A Total Knee Replacement (TKR) procedure, also referred to as Total Knee Arthroplasty (TKA), is a surgical procedure which involves resurfacing your knee joint and replacing the arthritic parts with artificial metal or plastic prosthesis components.
These components move together to allow near to normal function in the knee.
- Who is suitable for a Total Knee Replacement?
- What are the benefits of a Total Knee Replacement?
- What implants are used?
- How is a TKR procedure performed?
- What happens after surgery?
- Precautions following TKR surgery?
- Will physiotherapy be required?
- What complications and risks are there?
- Estimate of Fees
1Who is suitable for a Total Knee Replacement?
People with a stiff, painful knee that makes it difficult to perform even the simplest of movements and interferes with daily activities despite trying other non operative measures such as anti inflammatory medication, activity modification and joint rehabilitation exercises without significant improvement may be candidates for Total Knee Replacement Surgery.
Your knee surgery is recommended only after careful diagnosis of a knee problem, including your degree of pain and lack of mobility.
2What are the benefits of a Total Knee Replacement?
The main benefits of a successful Total Knee Replacement are a significant reduction in the symptoms of arthritis. These include:
- A reduction in knee pain -The pain will be rapidly and dramatically reduced and usually eliminated.
- Recovery of mobility - Your knee will function with less effort, almost regaining your original mobility.
- Improvement in quality of life -Your everyday activities and your social life will no longer be limited by pain and reduced mobility.
3What implants are used?
Up to three bone surfaces may be replaced in a total knee replacement procedure with highly biocompatible implants consisting of plastic and metallic components.
- The Femoral Component: This metal implant curves around the end of the femur (thighbone). It is grooved so the kneecap can move up and down smoothly against the bone as the knee bends and straightens.
- The Tibial Base Plate: This is typically a flat metal platform with a cushion of strong, durable plastic, called polyethylene. Some designs do not have the metal portion and attach the polyethylene directly to the bone. For additional stability, the metal portion of the component may have a stem that inserts into the center of the tibia bone.
- The Patellar component: This is a dome-shaped piece of polyethylene that duplicates the shape of the patella (kneecap), replacing the cartilage function and allowing the thigh and shin bone to slide on each other.
All components are designed so that metal always contacts with plastic. This provides smooth movement and results in minimal wear.
4How is a TKR procedure performed?
Knee replacement surgery requires the resurfacing of the bony surfaces of the knee joint. An artificial knee joint is designed to fit over the edges of the joint and to replace the painful joint with one that can be used pain free.
The surfaces of the thigh and and shin bones are replaced with high resistant metallic components called the femoral component and tibial baseplate. Between the femoral component and tibial baseplate a plastic insert is implanted. This replaces the cartilage function allowing the thigh and shin bone to slide on each other. It is not to remove the whole joint, but merely to resurface the diseased or traumatized bony edges.
Technical advances have given us new materials and new instrumentation to replace your problem knee. Professor Kohan prefers to perform the knee replacement using patient specific instrumentation for most patients unless there is a specific reason otherwise. This involves analyzing a diagnostic image of your leg and creating a surgical instrument in collaboration with a team of engineers that is tailored specifically to fit the exact shape of your knee.
This Patient Matched Technology enables precise preparation of your bone in surgery for accurate implanting of the prosthesis leading to a less traumatic procedure and to ensure the knee replacement is well aligned.
Once Professor Kohan has diagnosed that a Total Knee Replacement procedure is needed you will be required to have a CT scan of your leg at least 3 weeks prior to your scheduled surgery date.
A plastic 3D model is then created using the image of the CT scan. This enables Professor Kohan to select the best implant for you. Using the 3D model of your knee Professor Kohan then, in collaboration with a team of bio-medical engineers develops the surgical instruments to be used on your knee.
Professor Kohan will receive these patient matched instruments along with a plastic replica of your knee prior to your surgery date.
The procedure is performed as an inpatient meaning you will stay at the hospital overnight. The operation itself will take approximately 3 hours.
Incision: 15-20cms in length and it will run over the top of your knee joint. The incision can take a few weeks to settle down.
There will be a fine catheter in your knee. This is used to inject medications directly into the knee joint to relieve pain. You will also have a drip in your arm. This drip supplies you with fluid and blood if you need it.
