Knee Anatomy

As the better weather approaches and more people will be out enjoying a run and other sports – we thought that it would be a good time to explain a bit more about Knee anatomy.

The knee is one of the most important joints in the body and consists of two articulations – in simple terms this means two locations where bones meet to allow movement. In the knee the two articulations are:

  •  between the Femur (thigh bone) and the Tibia (Shin bone)
  • between the Femur and the Patella (knee cap) .

Movement at the knee joint is essential for most day-to-day activities such as walking and running. The knee is vulnerable to acute injuries  – such as those sustained during contact sports.

So……what structures are there in the knee that are vulnerable to injury?


Ligaments are thick fibrous bands (similar to ropes) whose job it is to hold the bones together. Knee ligaments are split into two groups;

  • Collateral ligaments that are on the outside of the joint
    • Medial Collateral ligament (MCL) is on the inside of the knee and it’s job is to resist against impacts from the outside of the leg
    • Lateral Collateral ligament (LCL) is on the outside of the knee and it’s job is to resist against impacts from the inside of the leg. It is much less common for the LCL to get injured.

Athletes playing contact sports such as rugby and football are at a higher risk of collateral ligament injuries, especially with potential for direct blows to the outside of the knee.

  • Cruciate ligaments are found INSIDE the joint
    • Anterior cruciate ligament (ACL) sits deep inside the middle of the joint and is the primary structure for stability within the knee.  This ligament is commonly injured in sporting activities as a result of twisting and sudden stopping movements.
    • Posterior cruciate ligament (PCL) attaches the back of the tibia and the front of the femur. Although it is shorter than the ACL it is stronger and therefore not injured as often as the ACL. The most common cause of PCL injury is high impact trauma such as a car accident or extreme force during a contact sport.


Good strength and flexibility in the knee muscles is very important as any weaknesses will leave you more prone to injury.  The two main groups of muscles in the knee are;

  • Quadriceps – a group of 4 muscles that are at the front of the thigh and go over the knee. The main function of these muscles is to straighten the leg. They also Work with the glutes (bottom muscles) and hamstrings to enable us to walk, run and jump as well as controlling movement of the knee cap.
  • Hamstrings – a group of 3 muscles found at the back of the knee and whose job it is to bend and rotate the knee. They help to stabilise the knee and protect the knee ligaments as well as allowing us to lift our legs off the ground when walking etc. It also provides the strength that we need in order to perform task like running and jumping.

Of course the above are just some of the structures that are at risk of injury and there are other conditions that athletes are prone to such as Patella Tendinosis.

The important points to remember are:

  • Look after your joints and all the structures that support and work with them. This includes using the right equipment and warming up/down properly.
  • Accurate, correct and timely diagnosis and subsequent treatment are important and will greatly increase your chances of a full and quick recovery. It may even been the difference between needing surgery and not!

You can read more into the knee structures on our Knee information pages

Posted in Our Blog.

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