A Total Knee Replacement (TKR) or Total Knee Arthroplasty (TKA) 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).
Causes of arthritis 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 arthritis is made on history, physical examination, and 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, your family, and your primary care doctor.
The benefits following surgery are relief of the 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, modification of your activities, cortisone injections, or viscosupplementation.
Once these have failed, it is time to consider surgery. Most patients who have TKR surgery are between 60 to 80 years, but each patient is assessed individually and patients as young as 30 or old as 90 are occasionally 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.
Surgery is performed under sterile conditions in the operating room under spinal or general anesthesia. You will be on your back and a tourniquet is applied to your upper thigh to reduce blood loss. Surgery takes approximately two hours.
The surgeon makes an incision along the front of the knee and 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 undersurface of the patella (knee cap) is also usually replaced.
The real components are then inserted with cement and the knee is again checked to make sure the knee joint is working properly. The knee is then carefully closed with sutures and staples, a drain is usually inserted, and the knee is then 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. You will be given pain medications as needed to help with pain control. To avoid lung congestion, it is important to breathe deeply and cough up any phlegm you may have.
Once stable, you will be taken to the ward. The post-op protocol is surgeon-dependent but, in general, your drain will come out at 24 hours. You will be allowed to bear weight on your knee right away and you may get out of bed, sit in a chair, and walk around your room as tolerated. The surgical dressing will be changed on the second post-op day to make movement easier. Your rehabilitation and mobilization will be supervised by a physical therapist. Your medications and overall health will be managed by a hospitalist.
Your surgeon will use one or more measures to prevent blood clots in your legs. These include aspirin, blood-thinning medications, inflatable leg coverings, and compression stockings.
Usually, you will remain in the hospital for 2-3 days and then, depending on your needs, you can either return home or proceed to a rehabilitation facility. You will be discharged from the hospital being able to bear weight on your knee as tolerated. You may use a walker or cane if needed.
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 receive home physical therapy for your knee for two weeks following surgery. Many of the long-term results of knee replacement surgery depend on how much work you put into your rehabilitation following your surgery. Patients who work hard in physical therapy following surgery tend to get better faster.
You will follow up with your surgeon two weeks after surgery. The surgical staples used to close the knee incision are removed at this visit. You will then be referred for outpatient physical therapy.
Bending your knee is variable, but by 2 weeks it should bend to at least 90 degrees. The goal is to obtain 120-130 degrees of movement and be able to fully straighten your knee.
Once the surgical incision is healed, you may shower. You can drive at about 6 weeks once you have regained control of your leg. You should also be walking reasonably comfortably by 6 weeks. More physical activities, such as exercise and leisure sports, usually take 3 months to do comfortably.
You will usually have a 6-week check-up and a 12-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. 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, redness, or if you feel generally poor, you should see your doctor as soon as possible.
As with any major surgery, there are 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.
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 are approximately 1%. If infection occurs, it can be treated with antibiotics but may require further surgery. Very rarely, your new knee prostheses 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.
Fractures or Breaks in the Bone
Fractures or breaks in the bone can occur during surgery or afterwards if you fall. To repair these, you may require surgery.
Stiffness in the Knee
Ideally, your knee should bend beyond 120 degrees but, on occasion, the knee may not bend as well as expected. Sometimes a manipulation is required. This means going to the operating room where the knee is bent for you under anesthesia.
The plastic liner eventually wears out over time (usually 15 to 25 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. 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 more straight 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).
The patella (knee cap) can dislocate. This means that 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 they can tear 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.
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 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, your family, and your primary care doctor.
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. Be sure to discuss your concerns thoroughly with your surgeon prior to surgery. If you are undecided, it is best to wait until you are sure this is the procedure for you.