MCL vs ACL Tear - What's the Difference?

What’s the difference between MCL vs ACL injuries? There are four ligaments of the knee designed to stabilize the knee and keep it functioning optimally with your daily activities. A ligament tear, also known as a strain, can occur for a variety of reasons. However, it is most often a result of high impact. One of the most common knee injuries is an anterior cruciate ligament tear, or ACL tear. There are 3 other ligaments in the knee that are also susceptible to tears, including the medial collateral ligament (MCL).

Keep reading to understand the difference between these two fairly common knee injuries. If you’ve sustained a knee injury, understanding what tissues are involved and the mechanisms that cause a tear can help you choose the best possible treatment moving forward.

MCL vs ACL - What’s the Difference?

There are a few key factors to keep in mind when understanding the difference between an MCL tear and ACL tear. We’ll dive into some of the specifics so that you can start to differentiate between the two following a ligament tear.

Location

The ACL and MCL both provide stability and protection to the knee, but the way they provide support varies due to location.

• Where is the ACL Ligament Located?

  The ACL ligament crosses the inside of  the knee joint itself, connecting the thigh bone (femur) to the shinbone (tibia). Together with the posterior cruciate ligament (PCL), these two central ligaments prevent excessive forward and backward movement of the knee.

  More on ACL Tears

• Where is the MCL Ligament Located? 

  The MCL ligament, along with the lateral collateral ligament (LCL), provide stability to the sides of the knee. The MCL connects the inner thigh bone and shinbone, protecting the joint from awkward sideways motion.

Symptoms

A few discerning symptoms can help you get an idea of what type of knee injury you are dealing with. Although, when the knee is involved you can expect a lot of the same general symptoms, such as knee pain, swelling, and knee instability.

• ACL Symptoms

  The ACL is considered the primary stabilizing ligament of the knee. Thus, injury often results in a feeling of instability or a sense that the knee will give out with weight bearing. Additionally, an ACL tear is often accompanied by a large pop or snapping sensation when the injury occurs. A larger tear usually involves severe pain and quick onset of swelling as well.

  Learn More About ACL Injuries Here

• MCL Symptoms

  Is more of an accessory ligament for knee stability, making the symptoms associated with it typically less severe than an ACL tear. The most defining symptom is pain along the inner knee joint with palpation. Symptoms of instability, pain and swelling are also possible but tend to be less severe.

  Learn More About MCL Injuries Here

Causes & Risk Factors

The basic causes and risk factors associated with a knee ligament injury are the same regardless of which one is affected.

• Sports or activities that can cause a sudden high impact to the knee are the biggest cause of injury.

• Sudden changes in direction, pivoting, and jumping during these sports are also a major cause.

• Direction of impact will be the biggest determining factor for which ligament would be affected and damaged.

• A torn ACL is most often caused by a direct impact to the front of the thigh or back of the calf. This causes the knee to separate beyond its normal tissue health and tear. Common contact sports that lead to an ACL tear with impact include football, basketball, soccer, and downhill skiing.

• An MCL tear is sustained by a slightly different direction of impact that originates from the outside of the knee, causing the knee to awkwardly buckle inward/medially.

It’s important to note that a severe impact can often cause the tearing of multiple ligaments at once. The ACL and MCL, in addition to the menisci and other cartilage within the knee, are often all injured at once with severe injuries.

Which Injury is Worse?

Generally speaking, an ACL injury fares worse than an MCL injury. Due to the ACL’s location in the inner knee, a severe injury that results in instability will most likely require surgery. Whereas, an MCL injury doesn’t usually warrant surgical intervention. Since any type of surgery is invasive, it can require up to 6 months to fully recover from ACL surgery. Additionally, the ACL is a larger ligament that provides significant stability to the knee. Thus, an ACL injury is more likely to lead to future complications, such as osteoarthritis, when compared to an MCL tear.

Treatment for an ACL Tear

Treatment for an MCL Injury

How to Get a Proper Diagnosis

If your knee symptoms last more than a few days, a formal assessment should be done by your orthopaedic doctor or physical therapist following a knee injury. Firstly, they will talk to you about your history and what the mechanism of injury was (for example; they’ll want to know how you were hit and if you heard a popping sound). Then, a physical exam is often enough to determine what type of knee injury you are dealing with.

There are special orthopedic tests that can be utilized to determine if there is damage or laxity within the ACL, PCL, MCL, LCL, meniscus, and more. Plus, they will assess your knee strength, range of motion, and coordination.

If your doctor suspects a more severe injury, such as a large or complete tear or even a fracture, diagnostic imaging tests can be ordered too. An x-ray can rule out fractures, while an MRI can assess the extent of soft tissue damage within the knee. Ultimately, professional guidance will help you get the best possible recovery and results.

Next Steps

Once you know what type of knee injury you are dealing with and the extent of damage, it’s time to start the recovery process. Whether a surgery like ACL reconstruction is needed will depend on the state of your knee function and level of instability. Either way, appropriate pain management, a round of physical therapy, and finding a knee brace for your sport or any other higher level activity can help you on your way to restoring normal knee function. Talk to your doctor and physical therapist to get started and seek immediate medical advice you have any concerns about your symptoms.

References:

https://www.mayoclinic.org/diseases-conditions/acl-injury/symptoms-causes/syc-20350738

https://www.medicalnewstoday.com/articles/324738#symptoms

https://coremedicalwellness.com/acl-or-mcl-injury-know-the-difference/

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