Normal Anatomy of the Knee Joint

The knee joint is a complex hinge joint that plays a crucial role in supporting body weight, enabling movement, and facilitating activities such as walking, running, and jumping. It is the largest joint in the human body and connects the thigh bone (femur) to the shin bone (tibia) and the kneecap (patella). Here’s a detailed overview of the normal anatomy of the knee joint:

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Bones of the Knee Joint:

The knee joint is primarily formed by three bones: the femur, tibia, and patella.

  • Femur: The thigh bone is the uppermost bone of the knee joint. Its lower end forms two rounded condyles that articulate with the tibia.
  • Tibia: The shin bone is the larger bone of the lower leg. It forms the lower part of the knee joint and bears most of the body’s weight.
  • Patella: The kneecap is a small, triangular bone located in front of the knee joint. It articulates with the femur and provides protection to the joint.

Articular Surfaces:

The ends of the femur and tibia are covered with a smooth layer of cartilage known as articular cartilage. This cartilage allows for smooth and frictionless movement of the joint.

Ligaments of the Knee:

Ligaments are strong bands of tissue that help stabilize the knee joint and prevent excessive movement. The major ligaments of the knee include:

  • Anterior Cruciate Ligament (ACL): This ligament prevents the tibia from moving too far forward in relation to the femur and provides rotational stability.
  • Posterior Cruciate Ligament (PCL): The PCL prevents the tibia from moving too far backward in relation to the femur and also contributes to rotational stability.
  • Medial Collateral Ligament (MCL): This ligament runs along the inner side of the knee and provides stability against forces pushing the knee inward.
  • Lateral Collateral Ligament (LCL): The LCL runs along the outer side of the knee and provides stability against forces pushing the knee outward.


The knee joint contains two C-shaped pieces of cartilage called menisci (singular: meniscus). These act as shock absorbers between the femur and tibia, distributing weight and reducing friction.

Synovial Membrane and Fluid:

The knee joint is lined by a synovial membrane, which produces synovial fluid. This fluid lubricates the joint, reducing friction during movement and nourishing the cartilage.


Several muscles surround the knee joint and contribute to its movement and stability. The quadriceps muscles on the front of the thigh extend the knee, while the hamstrings on the back of the thigh flex the knee.


Bursae are small fluid-filled sacs located around the knee joint. They reduce friction between structures such as tendons and bones, enhancing smooth movement.


The knee joint enables bending (flexion) and straightening (extension) of the leg, as well as limited rotation. It is essential for weight-bearing activities and is a critical component of human movement.


Understanding the normal anatomy of the knee joint is important for maintaining joint health and addressing any issues that may arise. If you experience persistent knee pain, limited mobility, or other knee-related symptoms, seeking medical evaluation and guidance from a healthcare professional is important for proper diagnosis and treatment.

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