Click on the animation below for a step by step guide on Total Knee Replacement Surgery:
For information on how to prepare for surgery click here.
5What happens after surgery?
Immediately after surgery, you will wake up in the recovery room. You may feel a bit groggy. Professor Kohan and his staff will monitor you, checking your blood pressure, temperature and pulse. Dr Kerr will also assess your pain level. Post-operative x-rays will be performed in recovery.
After 45 minutes – 1 hour you will then be transferred back to your room on the ward.
When you arrive to your room, you will have:
- A compression garment around the operation site to apply pressure there. This is removed 24 hrs after surgery.
- A pain catheter which will be removed before discharge. We inject local anaesthetic through this to maintain the pain relief.
- TED Stockings (knee high white stockings) on your legs which must be worn for 2 weeks post procedure.
- A drip in your arm. This will provide hydration and blood if you need it
Approximately 2 hours after surgery a physiotherapist will get you out of bed and help you walk for the first time with your new knee.
Your hospital stay will be a combination of rest and rehabilitation.
In the first week following surgery you may experience:
- Swelling – From your thigh down into your foot is common. This at times may be quite marked. The swelling will increase for the first few days after surgery and will gradually diminish. Some swelling can be present for 12 months or so. The swelling may be diminished by walking as the muscle function will push the fluid away. When you stop walking, the limb should be elevated above the level of the hip.
- Bruising – Marked bruising can be found in some patients. This can be found from your thigh down into your foot. At times the bruising can be quite dramatic but it will resolve. It is the result of some residual bleeding making its way to the surface. The body will eventually remove the bruising. It is also the result of the blood thinning tablets you will be taking.The blood thinning tablets will tend to make the bleeding after surgery a little more marked because the blood clotting is impaired. This is however preferable to developing a blood clot.
- Blistering – On occasions blisters will develop near the operation and possibly above it. The blistering is due to surface fluid. It looks dramatic but it is of no consequence and always resolves. One cause may be the bandage rubbing on the skin. Sometimes, when the blood dries in the bandage it can be like cardboard and rub on the skin producing these blisters. We change the bandage after about a week but would prefer not to interfere with that earlier because of the risk of infection. After about a week the wound is sealed enough to be a reasonable barrier against infection. Another cause for the blistering is tissue swelling. This is associated with the bruising and is a result of fluid leaking into the skin. These blisters always go away. They may burst and leak fluid and again the appearance may be dramatic. Sometimes if they are large we may burst them. This is so that the dressings sit more comfortably.
- Muscle soreness – Your muscles can feel stiff and sore to touch. During the operation some stretching and pulling of the muscles occurs. This may result in some pain like a corked thigh. Occasionally you may feel cramps and spasms. The discomfort however will resolve and activity such as walking, stretching, physiotherapy, etc, will help to speed the improvement.
- Heat – The operated site may feel hot and the heat may last for 12 months. As part of the healing process the operation site requires more blood supply from the body and it is this extra blood supply which is the cause of the local heat.
For the first 2 weeks after surgery your activity level is usually limited however you will be able to walk independently, use the bathroom and perform normal activities of daily living. It is important however, to keep on trying to use the knee as normally as possible.
After 6 weeks you will be able to engage in moderate activities, i.e. driving a car and climbing stairs.
Within 8 weeks you will have resumed most of your normal activities. Complete surgical healing takes 6 – 8 weeks but sometimes longer if the arthritis was very severe or the knee very deformed. During this time some swelling and discomfort is normal and should be manageable with the prescribed medication.
6Precautions following TKR surgery?
Precautions to take following knee surgery include:
- Avoid chairs that are low.
- Avoid slippery surfaces.
- Avoid twisting your knee for 6-8 weeks after surgery.
- Avoid siting in the same position for long periods. 45 minutes at a time should be enough. Sitting for long periods increases the likelihood of stiffness.
The incision is sutured with skin staples which will be removed 10-12 days after surgery. You will have a firm bandage from your foot to your thigh following surgery which is usually removed on day 5 at your first post op appointment.
The nurses in the hospital will help you change the dressing if needed before you leave the hospital.
You must not get the incision wet until the staples are removed – a sponge bath instead of a shower is therefore recommended for 5 days post surgery.
You may shower after the sutures are removed but may not bathe or swim for 2 more weeks after that.
