How Your Knee Works

A healthy knee bends easily and rotates slightly. The joint absorbs stress and moves smoothly. This allows you to walk, squat, and turn without pain.

Front view of knee joint.

A healthy knee

The knee is a hinge joint, formed where the thighbone (femur) and the shinbone (tibia) meet. It is the largest joint in the body. The joint is covered with smooth tissue and powered by large muscles. When all the parts listed below are healthy, a knee should move easily:

  • Cartilage is a layer of smooth tissue. It covers the ends of the thighbone and shinbone. It also lines the back side of the kneecap. Healthy cartilage absorbs stress and allows the knee to bend easily.

  • Muscles power the knee and leg for movement.

  • Tendons attach the muscles to the bones.

  • Ligaments are bands of tissue that connect bones and brace the joint.

  • Bones that make up your knee joint include your thighbone (femur), shinbone (tibia), and kneecap (patella).

  • Menisci are 2 wedge shaped pieces of cartilage that absorb shock between the thighbone and shinbone.