Knuckle Cracking and Hand Osteoarthritis

If you’re like many, cracking your knuckles can become habit and you may wonder if this is causing harm. Many report that joints feel better, looser and more mobile after “cracking” them. The medical term for the popping sound that you hear is crepitus. Kids may think that cracking knuckles is fun and creates a cool noise thus turning this act into a habit.

Is cracking knuckles normal?

In most cases, yes, it is normal to have joints that crack or pop. Normally, there is no pain associated with doing it.

How does the sound occur?

Researchers have pondered this notion for many years and have come up with various theories. Consistent with all theories is the release of gases upon cracking. According to MaryLynn Jacobs and Noelle Austin in their book “Orthotic Intervention for the Hand and Upper Extremity,” the joints that make up the bony architecture of our hands are individually covered by a joint capsule. The joint is covered by a synovial lining that creates nourishment and lubrication for the joint. Within the space of this joint, capsule synovial fluid is found which acts as a lubricant and contains nutrients for the adjacent bone surfaces. Scientific Reports explains that a variety of gases (nitrogen gas) are continuously dissolved in this fluid. When a knuckle is cracked, the stretching of the capsule decreases the pressure joint pressure and creates a vacuum which is filled by the gas previously dissolved in the synovial fluid. This in turn produces a “bubble” which then bursts creating the characteristic “popping” sound. The gases re-dissolve in the synovial fluid overtime which explains why knuckles cannot be “re-cracked” immediately.

Does cracking knuckles have side effects?

Little to no evidence exists that cracking knuckles is linked to arthritis or any other joint damage. However, reports in Harvard Health associate knuckle cracking with injuries of the ligaments surrounding the joint or dislocation of the tendons (attachments of muscles to bones) which improved with conservative treatment. A study found that after many years of cracking, habitual knuckle-crackers may have reduced grip strength compared with people not cracking their knuckles.

Does it make a difference whether a child or adult cracks their knuckles?

No there is no difference whether a child or adult cracks their knuckles, but if the cracking turns into a habit, one could speculate that this habit could cause thickening of the synovial lining by consistent repetition.

Does cracking your knuckles worsen arthritis?

Cracking you knuckles does not make arthritis worse, but this is a common question poised to hand therapists. Consider this, if your joints are undergoing changes due to an arthritic process (such as osteoarthritis or rheumatoid arthritis), placing joints under undue stress by cracking them, could cause ligament laxity, joint displacement and/or possible tissue tearing. Pain is an important factor, if there is pain upon cracking — stop! This may be indicative of something going on in your joint(s) that needs medical attention.

By: MaryLynn Jacobs, MA, OTR/L, CHT

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