Anterior Cruciate Ligament Injury

Injury to the cruciate ligaments is a common but severe injury to the knee. The knee joint is the largest joint in the body. It is a ‘hinge’ joint that allows the knee to flex and extend. Additionally, it has the ability to rotate and glide. The knee joint is formed by the tibia (shinbone), the femur (thighbone) and the  patella  (kneecap). Ligaments  connect  the  bones  of  the  joint for  stability and  allow controlled movement. Ligaments on the inner and outer side of the knee (collateral ligaments) prevent the knee from bending inwards or outwards. Ligaments in the centre of the knee, called the cruciates, prevent excessive rotation of the knee. Typically the anterior cruciate ligament is torn when a severe injury occurs to the knee involving excessive twisting which ruptures part or all of the ligament.

Injury to the anterior cruciate ligament results in increased forward movement and rotation of the tibia relative to the femur bone. This results in a feeling of instability and excessive movement of the knee. These symptoms  are  more  pronounced  with  rotation  caused  by  sudden  changes  in direction and twisting movements rather than with walking and running. Injury to the ACL is frequently associated with other injuries to the knee such as damage to the meniscal cartilages (shock absorbers of the knee), the bearing surface of the knee, and other ligaments of the knee. Typically, an injury to the anterior cruciate ligament results in significant bleeding into the knee. The knee is frequently very swollen with blood under pressure inside the knee resulting in marked pain, stiffness and immobility.

Download our information sheet to learn more about Anterior Cruciate Ligament Injuries and treatment options.