ACL vs MCL Tear: What’s the Difference?

Key Differences Between an ACL vs. MCL Tear

The ACL, or the anterior cruciate ligament, is in the center of the knee, connecting your thigh bone (femur) to your shin bone (tibia). It helps to keep your knee steady and prevents it from turning too far. The MCL, or the medial collateral ligament, runs along the inner side of the knee joint. It helps your knee to rotate and keeps it from bending too far inward.

It is important to note that the knee contains four major ligaments. In addition to the ACL and MCL, there is the posterior cruciate ligament (PCL) and the lateral collateral ligament (LCL). However, ACL and MCL tears are the most common.

While both ACL and MCL tears can affect knee stability, their causes, symptoms, and treatments vary. Understanding these injuries starts with understanding the individual functions of these two ligaments.

What Is the ACL?

The anterior cruciate ligament (ACL) runs diagonally in the middle of the knee between the femur and the tibia. It’s one of the four major ligaments in the knee, responsible for stabilizing the joint during rotational movements. The ACL helps prevent excessive anterior tibial translation relative to the femur and provides rotational stability.

When the ACL tears, it can lead to instability in the knee joint, making activities like running, cutting, or pivoting difficult. Without the ACL's stabilizing function, the knee may feel wobbly or give out during movements. Additionally, an ACL tear can contribute to long-term complications such as an increased risk of developing knee osteoarthritis or damaging the meniscus.

What Is the MCL?

The medial collateral ligament (MCL) is a band of tissue located on the inside of the knee joint. Like the ACL, it connects the femur to the tibia. However, the MCL’s purpose is to provide stability against forces that push the knee inward. The MCL is crucial for maintaining proper alignment and preventing excessive valgus stress on the knee.

A tear in the MCL often causes pain and swelling on the inner side of the knee, particularly when bearing weight or bending the knee. Depending on the severity of the tear, individuals may experience difficulty with activities that involve side-to-side movements or pressure on the knee.

How Does an ACL vs. MCL Tear Occur?

ACL and MCL tears are both common sports injuries. ACL tears often occur during sports activities that involve sudden stops or changes in direction. Common scenarios include pivoting while landing from a jump or making a sudden change in direction in contact sports like soccer or basketball.

On the other hand, MCL tears typically result from a direct blow or impact to the outside of the knee, leading to a forceful inward turning or twisting of the knee, as occurs during a tackle in football or a collision in skiing.

ACL vs. MCL Tear Symptoms

ACL and MCL tears share a variety of symptoms, including knee pain, swelling, and stiffness, as well as limitations in range of motion that affect daily activities. The following breakdown provides additional symptoms for both ACL and MCL tears.

ACL Tear Symptoms

The majority of ACL tears occur in patients under the age of 50. The tear is often associated with a sudden popping sound and sensation at the time of injury, followed by significant swelling within the first few hours. Patients with an ACL tear experience symptoms such as knee instability, making activities like walking or standing difficult.

Additionally, individuals with an ACL tear often report a feeling of the knee giving out or buckling, particularly during pivoting or sudden changes in direction.

Pain and tenderness around the knee joint are also common, along with difficulty bearing weight on the affected leg.

MCL Tear Symptoms

An MCL tear typically presents with pain and tenderness along the inner side of the knee joint. Swelling may develop gradually over several hours or days following the injury.

Patients may experience knee stiffness, particularly when bending or straightening the leg. Movements that involve bending the knee inward or applying pressure to the inner knee can exacerbate pain and discomfort.

Unlike ACL tears, individuals with MCL tears may not experience knee instability, but they may have difficulty with activities that require side-to-side movement or weight-bearing on the injured leg.

How Are ACL and MCL Tears Diagnosed?

Diagnosis typically begins with a thorough physical examination by an orthopedic surgeon, including assessment of symptoms, range of motion, and joint stability. Imaging tests such as MRI scans are often used to confirm the diagnosis and assess the extent of ligament damage. Additionally, stress tests may be performed to evaluate the stability of the knee joint and identify specific knee ligament injuries.

Treatment Options for ACL and MCL Tears

The treatment plan for both ACL and MCL tears varies depending on the severity of the injury and individual factors.

Non-surgical approaches may include:

• Rest
• Ice
• Elevation
• Non-steroidal anti-inflammatory drugs (NSAIDs)
• Physical therapy
• Bracing to stabilize the knee

Surgical intervention is almost always recommended for ACL tears and may be recommended for more severe MCL tears or cases of persistent instability.

Treatment Options for ACL Tears

For partial tears of the ACL or individuals with a low activity level, conservative management may be recommended. This typically involves non-surgical treatment such as rest, physical therapy to improve knee stability and strengthen the surrounding muscles, and the use of a knee brace to support the joint during activities.

However, for the vast majority of ACL tears we see (about 95%), surgical reconstruction is necessary. ACL reconstruction surgery involves replacing the torn ligament with a graft, typically from the patient’s own hamstring tendon, quad tendon, patellar tendon, or a donor tendon. Surgery aims to restore stability to the knee joint and reduce the risk of future injuries.

Treatment Options for MCL Tears

Most MCL tears can be managed conservatively with rest, ice, compression, and elevation (RICE therapy), along with the use of nonsteroidal anti-inflammatory drugs (NSAIDs) to reduce pain and swelling. Physical therapy is often prescribed to help restore range of motion, strengthen the knee muscles, and improve overall stability. Additionally, using crutches or wearing a knee brace may be recommended to protect the injured ligament and provide support.

In rare cases of severe MCL tears, or when the ligament fails to heal properly with conservative treatment, surgical repair or reconstruction may be considered. Surgery aims to reattach the torn ligament to its anatomical position or reconstruct it using graft tissue. This helps restore stability to the knee joint and allows individuals to return to their pre-injury level of function.

How Does Recovery Differ for ACL vs. MCL Tears?

Recovery timelines for ACL and MCL tears are vastly different. ACL tears usually require surgery, followed by 6-12 months of rehab to rebuild strength, mobility, and knee stability. MCL tears, in contrast, can often heal on their own with physical therapy in just 6-8 weeks. This therapy focuses on managing pain, gradually returning to activities, and strengthening exercises to support the ligament as it heals. MCL tears requiring surgical intervention can take up to 12 months to heal.

Turn to Alexander Orthopaedics for Your Knee Injury Treatment

If you’re experiencing symptoms of an ACL or MCL tear, don’t wait to seek professional care. Our experienced orthopedic team at Alexander Orthopaedics specializes in diagnosing and treating knee injuries, offering personalized care and advanced treatment options to help you recover and return to the activities you love. Contact us today to schedule a consultation.