Medial Collateral Ligament (MCL) Injury

  • Medical Author:
    Benjamin Wedro, MD, FACEP, FAAEM

    Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Medial collateral ligament (MCL) injury facts

  • The medial collateral ligament is one of four ligaments that help stabilize the knee.
  • MCL injuries are also called sprains or tears.
  • The MCL may be damaged by a direct blow or may be noncontact because of cutting or sudden deceleration or stopping.
  • Sprains can be graded as follows:
    • Grade 1 (Fibers are stretched but not torn.)
    • Grade 2 (Ligament fibers are partially torn.)
    • Grade 3 (The ligament is completely torn.)
  • The medical meniscus and anterior and posterior cruciate ligaments are structures in the knee that are also commonly injured.
  • Diagnosis of medial collateral ligament injury is usually made by the history and physical examination. X-rays and MRI of the knee may be needed.
  • Treatment does not usually require surgery. Physical therapy is recommended to return range of motion of the knee joint and to increase the strength of the muscles that surround and protect the knee.

What is the medial collateral ligament (MCL)?

The knee joint allows the lower leg to flex (bend) or straighten (extend). To make certain that those are the only two motions that occur, there are four ligaments in the knee that help control and protect it.

  • The medial collateral ligament (MCL) is located on the medial aspect of the knee (medial = the closest to the center of the body).
  • The lateral collateral ligament (LCL) is located on the lateral aspect of the knee (lateral = away from the center of the body).
  • The anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) prevent anterior (frontward) and posterior (backward) movement of the knee joint.

Ligaments are tough bands of tissue that span a joint and attach to the bones on each side of it. The MCL is located on the inner side of the knee and is attached to the femur and tibia bones. It holds the knee stable against stress when a force is place on the outer part of the leg that could potentially buckle the knee toward the center of the body.

Picture of the ligaments in the knee joint
Picture of the ligaments in the knee joint

The muscles that surround the knee, especially the quadriceps muscles located in the front of the thigh, and the hamstrings located in the back of the thigh, are also important stabilizers of the knee joint.

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Exercises for MCL Injuries

During physical therapy for rehabilitation of a knee injury, the patient will be given specific exercises by the physical therapist in order to strengthen and stabilize the knee joint. These exercises include strengthening the front of the thigh (quadriceps), back of the thigh (hamstrings), calf, and hip.

Some exercises that your physical therapist may recommend include the following:

  • Quad sets
  • Straight leg raises
    • Straight-leg raise to the front
    • Straight-leg raise to the back
  • Hamstring curls
  • Heel raises
  • Heel dig bridging
  • Shallow standing knee bends

What are the different types of medial collateral ligament (MCL) injuries?

An injury to a ligament is called a sprain. Like any other sprain, MCL injuries are graded by their severity. When the fibers of the ligament are stretched but not torn, this is referred to as a grade 1 sprain. Grade 2 sprains are when the ligament fibers are partially torn. When the ligament is completely torn or disrupted, this is a grade 3 sprain.

Because of the anatomy and how the MCL is related to the medial meniscus (cartilage) and the ACL (anterior cruciate ligament), these two structures may also be damaged in association with an MCL injury.

What are causes and risk factors of medial collateral ligament (MCL) injuries?

MCL injuries are the most common ligament sprain of the knee. They are often sports-related and can occur in any age group. Contact sports are the most common risks, including football, hockey, wrestling, and martial arts. Males tend to be more at risk than females.

MCL injuries occur usually from a sudden impact to the outer part of knee. The injury may be either due to contact, being hit on the outside part of the knee, or noncontact due to twisting, cutting, or stopping suddenly (deceleration).

What are medial collateral ligament (MCL) injury symptoms and signs?

Pain is the first symptom of an MCL injury. It typically occurs almost immediately and is located along the course of the ligament. Sometimes this is associated with swelling within the knee joint. Occasionally, swelling develops in a matter of minutes. The pain of an MCL sprain will also cause the person to limp in order to protect the knee joint.

What tests are used to diagnose and assess medial collateral ligament (MCL) injuries?

