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MCL Injury - Medial Collateral Ligament Injury

Overview, Causes, & Risk Factors

A medial collateral ligament (MCL) is a broad band on the inside of the knee. An MCL injury involves some degree of stretching of this ligament. MCL injuries commonly occur when force is exerted on the outside of the knee and pushes the joint sideways. This places stress on the inside of the joint, resulting in ligament damage.

There are three degrees of ligament injuries. A first-degree injury consists of only mild stretching of the ligament. There is no looseness of the joint. A second-degree MCL is a partial tear of the ligament. In a third-degree injury, the ligament is completely ruptured, and the joint is unstable.

What are the causes and risks of the injury?

Most frequently, the MCL is injured during sports when there is a twisting injury or blow to the outside of the knee. This might occur in a clipping injury in football or in a skiing accident if the knee is twisted. An MCL injury may also be caused by overuse of the joint, or by a fall in an elderly individual.

Symptoms & Signs

What are the signs and symptoms of the injury?

A person with an MCL injury will experience pain in the inside portion of the knee. The individual will still be able to walk almost normally if the ligament has been only mildly stretched. If there is a severe tear, the individual will not be able to walk or bear weight on the leg. The amount of stiffness in the knee will depend on the amount of swelling.

Diagnosis & Tests

How is the injury recognized?

The healthcare provider will usually diagnose an MCL injury based on a physical exam and the person's description of the injury. Joint X-rays of the knee are also commonly performed. Most of the time, the bones appear normal. A special X-ray called an MRI is sometimes done.

Prevention & Expectations

What can be done to prevent the injury?

Many times, the injury cannot be prevented. However, a person should be in good shape and have good muscle strength before participating in sports. Sports safety guidelines should be followed for adults, adolescents , and children. Proper stretching exercises should be done before athletic activity. Ski bindings should be adjusted properly to prevent twisting the leg.

Treatment & Monitoring

What are the treatments for the injury?

Treatment for MCL injuries depends on a number of factors including:

  • the degree of MCL injury
  • other injuries that may have occurred at the same time
  • the person's age and future activities
  • The first step in treatment is the RICE method. This stands for rest, ice, compression with an elastic bandage, and elevation of the leg. Medicines such as nonsteroidal anti-inflammatory drugs (NSAIDs) can help reduce pain. More painful injuries or those where the knee is unstable may require a splint or brace to immobilize the knee as well as crutches.

    After an initial period of RICE, physical therapy is started. This is aimed at restoring the range of motion in the knee joint and increasing strength in the thigh muscle. The majority of MCL injuries will heal successfully without surgery. Cases in which the ligament has been completely torn and the knee is unstable may require surgery. Sometimes a special brace that allows knee movement while avoiding tension on the ligament is useful while the injury is healing.

    What are the side effects of the treatments?

    Medicines can cause allergic reactions and stomach upset. Long-term use of NSAIDs may harm the stomach, kidneys, or liver. The knee can become stiff if it is immobilized for too long. Surgery carries a risk of bleeding, infection, and allergic reaction to the anesthesia.

    What happens after treatment for the injury?

    If the ligament remains loose, the knee will feel unstable. There will be a tendency for the joint to give way, possibly leading to reinjury. If healing and physical therapy go well, the person can often return to normal activities.

    The healthcare provider will periodically check the flexibility and strength of the knee and assess the stability of the joint. Any new or worsening symptoms should be reported to the provider.


    Author:John A.K. Davies, MD
    Date Written:
    Editor:Crist, Gayle P., MS, BA
    Edit Date:08/28/01
    Reviewer:Adam Brochert, MD
    Date Reviewed:08/28/01