movement.
You may shower with your waterproof bandage. You can drive at about 3-4 weeks, once you have regained control of your leg. You should be walking reasonably comfortably by 6 weeks.
When you go home you need to take special precautions around the house to make sure it is safe. You may need rails in your bathroom or to modify your sleeping arrangements, especially if they are up a lot of stairs.
You will usually have a 1 week, 2 week and 4-6 week, 3 month check up with your surgeon who will assess your progress.
After you are released, you should continue to see your surgeon every 2-3 years for the lifetime of your knee replacement to check your knee and take X-rays. This is important as sometimes your knee can feel excellent, but there can be a problem only recognized on X-ray.
You are always at risk of infections especially with any dental work or other surgical procedures where germs (bacteria) can get into the blood stream and find their way to your knee.
If you ever have any unexplained pain, swelling or redness or if you feel generally poor, you should see your doctor as soon as possible.
Complications can be medical (general) or local complications specific to the Knee
Medical complications include those of the anesthetic and your general well-being. Almost any medical condition can occur so this list is not complete. Complications include:
Infection can occur with any operation. In the knee this can be superficial or deep. Infection rates vary. If it occurs, it can be treated with antibiotics but may require further surgery. Very rarely your new knee may need to be removed to eradicate infection.
Blood Clots (Deep Venous Thrombosis)
These can form in the calf muscles and can travel to the lung (Pulmonary embolism). These can occasionally be serious and even life threatening. If you get calf pain or shortness of breath at any stage, you should notify your doctor.
Stiffness in the Knee
Ideally your knee should bend beyond 100 degrees but on occasion, the knee may not bend as well as expected. Sometimes manipulations are required. This means going to the operating room where the knee is bent for you and under anesthetic.
The plastic liner eventually wears out over time, usually 15 to 20 years and may need to be changed.
Wound Irritation or Breakdown
The operation will always cut some skin nerves, so you will inevitably have some numbness around the wound, especially around the lateral (outside) region of your knee. This does not affect the function of your joint. You can also get some aching around the scar. Vitamin E cream and massaging can help reduce this.
Occasionally, you can get reactions to the sutures or a wound breakdown that may require antibiotics or rarely, further surgery.
The knee may look different than it was because it is put into the correct alignment to allow proper function.
Leg length inequality
This is also due to the fact that a corrected knee is straighter and is unavoidable.
An extremely rare condition where the ends of the knee joint lose contact with each other or the plastic insert can lose contact with the tibia (shinbone) or the femur (thigh bone).
Patella (knee cap) can dislocate. This means it moves out of place and it can break or loosen.
There are a number of ligaments surrounding the knee. These ligaments can be torn during surgery or break or stretch out any time afterwards. Surgery may be required to correct this problem.
Damage to Nerves and Blood Vessels
Rarely these can be damaged at the time of surgery. If recognized they are repaired, but a second operation may be required. Nerve damage can cause a loss of feeling or movement below the knee and can be permanent.
Fractures or breaks in the bone can occur during surgery or afterwards if you fall. To repair these, you may require surgery.
Discuss your concerns thoroughly with your Orthopaedic Surgeon prior to surgery.
Surgery is not a pleasant prospect for anyone, but for some people with arthritis, it could mean the difference between leading a normal life or putting up with a debilitating condition. Surgery can be regarded as part of your treatment plan—it may help to restore function to your damaged joints as well as relieve pain.
TKR is one of the most successful operations available today. It is an excellent procedure to improve the quality of life, take away pain and improve function. In general 90-95% of knee replacements survive 15 years, depending on age and activity level.
Surgery is only offered once non-operative treatment has failed. It is an important decision to make and ultimately it is an informed decision between you, your surgeon, family and medical practitioner.
Although most people are extremely happy with their new knee, complications can occur and you must be aware of these prior to making a decision. If you are undecided, it is best to wait until you are sure this is the procedure for you.