Unfortunately, knee injuries are incredibly common, especially for athletes. The most feared among them are undoubtedly ACL and MCL tears. Either injury could sideline an athlete for months or even an entire season.
While it is easy to lump the two knee injuries in the same category, they are actually quite different. Understanding the difference will help you make decisions about your treatment options. Regardless of the type of torn ligament, your orthopedic specialist will likely recommend surgery followed by physical therapy to help you recover.
Anatomy
Your knee joint is formed where three bones meet: your femur (thighbone), tibia (shinbone), and patella (kneecap). Your kneecap sits in front of the joint to provide some protection.
Bones are connected to other bones by ligaments. There are four primary ligaments in your knee and they act like strong cords to hold the bones together and keep your knee stable. The most commonly injured ligaments are the ACL and MCL, which is what we will focus on in this article.
- Anterior Cruciate Ligament (ACL) – The ligament, located in the center of the knee, that controls rotation and forward movement of the tibia (shin bone).
- Posterior Cruciate Ligament (PCL) – The ligament, located in the center of the knee, that controls backward movement of the tibia (shin bone).
- Medial Collateral Ligament (MCL) – The ligament that gives stability to the inner knee.
- Lateral Collateral Ligament (LCL) – The ligament that gives stability to the outer knee.
What is the Anterior Cruciate Ligament?
The knee is a hinge joint held together by four ligaments. A ligament is a structure in the knee that holds the bones together and helps to control joint movement or motion. There is a ligament on each side of the knee (the collateral ligaments) and two ligaments deep inside the knee. The two ligaments inside the knee that “cross” each other are called the anterior cruciate ligament (ACL) and the posterior cruciate ligament (PCL). Both ligaments attach on one side to the end of the thighbone (femur) and on the other to the top of the shinbone (tibia).
During activity, the ACL controls how far forward the tibia can “slide” relative to the femur: it essentially acts to prevent too much forward movement. While some degree of motion or sliding is normal and is required for knee function, too much motion may damage other structures in the knee which can lead to long term problems in some patients.
What is an ACL Tear?
An ACL injury is a tear or sprain of the anterior cruciate ligament— one of the strong bands of tissue that help connect your thigh bone (femur) to your shinbone (tibia). The Anterior Cruciate Ligament (ACL) is responsible for steadying the knee, keeping the knee from turning too much and preventing the tibia from overextending itself.
ACL injuries most commonly occur during sports that involve sudden stops or changes in direction, jumping and landing — such as soccer, basketball, football and downhill skiing. Many people hear a pop or feel a “popping” sensation in the knee when an ACL injury occurs. Your knee may swell, feel unstable and become too painful to bear weight.
Depending on the severity of your ACL injury, treatment may include rest and rehabilitation exercises to help you regain strength and stability, or surgery to replace the torn ligament followed by rehabilitation. A proper training program may help reduce the risk of an ACL injury.
Symptoms of ACL Tear
You may hear a sudden pop and/or feel a sudden shift in your joint at the time of an ACL injury. Most people are surprised at how loud the pop can be, and sometimes bystanders can even hear it on the sideline of a football or soccer game.
Right after an ACL tear, you can rapidly develop hemarthrosis (bleeding into your joint). This causes swelling, redness, warmth, bruising, pain, and a bubbling sensation in the joint.
What to Look For
The signs and symptoms of an ACL injury are not always the same, so it is important to see a healthcare provider if you experience any of the following:
- A loud pop or a “popping” sensation in the knee
- Severe pain and inability to continue activity
- Rapid swelling
- Loss of range of motion
- A feeling of instability or “giving way” with weight bearing
Treatment of ACL Tear
Do R.I.C.E. therapy immediately after the injury:
- R: Rest.
- I: Ice.
- C: Compression.
- E: Elevation.
The type of treatment you receive is up to you. Many people with ACL tears decide to have surgery so that they can return to the activities they did before the injury. If your activity level is not as high, you might choose to not have surgery. But, keep in mind that your torn ACL won’t heal on its own.
What is the Medial Collateral Ligament?
The medial collateral ligament (MCL) is one of four major ligaments that are critical to the stability of the knee joint. A ligament is made of tough fibrous material and functions to control excessive motion by limiting joint mobility.
