Read below about pop in the knee, including causes and common questions. Or get a personalized analysis of your pop in the knee 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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A.I. Health Assistant Causes for Pop in the Knee

The list below shows results from the use of our A.I. Health Assistant by Buoy users who experienced pop in the knee. 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.Patellofemoral Pain Syndrome

    The kneecap (patella) is located directly in front of the thigh bone (femur), and should normally glide freely up and down. In this condition, called patellofemoral pain syndrome, the kneecap may rub against the thigh bone instead of gliding smoothly, causing damage and pain.

    Most people get better within weeks to months of physical therapy.

    Rarity:
    Common
    Top Symptoms:
    knee pain, pain in one knee, knee pain that gets worse when going up stairs, dull, achy knee pain, knee pain that gets worse when squatting
    Symptoms that always occur with patellofemoral pain syndrome:
    knee pain
    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.Dislocated Kneecap

    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.

    Resolves upon reduction of dislocation.

    Rarity:
    Uncommon
    Top Symptoms:
    pain in one knee, knee pain from an injury, knee injury, swollen knee, knee instability
    Symptoms that always occur with dislocated kneecap:
    kneecap sliding out to the side, knee pain from an injury
    Urgency:
    In-person visit

    Pop in the Knee Checker

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  5. 5.Acl Injury

    The ACL (anterior cruciate ligament) is a super-important tendon that connects the femur (thigh bone) to the tibia (shin), keeping the tibia from flying forward every time a step is taken. Tearing happens in a lot of accidents and sports, unfortunately.

    Full recovery may take months of physical therapy.

    Rarity:
    Rare
    Top Symptoms:
    knee pain, pain in one knee, knee instability, swollen knee, knee pain from an injury
    Symptoms that always occur with acl injury:
    knee pain
    Symptoms that never occur with acl injury:
    mild knee pain
    Urgency:
    Hospital emergency room
  6. 6.Posterior Cruciate Ligament (Pcl) Injury

    The PCL (posterior cruciate ligament) is located in the back of the knee and connects the big thigh bone (femur) to the big shin bone (tibia). It keeps the tibia from moving backwards. An injury to the PCL requires a huge force, making it much rarer than an ACL tear.

    6-12 months

    Rarity:
    Ultra rare
    Top Symptoms:
    constant knee pain, severe knee pain, pain in one knee, knee pain from an injury, swollen knee
    Symptoms that always occur with posterior cruciate ligament (pcl) injury:
    inability to bear weight immediately after injury, pain in one knee, knee pain from an injury, severe knee pain, constant knee pain
    Urgency:
    Hospital emergency room
  7. 7.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
  8. 8.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
  9. 9.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

Questions Your Doctor May Ask About Pop in the Knee

  • Q.While you are standing, take a look at your knees. Do they appear to bend towards each other, rather than follow a straight line along your legs? (Knock-kneed)
  • Q.Did you recently injure your knee?
  • Q.Do you often feel your knees buckling?
  • Q.Did you feel your knee cap pop out of place?

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

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Pop in the Knee Symptom Checker Statistics

  • People who have experienced pop in the knee have also experienced:

    • 21% Knee That Clicks During Movement
    • 21% Knee Locking
    • 13% Knee Pain
  • People who have experienced pop in the knee were most often matched with:

    • 33% Osteochondritis Dissecans
    • 33% Patellofemoral Pain Syndrome
    • 33% 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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