Total knee replacement means re-surfacing the bones of your knee with a prosthesis
(artificial knee joint). The natural knee joint consists of the main joint between the thigh
and the leg bones (Tibio-Femoral Joint) and the joint between the kneecap and the thigh
bone (Patellofemoral Joint). Depending on which surfaces of your knee is affected by
arthritis; one or both surfaces may be replaced in the operation. The decision as to
whether to replace the patellar (Knee Cap) surface is usually made during the operation.
Like a normal knee, your prosthesis has smooth weight-bearing surfaces. The femoral
component covers your thighbone, the tibial component covers the top of the shinbone,
and the patellar component covers the underside of your kneecap. The femoral
component and the tibial component are both made of metal. In between these two
metal parts, a cushion made of a special type of plastic is inserted. The patellar
component is made of plastic as well.
The plastic used in knee replacement is made of
special materials. This makes it extremely tough and resistant to friction and wear.
There are many designs of knee prosthesis available today and your orthopaedic
surgeon chooses the prosthesis he considers most suitable for you. Some knee
prosthesis require the use of medical cement to fix the components to bone (Cemented
prosthesis), and others depend on natural bone ingrowth for fixation of the components
(Uncemented prosthesis).
The Operation
» The Anaesthetist will examine you before the operation. This doctor will discuss with you the choice of anaesthetic.
» An intravenous line is started before the anaesthetic is given and this line is generally maintained for 3 days.
» The operation is performed through a straight, longitudinal skin incision over the front of the knee. The worn surfaces of the thighbone and shinbone are shaved and replaced with the prosthesis. If your surgeon decides to replace the patella, the surface of this bone is also shaved and replaced with prosthesis. A surgical drain is placed in the joint at the conclusion of the operation. A bulky dressing is applied after closure of the wound.
» Your surgeon may decide to modify some parts of the operative procedure according to findings at the operation.
» You and your family can expect the operation to take about 90 minutes.