Total Knee Replacement
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 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).
- Trauma (fracture)
- Increased stress e.g., overuse, overweight, etc.
- Connective tissue disorders
- Inactive lifestyle e.g., Obesity, as additional weight puts extra force through your joints which can lead to arthritis over a period of time
- Inflammation e.g., Rheumatoid arthritis
- Prior injuries such as meniscus cartilage or ligament tears
In an Arthritic Knee
- 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.
- A bowleg or knock-knee deformity may occur
- The tissues of the arthritic knee are 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 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, family and your local doctor.
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 a chair, gardening, etc.
- Pain waking you at night
- Deformity-either bowleg or knock knees
- Inability to exercise
Prior to surgery you will usually have tried some conservative treatments such as simple analgesics, weight loss, anti-inflammatory medications, modification of your activities, canes, or physical therapy.
Once these have failed it is time to consider surgery. Most patients who have total knee replacement are between 60 to 80 years, but each patient is assessed individually and patients as young as 20 or old as 90 are occasionally operated on with good results.
Your surgeon will send you for routine blood tests and any other investigations required prior to your surgery
You will be asked to undertake a general medical check-up with your primary care physician and other specialists such as your cardiologist or lung specialist.
You should have any other medical, surgical or dental problems attended to prior to your surgery.
Make arrangements for help around the house prior to surgery. Remove area rugs, furniture or other objects that may cause tripping. Consider installation of shower bars and other assistive devices.
Cease aspirin or anti-inflammatory medications 10 days prior to surgery as they can cause bleeding.
Cease any naturopathic or herbal medications 10 days before surgery.
Stop smoking as long as possible prior to surgery.
Maintain a healthy, high protein diet.
Continue low impact exercises to maintain your strength, endurance and range of motion of your upper and lower extremities.
Day of your surgery
You will be admitted to the hospital, usually on the day of your surgery.
Further tests may be required on admission.
You will meet the nurses and answer some questions for the hospital records.
An IV will be started.
You will meet your Anesthesiologist, who will ask you a few questions.
You will be given hospital clothes to change into.
The operation site will be shaved and cleaned.
Approximately 30 minutes prior to surgery, you will be transferred to the operating room.
An IV will be started and antibiotics will be administered prior to the surgery.
You will be given a medication to calm your nerves if necessary.
Each knee is individual and Dr. Fox takes this into account by having different sizes for your knee available. 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 placed on your back during the surgery and a tourniquet will be applied to your upper thigh to reduce blood loss. Surgery takes approximately one to two hours.
The knee joint is exposed once the incision is made. The shortest possible incision is utilized but may have to be lengthened depending on the patient's size, extent of deformity of the knee and the amount of stiffness.
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 resurfaced with a plastic button-shaped component. The knee cap is not removed.
Dr. Fox makes sure in the operating room that your knee is able to fully straighten and maximally bend, and that it is as stable as possible. The components are made of hard structures and have no shock absorption. Therefore, with certain motions of the knee you may hear or feel a noise or clunking sensation. This occurs in probably with every total knee prosthesis but most patients do not notice these signs. It does not necessarily mean that the prosthesis is loose, broken or worn out.
The real components are then inserted usually with bone cement and the knee is again checked to make sure things are working properly. The bone cement has the benefit of stabilizing the components on to the bone right away which allows you to bear weight within hours of the operation. In certain patients who may have a higher risk of infection, antibiotics can be mixed with cement to decrease the risk of infection. The knee is then carefully closed and the knee dressings and bandages are placed. The knee joint is injected with morphine, Novocain and an anti-inflammatory agent which should give you excellent relief of pain throughout the night and extending into the next day.
You should be ready to be discharged on the second post operative day. If, for example, you have your surgery on a Monday, you should be ready for discharge from the hospital on Wednesday. Prior to coming to the hospital it is imperative that you make arrangements for discharge with family or friends to help care for you at home. If you will not have adequate assistance at home or are not progressing with physical therapy the social workers at the hospital will make arrangements for you to go to a rehabilitation center.
When you wake, you will be in the recovery room with an intravenous catheter in your arm, a tube (catheter) in your bladder and a number of other monitors to check your vital signs such as pulse, blood pressure and breathing.
