Knee buckling is when one or both of your knees give out. It's also referred to as knee instability or weak knees. While it's often accompanied by pain, this isn't always the case. What is the cause of being weak in the knees?The knees are the largest joints in the human body. It is a hinge joint a made by joining three bones known as the Shinbone or tibia, the Thighbone or Femur, and the Kneecap bone or Patella. Healthy individuals have functional supporting tissues if the knee 3 joints like ca