People often ask me, "Am I going to get arthritis because I crack my knuckles?" This topic is controversial even among medical professionals.1 Research gives us some insights.

If knuckle cracking is accompanied by pain, swelling, or stiffness, it may be hand osteoarthritis.
See
When Hand Pain Is Osteoarthritis

How knuckles crack

Located where the fingers meet the hand, knuckles are sometimes called metacarpophalangeal joints (MCPs).

  • The clicking, cracking, popping, or snapping that occurs when you crack your knuckles is associated with tiny gas bubbles.
  • To produce a cracking sensation, a finger is forced forward or backward (doctors call this hyper-flexion or hyper-extension at a metacarpophalangeal joint) or pulled straight away from the hand. Any of these movements can cause a change in pressure in the joint. The pressure change causes tiny gas bubbles to form in the knuckle’s joint fluid.
  • It is not clear whether the cracking noise is produced when bubbles form or when the bubbles pop.2
  • It usually takes 15 or 20 minutes for the gas bubbles to dissipate and for the bones of the joint to return to their normal positions.3 This is why you can’t crack the same knuckle twice in a row.

It seems logical that habitual knuckle cracking causes arthritis or other degenerative changes in the hand. But what do medical researchers say?

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Conflicting research on knuckle cracking and arthritis

Research studies comparing knuckle crackers' to non-crackers have had mixed results.1 A couple of studies have reported an association between knuckle cracking and hand arthritis.4,5 Others found no significant connection.6,7

Watch Hand Osteoarthritis Video

So, is it okay to continue your knuckle cracking? Well, I wouldn’t recommend it. Even studies that found no connection between knuckle cracking and arthritis reported other signs of joint changes.1,7,8

Possible changes in the hand

Research suggests people who often crack their knuckles may have:

  • More swelling in their hands7
  • A weaker grip7
  • A slightly larger range of motion in their hands8,9—while this seems like a good thing, hypermobility can put a joint at risk of osteoarthritis and other injuries
  • Signs of cartilage changes in their knuckle joints that indicate possible scarring and a higher risk of developing osteoarthritis1

Like the research regarding knuckle cracking and arthritis, the research regarding these potential effects also sometimes conflicts. For example, the same study1 that reported knuckle crackers had cartilage changes did not find they had weaker grip strength.

Studies examining knuckle cracking tend to be small, ranging from 35 to 300 people. Also, most compare knuckle crackers and non-crackers at a single point in time. Larger, longer-term studies that measure changes in hands over time are necessary to draw more clear conclusions.

Other habits associated with knuckle cracking

One research study of 300 people reported that people who cracked their knuckles were more likely to have manual labor jobs and smoke.7

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Manual labor can be a risk factor for osteoarthritis. If you have a manual labor job, finding ways to reduce daily stress on your joints may be more important than quitting knuckle cracking to lower your risk of arthritis.

See Osteoarthritis Causes

Likewise, quitting smoking or other nicotine use can reduce your risk of serious medical problems, including lung cancer, heart disease, stroke, and chronic obstructive pulmonary disease (COPD).

Learn more:

Recognizing Osteoarthritis in the Hand

Treatments for Osteoarthritis in Hands

References

  • 1.Yildizgören MT, Ekiz T, Nizamogullari S, Turhanoglu AD, Guler H, Ustun N, Kara M, Özçakar L. Effects of habitual knuckle cracking on metacarpal cartilage thickness and grip strength. Hand Surg Rehabil. 2017 Feb;36(1):41-43. doi: 10.1016/j.hansur.2016.09.001. Epub 2016 Oct 11. PubMed PMID: 28137441
  • 2.Rizvi A, Loukas M, Oskouian RJ, Tubbs RS. Let's get a hand on this: Review of the clinical anatomy of "knuckle cracking". Clin Anat. 2018 Sep;31(6):942-945. doi: 10.1002/ca.23243. Epub 2018 Oct 18. Review. PubMed PMID: 30080300.
  • 3.Unsworth A, Dowson D, Wright V. 1971. ̳Cracking joints‘ A bioengineering study of cavitation in the metacarpophalangeal joint. Ann Rheum Dis 30:348–358. As cited in Rizvi 2018.
  • 4.Watson P, Hamilton A, Mollan R. Habitual joint cracking and radiological damage. BMJ 1989;299:1566.
  • 5.Watson P, Kernohan WG, Mollan RA. A study of the cracking sounds from the metacarpophalangeal joint. Proc Inst Mech Eng 1989;203:109–18.
  • 6.Deweber K, Olszewski M, Ortolano R. Knuckle cracking and hand osteoarthritis. J Am Board Fam Med 2011;24:169–74.
  • 7.Castellanos J, Axelrod D. Effect of habitual knuckle cracking on hand function. Ann Rheum Dis. 1990;49(5):308–309. doi:10.1136/ard.49.5.308
  • 8.Sandoz R. The significance of the manipulative crack and of other articular noises. Ann Swiss Chiro Assoc 1969;4:47–68. As cited in Yildizgören MT, Ekiz T, Nizamogullari S, Turhanoglu AD, Guler H, Ustun N, Kara M, Özçakar L. Effects of habitual knuckle cracking on metacarpal cartilage thickness and grip strength. Hand Surg Rehabil. 2017 Feb;36(1):41-43. doi: 10.1016/j.hansur.2016.09.001. Epub 2016 Oct 11. PubMed PMID: 28137441.
  • 9.Boutin RD, Netto AP, Nakamura D, et al. "Knuckle Cracking": Can Blinded Observers Detect Changes with Physical Examination and Sonography?. Clin Orthop Relat Res. 2017;475(4):1265–1271. doi:10.1007/s11999-016-5215-3
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