Your second post-op appointment is to remove the skin clips from your wound. Some swelling and warmth on and around the incision area is expected. If you develop increased redness, drainage or a fever please call the office immediately.
Bruising around the thigh area is also common. It may extend down into your ankle and should resolve in 10 – 14 days.
You may apply Vitamin E or some moisturizing lotion on and around the incision area after the staples have been removed.
Upon discharge from hospital you will be walking with crutches. You may discontinue using crutches after being assessed by Professor Kohan at your postoperative visit. After this time you may use a cane or if you feel confident you may discontinue using any walking aids at all.
For the first 2 weeks following your procedure you may go up and down stairs as needed but only straight legged. After this time there should be enough flexibility and repair from the muscles around your knee to walk relatively normally.
Each individual has his/her own set of expectations. Each patient is treated as an individual with general health, age and attitude considered.
An important thing to remember is that you are not sick. You have a problem with your knee that needs to be fixed.
Getting back on your feet after surgery is the most important goal. ‘Motion is Lotion.’
7Will Physiotherapy be required?
Gentle exercises help strengthen the muscles around your new knee and regain your knees range of motion.
As soon as possible your physiotherapist helps you start walking a few steps at a time to promote healing. As you progress from crutches and then to a cane you may feel somewhat off balance at first. Gait training helps you regain confidence and your normal walking motion before going home.
Results of a knee replacement are classified as excellent if activities of daily living can be performed without pain or restrictions. (This does not include running sports). Results are classified as good if occasional mild pain occurs and only slight restrictions of movement are present.
For the past 5 years studies have usually recorded 95% good to excellent results.
Your prosthetic knee can wear out or loosen and may require replacement if necessary. On the other hand, people live longer now and you may out-live your new knee. Regular review is recommended.
In order to reduce stiffness and obtain maximum function of your knee it is important to maintain a good balance of rest and exercise. Listen to your body, too much activity will produce increased swelling, and/or pain, too little will prolong your recovery, and/or limit your knee mobility.
To promote circulation, remember to do your ankle, foot stretching exercises regularly.
On the second day post surgery, remove the knee brace and begin moving the knee and walk, as your knee will allow. The fourth day after surgery you may begin your leg exercises.
Sit in a chair so that your bottom is at the back of the chair; place your feet on a phone book.
Cross your legs at the ankles (good one over the operated leg). Push back leg with front leg until stretch is felt and hold for 15 seconds.
Raise foot of operated leg, straightening it out and hold it for 15 seconds. Repeat 15 times.
Do these exercises 3 – 4 times a day. Continue doing these exercises until you return to your normal activities.
8What complications and risks are there?
As with all surgery there are certain risks and potential complications. Although the incidence of these risk factors is low each patient needs to be informed of the possible complications prior to surgery:
Infection is uncommon occurring in less than two percent of operations. It is usual for each patient to be is given intravenous antibiotics at the time of their joint surgery however, this cannot possibly cover all types of infection which may be encountered. Infection in the postoperative period in most patients is treatable. It may require longer hospitalisation, treatment with antibiotics for a longer period than normal and washout of the joint.
In some cases, the implant will be removed to treat the infection before reimplanting a new joint. In rare cases when the infection cannot be treated successfully, a patient may need to have the artificial joint removed permanently. Infection is uncommon and we take precautions to avoid this problem.
Delayed infection has been reported years after joint replacement, and appears to be related to the ability of the implants, in general, to harbor bacteria transported by the blood stream from other sites of the body. Bladder or kidney infections can be a source but dental abscesses, infected ingrown toe nails, or skin infections may also be a significant danger to a joint implant.
Please call the office, or contact your family doctor if infection is suspected in any area. If dental surgery, bladder surgery, bowel surgery or rectal surgery is planned, the physician or dentist should be informed that you have had a joint replacement.
Blood Clots (The medical term for this is Deep Venous Thrombosis)
Another potential risk is the occurrence of blood clot or thrombosis after a joint replacement. Because our patients are mobilised very soon after surgery, this potential risk is small. In addition to early mobilisation patients are treated with calf compressors to prevent Thromboembolic disease (the development of clots in the lower extremities) during surgery. Post surgery TED stockings and low doses of aspirin or other anticoagulation (blood thinners) medications are prescribed depending on the patient’s medical history.
