Total and partial knee replacement surgery
What is a total knee replacement?
A total knee replacement is where the damaged ends of the femur (thigh bone) and tibia (shin bone) are removed and a man-made prosthesis is inserted to act as a new joint. The patella (knee cap) is also resurfaced so that it slides efficiently against the new surface of the prosthesis.
A partial knee replacement is similar to the above, but not all of the knee joint is replaced. Often it will be either the medial (inside) or lateral (outside) condyle that is replaced. The advantage of a partial over a total knee replacement is that it retains more healthy, natural tissue.
When is a knee replacement needed?
Knee replacements are normally seen as the last option, when all other forms of treatment have ceased to be effective in relieving the pain and discomfort. A knee replacement is considered when the knee joint is sufficiently worn or damaged to the extent that mobility is reduced and pain is experienced, even when resting.
Alternatives to knee replacements include:
- Weight loss - It is reckoned that a pound of weight equates to 4 pounds of load going through the knee joint. Therefore, any degree of weight loss is beneficial in reducing the loads and stresses on the knee.
- Exercise - Whilst many forms of exercise may prove painful (and should therefore be avoided) there are other forms of gentler, lower impact exercise that may help to strengthen the muscles around the joint. Some examples of low impact exercises include: swimming, cycling, aqua-aerobics, simple chair-based exercises, or hydrotherapy.
- Knee Supports/Braces - Using a knee support (such as the Active650 Knee Support) can help to reduce the strain on the joint and surrounding tissues, improving stability and confidence in the knee.
- Drugs - Non-steroidal anti-inflammatories (NSAIDs) can help to reduce both pain and swelling. These are readily available over the counter and include drugs such as ibuprofen and paracetamol.
What happens in a knee replacement operation?
- Initially, the surgeon will make an incision and expose the knee cap, which is then drawn to one side to expose the joint.
- The damaged/worn end of the thigh bone is carefully cut away.
- The damaged/worn end of the shin bone is carefully cut away.
- The exposed ends are measured and shaped to fit the prosthetic replacement. The precise location and fit is finalised, the bone ends are cleaned, and the prosthesis is fitted.
- If necessary, the back of the knee cap can be resurfaced with a prosthesis at this stage.
- The wound is closed with either staples or stitches and a dressing is applied.
- The whole process takes around 2-3 hours.
What anaesthetic is used?
The most common form of anaesthetic used during the operation is a general anaesthetic; where you are fully unconscious throughout the procedure. An alternative option is to have a spinal anaesthetic, which is where anaesthetic is injected into the nerves at the base of the spine. When this is used, you will go numb from the waist down and remain conscious during the operation.
How long does it take to recover from knee replacement surgery?
Most normal activities are able to be resumed after 3 months, albeit, in a reduced capacity. It is reckoned that full activities will be achieved after 6-12 months in most cases. You will be encouraged to move the joint as soon as possible and will be given an exercise programme by a Physiotherapist.
Can you kneel down after having a knee replacement?
There are differing views on this even though there is no evidence to suggest that you can't. Many people with knee replacements are reluctant to kneel down, based solely on a fear of stressing the new joint. Some people find that a tenderness around the scar area prevents them from putting weight on their knees. Ultimately though, ask your surgeon for an opinion on kneeling and be lead by a combination of this and what you find it physically possible to do.
How long does a knee replacement last?
The prostheses that are currently being used should last 15-20 years, provided that they are not subjected to high impact activities (eg. running, jumping etc). Whilst knee replacements can be replaced themselves, it is more likely that a prosthesis will be resurfaced before it is replaced.
