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St. Mary's Center for Orthopaedics

Medial Collateral Ligament Injuries

What is the Medial Collateral Ligament?

The knee is the largest joint in your body and one of the most complex. It is also vital to movement.  Your knee ligaments connect your thighbone to your lower leg bones. Knee ligament sprains or tears are a common sports injury.

The medial collateral ligament (MCL) runs along the medial (inner) side of the knee joint. It is longer and wider than the other ligaments of the knee. The MCL is also different because it is continuous with the knee joint capsule, has both deep and superficial portions and is attached to the medial meniscus. Some of the ligament’s fibers are tight in full knee extension (fully straightened knee) and help resist hyperextension, while some of the fibers are tight in full knee flexion (fully bent knee). The MCL works to stabilize the medial side and provide rotational stability

What is an MCL Injury?

The MCL is the most often sprained ligament in the knee. An MCL sprain is a partial or full tear of the ligament’s fibers. This can be a contact or noncontact injury, occurring when the knee is forced inward with a stress or impact to the outer side of the knee. Injuries are most common in athletes during sport activities when the knee is bent. These injuries are more common in males than females. A MCL injury may occur with an ACL tear and a medial meniscus tear as well.  An MCL sprain can also occurs with a kneecap dislocation. Fortunately, the MCL has a blood supply and therefore has a high potential for healing without surgery, if injured in isolation.

Injured ligaments  are graded on a severity scale:

  • Grade I – The ligament is mildly damaged in a Grade 1 Sprain. It has been slightly stretched, but is still able to help keep the knee joint stable.
  • Grade II – A Grade 2 Sprain stretches the ligament to the point where it becomes loose. This is often referred to as a partial tear of the ligament.
  • Grade III – This type of sprain is most commonly referred to as a complete tear of the ligament. The ligament has been split into two pieces, and the knee joint is unstable.

What Causes a MCL Injury?

  • Injuries to the collateral ligaments are usually caused by a force that pushes the knee sideways. These are often contact injuries, but not always.
  • Medial collateral ligament tears often occur as a result of a direct blow to the outside of the knee. This pushes the knee inwards (toward the other knee).
  • Blows to the inside of the knee that push the knee outwards may injure the lateral collateral ligament.

What are the Signs and Symptoms of MCL injury?

Pain, stiffness and swelling are common complaints with a MCL injury. However, since the MCL is congruent with the joint capsule, and is not inside the joint, swelling does not always occur. The knee will likely be tender to touch along the medial side, often just below the knee joint where the ligament attaches to the bone of the lower leg. Patients with a MCL injury often walk with their knee slightly bent to reduce the pain. Some patients with a more severe MCL injury also complain of side to side instability.

How is a MCL Injury Diagnosed?

  • Physical Examination and Patient History
  • During your first visit, the doctor will talk to you about your symptoms and medical history.
  • During the physical examination, the doctor will check all the structures of your injured knee, and compare them to your non-injured knee. Most ligament injuries can be diagnosed with a thorough physical examination of the knee.

Other tests which may help your doctor confirm the diagnosis includes:

  • Imaging Tests
  • X-rays. Although they will not show any injury to your collateral ligaments, X-rays can show whether the injury is associated with a broken bone.
  • MRI. This study creates better images of soft tissues like the collateral ligaments.

What is the Treatment for an Isolated MCL Injury?

Isolated MCL sprains are most often treated conservatively, without the need for surgery. Physical therapy is prescribed to help the patient return to normal activities as quickly and safely as possible.

Nonsurgical Treatment:

  • Ice. Icing your injury is important in the healing process. The proper way to ice an injury is to use crushed ice directly to the injured area for 15 to 20 minutes at a time, with at least 1 hour between icing sessions. Chemical cold products (“blue” ice) should not be placed directly on the skin and are not as effective.
  • Bracing. Your knee must be protected from the same sideways force that caused the injury. You may need to change your daily activities to avoid risky movements. Your doctor may recommend a brace to protect the injured ligament from stress. To further protect your knee, you may be given crutches to keep you from putting weight on your leg.
  • Physical therapy. Your doctor may suggest strengthening exercises. Specific exercises will restore function to your knee and strengthen the leg muscles that support it.
  • For grade II and III sprains, the knee is often braced for walking, and sometimes the patient is initially required to be on crutches.
  • Return to normal activities is expected in about 2 weeks for a grade I sprain, 4 weeks for a grade II sprain, and 6 to 8 weeks for a grade III sprain.

However, each patient responds to injuries and rehabilitation differently and may take slightly longer to return their prior level of function. Some patients may also need to wear a brace when they return to sport.

Surgical Treatment

Most isolated collateral ligament injuries can be successfully treated without surgery. If the MCL is injured along with other structures in the knee, the treatment will follow a different course. If the ACL is also torn, surgery to repair the ACL will often be delayed for 5-7 weeks to allow the MCL to heal initially. In some cases, the MCL may be surgically repaired, or replaced with other tissue. This postoperative treatment will include physical therapy for up to 5 months, or longer if the ACL was reconstructed as well.