Read below about knee locking, including causes, treatment options and remedies. Or get a personalized analysis of your knee locking from our A.I. health assistant. At Buoy, we build tools that help you know what’s wrong right now and how to get the right care.

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Knee Locking Symptoms

"Knee locking" is quite literally when your knee locks up momentarily, inhibiting your ability to move in any direction. This can also be described as "catching" where it feels as if your knee gets caught during extension or flexion, the knee "giving out," or as a popping sensation with knee movement. Unfortunately, there is no "key" or secret trick to unlock your knee joint, though various treatments exist to help with knee locking symptoms.

The human knee is a relatively complex joint, composed of numerous bones, cartilage, tendons, and ligaments. The bones form the knee joint and the muscles and tendons act around these bones to articulate the joint. The ligaments (such as the anterior crucial element ligament or "ACL") exist to provide stability and make sure the knee only moves in the way it is supposed to. Finally, the cartilage, here known as the medial and lateral "meniscus," exists to provide shock absorption, stabilization, and smooth movement of the knee joint.

Knee locking symptoms may be associated with:

Knee Locking Causes Overview

The knee is composed of bone, cartilage, tendons, and ligaments. Damage to any of these structures can lead to knee locking and instability, though the culprit is often the meniscus, the component made of cartilage. "True" knee locking, where the ability to extend the knee is restricted for a few minutes, is generally caused by damage to bones or cartilage that compose the knee itself. "Pseudo" knee locking, where very brief locking is caused by temporary muscle spasm in response to pain, is usually due to damage of surrounding structures.

Musculoskeletal causes:

  • Wear and tear: Knee locking is often caused by years of wear and tear on the joint, leading to accumulated damage to the bones and cartilage that compose the knee.
  • Cartilage damage: Damage to the cartilage of the knee, which provides for smooth motion, can lead to catching and popping.
  • Muscle and tendon damage: Overuse and strain of the muscles and tendons that act on the knee can cause pain, which leads to difficult movement and a sensation of catching.
  • Ligament damage: Damage to the ligaments supporting the knee can lead to instability and locking.
  • Trauma: Trauma to the knee joint can result in free-floating bone fragments which cause true locking of the knee. Here the movement is restricted by the fragment, like putting a stick through the spokes of a bicycle wheel. Trauma can also cause swelling, which may lead to knee locking.
  • Inflammation: Inflammation of the joint due to damage, autoimmune disease, or infection can lead to knee locking.

A.I. Health Assistant Causes for Knee Locking

The list below shows results from the use of our A.I. Health Assistant by Buoy users who experienced knee locking. This list does not constitute medical advice.

  1. 1.Osteochondritis Dissecans

    At joints where bones meet, bones are covered with a layer of cartilage which provides shock absorbance and lubrication. Osteochondritis dissecans is a condition where a piece of cartilage with a thin layer of bone detach from the larger bone, causing pain.

    Conservative treatment should resolve the problem in 3-6 months.

    Rarity:
    Rare
    Top Symptoms:
    pain in one knee, knee stiffness, knee instability, knee pain that gets worse during a run, pop in the knee
    Urgency:
    Primary care doctor
  2. 2.Meniscal Injury

    A torn meniscus is one of the most common knee injuries. Any activity that causes forceful twisting of the knee, especially when putting the pressure of one's full weight on it, can lead to a torn meniscus.

    6 to 8 weeks

    Rarity:
    Common
    Top Symptoms:
    pain in one knee, knee stiffness, knee instability, pain in the inside of the knee, swollen knee
    Urgency:
    Primary care doctor
  3. 3.Repeated Kneecap Dislocation (Patellar Subluxation)

    Recurrent patellar subluxation is the continued instability of the kneecap, which causes anterior knee pain and usually occurs laterally. It occurs unpredictably with varying durations.

    Recovery timeline is dependent on treatment type.

    Rarity:
    Uncommon
    Top Symptoms:
    pain in one knee, dull, achy knee pain, pain in the front of the knee, pain in the inside of the knee, swollen knee
    Symptoms that always occur with repeated kneecap dislocation (patellar subluxation):
    kneecap dislocation
    Urgency:
    Primary care doctor
  4. 4.Severe Kneecap Dislocation

    The kneecap connects the muscles in the front of the thigh to the shinbone (tibia). When the kneecap slips out of the groove, problems and pain often result.

    Physical therapy may be needed, but people usually resolve normal activities within 1 to 3 months.

    Rarity:
    Rare
    Top Symptoms:
    constant knee pain, pain in one knee, knee pain from an injury, knee injury, kneecap dislocation
    Symptoms that always occur with severe kneecap dislocation:
    knee pain from an injury, kneecap dislocation, constant knee pain
    Urgency:
    Hospital emergency room

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  5. 5.Synovial Chondromatosis

    Synovial chondromatosis is a disease affecting the synovium, which is a thin flexible membrane around a joint. It can often be confused with tendinitis and/or arthritis.

    Surgery is the only effective treatment at this time, but this condition is considered benign, and spreading to other tissue is very rare.

