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How to Unlock a Locked Knee

The first step in treating or unlocking a locked knee is to determine the cause of the locking. Treatment depends largely on the cause as there can be a variety of reasons a knee “stiffens up,” is locked in the bent position, “freezes,” is unable to straighten, or will not move. The main causes for a locked knee are loose bone or cartilage fragments, a torn meniscus, or severe knee pain.

Understanding the anatomy of the knee may help to review if you or someone you know is experiencing locked knee. See our related articles on knee joint function (physiology) and structure (anatomy).

What is Locked Knee?

A locked knee is when the knee is unable to move out of a straight or bent position which can cause pain, discomfort, and mobility issues.

There can be a number of different causes including mechanically related causes and pain related causes. Each type of cause indicates a different type of treatment method, so it is important to determine the cause of the locked knee prior to treatment or unlocking the locked knee.

What causes a knee to lock?

In general, the following three sub-points are the most common types of causes of a locked knee.

Knee Pain

Technically, when a knee “locks” due to severe knee pain it is considered a pseudo-lock. In other words movement is not actually impeded by anything, but the person is unable to move the knee due to severe pain. The knee is not locked, but rather the person is unable to move it out of a bent or straight position due to severe pain.

Knee pain can be due to a number of different reasons such as:

  • Knee injury like fracture, dislocation, infection (tendonitis, bursitis), or tendon tear, sprain or strain
  • Knee swelling or inflammation with possible relation to degenerative diseases like arthritis
  • Plica Syndrome: Plica is the anatomical term for a certain type of tissue structure in the knee. It is a fold of a thin tissue substance, plica, that provides a stable lining to the knee. Plica syndrome is when this tissue fold becomes damaged, injured, or inflamed, causing severe pain.
  • Patellar Maltracking: Some people have abnormal alignment of the leg and or knee, causing the patella (knee cap) to move out of place. This out of place patella can cause rubbing or pressure on other parts of the knee resulting in severe pain, which can result in a locked knee.

Loose Fragments

Loose fragments in the knee joint such as small or large pieces of bone or cartilage can move or float into an inappropriate location and lodge into the knee joint in a way causing the knee to become locked in a certain position.

Loose fragments may be caused by trauma or knee injury such as a break or fracture, arthritis, tumors, or inflammation.

Torn Meniscus

Menisci KneeA knee injury known as torn meniscus can also cause the knee to lock in either a straight or bent position. When a meniscus is torn, parts of it can break off and lodge undesirably between the femur (thigh bone) and tibia (one of the lower leg bones), causing the knee joint to “catch” and lock.

A meniscus is a disc-shaped structure that provides frictionless movement and shock absorption in the knee joint. There are two in each knee joint, a medial (inner) and lateral (outer) meniscus. Menisci are susceptible to damage with certain sudden, twisting, falling, awkward landing movements.

What to do when your knee locks:

If your knee locks suddenly, try to get to a resting position and get help to call your physician. They may be able to help direct you in a treatment you can do at home or instruct you to be seen in a hospital, clinic or doctor’s office.

The following information may be helpful when thinking about treatment options for a locked knee.

Diagnosis of the reason behind locked knee:

A doctor’s office, urgent care center, or other clinic will likely begin with an assessment and examination of the knee and an interview of questions to help discover the underlying cause of the locked knee.

Included in the initial examination, MRI or X-Ray imaging may be used to help view the internal structures of the knee joint.

The healthcare team will begin to rule out if the knee is a true lock (mechanical lock) or a pseudo lock (pain related).

  • Pseudo lock- severe knee pain does not permit the affected person to move their knee.
  • True lock- a torn meniscus or loose fragments do not permit the affected knee joint to move.

Locked Knee Treatment: Non-Surgical

If knee pain is the cause for a locked knee, addressing pain will help to unlock the knee joint.

Knee TreatmentR.I.C.E.

This acronym stands for rest, ice, compression and elevation.

Pain may be alleviated by resting from physical activity; applying ice to the knee for 20 minutes every 4 hours; using a wrap or compression device over the joint; and elevating the knee and leg on a pillow or cushion above the level of the heart.

NSAIDs

Non-steroidal-anti-inflammatory drugs or other over-the-counter pain relievers such as Tylenol, Ibuprofen, Naproxen, and Aspirin can help reduce both pain and inflammation and could be used to help alleviate pain and thus helping to unlock a locked knee due to pain.

Corticosteroid Injections

Cortisone is an anti-inflammatory medication that can be injected into a painful or swollen joint. Reducing inflammation often helps reduce pain which can allow for the unlocking of a knee.

Anesthetic Injection

Injecting a local anesthetic into the knee joint can help provide immediate pain relief that allows the affected knee to be able to move again.

Physical Therapy

Trained professionals specializing in physical therapy or rehabilitation therapy may be able to provide exercises, stretches and movements that help to reduce causes of pain and inflammation in the knee joint. In addition, physical therapy may be recommended following a knee arthroscopy procedure to prevent the occurrence of knee locking in the recovery period or afterward.

Locked Knee Treatment: Surgical

When loose fragments of bone or cartilage or a torn meniscus is the cause of a locked knee, a likely treatment will include a surgical procedure.

Arthroscopy

A minimally invasive procedure known as knee arthroscopy is the preferred treatment option for a torn meniscus. This procedure is done by inserting special tools into a few incisions made around the knee, and repairing or suturing the torn meniscus.

Recovery from a torn meniscus surgery can have some undesirable results such as locking, popping, or clicking, read our article on knee popping after meniscus surgery.

Arthrotomy

In other cases where there are large pieces of loose fragments inside the knee, an open procedure and more invasive surgery may need to be completed to repair the knee. This type of procedure is known as an arthrotomy.

How to help someone who’s knee has locked:

If someone you are with is experiencing a locked knee, assist them to sit or lay down, or reach a comfortable position of rest.

Then, assist them to address their pain. Consider providing them with an ice pack and something to elevate their leg on (if it is possible to elevate the locked knee). Consider obtaining a pain medication (such as Tylenol, Aspirin, Ibuprofen or Naproxen) and a glass of water for them.

Assist them to find medical help. Consider, calling their physician and driving them to the doctor’s office or urgent care center.

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