Read below about buckling knee, including causes, treatment options and remedies. Or get a personalized analysis of your buckling 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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Buckling Knee Symptoms

How embarrassing! You were just walking down the street, minding your own business, when your knee gave out on you. You slipped and fell in front of what felt like half the town. In all honesty, the only person who saw you was the mailman.

What you've just experienced is a buckling knee. It can occur to just about anyone and at just about any time. But if you become someone who experiences knee buckling on a regular basis, you'll find out that the event is annoying embarrassing, potentially dangerous, and becomes more concerning the more it happens.

If you think you have a buckling knee, you might be experiencing:

Our knees bear quite a bit over the course of our lifetime. Some of the most important bones in our body meet at the knee. The kneecap, or patella, sits in front of the femur and tibia. The leg bones meet directly behind the patella where they are cushioned with articular cartilage and the bones are connected by the anterior cruciate ligament and patellar tendon.

These parts usually work in harmony as they should, allowing a fluid motion that results in the bending of the knee that's required for walking or running. But when something is damaged or just not working right, the result can be a knee that can't function properly that buckles instead of bends.

Let's determine the cause of your buckling knee so that you can treat any possible existing condition. Hopefully you can prevent this phenomenon from occurring again, especially at an important time like your wedding or graduation.

Buckling Knee Causes Overview

If your buckling knee seems like an isolated incident, you might not need to or be able to determine a cause quite yet.

But if your knee seems to be giving you problems on a regular basis, consider the following cause categories.

  • Traumatic causes are common: Whether you're a seasoned athlete or hit the gym once a month, moving your knee in the wrong direction can cause trauma that leads to an unstable knee joint. In mild cases, a little rest should solve the problem. But in more serious traumas, such as when a ligament or tendon is damaged, healing can take more effort and time.

  • Serious medical causes are rare, but they are possible: A treatable example would be chondrocalcinosis, which is a build-up of calcium in the knee. Another common medical cause behind a buckling knee is arthritis. Arthritis isn't curable but there are ways to minimize its effects on the body.

  • There are other causes behind buckling knees that aren't related to trauma or disease: Aging can be a factor. It's incredibly rare for a child to experience a buckling knee, but for those much further along in life, a buckling knee can be just another aging symptom like wrinkles or hair loss.

A.I. Health Assistant Causes for Buckling Knee

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

  1. 1.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
  2. 2.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
  3. 3.Knee (Mcl) Sprain

    The medical collateral ligament (MCL) links the thigh bone and the shin bone on the inner side of the knee joint. An MCL sprain is any damage done to this ligament (usually through twisting/force during sports).

    From 2 weeks (first-degree sprains) to between 6 to 8 weeks (second-degree sprains)

    Rarity:
    Uncommon
    Top Symptoms:
    pain in one knee, knee pain from an injury, knee injury, pain in the inside of the knee, sports injury
    Symptoms that always occur with knee (mcl) sprain:
    pain in one knee, knee pain from an injury
    Symptoms that never occur with knee (mcl) sprain:
    mild knee pain
    Urgency:
    Primary care doctor
  4. 4.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

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  5. 5.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
  6. 6.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
  7. 7.Knee Sprain (Lcl)

    The LCL is the ligament on the outside of the knee, keeping it from bending away from the body. It is most commonly injured while playing sports (ouch!) when a force is placed on the knee from the inner half of the knee.

    Days to 6-12 months, depending on severity

    Rarity:
    Rare
    Top Symptoms:
    pain in one knee, knee pain from an injury, knee injury, pain in the outside of the knee, sports injury
    Symptoms that always occur with knee sprain (lcl):
    pain in one knee, knee pain from an injury
    Symptoms that never occur with knee sprain (lcl):
    mild knee pain
    Urgency:
    Hospital emergency room
  8. 8.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

Buckling Knee Treatments and Relief

You should never ignore a buckling knee. In most cases, home treatment is all you need. But there are signs that point to a necessary doctor's visit.

Call your doctor if you experience any of the following:

The following treatments could have your knee functioning properly again.

  • RICE Technique: The RICE method can be applied if an injury is suspected. Rest the knee, Ice it for 20 minutes at a time, use Compression when possible, and keep the leg Elevated.
  • Medication: If the pain is intense, NSAIDs, such as Motrin or Advil, can be taken for relief.
  • Supportive Device: If further support is needed, knee braces can be used to facilitate movement while the tissues are healing.
  • Surgery: Severe cases may require surgery. If there are bone or tissue fragments present in the joint, surgical removal is needed to prevent further injury and restore the fluid motion of the knee.

Knee buckling is a simple health issue, but learning its cause and determining a treatment can save you from annoying and embarrassing moments. If your knee isn't improving on its own, it may get worse with time, so start the search for a cause and cure sooner than later.

FAQs About Buckling Knee

Here are some frequently asked questions about buckling knee.

What does it mean when your knees lock up?

Knee locking is most commonly caused by meniscal tears, often from a traumatic incident or constant wear and tear. Knee buckling can be a sign of osteoarthritis of the knee, tears of a portion of cartilage called the "meniscus," or a tear if a ligament or muscle. These tears can often be contoured or repaired by orthopedic surgeons, and if knee locking is severely limiting your mobility, you may want to consider surgery.

Can arthritis lead to knee buckling?

Osteoarthritis or arthritis from old age can lead to knee buckling. Osteoarthritis is caused from inflammation and a wearing away of the cartilage of the "articular" contact surfaces of the joints. It happens frequently in the hips and knees. This loss of cartilage and break down of bones on the surfaces where they contact each other can "roughen" the surfaces, and cause them to catch on each other — causing knee buckling.

Can buckling knees mean a torn ligament?

Yes. A torn ligament can cause knee buckling as it can destabilize connections between bones. More commonly, a torn tendon will cause knee buckling, because tendons attach muscle to bone, and detaching muscle from bone will keep a muscle from being able to exert force on a knee. If you tear a tendon, you may also have a bulge of the associated muscle as it is no longer connected to bone. It may bunch in an area of the leg or arm causing a grossly enlarged muscle, often called the "Popeye" effect after the cartoon character whose muscles buldged out after eating spinach.

What does it mean if your knees give out?

Knees can give out for a variety of reasons. The body monitors the amount of force placed on a muscle, and in certain situations, if you exceed that force, the muscle will "give out" to protect itself from being torn. However, a knee will also give out if a muscle is torn, or can give out from wear and tear on bones from osteoarthritis.

When should you seek medical attention for buckling knees?

Knee buckling in the absence of strenuous activity is abnormal and you should seek medical attention if this happens. If your knees buckle during strenuous activity, and you experience residual pain, "grinding," inability to bear weight, or knee locking, you should seek medical attention. The doctor may test the "range of motion" of the knee or move it through a series of positions to evaluate it and then help you develop a treatment plan or refer you to a specialist.

Questions Your Doctor May Ask About Buckling Knee

  • Q.Do you feel like your knee is unstable, weak, or giving out?
  • Q.What is your body mass?
  • 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 feel your knee cap pop out of place?

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

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Buckling Knee Symptom Checker Statistics

  • People who have experienced buckling knee have also experienced:

    • 23% Knee Pain
    • 6% Knee That Clicks During Movement
    • 5% Pop in the Knee
  • People who have experienced buckling knee were most often matched with:

    • 42% Acl Injury
    • 28% Meniscal Injury
    • 28% Knee (Mcl) Sprain
  • 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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