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Knee Locking

What to do when your knee gets stuck.
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Last updated August 27, 2020

Knee locking questionnaire

Use our free symptom checker to find out what's causing your knee locking.

Knee locking questionnaire

Use our free symptom checker to find out what's causing your knee locking.

Knee locking symptom checker

What is knee locking?

Knee locking is when your knee briefly becomes stuck in one position, either when it’s bent or straight. You might feel like your knee is popping or catching when you try to move your leg, or that it buckles under you when you’re standing. 

Your knee joint is made of bone, cartilage, tendons, and ligaments. Damage to any of these parts can lead to knee locking and instability. But the most likely culprit is the meniscus, which is the part of the knee that contains cartilage.

There are two kinds of knee locking. "True knee locking” is when you can’t straighten your knee for a few minutes. It’s usually caused by damage to the bones or cartilage within the knee.

“Pseudo knee locking” is when pain causes a temporary muscle spasm and the knee briefly locks up. This is often due to damage in the area surrounding your knee. There are other issues that can lead to knee locking, like wear and tear on your joints.

You can often try to treat a locked knee at home with rest, ice, and ibuprofen (Advil). If it’s not improving, see a doctor. In some cases you might need surgery or other medical treatments. If it comes on suddenly or is painful and makes it hard to walk, see a doctor immediately.

What can stop a knee from locking?

"Improving your strength helps stabilize your knee and can prevent future injuries. Ask what exercises you can do to strengthen your leg muscles. Once you have an exercise regimen, stick to it. Your knees will thank you!" —Dr. Anne Jacobsen

Causes of knee locking

1. Meniscus tear

Symptoms

  • Knee pain on the inner or outer sides of the kneecap
  • Knee swelling
  • Knee catching, locking, or giving way
  • Knee stiffness

Your knees have two pieces of cartilage, called meniscus, that act as shock absorbers where the knee hits your thigh bone and shin bone. They can become damaged or torn during forceful, twisting movements, or if your knee is hit, like during a tackle. The torn part of the meniscus can get stuck in the knee joint, causing it to lock up. Because the meniscus gets thinner and weaker with aging, older people may tear it during normal activity.

Treating a meniscus tear

Depending on the injury, the tear could heal on its own with rest, ice, elevation, and NSAIDs. In other cases, you might need arthroscopic surgery (through small incisions) followed by rehabilitation.

2. Ligament injury

Symptoms

  • Knee injury (you may feel a “pop”)
  • Knee pain on the inner or outer sides of the kneecap
  • Knee swelling
  • Knee locking or decreased range of motion
  • Instability or a feeling like your knee “gives way”

There are two strong bands of tissue called ligaments that cross over the middle of your knee to keep it stable. One is the ACL (anterior cruciate ligament), which attaches the thigh bone to the shin bone. It can stretch or tear with a direct hit to the knee or with sudden stopping or pivoting.  The PCL (posterior cruciate ligament) is behind the ACL and is much less commonly injured.

Two additional ligaments, the LCL (lateral collateral ligament) and MCL (medial collateral ligament) are on the sides of the knee. The LCL is more likely to be injured than the MCL, usually by a force to the inner side of the knee or overextension of the knee joint.

Treating a ligament injury

Treatment usually includes rest, ice, elevation, NSAIDs, compression with a wrap, and rehabilitation. Sometimes surgery is needed.

Knee locking questionnaire

Use our free symptom checker to find out what's causing your knee locking.

Knee locking symptom checker

3. Arthritis

Symptoms

Arthritis is pain and inflammation in one or more of your joints. The CDC estimates that 23% of American adults have it. Any joint in your body can be affected by arthritis, but knee arthritis is very common. This is because the knee is a weight-bearing joint that is exposed to a lot of stress throughout your life.

There are several types of arthritis. Osteoarthritis, which is caused by wear and tear on a joint, is the most common form. Rheumatoid arthritis and psoriatic arthritis are autoimmune diseases that target the healthy tissues covering your joints.

Treating arthritis

Your doctor can diagnose arthritis by examining the joint and sometimes using X-rays to look at damage. Treatments include medications, cortisone (steroid) injections into the joint, and in severe cases, knee replacement surgery.

