Components of an artificial knee joint
A knee endoprosthesis is based on the human knee joint. Like a natural knee joint, it therefore consists of a femoral component and tibial component and in some cases a patellar component is also implanted.
Materials used
The artificial prosthesis components are made of different materials:
Nowadays, femoral and tibial components often use metal alloys, of which cobalt-chromium-molybdenum alloy has proved exceptionally suitable because of its good tolerance and durability. In addition, prosthesis components made of special plastic polymers are used which imitate the lubricative cartilage layer found in human joints.
The surgeon will decide which materials to use depending on the patient's anatomy.
Types of prostheses
Various types of prosthesis can be used, depending on the disorder and the patient. A distinction is made between a knee resurfacing and an axially supported knee endoprosthesis:
Knee resurfacing
In many cases it is sufficient to merely replace the damaged knee structures close to the joint. A metal cap covers the natural femoral condyle and a metal plate is attached to the tibial plateau. In between, a plastic insert acts as a low-friction bearing. The back of the kneecap can also be replaced by a plastic cap.
Consequently, only the damaged surfaces are replaced and the term used is 'resurfacing'. Bone tissue is preserved and the important supportive cartilage structures remain intact for the most part.
At the present time this is regarded as a standard operation for knee joint replacement.
