Why Your Knee Locks and What You Can Do About It

A "locked knee" is a term used to describe an inability to either bend or straighten their knee. A locked knee can be a very painful condition that limits not only the ability to bend, but also the ability to walk, step up, or even sit down comfortably.

Finding relief from the discomfort of a locked knee is dependent on first determining the cause of the problem, and then addressing the source of the problem to allow the knee to bend normally again.

There are two general types of locked knees. The locked knee can either be caused by a mechanical block to knee motion, or a locked knee can be caused by pain that is too severe to allow knee motion. The good news is that there are effective treatments for people who have a locked knee.

Tests That Can Diagnose a Locked Knee
Verywell / Brianna Gilmartin

Causes and Diagnosis

The first step of your healthcare provider is to determine if the knee is not bending as a result of pain, or a result of something inside physically impeding motion of the joint.

When a locked knee is caused by a mechanical block to motion, there is something that is physically being caught within the mechanism of the knee. Often the cause of a locked knee in this situation is a "bucket handle" meniscus tear.

When this type of meniscus tear occurs, a large fragment of the torn meniscus can become wedged within the knee, preventing normal movement of that knee.

You can also have a locked knee when you have severe pain with any knee motion. While it may be difficult for a patient to determine whether or not there is a physical block to their knee motion, or if pain is the issue, a good physical examination can usually separate these two types of problems.

Sometimes a test can be helpful to determine the cause of a knee that will not bend. X-rays of the knee joint can show loose bone, fractures, and swelling within the joint. They can also be helpful when they are normal to ensure there is nothing more serious taking place in or around the joint that is preventing the knee from bending.

If an X-ray does not help lead to the diagnosis, a magnetic resonance imaging (MRI) scan can also be helpful. MRIs can show cartilage, ligament, and tendon problems. Specifically, torn or abnormal meniscus tears, or loose cartilage, will typically show up on an MRI examination.


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When there is a physical block to knee mobility such as a bucket-handle meniscus tear or a loose piece of cartilage, the typical treatment is to remove the impediment with arthroscopic knee surgery.

Sometimes your healthcare provider may try injecting the knee with a local anesthetic to alleviate the discomfort and try to move the impediment, but typically the cartilage or meniscus will be removed.

If the issue preventing motion is just a pain issue, then the pain needs to be managed. Typically simple pain-relieving treatments such as ice, anti-inflammatory medications, and rest, will allow the pain to subside.

If these simple steps are not helpful, often an injection of a local anesthetic or a cortisone shot can help to reduce the discomfort to a point that allows you to bend the joint again.

Seldom are prescription pain medications necessary to alleviate the pain of a locked knee, and these medications should be used with caution because of possible side-effects.

If you are unable to bend your knee joint, you should be evaluated by a healthcare provider who can determine the source of your problem, or if further tests are needed to determine the cause. Once the underlying problem has been identified, a treatment plan can be initiated to get you moving again.

A Word From Verywell

Having a knee that's unable to be bent, also called a locked knee, is typically a sign of a significant problem with the knee joint. Determining if pain is limiting mobility, or if there is something physically stuck inside the knee joint, can help to determine the most appropriate steps in treatment.

Fortunately, most people with a locked the are able to recover the mobility with the proper treatment.

Frequently Asked Questions

  • Can you walk on a locked knee?

    If the knee is locked, it may be quite difficult to walk on it. For example, if a painful meniscus tear is the issue but it does not block movement of the knee, you could be able to walk on it. But if it does make it impossible to bend or straighten the knee, you may not be able to walk without extreme pain.

  • Where is the pain felt with a meniscus tear?

    When a meniscus tear first occurs, you will likely feel a pop in your knee. After the initial tear, you may feel pain directly in the joint, especially when putting pressure on the knee, and it may swell. You may also experience a feeling like the knee is going to give out when attempting to walk.

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4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Goodman AD, Chase A, Owens BD. Locked knee in a 15-year-old girl: The knee examination. J Pediatr. 2017;185:245-245.e1. doi:10.1016/j.jpeds.2017.02.037

  2. OrthoInfo. Arthritis of the knee. Updated June 2014.

  3. UW Medicine. Torn meniscus.

  4. Penn Medicine. Meniscus tears: Why you should not let them go untreated. Updated November 10, 2020.

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