4. Dislocated kneecap

Symptoms

  • Knee injury associated with a “pop”
  • Constant pain at the front of the knee
  • Knee locking or catching
  • Knee swelling
  • Difficulty with walking or inability to walk

The kneecap (patella) connects the muscles in the front of your thigh to your shinbone. If your kneecap slips out of its groove and becomes dislocated, it can cause your knee to lock. This injury usually happens during sports, when your knee is hit directly or you twist while your knee is bent.

Treating a dislocated kneecap

The kneecap can be moved back in place while you are awake—it’s a very quick procedure. Pain medication may be given to help with the brief discomfort, but you’ll feel better when it’s back in its normal place.

A brace, crutches, rest, ice, and NSAIDs will help it heal. If the bone is broken or if the kneecap becomes dislocated more than once, you may need surgery.

Is a dislocated kneecap the same as a dislocated knee?

A kneecap (patellar) dislocation is not the same as a knee dislocation! When the actual knee joint becomes dislocated, it is much more serious—it can injure blood vessels—and is usually related to a significant impact, like a bad car accident. —Dr. Jacobsen

5. Plica syndrome

Symptoms

  • Knee pain, especially when going up or down stairs
  • Knee clicking
  • Knee locking or catching
  • Knee swelling
  • Knee gives way

Plica are thin folds found in the tissue lining your knee joint. They help your knee bend, but injury or overuse can lead to irritation and inflammation. This causes pain and a feeling that the knee is locking or buckling.

Treating plica syndrome

An X-ray can’t show plica syndrome (the plica are soft tissues that don’t show up), but a doctor may use X-rays to rule out other problems. Plica syndrome usually gets better with NSAIDs, rest, and physical therapy exercises that strengthen your leg muscles. Sometimes surgery is needed to remove the damaged tissue.

6. Loose bone fragment

Symptoms

  • Sensation of “something” in your knee
  • May be able to feel a bump through your skin
  • Knee pain
  • Knee swelling
  • Knee stiffness
  • Knee locking

Occasionally, a bone fragment in the knee can break off. This may be due to trauma, like a fall, but can also be from a cartilage injury or degenerative joint disease. In some situations, you may not even realize you have a loose bone fragment until it causes symptoms.

Treating bone fragments

If the bone piece is causing your knee to lock, you’ll need arthroscopic surgery (through small incisions) to remove it.

7. Patellar tracking disorder

Symptoms

  • Knee pain over the front of the kneecap
  • Pain worsens when going down stairs or standing up after sitting
  • Knee locks or catches
  • Knee popping
  • Knee instability or giving way

Patellar tracking disorder is when the kneecap shifts out of place when you bend and straighten your leg. It happens when there’s a problem with the bones, tendons, muscles, ligaments, or cartilage that hold the kneecap in its normal position.

Over time, this abnormal movement produces symptoms. If you have patellar tracking disorder, you’re also at a higher risk for kneecap dislocation.

Treating patellar tracking disorder

Patellar tracking disorder is treated with rest, ice, NSAIDs, knee taping or knee brace, and physical therapy to strengthen the leg muscles. Surgery is rarely needed.

Other possible causes

Less common reasons for knee locking include:

  • Gout: Excess uric acid forms crystals in the knee joint, causing pain, swelling, and redness.
  • Adhesive capsulitis: This is a thickening of the tendons and ligaments surrounding the knee joint, usually caused by long-term restriction of movement (like from bed rest).
  • Osteochondritis dissecans: Limited blood flow to the bone causes loose bone and cartilage in the joint.
  • Synovial chondromatosis: It’s a non-cancerous tumor that grows in the lining of the knee joint.
  • Pigmented villonodular synovitis: There is a thickening of the thin tissue that lines the joint.

Knee locking questionnaire

Use our free symptom checker to find out what's causing your knee locking.

Knee locking symptom checker

When to call the doctor

  • Your knee hurts for more than 1 week, despite at-home measures like rest.
  • You have knee pain from an injury.
  • You’re unable to put weight on your knee.
  • You’re unable to fully bend or straighten your knee for more than a few minutes at a time.
  • There is significant knee swelling.

Should I go to the ER?

