What is a medial collateral ligament (MCL) injury?

A medial collateral ligament injury (commonly referred to as an MCL injury) is a tear or sprain to the medial collateral ligament. The MCL is located on the inner side of the knee but outside the joint.

The medial collateral ligament connects the lower leg bone to the thighbone, and its function is to keep the knee from bending inward.

Common related conditions
Anterior Cruciate Ligament (ACL) Injury Lateral Collateral Ligament (LCL) Injury Posterior Cruciate Ligament (PCL) Injury Meniscus Tear or Strain

Causes of medial collateral ligament (MCL) injury

An MCL injury is typically caused by a direct blow to the outer aspect of the knee. It is most common in contact sports such as football, basketball and soccer. Other causes of a MCL injury are:

  • Sudden change in direction that causes increased pressure on the knee
  • Trauma to the outside of the knee
  • Squatting
  • Landing awkwardly on the knee

Risk factors for medial collateral ligament (MCL) injury

  • Age — MCL injuries are most common in adults ages 20-34 and 55-65.
  • Contact sports — people who play contact sports (football and basketball) are at a higher risk of suffering an MCL injury.

Symptoms of medial collateral ligament (MCL) injury

The most common symptoms of a medial collateral ligament injury are pain, tenderness and swelling. As time passes, pain will intensify, and it may become harder to move your knee.

You could hear a loud popping sound at the time of the injury or feel like your knee is going to give out. You could also feel locking or catching in the knee joint.

Diagnosis of medial collateral ligament (MCL) injury

MCL injuries are diagnosed in a physical exam with your orthopedic physician. In the physical exam, your doctor will check the range of motion in your knee.

Your provider will also take a full medical history to determine how the injury occurred, what your symptoms are and what movements make the symptoms more severe.

In most cases, the physician will also order an x-ray or MRI to confirm the MCL injury diagnosis.

Treatments for medial collateral ligament (MCL) injury

MCL injuries can typically be healed with anti-inflammatory medications, rest, ice, compression and elevation. Your doctor also may recommend staying off the leg, wearing a brace and using crutches to facilitate healing.

Physical therapy and rehabilitation - physical therapy may be prescribed to improve the flexibility in the muscles and restore strength to the knee.

If there is a severe tear in the MCL, more advanced treatment may be necessary including:

  • Knee arthroscopy — minimally invasive surgical procedure to diagnose and repair a MCL injury; small incisions are made in the knee and a camera is inserted to visualize the injury and determine treatment.
  • Platelet rich plasma (PRP) injection — newer therapy where a blood sample is taken from the patient, spun in a centrifuge, growth factors are isolated and then they are injected back into the affected site to stimulate faster healing.

Recovery from medial collateral ligament (MCL) injury

Recovery from a medial collateral ligament injury will depend on the severity of the injury.

  • Mild MCL injury — patients can return to normal activity within a couple of weeks.
  • Moderate MCL injury — will take a month or more to heal.
  • Severe MCL injury — recovery time for a severe MCL injury is two to four months or more.

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