Crackling knees can be unnerving. Any time you hear that noise you may brace for the worst, but be puzzled when you feel nothing at all.
But unless the sound is accompanied by pain, discomfort or swelling, there is no need to worry.
The crackling/popping sound you hear is called crepitus, and may be nothing more than bubbles of gas popping in your joints.
Another possibility could be your knee cartilage losing its smoothness, causing bones and tissue to rub together noisily when you bend your legs. Once the cartilage gets rough, though, it may be at risk to begin to wear down, leading to arthritis. To help prevent additional knee problems, work on strengthening the muscles in the front of your thigh, called the quadriceps.
If the noise occurs during squatting exercises, you may be going too low. Squatting to the point at which your hips go below your knees can put too much stress on your joints.
You can still reap the exercise’s benefits by doing partial squats, in which your knees do not bend more than 90 degrees. Just be sure to do more repetitions at a faster rate.
If your condition worsens, or you do experience pain, discomfort or swelling when your knees bend during your normal daily routine, you should contact your doctor to have your knee evaluated.