How does an artificial knee joint work?

The artificial prosthesis components are made of different materials:

  • metal alloys (cobalt-chromium-molybdenum alloys in particular due to good tolerance and durability)
  • special plastic polymers (imitation of the lubricative cartilage layer)

The surgeon will decide which materials to use depending on the patient's anatomy.

Types of prosthesis

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:

Artificial knee joint: 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 may 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.

Artificial knee joint: Axially supported knee endoprosthesis

In the event of unstable bone conditions, severe leg axis discrepancies or loose collateral ligaments an axially supported knee endoprosthesis has to be implanted. This artificial joint also consists of a femoral component and a tibial component. Both components have a long stem and are attached inside the femur and tibia respectively. In combination, the two components make up a hinge joint which ensures a high level of stability even if the collateral ligaments of the knee joint are unstable. However, with this method a larger amount of bone tissue is removed in order to attach the joint.