What are ACL, MCL, and meniscus tears?
Knee injuries are common, particularly among athletes and active individuals. One of the most prevalent sports-related injuries is tears within the knee joint.
The knee is a complex joint that consists of various ligaments and structures. Tears can occur across different parts of the knee, such as the anterior cruciate ligament (ACL), medial collateral ligament (MCL), or the meniscus.
Each structure plays a distinct role in knee stability and function, and injuries to these structures can have significant impacts on mobility and quality of life. Hence, identifying the specific type of tear is crucial for appropriate diagnosis and treatment.
ACL tear
An ACL injury occurs when the ACL is either stretched, partially torn, or completely torn. The most common injury is a complete tear.
The ACL is a key ligament located at the centre of the knee that connects the thighbone (femur) to the shinbone (tibia). It prevents the shinbone from sliding out in front of the thighbone. The posterior cruciate ligament (PCL) works with the ACL. It prevents the shinbone from sliding backward under the thighbone.
Doctors will usually grade ACL injuries and tears. These grades are a quick way to describe the extent of your injury. ACL injury grades range from one (the least severe) to three (the most severe):
Grade 1:
The injury stretched your ACL sufficiently to cause damage, yet it remains intact, holding your knee bones together.
Grade 2:
The injury significantly stretched your ACL, causing it to partially tear and loosen.
Grade 3:
A complete tear resulting in the separation of your ACL into two separate pieces.
MCL tear
An MCL injury occurs when there is damage to your medial collateral ligament (MCL), causing a tear. A partial tear occurs when some fibres in the ligament rip, while a complete tear splits the ligament into two pieces.
The MCL is located on the inner side of the knee and helps stabilise the joint against forces that push it inward. It also helps to keep the tibia from moving too far to the side.
Similar to ACL injuries, MCL injuries are also graded by severity, such as:
Grade 1:
A grade 1 MCL tear is a mild tear in which less than 10% of fibres in your ligament are torn and your knee is still stable.
You’ll likely have some tenderness and mild pain if you have a grade 1 tear.
Grade 2:
A grade 2 MCL tear is a moderate tear, meaning your MCL is partially torn — usually the superficial part of your MCL.
Your knee will likely be loose when it’s moved by hand, and you’ll probably have intense pain and tenderness along the inner side of your knee.
Grade 3:
A grade 3 MCL tear is a severe tear, meaning that your MCL is completely torn — both the superficial and deep parts.
Your knee will likely be very unstable and loose, and you’ll probably experience intense pain and tenderness.
If you have a grade 3 MCL tear, it is common for them to also have other knee injuries, particularly damage to their anterior cruciate ligament (ACL).
Meniscus tear
A meniscus tear is a tear in the tough cartilage inside your knee. The meniscus consists of two C-shaped pieces of cartilage that act as a cushion between the femur and tibia. It helps to absorb shock and provide more stability to the knee joint.
There are two types of meniscus tears:
Medial meniscus:
A medial meniscus tear affects the cartilage on the inside of your knee.
Lateral meniscus:
A lateral meniscus tear affects the cartilage on the outside of your knee.
How Do These Knee Injuries Occur?
ACL tears:
ACL tears are typically acute injuries that frequently occur during sports, particularly in situations involving high-impact collisions, sudden changes in direction, and jumping.
MCL tears:
MCL tears typically result from a blow to the outer knee or a sudden change in direction.
Meniscus tears:
Tears can occur due to frequent or rough twisting or rotation of the knee.
Other causes include trauma or gradual degeneration with age.
Symptoms of ACL, MCL, and Meniscus Tears
ACL tear:
Popping sound
Immediate swelling
Knee pain
A feeling of instability and difficulty bearing weight as if your knee is giving way
MCL tear:
Pain and tenderness on the inner knee
Swelling
Some difficulty with weight-bearing
Possible locking or buckling of the knee
Meniscus tear:
Knee pain (especially when twisting)
Swelling
Stiffness
Trouble straightening your knee
Sensation of your knee locking in place
The information provided is intended for general guidance only and should not be considered medical advice. If you are experiencing any of the symptoms listed above, please consult with an orthopaedic specialist to learn more about your unique situation. Request an appointment with Thomson Medical today.
How do I tell the difference between the three?
While symptoms of the three different tears often overlap, some distinctions can be made:
ACL injuries typically cause a popping sensation and immediate instability.
MCL injuries present with pain and tenderness along the inner knee.
Meniscus tears often cause locking, catching, or a feeling of the knee giving way.
However, only a thorough clinical assessment with an orthopaedic specialist and the use of imaging technology such as X-rays or MRIs can definitively distinguish between these injuries.
What is an "unhappy triad"?
A combined ACL, MCL, and meniscus tear is known as an "unhappy triad" or "knee blowout". This is a complex knee injury that can result from high-force contact to the lateral (outside) part of the knee. It often occurs when the foot is fixed to the floor, such as during sports such as football, rugby, or motocross.
If you suffer from this condition, it typically means that you have severely restricted movement and experience a lot of pain and discomfort. A complete medical examination, conducted by a professional orthopaedic specialist, is the best course of action in the case of severe trauma to the knee.
This type of injury will almost always require surgery—usually the ACL and often the meniscus. Sometimes, surgeons also operate on the MCL. This decision depends on your current function and whether your surgeon thinks the MCL can heal without surgery.