The diagnosis of an MCL sprain is usually made by history and physical examination. The patient often knows the mechanism of injury, that is precisely what they were doing and what position their body was in when the injury occurred. This helps the health-care professional understand the stresses that were put on the knee joint. Other questions might include whether the patient was able to walk, whether the knee began to swell, and how long it took for that to happen after the injury.

The physical examination includes looking at the knee to see whether or not it is swollen and touching the knee in various places to find places of tenderness and pain. With MCL sprains, there is tenderness along the course of the ligament on the inner aspect of the knee.

The ligament can also be stressed on physical examination. By pushing on the outer side of the knee, the examiner can determine if the MCL is stable or unstable. This can be a rough assessment of the grade of sprain, where a grade 1 sprain is stable and a grade 3 sprain is unstable.

Physical examination concentrates on the knee joint and the hip and ankle to identify any other associated injuries.

Plain X-rays of the knee can be used to identify fractures of the femur and tibia bones. An MRI is the best way to actually visualize the MCL and determine the grade of sprain, but it is not always necessary. If there is concern that there is also a tear of the medial meniscus or anterior cruciate ligament, an MRI may be appropriate.

What is the treatment for a medial collateral ligament (MCL) injury?

MCL sprains tend to heal with rest and physical therapy to help return range of motion and strengthen the muscles that surround and protect the knee.

Grade 1 and 2 sprains tend to heal within one to two weeks. The initial treatment often includes wearing a knee sleeve or hinged knee brace for comfort and protection and to increase range of motion and activity as tolerated. Crutches are usually needed for a few days.

Grade 3 sprains are now usually treated similarly but forgo a knee sleeve for a hinged brace. Some health-care professionals suggest immediate range of motion while others like to wait a few weeks before allowing the knee to move. Return to play or work is usually permitted in six to eight weeks.

Is surgery required for medial collateral ligament (MCL) injuries?

Historically, grade 3 MCL sprains were candidates for surgery, but more recently, surgery is only considered in patients where conservative (nonsurgical) treatment has failed.

Surgery is considered as a primary treatment in patients who have also damaged their medial meniscus and/or their anterior cruciate ligament.

Are there any home remedies for MCL injuries?

The initial treatment for an MCL sprain is the same as other sprains, including rest, ice, compression, and elevation. Because of the associated pain, using crutches to assist with walking is appropriate.

Anti-inflammatory medications like ibuprofen (Motrin, Advil) or naproxen (Aleve) may be helpful for pain control. While these are over-the-counter medications, there may be reasons when this class of medications may not appropriate for a specific patient. It is wise to check with a health-care provider or pharmacist for any questions or concerns.

What are possible complications of medial collateral ligament (MCL) injuries?

Instability is the major complication of a grade 3 MCL sprain. While avoiding surgery and undergoing physical therapy is the mainstay of treatment, there are some patients where the MCL remains unstable and the ligament is lax or loose. These patients often benefit from surgery to repair the MCL but only after initial nonsurgical therapy has failed.

What is the prognosis of a medial collateral ligament (MCL) injury? What is the recovery time for an MCL injury?

Most athletes with MCL injuries are able to return to play within a few weeks of injury. Those who have sustained grade 1 and 2 sprains can be competing within one to two weeks, while those with grade 3 sprains may need longer, about six to eight weeks to recover.

Is it possible to prevent a medial collateral ligament (MCL) injury?

MCL sprains cannot usually be prevented except by avoiding traumatic physical contact. They are the consequence of being active in a sport or because of an unexpected accident. In sports, there is controversy as to whether or not wearing a brace can help to protect the MCL.


Donatelli, R.A., and M.J. Wooden. Orthopedic Physical Therapy, 4th Ed. St. Louis, Mo.: Churchill Livingstone, 2009

Roach, C.J., C.A. Haley, K.L. Cameron, M. Pallis, S.J. Svoboda, and B.D. Owens. "The Epidemiology of Medial Collateral Ligament Sprains in Young Athletes." Am J Sports Med 42.5 May 2014: 1103-1109.

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