Overstretched or Torn Ligaments of the Knee

Ligaments are strong, but flexible, bands of tissue that connect bones around joints to stabilize them. In the knee joint, there are four main ligaments: the medial collateral ligament (MCL), lateral collateral ligament (LCL), anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL). If these ligaments are overstretched or hit, injury can occur.

  • The MCL and LCL run along each side of your knee. Injuries to these ligaments typically occur because the knee is hit from the outside or inside or twisted awkwardly.
  • The ACL, which is in the middle of your knee, can be injured if you stop moving too suddenly, change direction too quickly, make a wrong landing from a jump or get hit in the knee from the front.
  • The PCL, which is located deeper within the knee behind the ACL, can be injured if your knee is hit with a great deal of force while it is bent.

A knee ligament injury can be either partial (the ligament is loose and partially torn) or complete (the ligament is completely torn).

Though knee ligament injuries can happen to anyone who is active, they’re more common in athletes – especially ACL tears and MCL tears.

Symptoms, Diagnosis and Outlook

The signs and symptoms of a knee ligament injury are:

  • Pain and swelling of the knee (MCL and LCL injuries cause pain on the sides of the knee, while ACL and PCL injuries cause pain in the center)
  • A popping sound at the time of injury
  • An unstable feeling in the affected knee
  • Inability to bear weight on the affected knee
  • A loss in range of motion

The pain and swelling may go away when you rest, but then return when you’re active. If you can’t walk or the pain and swelling don’t improve after a few days of rest, make an appointment with an orthopaedic and sports medicine specialist. He or she can diagnose your injury through a physical exam and magnetic resonance imaging (MRI) when indicated. A quick diagnosis is important to prevent further damage to your knee.

Some knee ligament injuries require surgery to fully restore the function of the knee. This is especially true if you’re an athlete looking to return to your sport. Mild knee ligament injuries can sometimes be rehabilitated with only rest and possibly physical therapy, guided by your doctor’s advice.

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