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Understanding Knee Replacement

The knee is a hingelike joint, formed where the thighbone (femur), shinbone (tibia), and kneecap (patella) meet. It is supported by muscles, tendons, and ligaments and lined with cushioning cartilage. Over time, cartilage can wear away. As it does, the knee becomes stiff and painful. A knee prosthesis (artificial joint) can replace the painful joint and restore movement.

Image of a healthy knee

A healthy knee

A healthy knee joint bends easily. Cartilage, a smooth tissue, covers the ends of the thighbone and shinbone and the underside of the kneecap. Healthy cartilage absorbs stress and allows the bones to glide freely over each other. Joint fluid lubricates the cartilage surfaces, making movement even easier.


Image of a problem knee

A problem knee

A problem knee is stiff or painful. Cartilage cracks or wears away due to usage, inflammation, or injury. Worn, roughened cartilage no longer allows the joint to glide freely, so it feels stiff and painful. As more cartilage wears away, exposed bones rub together when the knee bends, causing pain. With time, bone surfaces also become rough, making pain worse.


Image of a knee prosthesis

A knee prosthesis

A knee prosthesis lets your knee bend easily again. The roughened ends of the thighbone and shinbone and the underside of the kneecap are replaced with metal and strong plastic components. With new smooth surfaces, the bones can once again glide freely jwithout arthritic pain. A knee prosthesis does have limitations. But it can let you walk and move with greater comfort.

© 2000-2015 The StayWell Company, LLC. 780 Township Line Road, Yardley, PA 19067. All rights reserved. This information is not intended as a substitute for professional medical care. Always follow your healthcare professional's instructions.