Knee Locking? Why Your Meniscus Is Torn and Medical Next Steps

If your knee feels like it's catching, locking, or getting stuck, a meniscus tear is one of the most common causes. Many people describe it as:

• "My knee won't fully straighten."
• "It feels like something is blocking it."
• "It clicks and then gets stuck."

Knee locking is not something to ignore. While it's often treatable, it can signal a mechanical problem inside the joint that may need medical attention.

Here's what you need to know about why a meniscus tear causes knee locking and what to do next.

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What Is the Meniscus?

Each knee has two pieces of rubbery cartilage called the menisci (plural of meniscus). They act like shock absorbers between your thigh bone (femur) and shin bone (tibia).

The meniscus:

• Cushions and stabilizes the knee
• Distributes weight evenly
• Helps the joint glide smoothly

When one of these cartilage pads tears, it can interfere with normal knee movement.

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What Is a Meniscus Tear?

A meniscus tear happens when the cartilage is damaged, usually from:

• Twisting or pivoting quickly (sports injuries)
• Squatting and lifting heavy weight
• Sudden changes in direction
• Age-related wear and tear (degenerative tears)

You don't always have to be an athlete. In adults over 40, meniscus tears often happen with simple movements like turning while standing up.

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Why Does a Meniscus Tear Cause Knee Locking?

Not all meniscus tears cause locking. But certain types are more likely to.

1. A Flap of Torn Cartilage Gets Stuck

When part of the meniscus tears, a loose flap can move into the joint space. This may:

• Block full straightening
• Cause catching or clicking
• Create a "locked" sensation

This is called mechanical locking and often needs medical evaluation.

2. A "Bucket-Handle" Tear

This is a more serious type of meniscus tear where a large piece of cartilage flips inward like a handle.

It can:

• Physically prevent the knee from straightening
• Cause sudden, complete locking
• Lead to significant swelling

True mechanical locking (where you physically cannot move the knee) is different from stiffness due to swelling.

3. Swelling and Inflammation

Even without a large tear, inflammation can:

• Tighten the joint
• Limit bending or straightening
• Make the knee feel stuck

This type of "locking" may improve with rest and treatment.

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Common Symptoms of a Meniscus Tear

A meniscus tear often causes:

• Knee locking or catching
• Clicking or popping
• Pain along the joint line
• Swelling (usually within 24–48 hours)
• Difficulty bending or straightening the knee
• Feeling like the knee might give out

If you're struggling with limited mobility and wondering what might be causing it, try this free Can't bend the knee symptom checker to explore possible causes and get guidance on next steps.

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When Is Knee Locking Serious?

Not all locking is an emergency. However, you should seek prompt medical care if:

• The knee is completely stuck and won't move
• You cannot bear weight
• There is significant swelling
• The pain is severe
• The knee looks deformed
• You had a major injury (fall, car accident)

These may signal a large meniscus tear, ligament injury (like ACL), or fracture.

If you experience signs of infection (fever, redness, warmth spreading) or symptoms suggesting a blood clot (calf swelling, chest pain, shortness of breath), seek urgent medical care immediately.

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How Doctors Diagnose a Meniscus Tear

A healthcare professional will typically:

1. Ask About Your Symptoms

They may ask:

• When did the locking start?
• Was there a twisting injury?
• Does it click or pop?
• Does it fully lock or just feel stiff?

2. Perform a Physical Exam

Doctors check:

• Joint line tenderness
• Range of motion
• Stability of ligaments
• Specific meniscus stress tests

3. Order Imaging (If Needed)

• MRI is the best test for confirming a meniscus tear.
• X-rays don't show the meniscus but can rule out arthritis or fractures.

Not everyone needs an MRI immediately. Many mild tears improve with conservative treatment.

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Medical Next Steps: Treatment Options

Treatment depends on:

• Your age
• Activity level
• Type of meniscus tear
• Severity of locking
• Presence of arthritis

1. Conservative (Non-Surgical) Treatment

Many meniscus tears improve without surgery, especially degenerative tears.

Typical treatment includes:

• Rest from aggravating activities
• Ice 15–20 minutes several times a day
• Compression with a knee sleeve
• Elevation
• Anti-inflammatory medication (if approved by your doctor)
• Physical therapy

Physical therapy focuses on:

• Strengthening the quadriceps and hamstrings
• Improving stability
• Restoring range of motion

For many people, symptoms improve within 4–8 weeks.

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2. Injections

In some cases, your doctor may suggest:

• Corticosteroid injections to reduce inflammation
• Other joint injections depending on your specific condition

These can help with pain but do not repair the torn cartilage.

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3. Surgery

Surgery may be recommended if:

• The knee is mechanically locked
• A large or bucket-handle tear is present
• Symptoms persist after conservative care
• You are younger and active
• The tear is repairable

Most procedures are done arthroscopically (minimally invasive).

There are two main types:

• Meniscus repair (stitching the tear)
• Partial meniscectomy (removing the torn portion)

Whenever possible, preserving the meniscus is preferred because removing it increases long-term arthritis risk.

Recovery varies:

• Meniscus repair: several months of rehab
• Partial removal: often quicker recovery

Your orthopedic specialist will help determine the best option.

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What Happens If You Ignore a Meniscus Tear?

Some small tears may not cause long-term harm. However, ongoing mechanical locking or untreated tears can:

• Increase cartilage wear
• Lead to early arthritis
• Cause repeated swelling
• Limit activity

That doesn't mean you need surgery immediately. But persistent locking deserves evaluation.

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Can a Meniscus Tear Heal on Its Own?

It depends on the location.

The outer third of the meniscus has a blood supply and may heal.
The inner portion has very limited blood flow and does not heal well on its own.

This is why some tears improve with therapy, while others require surgical repair.

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Practical Steps You Can Take Now

If your knee is locking:

• Stop activities that trigger the locking
• Avoid deep squatting or twisting
• Apply ice if swollen
• Use support if needed
• Monitor whether the knee fully unlocks

If the locking continues or worsens, schedule a medical evaluation.

You may also benefit from starting with a free, online symptom check for Can't bend the knee to organize your symptoms before seeing a doctor.

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When to Speak to a Doctor

You should speak to a healthcare professional if:

• Locking happens repeatedly
• The knee won't fully straighten
• Swelling doesn't improve
• Pain limits daily activities
• You suspect a sports-related injury
• You are unsure what's causing the problem

While most meniscus tears are not life-threatening, untreated joint problems can worsen over time. Prompt evaluation helps prevent long-term damage.

If you experience severe pain, inability to bear weight, signs of infection, or symptoms of a blood clot, seek immediate medical care.

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The Bottom Line

Knee locking is often caused by a meniscus tear, especially when the knee feels stuck, catches, or won't straighten. Some tears improve with rest and physical therapy. Others—particularly those causing true mechanical locking—may require surgical treatment.

The key is not to panic, but also not to ignore persistent symptoms. Early evaluation gives you more options and better outcomes.

If your knee won't bend or straighten properly, consider starting with a free online symptom check and then speak to a doctor to determine the safest and most effective next steps for you.