You should call 911 if:

  • You had a traumatic injury (like a car accident or a fall) and you can’t move your knee.
  • You have extreme difficulty walking or can’t walk.
  • The pain is sudden or severe.
  • Your leg or foot are numb or weak.
  • The skin on your leg or foot feels cool.
  • The skin on your knee is hot, red, or swollen, especially if you also have a fever.

Treatments

At-home care

You can try these at-home treatments:

  • Rest: Avoid activities that put stress on the knee, such as running or jumping, and allow time to recover. Avoid exercises that cause you to bend your knees excessively. Over time, you can slowly increase how much you exercise to strengthen the muscles around your knee.
  • Stretching: Simple, at-home stretching of the muscles that support the knee can strengthen them and stabilize the joint. Your doctor may suggest more personalized recommendations, but here are some examples of exercises that may be helpful.
  • Ice packs: You can use ice packs to reduce the inflammation, swelling, and pain.
  • Pain medications: Taking over-the-counter acetaminophen (Tylenol) or NSAIDS such as ibuprofen (Advil, Motrin) can reduce the discomfort and pain.

Specialty treatment options

If your knee continues to lock or is painful, your doctor may suggest one of these tests or treatments:

  • Imaging: Using an X-ray or MRI to pinpoint the cause of knee locking
  • Physical therapy: Stretches and exercises to strengthen and stabilize the knee
  • Brace: Reducing knee movement and stabilizing the joint can help protect it
  • Medication: Prescription injections to reduce inflammation and control symptoms
  • Surgery: This is an option for serious knee injury or long-lasting arthritis. The surgery can range from a simple repair of the knee cartilage to a full joint replacement for severe chronic damage. True knee locking, as caused by bone or cartilage damage, often requires surgery.

Tips for a smooth recovery

"Knowing ahead of time how much time you’ll need to rest and rehabilitate will prepare you to take care of yourself. Rushing the timeline could lead to a repeat injury if you do too much too quickly. And sticking to the recommended treatment regimen will set you up to recover as soon as you can." —Dr. Jacobsen

Hear what 1 other is saying
Knee locking for hoursPosted September 20, 2021 by B.
The first time my knee locked up I was 15 camping in a pine forest, I was kneeling down, putting all my weight on my right knee and it gave way. It popped and then locked in place. I was stuck for 3 hours. I had to position myself and with some help, we managed to slowly push my knee out straight. It was locked where you could not move your knee in any direction. After being in a certain position, it relaxed where I was able to move it a little more to the ground. When it was straight out it jerked viciously back into place. Since this time my knee has done this mainly on the right knee, 6 more times. I am now 22. Sometimes I have been on my own or sometimes with friends or family. I have never been to get it checked out by the GP as once it's back straight in place I am able to walk and do things as normal, although I am a little bit anxious. Within a few days, I am back up to normal and able to do everything again. The last time it happened was almost 2 weeks ago. The moment I got up out of bed my knee gave way and locked in place. I panicked as the pain is horrendous. I was only stuck in place for an hour this time as it had only locked halfway to being straight rather than kneeling down and having to push my knee the whole way. As it got to the last part where it jerks back into place, I was going very slowly and it jerked but caught back into the locked space. Something still isn't right with my knee. I have not been able to go back to normal. My knee catches while walking and doing normal activities like going to the shop and up and down stairs. This is the first time I have gone to the GP about it due to it not going back into place properly. I have not found similar stories online or what to do if this happens. I have an X-ray in a month to see if we can find the cause, so at least something is getting done. When my knee goes, it's not a dislocation. My knee doesn't look at an angle, and the pain is under my knee. I am stuck from an hour up to 3–4 hours. The knee is completely locked and I am unable to move it. It usually happens when there is pressure on the knee and it is bent in a certain way. Usually, I am kneeling down when it goes. I have tried doing research, but I cannot find much around this. My mum has osteoporosis and my grandad has arthritis in his knees. My family does not have symptoms at all similar to mine.
Dr. Jacobsen is a board-certified Emergency Medicine physician and writer for Buoy Health. She received her undergraduate degrees in Chemistry and Biology from Macalester College (2006) and graduated from the University of Kansas School of Medicine (2010). She completed an Emergency Medicine residency program at the University of Missouri-Kansas City (2013). She practices community Emergency Medic...
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