The Four Major Ligaments

The three bones of the knee are bound by four major ligaments which stabilise the knee. These ligaments are:

  • Anterior cruciate ligament (ACL): located in the centre of the knee, controlling rotation and forward movement of the tibia.
  • Posterior cruciate ligament (PCL): crosses behind the ACL at the centre of the knee, controlling the backward movement of the tibia.
  • Medial collateral ligament (MCL): located at the inner knee, giving it stability in that area.
  • Lateral collateral ligament (LCL): located at the outer knee, providing outer knee stability.
ligament pic

How do ligament injuries occur?

Ligament injuries such as sprains and tears occur usually as a result of a sporting accident. This is because any acute, direct contact or hard muscle contraction (such as sudden pivoting) can cause sprains or tears. Sports such as netball, skiing and rugby involve a high number of such movements.


ACL injuries are the most common type of ligament injuries to occur. They are typically felt as the knee ‘buckling’ or ‘giving way’ after an incident, or during certain activities. If this frequently happens, there is a risk of damage to the cartilage of the knee. This in turn puts the knee at risk of developing osteoarthritis.


Why might I need surgical intervention?

Knee reconstructions are performed to stop or prevent instability. In most cases, instability can be predicted soon after the injury occurs. At this stage, your surgeon will make an informed decision to either reconstruct or rehabilitate your knee. This depends on several factors such as:

  • How much the ligament has healed by the time you’ve presented to your surgeon.
  • Other injuries to the knee.
  • Whether you have a single or combined ligament injury.
  • The intrinsic stability of the knee.
  • Your activity levels and how soon you must return to sport.
  • Your ability to modify daily activities and movements.


References (2019). Combined Knee Ligament Injuries - OrthoInfo - AAOS. [online] Available at: [Accessed 6 Aug. 2019].

Hopkins Medicine. (2019). Knee Ligament Repair. [online] Available at: [Accessed 6 Aug. 2019].