Glossary
Medial collateral ligament (MCL)
Quick answer
The medial collateral ligament (MCL) is a broad, flat band on the inner side of the knee, running from the femur to the tibia. It stops the knee buckling inwards and helps control rotation, notes Doha knee surgeon Dr. Pablo Gelber, who assesses ligament injuries at Aman Hospital.
What it is
The MCL lies outside the joint capsule on the inner side of the knee. It has a superficial layer, which is long and strong, and a deep layer that blends with the capsule and attaches to the medial meniscus. Together with structures at the back inner corner of the knee, it resists a force pushing the knee into a knock-kneed position.
Why it matters for patients
The MCL is one of the most commonly injured knee ligaments. It is typically sprained when the outside of the knee is struck, for example in a football tackle, or when a skier's knee falls inwards. People feel pain and tenderness on the inner side of the knee, sometimes with a sense of looseness.
Injuries are graded from mild stretching to a complete tear. Because the MCL has a good blood supply, most tears heal without surgery, using a hinged brace when needed, early movement and physiotherapy. Surgery is considered mainly for severe tears with ongoing instability or when other ligaments, such as the ACL, are also torn.
How it is examined
A surgeon presses along the ligament and gently stresses the knee inwards with it straight and slightly bent. MRI shows the grade of injury and any associated meniscus or ACL damage.
Frequently asked questions
How long does an MCL sprain take to heal?
As a general range, mild sprains often settle in a few weeks and more severe tears over several weeks to a few months, depending on examination and how rehabilitation goes.
Is pain on the inner knee always the MCL?
No. The medial meniscus, the pes anserinus tendons and early arthritis can all cause inner knee pain. Examination helps tell them apart.
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