The MCL spans the distance from the end of the femur (thigh bone) to the top of the tibia (shin bone) and is on the inside of the knee joint. The MCL resists widening of the inside of the joint, which can be thought of as preventing “opening-up” of the knee. If the MCL is completely torn, the injury will cause the joint to have an additional 2 degrees to 5 degrees of laxity. If other surrounding soft-tissues are damaged, then the amount of laxity will approximately double. The MCL is not the only restraint to excessive opening on the inner side of the knee, but it is the primary restraint to this movement.
What is an MCL Tear?
The MCL’s primary function is to prevent the leg from over-extending inward, but it also is part of the mechanism that stabilizes the knee and allows it to rotate. In most cases, an MCL tear happens during a rigorous sporting activity, such as football or soccer. Injuries to the medial collateral ligament most often happen when the knee is hit directly on its outer side. This stretches the ligaments on the inside of the knee too far or can tear them.
When you experience an MCL injury, you may feel pain on the inner side of the knee, swelling and bruising at the inner side of the knee, stiffness in the knee, difficulty or pain when trying to bend or straighten the knee, a feeling as though the knee may give out or buckle and even pain or difficulty walking, sitting down, rising from a chair or climbing stairs.
Symptoms of MCL Tear
You may hear a sudden pop and/or feel a sudden shift in your joint at the time of an ACL injury. Most people are surprised at how loud the pop can be, and sometimes bystanders can even hear it on the sideline of a football or soccer game.
Right after an ACL tear, you can rapidly develop hemarthrosis (bleeding into your joint). This causes swelling, redness, warmth, bruising, pain and a bubbling sensation in the joint.
What to Look For
Symptoms of an MCL sprain (Medial knee ligament sprain) depend on the severity of your injury and include:
- Pain and/or tenderness on the inside of your knee.
- You may or may not have swelling depending on how bad your MCL injury is.
- Your knee may feel uncomfortable or weak.
- More severe sprains will be significantly painful with rapid swelling.
- You will have a positive result for the valgus stress test.
Treatment of MCL Tear
If you have a mild MCL strain, it can heal on its own with rest, ice, and other self-care. You will need to raise your sore knee when you put ice on it, keep weight off the joint, and protect and compress the injury with a knee brace or elastic bandage. To ease pain and swelling, your doctor may have you take NSAIDs (nonsteroidal anti-inflammatory drugs) like aspirin, ibuprofen, or naproxen.
For more severe damage, you may need physical therapy to rehab your knee when your MCL pain begins to fade. Your physical therapist will give you exercises to strengthen the leg muscles around your knee so it works properly.
It is rare for someone with an MCL injury to need surgery, since this ligament can often heal within a few weeks or months with the help of other measures. But you might need it, especially if another part of your knee is also injured.
Whether or not you need surgery, you may be able to play sports again within a few weeks or months. Your doctor can let you know when it is OK to get back to those activities, and they may ask you to wear a knee brace when you are active.
How to Tell the Difference
Both types of injuries are painful, and since ligaments are meant to provide joint stability, either type of injury will impair a person’s mobility. The limitations vary depending on which ligament was injured. However, while both cause a lot of discomfort, technically speaking, an ACL tear could be considered as worse, since it may require surgery to fully heal. On the other hand, a minor MCL tear can heal on its own.
ACL Tear: It is common for a person to actually hear a popping sound when he or she tears an ACL. They will also experience an immediate shooting pain. If the ligament is completely severed, the person will not be able to place their full body weight on the knee, since the joint becomes unstable.
In addition, a person with a torn ACL will see the following symptoms:
- Swelling
- Tenderness
- Knee gives out
- Inability to extend the injured leg
MCL Tear: When a person injures their MCL, they will experience similar symptoms as to those of an ACL tear. However, in addition to the shooting pain, swelling, and inability to carry the body weight, the person will also feel like they have a locked knee.
Call Ventura Orthopedics Today!
A torn ACL or MCL is a serious injury that should be assessed and treated by an orthopedic surgeon. At Ventura Orthopedics, our team of knowledgeable and experienced orthopedic and sports medicine physicians can diagnose your knee injury and provide the appropriate treatment. To learn more about treatment options for a knee injury or to schedule an appointment with one of our knee specialists, call us at 800-698-1280.
