Knee Anatomy

What does the knee consist of?

The knee is typically considered a hinge joint and one of the most expansive joints in the body. The knee can move back and forth extensively with limited side action. Several components form the knee joint, such as bones, ligaments, cartilage, tendons and soft tissue.

Three main types of bones in the knee move cohesively, making contact with each other:

• The thighbone (femur) comes into contact with the shinbone (tibia).
• The patella or kneecap moves along a part beneath the anterior portion of the femur.

Articular cartilage protects the surfaces of the bones, preventing painful friction between the points where the bones make contact. The articular cartilage is made of durable, flexible material, enabling it to protect the bones of the knee.

The knee meniscus is a cartilage pad found in the middle of the tibia and femur. Each knee contains two menisci- the medial and lateral meniscus.

The menisci function by minimising shock and reducing the impact on the knee when engaging in weight-bearing exercises or activities. In addition, the menisci support the knee and ensure swift motion between the articular surfaces.

The ligaments are sturdy tissue bands connecting the bones of the knee. The knee is made of four primary ligaments that attach the femur to the tibia:

• The anterior cruciate ligament
• The posterior cruciate ligament
• The medial collateral ligament
• The lateral collateral ligament

The tendons of the knee help form an attachment between the bone and muscle. The patellar tendon is considered the largest tendon in the knee. The patella tendon runs from the quadriceps of the thigh, attaching the patella to the anterior part of the tibia.

The bursa is a sac filled with liquid found in the centre of the bone and soft tissue. As a result, the bursae enable free and swift motion of the muscles and tendons as the knee joint moves.

A fine, superficial membrane referred to as the synovial membrane surrounds the joint. The synovial membrane secretes synovial fluid, a natural lubricant that protects the knee.

In addition, the muscles of the knee (quadriceps, hamstrings and muscles in the lower leg) help maintain flexibility and mobility of the joint.