Why replace the knee joint?
THE KNEE JOINT
The knee joint's purpose
The knee joint plays an important role in our daily lives, as it continually endures great forces. Its most important functions are supporting the body weight, transferring forces between the upper body and the legs, and ensuring accurate foot placement.
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Because the knee joint connects the two longest bones in the body, there is a great leverage effect. Because of those long load arms, enormous forces are exerted on the joint. In addition, the knee has the largest articular capsule of all joints. This is where the ligaments and tendons are attached. Since these are also exposed to great forces, they are frequently the cause of knee problems.
Anatomy of the knee
The knee is like a house with three rooms. Anatomically speaking, we distinguish between the medial tibio-femoral compartiment on the inside of the knee, the lateral tibio-femoral compartiment on the outside and the patello-femoral compartiment at the front. This "front room" contains the kneecap, which is surrounded by tendons and ligaments.
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The knee joint connects two major bones: the shin bone (tibia) and the thigh bone (femur). These both end in a softer layer of cartilage, which funtions as a shock absorber and allows the knee joint to move smoothly.
Cartilage and osteoarthritis
Seen through a microscope, cartilage consists of four layers, much like the floor in your house. Osteoarthritis is damage to the cartilage. We distinguish between four different stages of arthritis, depending on the number of layers that are affected.
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In stage 1 osteoarthritis, only the top layer (the "floor tile") is damaged. We speak of stage 2 arthritis when the second layer (the "screed") is affected as well. Stage 3 means the damage extends to the third layer (the "insulation"), and in stage 4 all layers have been affected, including the bottom layer (the "concrete foundation"). In this case, the dampening buffer between the bones has all but disappeared, leading to pain. The correct treatment depends on the extent of the damage and the affected area.
Orthopedic surgeon - specialized in the treatment of knee injuries