Knee structure

Anatomy of the knee

The knee, a major weightbearing joint, is the largest joint in the human body. Three bones take part in the articulation that forms the knee joint.

Femur (thigh bone)

Tibia (shin bone)

Patella (knee cap)

The bones have a lining of articular cartilage that provide a smooth surface for joint movement. Wear and tear affects articular cartilage. As the lining carilage wears away, the bones may become exposed. This process is called osteoarthritis. Bones are readily seen on an x-ray and help us diagnose fractures. The other non bony structures in the knee do not appear on x-ray and are best seen on an MRI scan.

The femur and tibia do not match up precisely. To improve the fit between these two bones, there are additional "C" shaped cartilages in the knee called menisci. There are two menisci. The medial meniscus is on the inner aspect of the knee while the lateral meniscus is on the outer aspect of the knee. The menisci are commonly torn in sporting injuries.

The joint is stabilised by ligaments. The major knee ligaments are:

Medial collateral ligament

Lateral collateral ligament

Anterior cruciate ligament

Posterior cruciate ligament

The knee is also supported by powerful muscle groups. The quadriceps muscle is in front of the knee while the hamstring muscles lie behind.