Is joint cracking (crepitus) harmful? Does knuckle cracking cause arthritis?

Why does cracking happen? Cavitation and tribonucleation

Joint cracking is something people quietly wonder about but rarely ask. Where that distinct "pop" in knuckle cracking comes from was debated for a long time. The real-time MRI study by Kawchuk et al., published in PLoS ONE in 2015, answered the question directly with imaging: the moment the joint surfaces separate, a gas cavity forms rapidly within the joint fluid, and the sound occurs precisely as this cavity forms. So the sound comes not from a bubble "bursting," as once thought, but from the cavity forming (a process called tribonucleation).

The key point: this is not cartilage wear or a damage process; it is an entirely mechanical, benign event related to the physics of the joint fluid. The reason you have to wait before you can crack the same joint again is that it takes time for the gas to redissolve into the fluid.

Does knuckle cracking cause arthritis? Busting the myth

This is one of the most common health myths — but there is no solid evidence behind it.

• Unger's 60-year observation on his own hand: One physician cracked the knuckles of only his left hand at least twice a day for over 60 years, and never cracked his right. When he later compared the two hands, there was no difference between them and no sign of arthritis in the cracked hand (Unger, 1998). Although a single-person observation, it is a striking and memorable counterpoint to the myth.
• Comparative studies: More systematic data point the same way. In deWeber et al.'s (2011) case-control study of hand osteoarthritis, the prevalence of arthritis in any joint was similar between crackers and non-crackers; cracking did not emerge as a risk factor for arthritis in that joint.

In sum: the available evidence does not show that habitual knuckle cracking causes arthritis in the fingers. (Note: this does not mean "no one ever has any problem"; there are rare reports of transient swelling or reduced grip strength with excessive, forceful cracking, but the arthritis link is not supported.)

Knee crepitus and the fear of osteoarthritis

Cracking or grinding from the knee is among the sounds that worry people most; many live with it under the fear "am I wearing out?" Here too the evidence is reassuring:

• Crepitus is very common even in healthy knees and is not, on its own, a sign of disease or wear. In de Oliveira Silva et al.'s (2018) study, although crepitus was common in women with anterior knee pain, the presence of the sound was not related to function, physical activity, or pain level — so the equation "lots of cracking, therefore things are bad" does not hold.
• The same holds over the long term: in Pazzinatto et al.'s (2019) longitudinal study using Osteoarthritis Initiative data, baseline knee crepitus was not associated with the need for a knee replacement (total knee replacement) in the following period.

So knee crepitus is not the "sound" of disease. What matters is whether other symptoms accompany the cracking: if there is pain, swelling, locking of the knee, or a sense of giving way, then evaluation is warranted — but what triggers that evaluation is those symptoms, not the sound. For the central role of exercise in managing knee osteoarthritis: does exercise help knee osteoarthritis?.

"It made a sound, so I'll stop": the truly harmful behavior

Perhaps the most important message here is this: the reaction to the sound harms more than the sound itself. Avoiding movement, sport, squatting, or stairs because your knee or finger makes a noise gradually turns into a fear of movement (kinesiophobia). As a result:

• Muscle strength and endurance decline,
• The loading that keeps the joint healthy disappears,
• Pain and dysfunction paradoxically increase.

While crepitus itself is harmless, becoming inactive out of the belief that "this sound heralds something bad" can cause real harm. The correct approach, if there is no pain, is to ignore the sound and keep moving and building strength.

For clinicians

The mechanism of joint sound was demonstrated as tribonucleation (cavity formation) with real-time MRI by Kawchuk 2015; this replaced the cavity-collapse hypothesis and supports the event being non-pathological. The lack of a knuckle-cracking–osteoarthritis association rests on both Unger's classic n=1 observation and deWeber 2011 case-control data (evidence limited but consistently null). For knee crepitus the distinction is critical: physiological crepitus prevalence is high in asymptomatic populations, and de Oliveira Silva 2018 and Pazzinatto 2019 show crepitus is not associated on its own with function, pain, or total knee replacement need. Crepitus may be statistically linked to patellofemoral joint MRI features, but this carries no prognostic/clinical meaning — presenting it to the patient as a "damage signal" fuels kinesiophobia. Practical threshold: distinguish crepitus from pain/swelling/mechanical symptoms (locking, giving way) and trauma history; in isolated crepitus the goal is reassuring education and maintenance of activity/strength.

Frequently asked questions

Related articles

• Does exercise help knee osteoarthritis?
• My MRI report says there's a tear but I have no pain (or very little) — what does it mean?
• Runner's knee (patellofemoral pain): why must the hip be trained, not just the knee?

Scientific references

This information is for general guidance only; it does not replace an examination, a diagnosis, or your physician's individual advice. Please consult a physician for your symptoms. About the author: Doç. Dr. Oğuz Yüksel — Academic Profile.