The knee joint is made up of 4 main ligaments that connect the thighbone to the shinbone, each playing a role in the stabilisation of this complex joint.

  • Anterior cruciate ligament (ACL). This ligament is located in the front of the knee and controls rotation and forward movement of the lower leg. The ACL is usually torn or damaged when the knee is involved in sudden stops or changes of direction – usually during trauma or sporting injuries.
  • Posterior cruciate ligament (PCL). This ligament is located at the back of the knee, controlling the backward movement of the lower leg and ensuring the knee doesn’t bend backwards. The PCL is damaged or torn by a direct blow to the bent knee during trauma or a sports injury.
  • Medial collateral ligament (MCL). This ligament is found on the inner side of the knee joint, providing stability to the inner knee, controlling the sideways motion of the knee. The MCL can become damaged by a sideways force on the knee in trauma or sports injuries.
  • Lateral collateral ligament (LCL). This ligament is located on the outer side of the knee, giving stability to the outer knee keeping the sideways motion of the knee controlled. The LCL is commonly damaged due to contact injuries in sports like soccer or rugby, or trauma.

When damaged or torn during a sports injury, the knee joint becomes unstable.


Those with a suspected ruptured or torn ligament in the knee may experience the following symptoms:

  • Sudden severe pain
  • A loud snap or popping sounds during the injury
  • Inability to bear weight on the affected leg
  • Instability and weakness in the knee joint
  • Swelling of the knee


The treatment for a ligament injury of the knee may involve rest, compression and pain-relieving medications, but will usually involve surgery at some point to stop future buckling of the knee when twisted. Knee ligament repair surgery will be advised to repair the torn ligament with stitches to restore stability and strength in the knee.

Surgery to repair a torn ligament in the knee is usually done by replacing the torn ligament with a graft from a nearby tendon. Using arthroscopic tools, a piece of healthy tendon is taken from the kneecap or hamstring and secured to the thighbone and shinbone using screws to replace the torn ligament.