Do you hear grating, cracking, or popping sounds when your bend your knees? Beware, it may be an early sign of developing knee osteoarthritis, researchers say.

In osteoarthritis -- a type of arthritis that occurs when flexible tissue at the ends of bones wears down, the cartilage in the knee joint gradually wears away.As the damaged knee joint moves, it may crackle and crunch -- known as knee crepitus. These noises in the knee are common and usually painless."Many people who have signs of osteoarthritis on X-rays do not necessarily complain of pain, and there are no known strategies for preventing the development of pain in this group of people," said Grace Lo, assistant professor at Baylor College of Medicine, Houston, US. According to Lo, if people have noisy knees, they are at higher risk for developing pain within the next year compared with the people who do not have noisy knees. 

Pain that accompanies the crackling and popping sounds could indicate a problem.Knee crepitus also can be one of the symptoms of rheumatoid or infectious arthritis, and may accompany several different types of knee injuries.For the study, detailed in the journal Arthritis Care and Research, the team looked at nearly 3,500 participants, at high risk for developing knee osteoarthritis.Among those who developed the disease within a year, more than 75 per cent had signs of osteoarthritis on radiographic images but no frequent knee pain at the start of the study.

The findings may be helpful for identifying individuals at risk for knee osteoarthritis, potentially assisting with earlier diagnosis and intervention, the researchers added.