Knee injuries extremely common while performing a wide range of activities, especially if they involve sudden stops, pivoting, or impact to the leg. Two of the most frequently injured parts of the knee are the anterior cruciate ligament (ACL) and the medial collateral ligament (MCL). Although these two ligaments are near each other and are essential in providing knee stability, they serve different purposes and are injured in different ways.
The Anatomy of the Knee
Some basic knee anatomy: the knee joint is supported by four ligaments that stabilize and control movement:
- Anterior cruciate ligament (ACL) – located in the center of the knee, preventing the tibia from sliding out in front of the femur.
- Posterior cruciate ligament (PCL) – also in the center of the knee, preventing the tibia from sliding backward.
- Medial collateral ligament (MCL) – located on the inside of the knee, preventing excessive inward movement of the knee joint.
- Lateral collateral ligament (LCL) – located on the outside of the knee, stabilizing the outer part of the knee.
What are ACL and MCL Injuries?
The ACL is one of the most commonly injured ligaments in the knee, particularly in high-impact sports like soccer, basketball, football, and skiing. The ACL provides stability by controlling the forward motion of the shin bone and limiting knee rotation. It is an essential part of the body for twisting motions in the knee, or when you undergo rapid direction changes.
The MCL, located on the inner side of the knee, playing an essential role in preventing excessive side-to-side movement. Unlike the ACL, the MCL is responsible for preventing inward movement, aka buckling of the knee. MCL injuries are common in contact sports like football and hockey but also occur in sports that involve lateral movements.
How Do These Injuries Occur?
ACL conditions are less likely to occur from a contact injury but can also result from trauma. The most common ways ACL injuries occur include:
- Sudden change of direction/ pivoting
- Landing awkwardly after a jump
- Sudden stopping or slowing down
- Direct impact or collision
MCL injuries usually happen as a result of a direct blow or a circumstances that pushes the knee inward, stretching or tearing the ligament. Here are some common causes of MCL injuries:
- Direct impact from the side
- Twisting or turning motions
- Overuse or strain
ACL/MCL Injury Symptoms
When the ACL is injured, the person may hear or feel a “pop” in the knee, followed by pain and swelling in the knee. Other symptoms include:
- Feeling like your knee is going to give out
- Inability to put weight on the knee.
- Decreased range of motion.
The symptoms of an MCL injury can vary depending on the severity of the tear, but the common signs include:
- Pain on the inner side of the knee.
- Swelling or stiffness around the joint.
- Buckling of the knee when trying to move.
- Tenderness along the ligament.
Differences in Treatment and Recovery
One key difference between ACL and MCL injuries is the treatment approach.
ACL injuries: an ACL tear typically requires surgical intervention, especially for athletes or active individuals. Surgery can involve reconstructing the ACL and months of Physical Therapy. Without proper treatment, an ACL tear can cause long-term damage to the knee, leading to further instability and injuries to other parts of the joint, like the meniscus or cartilage.
MCL injuries: MCL tears are often treated without surgery. Mild to moderate MCL injuries can heal with rest, bracing, and PT. Severe cases where the MCL is completely torn may require surgery. MCL injuries tend to be less severe than ACL injuries which, in part, is why surgery is less frequently necessary.
Prevention of ACL and MCL Injuries
While not all injuries are preventable, there are ways to reduce the risk of ACL and MCL injuries:
- Strengthening the muscles around the knee: Strong quadriceps, hamstrings, and calf muscles help stabilize the knee joint and reduce stress on the ligaments of the knee.
- Improving agility and coordination: Exercises that enhance balance, agility, and control can help prevent injuries from sudden knee movements.
- Proper technique and body mechanics: Learning how to pivot, land, and decelerate properly can reduce the risk of ACL injuries, while maintaining good form during lateral movements can protect the MCL.