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Knee ligament injuries

The knees can take a lot of punishment while playing sport or running, often resulting in knee ligament injuries.

Around a fifth of knee injuries from playing sport affect the anterior cruciate ligament or ACL.

A torn ACL can be painful and debilitating, but can often be treated successfully.

Anatomy of a knee injury

Ligaments are tough bands of tissue that connect the bones in your body. Two important ligaments in the knee, the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL), connect the thigh bone with the bones of the lower leg. But too much stress on these ligaments can cause them to stretch too far - or even snap.

posterior cruciate ligament revised

ACL and other ligament injuries can be caused by:

  • Twisting your knee.
  • Getting hit on the knee.
  • Extending the knee too far.
  • Jumping and landing on a flexed (bent) knee.
  • Stopping suddenly when running.
  • Suddenly shifting weight from one leg to the other.

These injuries are common in footballers, basketball players, skiers, gymnasts and other sports people.

There are four ligaments in the knee that are prone to injury.

  • Mentioned above, the anterior cruciate ligament (ACL) is one of the two major ligaments in the knee. It connects the thigh bone to the shin bone. ACL injuries are a common cause of disability in the knee and are more common in women than men.
  • The posterior cruciate ligament (PCL) is the second major ligament in the knee connecting the thigh bone to the shin bone.
  • The lateral collateral ligament (LCL) connects the thigh bone to the fibula; the smaller bone on the outside of the lower leg.
  • The medial collateral ligament (MCL) connects the thigh bone to the inside of the shin bone. 

What does a knee ligament injury feel like?

An ACL injury - or other ligament injury - is occasionally hard to diagnose. However, sometimes the person will know immediately that something is severely wrong, because of the pain, limitation of movement and rapid swelling that follow a ruptured internal ligament. Symptoms of a knee ligament injury are:

  • Pain, often sudden and severe.
  • A loud pop or snap during the injury.
  • Swelling.
  • A feeling of looseness in the joint.
  • Inability to put weight on the joint without pain.

If they're not treated at the time, ACL and other types of ligament injuries may continue to give trouble months or years later, causing the knee to give out when you twist or pivot.

If you have an acute injury severe enough to rupture your ACL, you will probably be taken straight to an A&E department. If the symptoms are not so severe and you go to your doctor, you will quickly be referred to an orthopaedic surgeon if an ACL injury is suspected. To diagnose an ACL or other ligament injury, you will need a thorough examination. If your knee is swollen with blood, the specialist may use a needle to drain it. You may also need X-rays, and an MRI (Magnetic Resonance Imaging) scan, as this can identify the structures inside the knee and clearly show the extent of the damage. Other tests may also be necessary.

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