Locked Knee: Causes, Symptoms, And Treatment

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Medical News TodaySubscribeWhat can cause someone’s knee to lock up?

Medically reviewed by Angela M. Bell, MD, FACP — Written by Charlotte Lillis — Updated on February 19, 2025

What is it?
Causes
Symptoms
Diagnosis
Treatment
Prevention
Summary

Locked knee occurs when a person cannot bend or straighten their knee. Causes include injury to the area and inflammation of the joint.

The knees are two of the most important joints in the body. Aside from supporting a person’s body weight, the knees enable everyday activities, such as standing up, walking, and climbing stairs.

Due to such frequent use, the knees are prone to injury and degeneration, both of which can lead to locked knees.

There are two types of locked knee: pseudo and true locked knee. Keep reading for more information about their causes, symptoms, and treatments.

What is locked knee?

A person standing with their hands on their knees 1 — Serena Burroughs/Stocksy

Locked knee occurs when a person is unable to either bend or straighten their knee. There are two types, according to an older 2014 article.

Pseudo locked knee

Pseudo locked knee occurs when severe knee pain triggers the knee muscles to spasm and contract. People may also refer to this as “false locked knee.”

It is an automatic defense mechanism that the body uses to discourage movement of the knee. Restricting the knee in this way helps prevent further damage.

Although muscle tightening and swelling make bending or straightening the knee painful, the knee joint itself is not physically incapable of moving.

True locked knee

True locked knee occurs when something physically prevents the knee from straightening.

When a person has true locked knee, their knee joint gets stuck in one position and cannot fully extend at all.

Causes

According to an older 2014 article, the causes of locked knee vary depending on the type.

Causes of pseudo locked knee

Some potential causes of pseudo locked knee include:

pain from a knee injury
inflammation from injury or osteoarthritis
plica syndrome, which is inflammation of the knee joint tissue
patellar maltracking, where the kneecap does not move correctly
patella dislocation (dislocated kneecap)

Causes of true locked knee

Some potential causes of true locked knee include:

Meniscal tear

The menisci are two pieces of C-shaped cartilage that sit either side of the knee joint. They act as a cushion between the bones of the shin and thigh.

If a meniscus tears, a fragment can break away and become stuck in the knee joint, causing the joint to lock.

A meniscal tear can occur during forceful twisting or rotation of the knee. Other causes include overuse and degenerative changes to the knee.

Loose bodies in the knee

Like cartilage, bone fragments can also embed themselves in the knee joint, causing it to lock.

Loose bodies such as cartilage and bone fragments can occur due to injury or a range of underlying conditions, such as:

osteoarthritis
osteochondritis dissecans
rheumatoid arthritis
chondral defect, which describes localized damage to the cartilage that lines the knee joint
tumor-like lesions

Symptoms

Symptoms of pseudo locked knee and true locked knee may differ slightly.

Symptoms of pseudo locked knee

The main symptom of pseudo locked knee is pain. A person may also experience the following symptoms:

a brief locking sensation in the knee
a sensation that the knee is catching
a feeling of looseness or instability in the knee

Symptoms of true locked knee

The primary symptom of true locked knee is the inability to fully straighten the knee. In some cases, a person with true locked knee may also experience pain.

If a loose body within a joint is causing true locked knee, a person might experience other signs and symptoms, including:

chronic stiffness in the knee
difficulty straightening the knee fully
popping sensation in the knee
feeling a bump at the site of a loose body in the knee
intermittent pain and swelling

Diagnosis

A doctor will begin by asking questions about symptoms, such as pain and swelling. They will then physically examine the knee to check for signs of bruising, inflammation, and tenderness.

During the examination, the doctor may push or pull on the knee to evaluate the joint. They may then ask the person to walk across the room to assess their mobility.

Sometimes, a doctor may recommend diagnostic imaging to examine the knee more closely. Examples of such tests include:

MRI
CT scan
X-ray
ultrasound

Other tests can help the doctor check for signs of inflammation or infection. These include blood tests and an arthrocentesis. This procedure involves taking a sample of fluid from the knee joint.

Treatment

Treatments will vary based on the type of locked knee a person has and its underlying cause.

Meniscal tears

The treatment for a meniscal tear depends on its location and severity.

If the tear is small and in the outer part of the meniscus, the doctor may recommend following the RICE procedure. The acronym RICE stands for:

Rest: Stop doing the activity that causes pain.
Ice: Apply a covered ice pack for 15 to 20 minutes at a time, several times each day.
Compression: Wear an elastic compression bandage.
Elevation: Lay with the knee higher than the heart. This helps to drain excess blood from the knee, reducing swelling.

Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, can also help to alleviate pain and inflammation.

In some cases, a doctor may recommend physical therapy to help the person regain movement in the knee joint.

If other treatments do not work, they may recommend surgical procedures.

Loose body in the knee

If a person has a loose piece of cartilage or bone that is causing the knee to lock, they may require surgery to remove it.

A doctor will also recommend treatment for any underlying conditions that lead to the loose body in the knee.

Other causes

Other causes, such as patellar maltracking or plica syndrome, usually require physical therapy alongside ice, rest, and anti-inflammatory medications.

Prevention

It is not always possible to prevent the injuries and conditions that can cause locked knee.

However, there are measures people can take to help protect their knees. These include:

avoiding playing contact sports
taking a break from activities that cause knee pain
exercising within physical limits
strengthening the leg muscles and core
maintaining flexibility
taking caution on slippery or unstable areas to help avoid falls

Summary

There are two types of locked knee — true and pseudo. In true locked knee, the knee is physically incapable of fully extending. In pseudo locked knee, the knee is physically capable of moving, but the person cannot move it due to severe pain or swelling.

Both types of locked knee typically require pain medications, ice, and rest. A doctor may also recommend physical therapy to help restore movement in the knee joint. If these measures do not work, some form of surgery may be necessary.

A person who experiences locked knee should contact a doctor as soon as possible for a diagnosis and treatment.

Osteoarthritis
Rheumatology
Bones / Orthopedics

How we reviewed this article:

SourcesMedical News Today has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Halloran L. (2014). Knee evaluations.https://www.npjournal.org/article/S1555-4155(13)00660-0/pdf
Meniscus tears. (2021).https://orthoinfo.aaos.org/en/diseases--conditions/meniscus-tears/
Zmerly H, et al. (2022). Assessment and management of loose bodies in the knee joint and related disease: A narrative review.https://pubmed.ncbi.nlm.nih.gov/34674623/

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Medically reviewed by Angela M. Bell, MD, FACP — Written by Charlotte Lillis — Updated on February 19, 2025

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Tag » How To Unlock A Locked Knee

Locked Knee: Causes, Symptoms, And Treatment

What is locked knee?

Pseudo locked knee

True locked knee

Causes

Causes of pseudo locked knee

Causes of true locked knee

Meniscal tear

Loose bodies in the knee

Symptoms

Symptoms of pseudo locked knee

Symptoms of true locked knee

Diagnosis

Treatment

Meniscal tears

Loose body in the knee

Other causes

Prevention

Summary

How we reviewed this article:

Latest news

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