A Prosthetic Knee (Total Knee Replacement)
Your damaged knee joint can be replaced with new smooth surfaced components, which make up a prosthetic knee. During knee replacement surgery, the damaged bone and cartilage surfaces from the knee joint are removed. The upper part of the prosthesis, or femoral component, is metal (cobalt chromium), and fits on the end of your thigh bone. The lower part, or tibial component, is a metal- backed tray (cobalt chromium or titanium) which fits on top of your shin bone. The tibial insert component is made of a plastic material called polyethylene. Finally, the patellar component is a polyethylene button that is cemented onto the underside of your kneecap.
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, 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 50 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.
- 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 a physician.
- 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.
- 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.
Day of your surgery
- You will be admitted to the hospital, usually on the day before your surgery.
- Further tests may be required on admission.
- You will meet the nurses and answer some questions for the hospital records.
- You will meet your anaesthetist, who will ask you a few questions.
- You will be given hospital clothes to change into and have a shower prior to surgery.
- The operation site will be shaved and cleaned.
- Approximately 30 minutes prior to surgery.
- you will be transferred to the operating room.
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 anaesthesia. 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) may be replaced depending on a number of factors and depending on the surgeon’s choice.
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 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.
- Activities After a Knee Replacement
- Knee Arthroscopy Exercise Guide
- Knee Replacement Exercise Guide
- Cincinnati Sports Medicine’s
When you wake, you will be in the recovery room with intravenous drips in your arm, a tube (catheter) in your bladder and a number of other monitors to check your vital observations.
Once stable, you will be taken to the ward. The post-op protocol is surgeon dependent, but in general you will sit out of bed and start moving your knee and walking on it within 24 hours of surgery (usually on the same day). The dressing will be reduced usually on the 2nd post op day to make movement easier. Your rehabilitation and mobilization will be supervised by a physical therapist.
To avoid lung congestion, it is important to breathe deeply and cough up any phlegm you may have. Please use the triflow provided by the therapist 3 times a day.
Your orthopaedic surgeon will use one or more measures to minimize blood clots in your legs, such as inflatable leg coverings, stockings and aspirin or injections into your abdomen to thin the 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 2-3 days. Then, depending on your needs, you will either return home or proceed to a rehabilitation facility. You will need regular 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.
Your sutures are sometimes dissolvable but if not, are removed at approximately 10 - 14 days.
Bending your knee is variable, but by 3 weeks should bend to 90 degrees. The goal is to obtain 110-125 degrees of movement.
Once the wound is healed, you may shower. You can drive at about 6 weeks, once you have regained control of your leg. You should be walking reasonably comfortably by 6 weeks with no aids.
More physical activities, such as sports as previously discussed, 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 have a 1 week, 2 week and 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. 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 or a have a fever 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.
Complications can be medical (general) or local complications specific to the knee.
Medical complications include those of the anaesthetic 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
- 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 anaesthetic (manipulation under anaesthesia).
- The plastic liner eventually wears out over time, usually 10 to 15 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).
- 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 will 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+ 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.
Why is surgery needed?
Surgery may be recommended for many reasons, the most common of which are:
- To alleviate pain
- To restore lost function
- To correct deformity
- To improve quality of life
Knee prosthesis durability can vary from patient to patient because each patient’s body places slightly different stresses on the new knee. However, the average patient can expect to obtain greater mobility and freedom from pain, which in turn will improve one’s quality of life.
plastic piece that covers the underside of your knee cap, giving it a new smooth surface. These new surfaces fit together, just as a normal knee does, and allows your knee to bend and straighten smoothly.
The knees bear a lot of impact from daily activities as well as sports. Accidents, overuse or wear-and-tear from aging can lead to injuries that impact mobility. This may require treatment, either non-surgical or surgical, to prevent it from getting worse. Find out what common knee conditions could be causing your symptoms.
Common sports knee conditions:
- Anterior cruciate ligament (ACL) injury
- Meniscus tear
- Cartilage damage – osteochondral lesions
- Anterior knee pain
* This is not a complete list of all the conditions that we recognise and treat. The information is designed for educational reference only and should not be taken as medical advice.
Please consult one of our qualified healthcare specialists for an accurate diagnosis before starting any treatment.
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