Man holding his knee.

Why Does My Knee Give Out?

Amanda Nitchos Knee pain


Lately, you’ve noticed that your knee gives out when climbing up and down stairs, walking on uneven surfaces, or shifting your body weight from one leg to the other. These everyday movements may have become difficult or painful and are accompanied by the feeling of your knee locking or instability when moving. You may have swelling in your knee and heard or felt a grinding, popping, or clicking sensation.

Possible Causes

Now you’re left wondering, why is my knee giving out? Why does my knee hurt? The knee joint is pretty complex and is made up of bones, ligaments, and cartilage, all of which can be weakened by injuries or the everyday wear and tear that comes with age. Although there are several causes for knee instability and pain, joint injury and osteoarthritis of the knee are two of the most common reasons for a knee to lock up and give out.

Your knees have four main ligaments that stabilize the patella, or knee cap and join the thigh and shin bones together. These ligaments are called:

  • medial collateral ligament (MCL) on the inside of the joint
  • lateral collateral ligament (LCL) on the outside of the joint
  • anterior cruciate ligament (ACL) in the middle of the joint
  • posterior cruciate ligament (PCL) in the middle of the joint

If your knee is giving out, one of the most common causes could be that you’ve injured one of your knee’s ligaments. When these ligaments are stretched or torn, the knee becomes unstable, causing it to give way unexpectedly and become painful while doing everyday activities.

You don’t have to be a pro athlete to experience a knee injury! Ligaments can be injured during activities that involve:

  • bending
  • twisting
  • quickly changing direction
  • sports – a blow to the knee

Another common cause for your knee giving way could be the onset of osteoarthritis of the knee, which is the breakdown and gradual loss of surrounding cartilage. This condition can be accompanied by pain, stiffness, swelling, and a grinding or grating sound when bending the knee.

Did you know? Osteoarthritis of the knee affects one out of every ten Canadians and doesn’t just affect the elderly, as its onset is now being detected 16 years earlier than it was in the 1990s. Although there isn’t one exact reason why osteoarthritis of the knee develops, some causes include:

  • family history of osteoarthritis
  • previous knee injury
  • being overweight
  • increasing age


Most treatments for a knee injury and osteoarthritis of the knee work best when started early. If your knee is giving out, you should seek an assessment from a qualified physiotherapist. After the assessment, your physiotherapist may recommend bracing to help stabilize your knee and will offer you a treatment plan to help:

  • reduce pain
  • strengthen the knee
  • increase range of motion
  • improve joint stability
  • modify your activity to prevent re-injury


Has your knee unexpectedly given out? Don’t wait! Get well and stay well by booking a free, no-obligation appointment today!

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