In patients without any history of thromboembolic problems we advise taking aspirin, 300 mg per day, for a period of six weeks.
These measures are in place to reduce the risk of forming a clot. In the event the patient is diagnosed with a blood clot intravenous or subcutaneous anticoagulation therapy may be required. However, some clots are small and of no clinical significance and so do not require any specific treatment other than the aspirin. This needs to be assessed on a case-by-case basis. If full anticoagulation is required however, this means a longer stay in hospital for the patient.
There is no perfect treatment and while trying to decrease the significant risk of deep vein thrombosis and the possibility of more serious complications such as pulmonary embolism (blood clots breaking off and traveling to the lungs), other potential side effects (such as bleeding) can occur with the drugs used to decrease this complication. These medications require extreme care in their use.
Nerve damage is another potential risk factor when considering joint replacement surgery. The nerves can be traumatised at the time of the operation through stretching and occasionally due to postoperative swelling. Precautions are in place to protect the nerves via superior surgical technique but the risk nevertheless, exists for these potential complications to occur. The risk factors are small and are dependant on the age and prior medical condition of the patient.
Diabetes, smoking and peripheral vascular disease are risk factors, as is the presence of previous back problems.
If nerve damage occurs rest and further examination of the nerve will be required and possible further surgery.
This is a rare complication of knee replacement surgery but can lead to weakness or altered feeling in the foot and ankle. It usually improves but can be permanent.
There are a number of ligaments surrounding the knee. These ligaments can be torn during surgery or break or stretch out any time afterwards. Although rare, surgery may be required to correct this problem.
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 could mean going to the operating room again where the knee is bent for you and under anesthetic.
Loosening of the Knee Replacement Implant
A small percentage of patients require revision surgery because of excessive wear or loosening of the prosthesis. This may cause pain and a limp, and the diagnosis can be confirmed with x-rays.
Excessive wear of the plastic liner is one of the most common reasons why revision knee surgery is performed.
Over 95% of patients who have a knee replacement have excellent relief of pain and improved mobility. Most patients never require a re-do of the knee replacement.
Dislocation is 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) which would cause acute pain and the inability to walk. It is more common in the first few weeks postoperatively and there are precautions that you can take to minimise this complication.
Leg Length Discrepancy
Every endeavor is made to maintain the legs at equal leg length, however, sometimes the leg can be slightly lengthened as a result of the knee replacement. This is also due to the fact that a corrected knee is more straight so sometimes unavoidable.
9Estimate of Fees
Generally our ‘Estimate of Fees’ is accurate however, on occasion unforeseen circumstances can arise during the operation which may require additional medical services or a different, more costly prosthetic device to be used. If this happens there may be additional costs to you that are not covered by the estimate.
This will be fully explained to you after the operation should it occur.
Estimate of Fees
- Aftercare Consultation Fees
There will be 2 ‘no charge’ consultations after your Total Knee Replacement procedure.
Aftercare appointments with Professor Kohan following your procedure include:
- 7 Days Post Surgery – This appointment is in order to check the skin cut & for Professor Kohan to asses your overall recovery.
- 14 Days Post Surgery – At this appointment the skin clips will be removed. An ultrasound will also be done by our radiographer in the rooms in order for Professor Kohan to check for blood clots.
- 6 Weeks Post Surgery – At this appointment Professor Kohan will asses the X-ray and monitor your overall recovery.
Consultations after this time attract a fee which is reimbursed in part from Medicare.
- Professor Kohan’s Surgical Fees
Medical Item No: 49518
- Surgical Assistant Fees
The surgical assistant fees will either be billed to you directly or Professor Kohan will bill you on his behalf.
- Anesthetic Fees
- Medicare Item No: 51303
You will meet with Dr Kerr, the anesthetist before your operation so that you can obtain an estimate of his fees. These will be billed to you directly.
- Hospital Fees
- Medical Item No’s : 17620, 17690, 21214, 23111, 22045, 18225
These fees should be discussed with the hospital directly. Please be sure to check with your health fund regarding a gap or out of pocket expenses.
- Prosthetic Fees
If you are privately insured the prosthesis used in a Total Knee Replacement procedure is usually fully covered by your Health fund.
- Ultrasound Fees
These fees are payable directly to the sonographer.