Knee crepitus refers to the audible crackling, creaking or grinding sounds that occur when you bend or straighten your knee. However 36% of people who had no pain and had never injured their knee also had knee crepitus. So, knee crepitus is common across the population, including among people with no knee problems at all. Noisy knees are more common among older adults with arthritis: 81% of people with osteoarthritis have knee crepitus. Given noisy knees are common in those without knee pain, injury or arthritis, you generally shouldn’t be concerned.