Your anatomy
Although the knee may look like a simple joint, it is actually one of the more complex joints in the body, as well as the largest. It consists of four bones:
- The femur
- The tibia
- The fibula
- The patella
A healthy knee moves easily, allowing you to walk, run, turn and kneel without pain. Made up of a complex structure of bones, cartilage, ligaments, muscles and tendons, these elements work together to create a highly flexible joint.
The femur, the large bone in your thigh, sits on top of the tibia or shin bone. The rounded end of the femur glides across the relatively flat surface of the end of the tibia whenever you flex or extend the knee joint to bend or straighten your leg. Just below and next to the tibia is the fibula, running parallel.
Ligaments, tough chords of tissue, lie along the sides and in the centre of the knee, connecting the femur to the tibia, providing stability and holding the bones in position. Ligaments work in harmony with the muscles (controlling movement) and the tendons (connecting the muscles to the bones) allowing you to bend and straighten your knee. The surfaces of the ends of the femur and tibia are covered by two half moon shaped areas of smooth, tough material called cartilage, which cushion the joint and help the bones to slide more easily.
Bursae, fluid-filled sacs, cushion the area where skin or tendons glide across bone. The knee is also covered by a thin, smooth tissue liner called the synovial membrane, which secretes a small amount of synovial fluid lubricating the joint, further reducing friction and facilitating movement. The patella or knee cap, attached to the muscles that allow you to straighten your knee, rides on the front of the knee joint as the knee bends and provides leverage, reducing the strain on these muscles.
The knee actually encompasses a wide range of motion – not only bending (flexion) and straightening (extension), but it also rotates both internally (towards the body) and externally (away from the body). Problems can arise when any of these parts of this complex joint become damaged through either injury or disease.
Important: The information and guidance provided here is general in nature and should not be considered as medical advice in any way. You should always seek detailed advice from a qualified medical practitioner.
