Injury advice > Knee Injuries > Anterior Cruciate Ligament Injury

Anterior Cruciate Ligament Injury

What is the anterior cruciate ligament?

There are 4 main ligaments that stabilize the knee 2 collateral ligaments (medial and lateral) and 2 cruciate ligaments both anterior (front) and posterior (back). These are fixed to the femur (thigh bone) and travel within the knee joint to the upper surface of the tibia (shin bone). The ligaments pass each other in the middle of the joint forming a cross shape, hence the name 'cruciate'.
The main function of the anterior cruciate ligament (ACL) is to prevent the tibia from shifting forwards below the femur. Both The ACL and PCL are vital for the stability of the knee particularly in sports that require a lot of twisting and changing of direction such football and rugby.

How can the ACL be injured?

Normally through twisting or impact at the side of the knee- often the outside, such as a rugby tackle.

Most ACL injuries come from twisting of the knee when the foot is firmly planted on the ground, deceleration or landing from a jump. If the ACL is injured through impact then it is very likely the medial ligaments and the menisci may also be injured - this known as "O'Donohue's triad".

Symptoms of an ACL injury:

  • It is often signified by an audible "pop" or "crack " at the time of injury.
  • They are normally extremely painful, in particular immediately after sustaining the injury.
  • Rapid swelling of the knee.
  • Inflammation of the injury
  • Difficulty in straightening the knee.
  • Positve signs in the "anterior drawer test"
  • Meniscal damage may be indicated by tenderness at the medial side of the joint.

Useful Products:

  • Cold Therapy - Apply ice or cold therapy to reduce pain and swelling.
  • Knee Braces - Help to support and protect the knee joint, reducing the chance of further injury.

Please see the Virtual Sports Injury Clinic for more information on how to treat Anterior Cruciate Ligament Injury