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 ‘prosthesis’.
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).
The Most common cause is age related degeneration which is termed as osteoarthritis.
Other causes include :
Inflammation e.g., Rheumatoid arthritis
Inactive lifestyle e.g., Obesity, as additional weight puts extra force through your joints which can lead to arthritis over a period of time
The cartilage lining is thinner than normal or completely absent. The degree of cartilage damage and inflammation varies with the type and stage of arthritis.
The capsule of the arthritic knee is swollen
The joint space is narrowed and irregular in outline; this can be seen in an X-ray image.
Bone spurs or excessive bone can also build up around the edges of the joint
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 and your family.
The benefits following surgery are relief of symptoms of arthritis. These include
- Severe pain that limits your everyday activities including walking, shopping, visiting friends, getting in and out of chair, gardening, etc.
- Pain waking you at night
- Deformity- either bowleg or knock knees
Prior to surgery you will usually have tried some conservative treatments such as simple analgesics, weight loss, anti-inflammatory medications, and 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 60 to 80 years, but each patient is assessed individually and patients as young as 20 or old as 90 are also operated on with good results.
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.
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) may be replaced depending on a number of factors and depending on the surgeon’s choice. Surgery takes approximately one-two hours.
The real components are then inserted with or without cement and the knee is again checked to make sure things are working properly. The knee is then carefully closed dressed and bandaged.
Usually, you will remain in the hospital for 5-7 days. You will need physical therapy on your knee following surgery.
You will be discharged on a walker or crutches and usually progress to a cane at six 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.
Your sutures are generally dissolvable but if not, are removed at approximately 10-15 days.
Bending your knee is variable. The goal is to obtain full knee bending at around 8-10 weeks of surgery.
You can drive at about 3 months, once you have regained control of your leg. You should be walking reasonably comfortably by 6-8 weeks.
More physical activities, such as certain permitted sports, may take 6 months to do comfortably.
You will usually have a 6 week check up with your surgeon who will assess your progress. You should continue to see your surgeon for the rest of your life to check your knee and take X-rays once a year. 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, you should see your doctor as soon as possible.
As with any major surgery, there potential risks involved. The decision to proceed with the surgery is made because the advantages of surgery outweigh the potential disadvantages
It is important that you are informed of these risks before the surgery takes place
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:
Allergic reactions to medications
Blood loss requiring transfusion with its low risk of disease transmission
Heart attacks, strokes, kidney failure, pneumonia, bladder infections Complications from nerve blocks such as infection or nerve damage Serious medical problems can lead to ongoing health concerns, prolonged hospitalization or rarely death.
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
On occasions, 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 under anesthetic.
Wear is a long term phenomenon requiring a revision surgery.
Wound Irritation or Breakdown
The operation will always cut some skin nerves, so you will inevitably have some numbness around the wound. This does not affect the function of your joint. You can also get some aching around the scar.
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.
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 recovers with time which may take upto 1-2 yrs. or may be permanent.
Fractures or breaks in the bone can occur during surgery or afterwards if you fall. To repair these, you may require surgery.
Surgery 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 20-25 years.
Surgery is only offered once your condition is in advanced stage and non-operative treatments have failed. It is an important decision to make and ultimately it is an informed decision between you, your surgeon and your family.