Medial Collateral Ligament (MCL) Tears

The medial collateral ligament (MCL) is a wide, thick band of tissue that runs down the inner part of the knee from the thighbone (femur) to a point on the shinbone (tibia) about four to six inches from the knee.

The MCL's main function is to prevent the leg from extending too far inward, but it also helps keep the knee stable and allows it to rotate.


If the medial collateral ligament has been damaged or torn, you will usually have:

  • Pain, which can range from mild to severe, depending on how serious the injury is
  • Stiffness
  • Swelling
  • Tenderness along the inside of the knee
  • A feeling that the injured knee may give way under stress or may lock or catch.


Causes and Risk Factors

Injuries to the medial collateral ligament most often happen when the knee is hit directly on its outer side. This stretches the ligaments on the inside of the knee too far or can tear them. It is not uncommon for athletes to suffer tears of the medial collateral ligament and anterior cruciate ligament at the same time. The ligament also can be injured through repeated stress. This causes the ligament to lose its normal stretch and elasticity similar to a worn-out rubber band.


Your doctor will generally ask you to describe how the knee was injured, whether you have had other knee injuries and how your knee has felt since the injury. You may be asked about your physical and athletic goals. This helps your doctor decide what treatment might be best for you.

During the physical exam, the inside of the knee will be checked for pain or tenderness. Pressure will be put on the outside of the injured knee while the leg is both bent and straight. Depending on the degree of pain or looseness of your knee joint, the injury will be classified as:

Grade 1 - Some tenderness and minor pain at the point of the injury.

Grade 2 - Noticeable looseness in the knee when moved by hand; major pain and tenderness at the inside of the knee; swelling, in some cases.

Grade 3 - Considerable pain and tenderness at the inside of the knee; some swelling and marked joint instability. The knee opens up about one centimeter (slightly less than half an inch) when the doctor moves your leg around. A grade three MCL tear often occurs along with a tear of the anterior cruciate ligament.
If the immediate pain and swelling makes it too difficult to judge how severe the injury is, you may need to wear a light splint, apply ice and raise the knee. Once the swelling and pain have lessened, your doctor will make the diagnosis.

Your doctor may order a magnetic resonance imaging (MRI ) scan. An MRI has an accuracy rate of nearly 90% in determining whether and how badly a medial collateral ligament tear is. It is not very good, however, at detailing a partial tear.


The medial collateral ligament has a good blood supply and usually responds well to non-surgical treatment. Depending on how bad the injury is, it may be enough to rest the knee, wear a brace, take over-the-counter pain relievers such as ibuprofen and have physical therapy.

To keep the knee from moving, your doctor may recommend a lightweight cast or brace that allows your knee to move backward and forward but limits side-to-side motion. This usually is recommended for 72 hours. Depending on how well your pain and swelling get better, you may be able to start a rehabilitative program in a few days.

Once pain and swelling have gone down, you should be able to start exercises to restore strength and normal range of motion to your knee. If you are still sore while doing exercises, you should proceed slowly to prevent further irritation. It may take a week to eight weeks to completely recover, depending on the seriousness of your injury.

A torn medial collateral ligament is rarely treated with surgery. When surgery is done, it is usually done through a small incision on the inside of your knee. It is not done arthroscopically, since this ligament is not inside the knee joint. If the medial collateral ligament has been torn where it attaches to the thighbone (femur) or shinbone (tibia), the surgeon will re-attach the ligament to the bone using large stitches or a metal screw or bone staple. If the tear was in the middle of the ligament, the surgeon will sew the torn ends together.