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

If your knee feels like it's locking, catching, or getting stuck, a meniscus tear is one of the most common causes. Many people describe it as a sudden block when trying to straighten or bend the knee. Others notice swelling, pain with twisting, or the feeling that something is "out of place."

Understanding what the meniscus does, how it tears, and what to do next can help you take the right steps without unnecessary worry.

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What Is the Meniscus?

Each knee has two menisci (plural of meniscus):

• Medial meniscus (inner side of the knee)
• Lateral meniscus (outer side of the knee)

These are C-shaped pieces of cartilage that:

• Act as shock absorbers
• Help distribute body weight across the knee joint
• Provide stability
• Protect the bones from wear and tear

When the meniscus is healthy, it allows smooth bending and straightening of the knee. When torn, it can interfere with normal movement.

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Why Does a Meniscus Tear Cause Knee Locking?

A torn meniscus can create a mechanical block inside the joint.

Here's how:

• A flap of torn cartilage may catch between the bones.
• A larger tear (like a "bucket handle" tear) can fold over and block motion.
• Swelling from the injury may tighten the joint space.
• The knee may reflexively tighten surrounding muscles, limiting movement.

True locking means the knee physically cannot fully straighten or bend. Some people experience "pseudo-locking," where pain and swelling make it feel stuck even though the joint isn't mechanically blocked.

If you're experiencing difficulty with knee movement and want to understand what might be causing it, try Ubie's Can't bend the knee symptom checker — it's free and takes just a few minutes to help identify possible causes before your doctor's appointment.

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Common Causes of a Meniscus Tear

A meniscus tear can happen suddenly or gradually.

1. Sudden (Traumatic) Tears

More common in younger or active individuals:

• Twisting the knee while the foot is planted
• Sudden pivoting during sports
• Squatting and turning at the same time
• Direct impact to the knee

You may hear or feel a "pop" at the time of injury.

2. Degenerative Tears

More common over age 40:

• Gradual wear and thinning of cartilage
• Small movements leading to tearing
• Often associated with early arthritis

In degenerative cases, the tear may occur during everyday activities like standing up or kneeling.

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Symptoms of a Torn Meniscus

Not every meniscus tear causes locking. Symptoms vary depending on the size and location of the tear.

Common symptoms include:

• Knee locking or catching
• Difficulty bending or straightening the knee
• Swelling (immediate or delayed by 24–48 hours)
• Joint line tenderness (pain along the inner or outer knee)
• A feeling of instability
• Pain with twisting or squatting

Some smaller tears may cause only mild discomfort.

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When Is Knee Locking Serious?

Knee locking deserves attention, especially if:

• You cannot fully straighten your leg
• The knee becomes increasingly swollen
• You cannot bear weight
• The knee feels unstable
• You develop fever, redness, or severe pain

True mechanical locking from a meniscus tear often requires prompt medical evaluation. While not typically life-threatening, untreated locking can lead to joint damage over time.

If symptoms are severe, worsening, or associated with other concerning signs, speak to a doctor right away.

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How Doctors Diagnose a Meniscus Tear

1. Medical History

Your doctor will ask about:

• How the injury happened
• When symptoms began
• Whether the knee locks or catches
• Past knee injuries

2. Physical Examination

They may:

• Press along the joint line
• Bend and rotate your knee
• Check range of motion
• Test stability

Certain movements reproduce pain in a torn meniscus.

3. Imaging

• X-rays: Rule out fractures or arthritis (they don't show the meniscus itself).
• MRI: The best imaging test for confirming a meniscus tear and determining its type and size.

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Types of Meniscus Tears

Different tear patterns influence treatment decisions:

• Small stable tears – may heal or improve with conservative care.
• Flap tears – can cause catching.
• Bucket-handle tears – often cause true locking.
• Degenerative fraying – common with aging.

The location matters too. The outer third of the meniscus has better blood supply and healing potential. The inner portion has limited blood flow.

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Medical Next Steps

Treatment depends on:

• Your age
• Activity level
• Tear type and size
• Severity of symptoms
• Presence of arthritis

1. Conservative (Non-Surgical) Treatment

Many meniscus tears improve without surgery.

Options include:

• Rest and activity modification
• Ice and elevation
• Anti-inflammatory medications (if appropriate for you)
• Physical therapy
  • Strengthening thigh muscles
  • Improving flexibility
  • Restoring range of motion
• Bracing in some cases

Research shows that in middle-aged and older adults with degenerative meniscus tears, physical therapy can be as effective as surgery for many patients.

Improvement may take several weeks.

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2. Injections

In some cases:

• Corticosteroid injections may reduce inflammation and pain.
• These do not repair the meniscus but may help with symptoms.

Your doctor will discuss risks and benefits based on your health profile.

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3. Surgical Treatment

Surgery is considered if:

• The knee is truly locked
• Symptoms persist despite therapy
• There is a large or unstable tear
• You are young and active with a repairable tear

The most common procedures include:

Arthroscopic Meniscus Repair

• The torn edges are stitched together.
• More common in younger patients.
• Requires longer recovery but preserves cartilage.

Partial Meniscectomy

• The damaged portion is trimmed away.
• Shorter recovery time.
• Removes damaged tissue but reduces cushioning.

Whenever possible, preserving the meniscus is preferred because removing tissue may increase the long-term risk of arthritis.

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Recovery Timeline

Recovery depends on treatment type.

Conservative care:

• 4–8 weeks for significant improvement
• Gradual return to activity

After partial meniscectomy:

• Walking within days
• Return to many activities in 4–6 weeks

After meniscus repair:

• Limited weight-bearing for several weeks
• Full recovery may take 3–6 months

Your orthopedic specialist will give a personalized plan.

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Can a Meniscus Tear Heal on Its Own?

Some tears can improve, especially:

• Small tears
• Tears in the outer vascular zone
• Degenerative tears responding to strengthening therapy

However, larger unstable tears usually do not "heal" without intervention.

Ignoring persistent locking is not recommended. Ongoing mechanical blockage can damage joint cartilage over time.

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Protecting Your Knee Moving Forward

To reduce stress on the meniscus:

• Maintain a healthy weight
• Strengthen quadriceps and hamstrings
• Avoid deep twisting under load
• Warm up before sports
• Use proper technique during exercise

Strong muscles support and stabilize the knee, reducing strain on the meniscus.

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When to Speak to a Doctor

You should speak to a doctor if:

• Your knee is locked and cannot straighten
• Swelling is significant
• Pain interferes with daily life
• Symptoms last more than a few days after injury
• You are unsure what is causing your symptoms

While most meniscus tears are not life-threatening, untreated knee injuries can lead to long-term joint problems. If symptoms are severe or worsening, seek medical care promptly.

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The Bottom Line

A torn meniscus is a common cause of knee locking, especially after twisting injuries or with age-related wear. The meniscus plays a critical role in cushioning and stabilizing your knee, so symptoms shouldn't be ignored.

The good news:
Many meniscus tears improve with conservative treatment. Surgery is reserved for persistent symptoms or true mechanical locking.

If your knee feels stuck, painful, or unstable, consider starting with a symptom check and then speak to a qualified healthcare professional. Early evaluation helps protect your joint and ensures you receive the right treatment at the right time.

Always speak to a doctor about any symptoms that are severe, worsening, or potentially serious.