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.
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:
The most common form of anesthetic used during the operation is a general anesthetic; where you are fully unconscious throughout the procedure. An alternative option is to have a spinal anesthetic, which is where anesthetic 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.
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 Physical Therapist.
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.
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.