The Difference Between an ACL Tear and MCL Tear

Knee injuries are very common among participants in certain activities, including soccer, basketball and volleyball. Although its action seems straightforward, the knee is a complicated joint with several muscles, bones, and ligaments working together to help you move. Understanding whether you have suffered an ACL tear or MCL tear will help you as you make decisions about treatment. Regardless of the type of torn ligament, your orthopedic specialist will likely recommend surgery followed by physical therapy to help you recover.

What Are the ACL and MCL?

The knee is the joint where the large femur bone of your thigh meets the tibia, or shinbone, and smaller fibula bone of your lower leg. There are four ligaments that stabilize these bones and join them together: the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), medial collateral ligament (MCL) and lateral collateral ligament (LCL). A knee injury could conceivably result in damage to any of these ligaments, but tears to the ACL and MCL tend to be more common.

The ACL is a ligament in the middle portion of the knee joint that stabilizes the femur and tibia. It prevents the femur from sliding backward on the tibia. In contrast, the MCL spans the inner side of the knee (where your knees press together), spanning from the end of the femur to the top of the tibia. The MCL prevents the femur from sliding from side to side.acl and mcl tears

Differences in Injury to the ACL and MCL

There are characteristic injuries that cause a tear to the ACL and MCL. A blow to the side of the knee or front of the shin often leads to over-rotation or hyperextension of the knee joint. This most frequently leads to a tear in the ACL. Some of the initial symptoms of this injury may include difficulty bending the knee and swelling in the knee area.

In contrast, injury to the MCL most frequently occurs when a blow occurs to the outer side of the knee. This stretches the inner knee joint, causing the MCL to tear. People who have suffered an MCL injury often say it feels as though their knee will “give out” at any second.

Implications for Treatment By Your Orthopedic Surgeon

Your orthopedic surgeon will likely request an MRI of the knee to diagnose the torn ligament or ligaments. This will inform treatment planning, which typically involves surgery to correct the tear. Ask about the prognosis, typical length of recovery and physical therapy requirements for your unique situation.


John Redmond, MD

Joint Replacement & Hip Preservation Specialist

Southeast Orthopedic Specialist is proud to introduce the newest member to our team, Dr. John Redmond. Dr. Redmond is a graduate of the University of Minnesota Medical School. He then completed his residency in Orthopedic Surgery at Mayo Clinic...



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