Once stable, you will be taken to the orthopedic floor or Total Joint Center. The physical therapists or nurses will assist you in sitting up at the bedside within hours of the surgery and even help you to stand and take a few steps. You will be allowed to bear weight on your new knee right away unless there is an unforeseen event. About 12 hours after the surgery your leg may be placed in a continuous passive motion machine (CPM). This device may help you to achieve the range of motion more quickly that you are destined to get once your knee is healed but will not necessarily allow you to get more range of motion. Dr. Fox makes sure you have full range of motion of your knee in the operating room so it will be up to you and your physical therapist to maintain that motion. Certain factors may decide the ultimate range of motion of your knee such as the amount of stiffness and deformity present before surgery. Your genetics may play a role. If you tend to form scar tissue easily in other areas, scar tissue may also form inside the knee. Obesity, age, prior lower extremity surgery or injuries and certain diseases may affect the outcome. You will be asked to aggressively exercise your leg in the post operative period to gain maximum range of motion and function. The dressing will be changed on the second post operative day and the wounds will be inspected.
To avoid lung congestion and pneumonia, it is important to breathe deeply and cough every hour while you are awake.
Dr. Fox will use one or more measures to minimize blood clots in your legs, such as inflatable leg coverings, stockings and injections into your abdomen to thin the blood. This helps to decrease the risk of blood clots or DVT's, which will be discussed in detail in the complications section.
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 2 days. Then, depending on your needs, either return home or proceed to a rehabilitation facility. You will need physical therapy on your knee following surgery. The social workers at the hospital help make arrangements for discharge.
You will be discharged on a walker or crutches and occasionally may advance to a cane within several days. You will be allowed weight-bearing as tolerated right after surgery.
Your sutures ( staples) are removed at approximately 3 weeks after the surgery.
Bending your knee is variable, but by 1 week or less you should be bending your knee to at least 90 degrees. The goal is to obtain 110-115 degrees of movement.
You may shower when you return home if you wrap your knee with Saran Wrap to keep the wound sealed. You can drive at between 3 and 6 weeks as long as you are not on narcotics and have gained good muscular control of your operated leg. You should be walking reasonably comfortably by 3 weeks.
More physical activities, such as golf, riding a bicycle, yoga or other low impact activities may take 3 months to do comfortably.
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 3 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 or redness or if you feel generally poor, you should see your doctor as soon as possible.
Risks and Complications
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.
Serious medical problems can lead to ongoing health concerns, prolonged hospitalization or rarely death. 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:
Allergic reactions to medications
Blood loss requiring transfusion with its low risk of disease transmission such hepatitis, AIDS or a transfusion reaction
Heart attacks, strokes, kidney failure, pneumonia, bladder infections, mental confusion ( mental confusion is relatively common in older patients when they are in the unfamiliar surroundings of a hospital. This confusion usually clears when the patient goes home.), stomach ulcers and diarrhea from antibiotics.
Complications from nerve blocks such as infection or nerve damage
Local Complications Include:
Infection can occur with any operation. In the knee this can be superficial or deep. Infection rates vary but are usually less than one half of one percent. If an infection occurs, it can be treated with antibiotics but may require further, more extensive surgery to more completely eradicate the infection and the use of long term antibiotic therapy.
Blood Clots (Deep Venous Thrombosis)
These can form in the calf areas 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 under anesthetic.
Stiffness may be the result of many factors such as significant preoperative stiffness, severe deformity, age of the patient, obesity, and probably most importantly, the patient's effort.
The plastic liner eventually wears out over time, usually 10 to 15 years and may need to be changed. Newer designs and materials are utilized in the knee components which may allow them to last longer. However you still to need to take proper care by avoiding high impact activities, maintaining an appropriate weight and get x-rays on a regular basis as determined by your surgeon.
Wound Irritation or Breakdown
The operation will always cut some skin nerves, so you will inevitably have some numbness around the wound, usually on the outside of the 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.
If both knees were deformed prior to surgery and only one knee is replaced, you may have "wind-swept" knees.
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).
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, leading to the need for bracing. The major blood vessels and nerves are behind the knee and risk of injury to those structures is relatively small.
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.
Joint replacement surgery can be extremely beneficial for most people with arthritis that limits their activity level. 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. Joint replacement surgery can improve your overall health by keeping you active and independent. With improved function exercise will become part of your daily routine which will help maintain an optimal weight, control your blood pressure and blood sugar.
Total knee replacement 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 discuss the alternatives, risks and certainly the benefits with Dr. Fox to make sure this is a procedure worth considering.