It is crucial to understand and distinguish between the three partial injuries to formulate the most efficient treatment plan.
How are these knee injuries diagnosed?
A complete medical examination, conducted by an orthopaedic specialist, is the best course of action in the case of severe trauma to the knee.
The specialist will review details of your injury and study your medical history to find similar previous injuries that could affect your knee function. They will also conduct a physical examination, assessing your symptoms by checking your knee stability, range of motion, and any swelling or tenderness.
Sophisticated imaging technology, including X-rays and MRIs, can be used to detect the full extent of the injury to individual parts of the knee joint. X-rays are used to rule out a bone injury, while knee MRI scans are used to visualise ligament and cartilage damage.
Treatment options
Non-surgical treatment
In most cases, non-surgical treatment is recommended for minor tears. It is also the best option for people who are not suitable candidates for surgery. This may include:
Rest, Ice, Compression, Elevation (RICE):
Reduces pain and swelling.
Physical therapy:
Improves strength, flexibility, and range of motion.
Braces or crutches:
Knee braces or crutches provide support and prevent further injury.
Medication:
Pain relief and anti-inflammatory drugs as needed.
Minor MCL injuries and some meniscus tears may heal with nonsurgical treatment, especially in less active individuals.
Surgical treatment
In more severe cases, surgical intervention may be necessary to restore stability and function to the knee joint. The type of surgery performed will depend on the specific injury:
ACL reconstruction or repair:
ACL reconstruction or repair is often necessary for athletes or individuals with significant instability.
In an ACL repair, the torn ligament is stitched back together.
In an ACL reconstruction, a new ligament is made from a piece of tendon from another part of the body or from a donor.
Meniscus repair or partial removal:
This depends on the location and severity of the tear.
In a meniscus repair, the torn cartilage is stitched back together.
In some cases, the torn cartilage may need to be removed. This is usually only done if the tear is too large to repair.
MCL repair:
MCL repair is rarely necessary, but it is considered in cases of severe or combined injuries.
After the surgery, you will need to wear a knee brace and follow a rehabilitation programme. The exercise programme provided by a physiotherapist improves your knee’s range of motion, strength, and flexibility.
The amount of time it takes for you to recover from surgery will vary depending on the type of injury and treatment.
Recovering from an ACL tear typically takes between 6 and 12 months. During this period, it is common to wear a knee brace and use crutches to assist with mobility.
The recovery time for an MCL tear is generally shorter, ranging from 3 to 6 weeks. Similarly, you will need to wear a knee brace to stabilise your knees.
The recovery time for a meniscus tear can vary depending on its severity. Following meniscus surgery, the recovery time is typically around 4 to 6 weeks. During this time, you may also need to wear a knee brace and attend physical therapy, which is important to regain strength, range of motion, and stability in the knee joint.
The information provided is intended for general guidance only and should not be considered medical advice. If you are curious to find out more about the different treatment options for varying knee injuries, please consult with an orthopaedic specialist. Request an appointment with Thomson Medical today.
How to prevent these injuries?
While not all knee injuries can be prevented, you can take steps to lower your risk.
Strengthen leg and core muscles:
Focus on quadriceps, hamstrings, and core stability.
Building strong muscles in your thighs, hips, and core can give your knees better support and stability.
Exercises like squats, lunges, and leg presses can help.
Using proper technique:
Use correct movement patterns during sports and exercise, especially when jumping or changing direction.
When jumping, focus on landing softly with your knees bent to reduce impact.
Avoid twisting with your feet planted when pivoting, as this can strain the meniscus.
If you're unsure about technique, consider working with an athletic coach or physical therapist.
Avoid overexertion:
Don’t exercise when fatigued, as tired muscles increase injury risk.
Exercises like yoga, Pilates, and balance drills improve coordination and control, potentially reducing injury risks.
Warm up and wear supportive footwear:
Reduces stress on knee ligaments.
FAQ
How do I know if I've torn my ACL, MCL, or meniscus?
Key signs include a popping sound (ACL, meniscus), swelling, pain, instability (ACL, MCL), and locking or catching (meniscus). Only a medical evaluation can confirm the diagnosis.
Which is worse, an MCL tear or a meniscus tear?
Severity depends on the grade and individual circumstances. MCL tears often heal with non-surgical treatment, while some meniscus tears may require surgery. Both can cause significant pain and disability if untreated.
What is worse, an ACL tear or a meniscus tear?
ACL tears generally cause more instability and often require surgical repair, especially in active individuals. Meniscus tears may heal on their own or need surgery depending on the type and location.
What's the most painful ligament to tear?
Pain perception varies, but ACL tears are often described as particularly painful, especially due to the associated instability and swelling.
Can a meniscus heal on its own?
Some small meniscus tears, particularly those on the outer edge with good blood supply, can heal without surgery. Larger or complex tears usually require intervention.
Can I bend my knee with a torn ACL?
You may still be able to bend your knee, but it will likely feel unstable and may give way, especially during twisting or turning movements.
The information provided is intended for general guidance only and should not be considered medical advice. For personalised recommendations and tailored advice, please consult a specialist at Thomson Medical. Request an appointment with Thomson Medical today.
For more information, contact us:
Thomson Specialists (Thomson Medical Centre) — Orthopaedic
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