Why Your Knees Are Buckling Inward – Reasons for Knee Instability

The knee may not be the largest joint in the body. But it’s a complex joint and when it has problems, it can be difficult to figure out the exact cause.

When you experience your knee buckling, it can be an unsettling feeling. The instability could be from a tendon, ligament, cartilage, or the bones being injured or damaged. So it’s important to see a medical professional to find out the problem.

Let’s have a look at knee buckling and what could be causing it.

What Does Knee Buckling Mean?

Knee buckling is a term used to describe the sensation that one or both of your knees are going to “give way” or “give out”.

You may feel as if your knee is bending the wrong way, moving side-to-side, or that it might collapse if you bear weight on it.

This sensation can affect anyone, but it’s most commonly associated with people who have osteoarthritis.

That said, knee buckling is often a symptom of an underlying issue that causes knee instability.

If you’re experiencing knee buckling frequently, it may increase your risk of falling and fall-related injuries.

Common Reasons for Knees Buckling

The sensation that your knees are unstable, weak, or about to give out can occur suddenly or develop gradually over time.

Knee buckling can occur for multiple reasons and the most common ones include:


Many types of arthritis can affect the knee, but osteoarthritis and rheumatoid arthritis are the most common.

Osteoarthritis causes the cartilage in the joints to break down, which causes the bones to rub against each, increasing friction in the joint.

Rheumatoid arthritis is an autoimmune disorder. Your body mistakes the synovium—the connective tissue that lines the inside of your knee joint—as a threat.

That threat triggers your immune system, which starts to attack the healthy cells and causes inflammation in the knee.

Both conditions can cause severe knee pain and lead to the knee joint becoming unstable.

Ligament Injuries

There are 4 major ligaments in the knee:

  • The Anterior Cruciate Ligament—ACL
  • The Posterior Cruciate Ligament—PCL
  • The Lateral Collateral Ligament—LCL
  • The Medial Collateral Ligament—MCL

A partial or complete tear to one or more of these ligaments can cause knee instability.

While it’s more common to injure a single ligament, like an ACL tear, it is possible to injure multiple ligaments in the knee in sports, through high-energy trauma like a car accident, or falling from a height.

The damage to the ligaments can cause instability in and around the knee leading to knee buckling.

A Torn Meniscus

You may tear your meniscus if you get up suddenly or participate in activities that include pivoting and turning while there’s pressure on the knee.

You can also develop a tear by changing direction suddenly. A torn meniscus will prevent your knee from rotating causing stiffness, swelling, and pain.

This tear can also make it difficult to move the knee and it may feel as though it’s locked in place.

Patellar Instability

Your patella or kneecap glides through the trochlear groove every time you bend and straighten your knee.

The kneecap is kept in place by tendons that attach to your thigh bone—femur—and the top of your shin bone—tibia.

If you suffer a direct blow to the knee, either in an accident or sports injury, your knee can partially or completely dislocate.

But your kneecap could slide off the trochlear groove if it’s too shallow or uneven, resulting in a partial or complete dislocation.

When your kneecap dislocates, it can cause damage to the underside of your kneecap or the V-notch at the end of your thigh bone.

Not only will this cause pain, but it will cause instability in the knee, and it can lead to arthritis developing in the knee.

Multiple Sclerosis

Multiple sclerosis is an autoimmune condition in which the body’s immune system attacks the protective coating of the nerves.

This nerve damage disrupts the communication between the body and the brain, causing many different symptoms to develop throughout the body.

It’s thought that some of the symptoms of multiple sclerosis can cause you to feel like your knees are buckling. These include:

  • Spasticity of the leg muscles
  • Muscle weakness
  • Balance problems
  • Muscle stiffness or tightness
  • Fatigue
  • Muscle spasms

The duration of the symptoms and the severity will vary from person to person.

With that said, your doctor may recommend corticosteroid injections to help reduce the inflammation in the legs.

Corticosteroid injections can also help reduce the sensation that your knees are buckling.

Damaged Femoral Nerve

The femoral nerve is not only a major nerve, but one of the largest nerves in your leg. It runs from your pelvis down the front of your thigh, where it branches out.

Your femoral nerve plays a vital role to basic functionality, like standing, walking, and maintaining balance, as it flexes your hip joint and thigh muscles. It’s what allows you to lift and straighten your leg.

The femoral nerve’s skin—cutaneous—branches along with the saphenous nerve in your quadricep and allows you to feel the following sensations:

  • Pressure
  • Pain
  • Temperature

You’ll be able to feel these sensations along the inner, front portion of your thighs, and along the inside of your lower leg and foot.

When the femoral nerve gets hurt, either from a direct injury, pelvic fracture or diabetes, you lose sensation in these parts of the leg.

This can lead to your knee feeling like it’s about to give out, but it can also cause a burning pain or tingling sensation around the knee.

What Treatments Are Available?

The treatment plan for your knees buckling will depend on the underlying cause and the severity of the condition.

During the treatment, your doctor will want to prevent falls, restore stability, and relieve any associated symptoms.

