It is very common for knees to be noisy. From a "snap" to a "crack" to a"pop". In the clinic we often find client's are more concerned about the noise their knee makes, than any pain or functional limitations they might have! This tends to be the case because they are worried the noise is "bone rubbing on bone" or their "joint wearing away" or that it means they will have arthritis one day. Hopefully this blog can help put some of those worries to bed.
*Clicks* are most likely caused by something known as cavitation. Cavitation is when bubbles of gas pop (just like when someone cracks their knuckles, which by the way DOES NOT lead to arthritis). These clicks are not a cause for concern and are normal. This study investigated knees and noises and found that that 99% of normal knees had crepitis. The medical term "crepitis" describes the rubbing sound made whilst making a joint move.
*A click when the knee is more or less in the same position* tends to be due to the knee cap (patella) mal-tracking. The knee cap should glide smoothly up and down in a groove on the bone (femur) below where it sits. Often, due to a muscle imbalance or poor hip, knee and foot alignment, the knee cap can run off track and produce a click sound. A physiotherapist can help work out the cause of these clicks and get a knee cap back on track!
*A click or clunk* on the outside of the knee can occur due to the ITB (a long band of connective tissue running down the outside of the thigh) sliding over the bone (femur). This often comes with pain. This click or clunk can be corrected through addressing any muscle imbalance or poor hip, knee and foot alignment with a physiotherapist.
*Pop or snap sound during an accident or fall* means you are likely to have injured a soft tissue structure like your ACL so it is best to go see a physiotherapist, GP or knee specialist who can assess and diagnose you.
The take-home message is noise from the knee is normal. However, if the knee is also painful you should get in touch or get it checked out by a medical professional.
Study quoted: McCoy G, McCrea JD, Beverland D, Kernohan G, Mollan RB. Vibration arthrography as a diagnostic aid in diseases of the knee. J Bone
Joint Surg (Br) 1987; 69-B, 2: 288-293