A ligament is a short band of tough fibrous connective tissue. Ligaments connect bones to other bones in and around joints. They do not connect muscles to bones, that is the function of tendons. Ligaments limit the amount of mobility in a joint, or prevent certain movements altogether.

There are four main ligaments that stabilise your knee (essentially hold it together). Two cruciate ligaments (anterior (ACL) and posterior (PCL), found deep within the joint) and two collateral ligaments found on either side of the knee joint.

Your medial collateral ligament (MCL) is the wide band-like ligament on the inner side of your knee connecting the bottom of the thigh bone (femur), to the top of your shin bone (tibia).

Your lateral collateral ligament (LCL) is a cord-like ligament on outside of your knee. It connects the thigh bone (femur) to the fibula (the smaller bone that makes up the outside of your shin). Together they work to control sideways movement of the knee.

The MCL is often injured during a sharp change in direction, twisting the knee whilst the foot is fi xed, landing badly from a jump, or the most common cause is a blunt force hit to the outside of the leg, forcing the knee inwards often during a rugby tackle.

The LCL is injured when the knee is forced from the inside, outwards which again can occur through a sharp change in direction, twisting the knee whilst the foot is fixed, incorrect landing technique, hyperextension of the knee or a blunt force hit to the knee, such as a tackle.

Injuries to either collateral ligaments often occur at the same time as injuries to other structures in the knee such as the cruciate ligaments and/or the meniscus (cartilage pads which provide shock absorption between the bones of the knee).

Injuries to the collateral ligaments usually happen at speed. Muscle weakness or incoordination predispose you to a ligament sprain or tear.

HOW DO YOU KNOW IF YOUR KNEE INJURY IS SERIOUS?

While it is always best to seek professional advice from your doctor or physiotherapist, here are seven signs that could indicate a severe knee injury.

  1. Obvious deformity. You may have a fracture or dislocation.
  2. You heard a “pop” or “snap”
  3. You’ve experienced swelling
  4. Greater than normal movement
  5. Less than normal movement eg. can’t straighten completely
  6. You are unable to weight-bear on your leg
  7. Your knee “gives way” or “buckles”.

SYMPTOMS AND SEVERITY OF COLLATERAL LIGAMENT INJURIES

The severity and symptoms of a ligament sprain depend on the degree of stretching or tearing of the ligament.

  • Mild grade I sprain, the ligaments may stretch, but they don’t actually tear. Although the joint may not hurt or swell very much, a mild sprain can increase the risk of a repeat injury.
  • Moderate grade II sprain, the knee ligament tears partially. Swelling and bruising are common, and the use of the joint is usually painful and difficult.
  • Severe grade III sprain, your ligament tears completely, causing swelling and sometimes bleeding under the skin. As a result, the joint is unstable and unable to bear weight. Often there will be no pain following a grade III tear as all of the pain fibres are torn at the time of injury.

REHABILITATION OF THE KNEE

The most successful and quickest outcomes result from the guidance and supervision of an experienced physiotherapist. Whether it is conservative management or following knee surgery, focus on restoring full knee motion, strength, power and endurance are crucial. You’ll also require balance, proprioception and agility retraining that is individualised towards your specific sporting or functional needs.