How does my knee joint work?

Anatomically, the knee joint is considered two separate joints. The first joint is between the femur and the tibia. The second is between the patella and the femur.

Motion of the knee is one direction like a hinge. The menisci are pieces of fibrocartilage that are different from the cartilage that lines the bones. The meniscus bears weight across a large surface area of the joint and provides shock absorption. In a normal knee, there is good alignment with a space between the femur and the tibia.
Dr. Michael Roizen, MD
Internal Medicine

Sandwiched between your two longest bones, which are the femur (thigh bone) and the tibia (shin bone), your knee works like a door hinge. It bends in only one direction, backward, never sideways or forward. Check it out, but not too hard.  Because of its limited range of motion, along with the heavy load it carries, plus the potential of torque (twisting motions), your knee is at risk for strain and injury.

YOU: The Owner's Manual for Teens: A Guide to a Healthy Body and Happy Life

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YOU: The Owner's Manual for Teens: A Guide to a Healthy Body and Happy Life

A few years ago, we wrote YOU: The Owner’s Manual, which taught people about the inner workings of their bodies—and how to keep them running strong. But you know what? There’s a big difference...

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.