Total knee replacement
Why do I need a total knee replacement?
There are a number of conditions which may require a knee replacement. The most common is osteoarthritis. This means that the articular cartilage lining the joint has worn out resulting in a painful stiff joint which may limit activity. The aim of a knee replacement is to alleviate pain and improve function. In general this is a successful operation with good outcomes.
Are there any alternatives to Knee Replacement?
Alternative treatments may be considered prior to knee replacement. These include painkillers, physiotherapy, weight loss, injections, walking aids or other operations. Only when these treatments are considered inappropriate or are unable to control your pain then a knee replacement is considered.
What is a Total Knee Replacement?
The operation involves removing the damaged surfaces of the knee joint and replacing them with a prosthesis (artificial joint).
The knee prosthesis is made of a metal alloy with a wear resistant high density polyethylene(plastic) bearing between the metal components.
The components are individually sized for each patient to ensure a very accurate fit and are implanted with the use of bone cement.
What are the risks of Knee Replacement Surgery?
The risks of surgery are very small. Even so it is important you are aware of them. The risks include:
There is a small risk of infections. Precautions are taken to prevent infection including the use of intravenous antibiotics during and after the operation. A very small percentage of joints may become infected at some stage and may need to be replaced.
A deep vein thrombosis (DVT) may form in the calf veins and may extend up to the thigh. Precautions are taken to reduce the risk of DVT. These include early mobilisation post operatively, support stockings and medication to thin the blood which is taken for a period of about ten days. If a clot forms, a part of it may break off and travel to the lungs. This is called a Pulmonary Embolism (PE). A PE is potentially life threatening so DVT prevention is taken seriously.
After knee replacement surgery stiffness of the joint can be a problem. Patients are encouraged to undertake exercises ideally starting preoperatively such as use of an exercise cycle. Postoperatively they will be encouraged to mobilise the joint under the supervision of a physiotherapist and given a number of exercises to improve joint movement.
Pressure on a nerve on the outer side of the knee can result in weakness of the lower leg and foot. if it does happen it usually resolves but rarely the weakness can remain.
Over a period of time a knee prosthesis may loosen and need further surgery to correct this. The majority of knee replacements would be expected to last 20 years or more although a small percentage will fail early.
The Patient Journey for Total Knee Replacement
Shortly before your operation you will be asked to attend a nurse led preassessment clinic. This comprises a medical examination including routine tests such as blood pressure, heart tracing (ECG) and simple blood and urine tests. This is to ensure that you are fit for the operation and that nothing needs to be treated prior to your admission
Patients are normally admitted on the day of surgery. You are advised not to eat or drink for 6 hours prior to your admission. You will seen by the ward staff, the anaesthetist and your surgeon who will mark the correct limb and confirm consent for the procedure.
The operation may be carried out either under general anaesthetic (patient asleep) or a spinal anaesthetic (patient awake). The choice of anaesthetic will be discussed with you by the anaesthetist. The operation takes approximately one and a half hours. Afterwards you will be taken to the recovery area and once well enough you will return to the ward.
After the operation you will have a bulky bandage around your knee, an intravenous drip for fluids and an oxygen mask. You will be given antibiotics, medication to thin the blood to help prevent clots and pain killers. The physiotherapist may get you out of bed later the same day and commence exercises and walking. The following day you will have a blood test and x-ray. All being well the bandage will be reduced and the drip removed. You will continue your exercises and increase your walking distance initially with the help of a frame but moving quite quickly on to sticks. Most patients will be in hospital for between three and five days. Prior to discharge the physiotherapist must be satisfied that you can walk safely with an aid and that you can manage stairs. Your wound will be checked and redressed and if you are generally well you may return home.
When at home it is important you continue your exercises. An exercise bike at home can be very useful in helping you regain strength and range of motion in your knee. Out patient physiotherapy will be arranged. You will feel quite tired during the first few weeks partly due to difficulty sleeping as your knee will be quite sore and swollen. You will normally be reviewed by your surgeon about two weeks after the operation. You should plan not to drive for about six weeks and you may be able to return to work between six and twelve weeks postoperatively depending on your recovery and the nature of your work.
The aim of your knee replacement is to alleviate pain and improve function to allow you to remain active. The level of activity expected depends on your general level of fitness but includes long country walks, golf and perhaps doubles tennis. Some patients are able to ski although are encouraged to stick to relatively gentle slopes.
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