Your doctor may recommend using walking aids, braces, physical therapy tape, or appropriate footwear to reduce stress on and around the injured area.

These walking aids will help keep your weight off your injured knee, while the brace will help support and stabilize the knee. Good shoes for knee pain should also be worn.

You may also want to do physical therapy. This will help strengthen muscles and improve balance and coordination, which can help prevent reinjury.

You’ll need to follow the RICE principle—RICE stands for rest, ice, compression, and elevation.

Rest your affected knee as much as possible and apply ice every 2 to 3 hours for 10 to 20 minutes.

Use a compression sleeve or bandage and wrap it snugly around the affected knee. This will help to reduce pain and swelling and promote healing.

Elevate your leg and support your affected knee by placing a pillow under it. While you’re sitting or lying down, keep your knee above your heart level.

Doing so will help reduce the swelling and is also an excellent time to apply ice.

To help manage the pain and reduce inflammation, you can use nonsteroidal anti-inflammatory medications.

These can help ease pain and reduce the swelling alongside knee buckling.

Your doctor may recommend surgery if your kneecap needs to be realigned or damaged ligaments, tendons, and cartilage need to be repaired.

What Therapy Is Recommended?

Research has shown that therapies that strengthen the muscles supporting the knee are effective at keeping the kneecap in its proper alignment.

Physical therapy that focuses on strength training can help alleviate pain, reduce stiffness, increase range of motion, and promote flexibility.

As the muscles that support the knee become stronger, they’ll be able to support and stabilize the joint. They’ll also be better able to absorb shock during weight-bearing activities like walking.

When your knee joint is stable and supported, it will be less prone to friction that causes pain and a feeling of instability.

Alaia, Michael J., et al. “Patellar Instability.” Bulletin of the Hospital for Joint Disease (2013), vol. 72, no. 1, 2014, pp. 6–17,
Accessed 20 Feb. 2022

Bronstein, Robert D., and Joseph C. Schaffer. “Physical Examination of Knee Ligament Injuries.” Journal of the American Academy of Orthopaedic Surgeons, vol. 25, no. 4, Apr. 2017, pp. 280–287,
www.pubmed.ncbi.nlm.nih.gov/28291144/, 10.5435/jaaos-d-15-00463
Accessed 20 Feb. 2022

Doshi, Anisha, and Jeremy Chataway. “Multiple Sclerosis, a Treatable Disease.” Clinical Medicine, vol. 16, no. Suppl 6, Dec. 2016, pp. s53–s59,
www.rcpjournals.org/content/clinmedicine/16/Suppl_6/s53, 10.7861/clinmedicine.16-6-s53
Accessed 20 Feb. 2022

Fanelli, David, and Gregory Fanelli. “Multiple Ligament Knee Injuries.” The Journal of Knee Surgery, vol. 31, no. 05, 13 Mar. 2018, pp. 399–409,
www.pubmed.ncbi.nlm.nih.gov/29534271/, 10.1055/s-0038-1636910
Accessed 20 Feb. 2022

Felson, David T., et al. “Knee Buckling: Prevalence, Risk Factors, and Associated Limitations in Function.” Annals of Internal Medicine, vol. 147, no. 8, 16 Oct. 2007, p. 534,
www.pubmed.ncbi.nlm.nih.gov/17938391/, 10.7326/0003-4819-147-8-200710160-00005
Accessed 20 Feb. 2022

Knoop, J., et al. “Knee Joint Stabilization Therapy in Patients with Osteoarthritis of the Knee: A Randomized, Controlled Trial.” Osteoarthritis and Cartilage, vol. 21, no. 8, Aug. 2013, pp. 1025–1034,
www.oarsijournal.com/article/S1063-4584(13)00815-7/fulltext, 10.1016/j.joca.2013.05.012
Accessed 20 Feb. 2022.

Lee, David M, and Michael E Weinblatt. “Rheumatoid Arthritis.” The Lancet, vol. 358, no. 9285, Sept. 2001, pp. 903–911,
www.pubmed.ncbi.nlm.nih.gov/11567728/, 10.1016/s0140-6736(01)06075-5.
Accessed 20 Feb. 2022.

Pereira, Duarte, et al. “Osteoarthritis.” Acta Médica Portuguesa, vol. 28, no. 1, 9 Oct. 2014, p. 99,
www.pubmed.ncbi.nlm.nih.gov/25817486/, 10.20344/amp.5477
Accessed 20 Feb. 2022

Refai, Nader A., and Prasanna Tadi. “Anatomy, Bony Pelvis and Lower Limb, Thigh Femoral Nerve.” PubMed, StatPearls Publishing, 2022,
Accessed 20 Feb. 2022

Stensby, James Derek, et al. “MRI of the Meniscus.” Clinics in Sports Medicine, vol. 40, no. 4, 1 Oct. 2021, pp. 641–655,
www.pubmed.ncbi.nlm.nih.gov/34509203/, 10.1016/j.csm.2021.05.004.
Accessed 20 Feb. 2022