ACL injuries are common in sports requiring sudden movements, while MCL tears often result from side collisions and direct blows.
Also Symptoms of ACL tears include a popping sound, severe pain, and knee instability, while MCL tears are characterized by inner knee pain and tenderness.
For this reason, I’m here to guide you about the difference between the two, how they occur, and how to treat them.
ACL and MCL Anatomy
The anterior cruciate ligament (ACL) is a ligament that connects the thigh bone to the shin bone. It is a vital ligament that helps control the forward movement and rotation of the knee.
On the other hand, we have the medial collateral ligament (MCL) that helps to counteract the inward forces on the knee. It helps to maintain the strength and stability of the knee from the inside and prevents any sideways movement.
The four ligaments, including the posterior cruciate ligament (PCL) and the lateral collateral ligament (LCL), work together to provide a strong support system that allows our knees to function properly in various activities.
How ACL Injuries Happen
ACL injuries often occur when there is a sudden change in direction, rotation, or a sudden stop. ACL injuries are common in sports such as football, basketball, and soccer. You may have seen an athlete twisting their knee and hearing a loud ‘pop’ sound.
As you can see, it can happen to anyone, not just athletes. A simple slip or a clumsy moment can cause an ACL injury.
Causes of MCL Tears
MCL tears are usually caused by a lateral impact or a sudden change in direction. This is common in contact sports where athletes are often hit hard.
Research found that about 74,000 injuries happen each year to MCLs in the U.S. population, which is 0.24 injuries per 1,000 people. Most high school athletes hurt their knees with MCL sprains.
A football player who takes a hard side tackle or a skier whose lower leg extends outward during a fall can easily cause MCL damage.
The repeated strain can cause the MCL to lose its elasticity over time. This makes the MCL more vulnerable to injury even with minor trauma. Common causes are:
- Side Collisions
- Sudden Directional Changes
- Forceful Impacts
Symptoms of ACL Tears
ACL tears are usually caused by a sudden impact. You may hear a popping sound, followed by severe pain and swelling that makes it difficult to continue the activity.
The feeling of instability, where your knee feels like it will give way, can be both physically and mentally painful. Isn’t it?
MCL Tear Symptoms
MCL tears have their own set of symptoms. You may feel pain on the inner side of the knee where the ligament is located. Tenderness in the area is common, especially when pressed. You may also experience a catching or locking sensation in the knee joint.
This can make it difficult to move around. These symptoms are:
- Pain on the inner side of the knee
- Swelling and bruising
- Stiffness and reduced range of motion
- Instability or “giving way”
- Tenderness along the MCL
- Popping sensation at the time of injury
- Difficulty bearing weight
ACL vs MCL
The main difference between the ACL (anterior cruciate ligament) and MCL (medial collateral ligament) is that the MCL is on the inside of the knee and keeps the knee from buckling inward, while the ACL is inside the knee joint and keeps the knee stable by stopping the tibia from moving forward.
ACL injuries are often caused by sudden stops or changes in direction, while MCL injuries typically result from direct impact to the outer knee.
Now let’s talk about the differences. I’ve listed the key differences between ACL vs MCL
| Feature | ACL | MCL |
|---|
| Full Name | Anterior Cruciate Ligament | Medial Collateral Ligament |
| Location | Inside the knee, crossing in the middle | On the inner side of the knee |
| Function | Stabilizes the knee during twisting and rotation | Prevents the knee from bending inward |
| Injury Cause | Sudden stops, twists, or changes in direction | Direct blow to the outer side of the knee |
| Common Symptoms | Popping sound, swelling, instability | Pain, tenderness, stiffness, swelling |
| Healing Process | Often requires surgery for severe tears | Usually heals with rest and physical therapy |
| Sports Affected | Common in soccer, basketball, skiing | Common in football, rugby, and other contact sports |
| Severity of Recovery | Longer recovery time (6–12 months if surgery is needed) | Shorter recovery time (4–8 weeks for mild injuries) |
ACL and MCL Location
The ACL (Anterior Cruciate Ligament) and MCL (Medial Collateral Ligament) are both important ligaments in your knee, but they are located in different areas and serve different functions.
- ACL (Anterior Cruciate Ligament): Located inside the knee joint, the ACL runs diagonally in the center of the knee, connecting the femur (thigh bone) to the tibia (shin bone). It helps stabilize the knee by preventing the tibia from moving too far forward and provides rotational stability.
- MCL (Medial Collateral Ligament): Found on the inner side of the knee, the MCL runs along the medial (inside) part of the knee, connecting the femur to the tibia. It helps stabilize the knee by preventing excessive inward movement and protects against side impacts.
Both ligaments are crucial for knee stability, but ACL injuries are more common in sports involving sudden stops, pivots, or jumps, while MCL injuries often occur due to direct blows to the side of the knee.
Knee Ligament Injury Diagnosis
It is important to understand the extent of your knee ligament injury to determine its impact on your stability and function. When movement is limited, it can lead to instability.
Diagnostic tools such as physical exams, MRI imaging, and knee arthroscopy can help visualize the injury. This can help to create a rehabilitation plan.
Read More: How to Sleep After ACL Surgery ? Advice from Orthopedics
Treatment Options
The right treatment for ACL and MCL tears can help you recover from the injury.
You can choose conservative or surgical treatment options depending on the severity of the injury.
Conservative Treatments
Nonsurgical treatment for ACL and MCL tears begins with rest, ice, and anti-inflammatory medications.
A hinged knee brace can provide stability while allowing for some movement. Physical therapy is important during the early healing phase, which usually lasts 2-6 weeks. MCL tears usually heal on their own.
Therefore, initial treatment for MCL tears focuses on bracing and support.
Surgical Interventions
Acute total ruptures of the MCL require surgery. ACL reconstruction and MCL repair may be necessary for complete tears or significant instability. The graft used for MCL reconstruction depends on the graft used for ACL surgery.
The timing of the surgery depends on the amount of swelling and the range of motion. The surgeries are usually delayed until the swelling subsides and the range of motion returns to normal.
Recovery Process
ACL surgery rehabilitation begins immediately. The focus is on reducing inflammation and achieving full knee extension within the first two weeks.
Once the swelling and pain subside, physical therapy is important to regain motion and strength.
During post-op appointments, we monitor pain, inflammation, range of motion, and muscle strength for up to six months.
Preventing Further Injury
Researchers have found that a lot of people with torn ACLs also have MCL injuries, both shallow and deep. The rates for superficial injuries are 16.5% and the rates for deep injuries are 24.8%.
Preventing further injury is important for athletes recovering from ACL or MCL injuries. Functional bracing may be recommended for 1-2 years post-surgery to help with recovery and boost confidence.
A supportive knee brace can help you feel secure as you ease back into physical activities.
Follow the above tips and your doctor’s instructions and you will have a smooth and fast recovery.