    Rarity:
    Ultra rare
    Top Symptoms:
    joint swelling, pain in one knee, pain in one hip, swollen knee, spontaneous knee pain
    Symptoms that always occur with synovial chondromatosis:
    joint swelling
    Symptoms that never occur with synovial chondromatosis:
    fever, night sweats, unintentional weight loss, warm red ankle swelling, warm red knee swelling, warm and red elbow swelling
    Urgency:
    Primary care doctor
  6. 6.Pigmented Villonodular Synovitis

    The synovium is a thin layer of tissue that surrounds joints, providing a small amount of fluid to lubricate the joint and aid in movement. In pigmented villonodular synovitis (PVNS), the synovium thickens and overgrows. This mass typically only affects one joint, is not cancerous, and does not spread to other parts of the body.

    Recovery from arthroscopic (minimally invasive surgery) is quick and can take a few weeks to a month.

    Rarity:
    Ultra rare
    Top Symptoms:
    joint pain, pain in the outside of the hip, pain in one knee, groin pain, deep, throbbing hip pain
    Symptoms that never occur with pigmented villonodular synovitis:
    knee instability
    Urgency:
    Primary care doctor
  7. 7.Knee Arthritis

    Arthritis is inflammation of one or more of the joints. Pain, swelling, and stiffness are the primary symptoms of arthritis. Any joint in the body may be affected by the disease, but it is particularly common in the knee.

    Knee arthritis is a chronic problem once it develops.

    Rarity:
    Common
    Top Symptoms:
    pain in both knees, knee stiffness, knee instability, swollen knee, morning joint stiffness
    Symptoms that always occur with knee arthritis:
    pain in both knees
    Urgency:
    Primary care doctor
  8. 8.Rheumatoid Arthritis

    Rheumatoid arthritis (RA) is a form of arthritis that causes pain, swelling, stiffness and loss of function in your joints. It can affect any joint but is common in the wrist and fingers. RA is an autoimmune disorder, meaning that it is caused by the immune system incorrectly attacking the joints when it shouldn't.

    RA is a chronic disease which requires lifelong control.

    Rarity:
    Rare
    Top Symptoms:
    fatigue, depressed mood, joint pain, muscle aches, daytime sleepiness
    Urgency:
    Primary care doctor
  9. 9.Psoriatic Arthritis

    Psoriasis is a skin disease that causes itchy or sore patches of thick, red skin with silvery scales. Some people who have psoriasis also get a form of arthritis (inflammation and swelling of joints) called psoriatic arthritis.

    This type of arthritis can be managed with treatment, and permanent damage can be prevented. However, the underlying cause (psoriasis) is currently incurable.

    Rarity:
    Rare
    Top Symptoms:
    shoulder pain, lower back pain, joint pain, upper back pain, hip pain
    Urgency:
    Primary care doctor

Knee Locking Treatments and Relief

Knee locking can develop suddenly or over time due to damage to the structures of the knee. Any sudden-onset and painful locking of the knee should be evaluated by a physician due to the potential for irreparable knee damage. Chronic or progressive-onset knee-locking can be managed at home but may require physician evaluation if it interferes with your quality of life or ability to walk.

At-home treatments:

  • Rest: Avoiding activities that put stress of the knee, such as running or jumping, can allow time for recovery. Exercises that include deep bending of the knee should be avoided. With time, you can slowly increase your exercise regimen to strengthen the muscles supporting the knee.
  • Stretching: Simple, at-home stretching of the muscles that support the knee can strengthen them and stabilize the joint.
  • Ice packs: Ice packs can be used to reduce the inflammation and swelling associated with knee locking.
  • Medications: Acetaminophen or NSAIDS such as ibuprofen can help reduce the discomfort and pain associated with knee locking.

Professional treatments:

  • Physical Examination: Your physician will perform specific maneuvers with the affected knee to determine what is causing the knee locking.
  • Imaging: Imaging of the joint may be performed to pinpoint the cause of the knee locking.
  • Physical Therapy: Professionally administered stretches and exercises can help strengthen and stabilize the knee.
  • Brace: Knee braces and immobilization may be used to reduce the forces to which the knee is exposed.
  • Medication: Certain medications which reduce inflammation can be used to help mitigate damage to the knee
  • Surgery: Surgery can be performed for serious knee injury or long-lasting arthritis. These surgeries range from a simple repair of the knee cartilage to knee replacement for chronic and severe damage. True knee locking, as caused by bone or cartilage damage, will often require surgery for repair or to reduce symptoms.

You should seek help without delay if you have:

  • Extreme difficulty or inability to walk
  • Sudden-onset and severe knee pain and locking
  • Traumatic injury to the knee with resultant locking

Questions Your Doctor May Ask About Knee Locking

  • Q.Do you feel like your knee is unstable, weak, or giving out?
  • Q.Do you often feel your knees buckling?
  • Q.Did you feel your knee cap pop out of place?
  • Q.Did you just suffer from a high impact injury (e.g., a fall, collision, accident or sports trauma)?

If you've answered yes to one or more of these questions, try our knee locking symptom checker to find out more.

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Knee Locking Symptom Checker Statistics

  • People who have experienced knee locking have also experienced:

    • 21% Knee That Clicks During Movement
    • 20% Pop in the Knee
    • 14% Knee Pain
  • People who have experienced knee locking were most often matched with:

    • 40% Meniscal Injury
    • 30% Osteochondritis Dissecans
    • 30% Repeated Kneecap Dislocation (Patellar Subluxation)
  • Source: Aggregated and anonymized results from visits to the Buoy AI health assistant (check it out by clicking on “Take Quiz”).

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