Medial Collateral Ligament Injury of the Knee (MCL Tear)

Written by Janelle Martel | Published on August 20, 2012
Medically Reviewed by George Krucik, MD

What Is an MCL Sprain?

The medial collateral ligament (MCL) is located on the inside of the knee. Ligaments hold bones together; the MCL connects the top of the shinbone (tibia) to the bottom of the thighbone (femur). Ligaments also add stability and strength to a joint.

Injury to the MCL is often called an MCL sprain. Ligament injuries can either stretch the ligament or tear it. MCL injury of the knee is usually caused by a direct blow to the knee. This type of injury is common in contact sports, and it is usually the result of a hit to the outer knee that stretches the MCL. Sometimes, an MCL tear can cause fractures in the growth plates at the end of the bones in adolescents.

Types of MCL Injuries

Your doctor may tell you that you have a first, second, or third degree MCL sprain.

Grade one is the least severe and means that the ligament has been stretched but not torn.

Grade two means that the ligament has been partially torn. This usually causes some instability in the knee joint.

Grade three is the most severe type of ligament injury and occurs when the ligament has been completely torn. Joint instability is common in a grade three MCL injury.

What are the Symptoms of an MCL Injury?

Symptoms of an MCL injury are similar to symptoms of other knee problems, so it is important that you have your knee examined by a doctor if you are experiencing them.

Symptoms of an MCL injury may include:

  • a popping sound upon injury
  • pain and tenderness along the middle of the knee
  • swelling of the knee joint
  • a feeling that the knee is going to give out when supporting weight
  • locking or catching in the knee joint

Problems with knee stability typically indicate grade two or grade three injuries.

How to Tell if You Have an MCL Injury

Your doctor can often tell if you have an MCL injury by examining your knee. During the examination, your doctor will bend your knee and put pressure on the outside of the knee. He or she will be able to feel if your inner knee is loose, which indicates an injury to the MCL.

It is important that you relax your leg muscles during the examination so your doctor can test the stability of your ligaments, not the muscles helping to hold the knee in place. You may feel some pain and tenderness in the knee during the examination.

Your doctor may order imaging tests to help diagnose your knee injury. A knee X-ray will give your doctor an image of the bones in your knee to help rule out other knee problems. During an X-ray, a technician will position your knee so that the machine can record images. This may cause some pain if your knee is tender or swollen, but the X-ray process will only take a few minutes. The X-ray will tell your doctor if there is an injury to the bones in your knee.

Your doctor may also order a magnetic resonance imaging (MRI) scan. This is a test that uses magnets and radio waves to create images of the body. You will lie down on a table and a technician will position your knee. The MRI machine often makes loud noises, so your technician will give you earplugs to protect your ears.

The table will slide into a scanner and images of your knee will be recorded. You will be able to communicate with your technician through a microphone and speakers in the machine. The images from the MRI will tell your doctor if you have a problem in the muscles or ligaments of the knee.

How to Treat an MCL Injury

Treatment options vary depending on the severity of the MCL injury. Most MCL injuries will heal with rest.

Immediate Treatment

Immediate treatment is necessary to ease pain and help stabilize the knee. Immediate treatment options include:

  • applying ice to reduce swelling
  • elevating the knee above the heart to help with swelling
  • nonsteroidal anti-inflammatory drugs (NSAID’s) to ease pain and swelling
  • compression to the knee using an elastic bandage or brace
  • rest, often using crutches to keep weight off of the injured knee


As you recover from your injury, the goal is to regain strength in the knee and prevent further injury. Treatments may include:

  • physical therapy to strengthen muscles and improve the knee’s range of motion
  • wearing a protective knee brace during physical activity
  • limiting activities that can cause further injury, such as contact sports


Rarely, an injury to the MCL requires surgery. This is necessary when the ligament is torn in such a way that it cannot repair itself or when the MCL injury occurs with other ligament injuries.

Before your surgery, your surgeon will use arthroscopy to make a thorough examination of the extent of your injury. Arthroscopy involves inserting a small, pencil-thin camera through a tiny incision. While other surgeries can be done arthroscopically (i.e., using this same incision and pencil-thin tool), MCL surgery cannot be done in this way. This is because the ligament is not inside the knee joint.

After the arthroscopic exam, your surgeon will then make a small incision behind your knee. If the ligament is torn where it attaches to either your shinbone or your thighbone, your surgeon will reattach it using large stitches, bone staples, or a metal screw. If the tear is in the middle of the ligament, your surgeon will stitch the ligament together.

The outlook for recovering from a MCL injury is good, whether surgery is required or not.

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