What Is a Trick Knee?

Medically Reviewed by Poonam Sachdev on December 16, 2021

A trick knee is a condition where your knee suddenly buckles beneath you. This means that your knee loses the ability to support your weight and gives out. In most cases, knee-buckling is associated with the existence of knee pain and can increase knee pain when it occurs.   

Knee-buckling may be just an extreme case of the larger problem of knee instability — where you feel as though your knee is sliding or shifting on the joint. Both problems can be very uncomfortable and interfere with your daily life.

Trick knees and knee-buckling are most often seen in older populations, especially people that have already been diagnosed with knee osteoarthritis. It can also develop after some knee surgeries in people of all ages. 

Ten percent of all adults have felt a knee give way. In the majority of these cases, the buckling included some form of prior knee pain.

Younger people may injure a part of their knee and not realize it. For example, slight tears in the anterior cruciate ligament (ACL) or the meniscus — the cushion of the knee — may heal badly. These situations could also lead to the development of a trick knee. 

What Causes a Trick Knee?

In about half of all cases of knee-buckling, the patients also had knee osteoarthritis. This is a type of arthritis where the cartilage in the knee joint has been slowly worn away over time. It’s most common in people ages 50 and older. The underlying causes and pain of osteoarthritis may increase the instability of the knee — leading to a greater chance of buckling.  

Weak quadriceps muscles at the front of your thigh are also common in patients who experience knee-buckling and may be part of the cause of your trick knee.  

What Are Treatments for Trick Knee?

Your doctor may recommend a brace to help support your trick knee. Physical therapy can also be helpful for building strength in the muscles around the knee and learning how to correct your posture so your weight is evenly distributed. In some cases, joint replacement surgery — where the surfaces of the knee joint are replaced with plastic — can improve stability as well.

If your knee-buckling is actually caused by an underlying condition — such as a torn ACL or meniscus — your doctor will recommend a treatment that is specific to this underlying condition. This could include surgery or anti-inflammatory medicines. In some cases, joint replacement surgery can improve stability, as well. 

There is a very good chance that you’ll fall when your knee buckles. This can lead to any number of further complications — such as sprains and broken bones. These further problems may require their own — specific — treatments. 

How Can I Prevent a Trick Knee?

Strengthening the muscles around the knees is important to prevent a trick knee.

The quadriceps (quads) are the most important muscles to work on in order to strengthen the knee. Your quads are located at the front of your thighs and are sometimes referred to as a “natural knee brace.” They are necessary for most everyday activities including:

  • Standing up and standing still
  • Getting out of your car 
  • Biking
  • Climbing stairs

By doing exercises to strengthen your quads, you’re helping these muscles support your knee. The more support it has, the less likely it is to buckle. These exercises can also help to manage the symptoms of your osteoarthritis, as well. 

You don’t want to focus only on your quads or your body; you should also work out your hamstrings — at the back of your thighs — and the gluteal muscle of your butt. Squats are a great example of an exercise that works out all three of these muscle groups.

In general, you should try to minimize damage to your knees by choosing exercise like: 

  • Low-impact aerobic activities. These include using the elliptical instead of running or choosing to swim instead of playing tennis. 
  • Strength training for your lower body. Focus part of your workout routine on your lower body with exercises like leg presses. Don’t do exercises that require leg extension, since these could further damage your knee.
  • Stretching. Stretch out your legs in a safe and non-painful way a little bit every day. This will help prevent further knee accidents that could increase your rate of knee buckling.  

You should talk to your doctor or make a plan with your physical therapist before choosing the exercise routine that is right for your knee. You could further damage your knee with the wrong exercises.

Show Sources


Annals of Internal Medicine: “Knee Buckling: prevalence, risk factors and associated limitations in function.”

Cleveland Clinic: “How to Strengthen Your Quads to Potentially Reduce Your Risk of Knee Osteoarthritis.

Interactive Journal of Medical Research: “Relationship of Buckling and Knee Injury to Pain Exacerbation in Knee Osteoarthritis: A Web-Based Case-Crossover Study.”

OrthoInfo: “Arthritis of the knee.”

Osteoarthritis Cartilage: “The impact of knee instability with and without buckling on balance confidence, fear of falling and physical function: the Multicenter Osteoarthritis Study.”

ScienceDaily: “Treatments that reduce knee buckling may help prevent falls in older adults.”

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