Can Cracking Knuckles Harm Your Hands?

For many people, cracking the knuckles of your hands is a satisfying routine. That sharp "pop" can bring a sense of relief, a momentary escape from tension or even just a comforting habit during idle moments. 

But while it might feel good, have you ever wondered if this common pastime could affect the health of your hands? Whether you're a frequent knuckle cracker or just curious about the science behind it, it’s worth exploring what really happens when you crack your knuckles.

We talk with Rachel Hein, M.D., a fellowship-trained hand surgeon with INTEGRIS Health Medical Group Hand Surgery, to learn more. 

“I often see patients in my clinic with hand pain from cracking their knuckles or repetitive motion,” Hein says. “While I educate my patients that this does not lead to long term damage, my recommendation is to stop performing repetitive activities that cause pain or discomfort.”

What happens when you crack your knuckles?

At a glance: When you crack your knuckles, the sound and sensation are caused by changes in the joint's fluid and the surrounding structures. 

The hand contains 27 bones and many joints allow for movement and flexibility.

• Within each joint is synovial fluid, a thick, slippery fluid that acts as a lubricant and shock absorber.

When stretching, pulling or bending the fingers, you increase the space between the bones in the joint.

• This movement reduces the pressure inside the joint capsule, which is filled with synovial fluid.
• The reduced pressure allows dissolved gases (mainly nitrogen, along with some oxygen and carbon dioxide) in the synovial fluid to form bubbles.
• As the joint space expands further, the gas bubbles collapse or burst, creating the characteristic "cracking" or "popping" sound.

After cracking, it takes about 25 to 30 minutes for the gases to re-dissolve into the joint fluid.

• This explains why you can't immediately crack the same knuckle again.

Why do people crack their knuckles?

Why it matters: Cracking knuckles is a common habit that people perform for various reasons – to relieve tension, reduce stress or simply to enjoy the satisfying sound and sensation it creates.

Relieving tension is one of the top reasons people crack their knuckles.

• The relief or release comes from the stretching of the joint capsule, which can momentarily reduce tension in the joint.

The habitual nature of knuckle cracking is also a way for some to cope with stress or anxiety.

• It can become a repetitive behavior, like biting your nails or tapping your fingers.

The sound of cracking knuckles is also satisfying to some.

• The audible "pop" or "crack" makes a sensory reward that reinforces the habit.

The perceived comfort can have an influence both physically and mentally.

• Some feel it improves joint mobility or reduces stiffness, even though there is no scientific evidence to support long-term benefits.
• The act of cracking knuckles may release endorphins, the body's natural "feel-good" chemicals, which can create a mild sense of relaxation or pleasure.

The social influence of knuckle-cracking can begin in childhood or teenage years.

• Habits can form from observing others or as a way to fit in socially.

Is cracking your knuckles bad for you?

Key points: Cracking your knuckles is neither harmful nor beneficial. If it provides you with relief and doesn’t cause pain, it’s fine to continue in moderation. However, if it becomes compulsive or causes discomfort, you should consider refraining.

The act of cracking doesn’t cause permanent changes to the joint structure. 

• However, excessive or forceful cracking could potentially strain ligaments or cause minor injuries.
• Don’t pull or press with too much force.
• If cracking your knuckles causes pain, swelling or discomfort, it could indicate an underlying joint issue, and you should consult a doctor.

That said, there are some mental or societal drawbacks to cracking knuckles.

• If the desire to crack your knuckles is a response to stress or anxiety, it may reinforce a cycle of nervous behavior rather than addressing the underlying cause.
• The sound of knuckle cracking can be irritating to people nearby.

Does cracking knuckles cause arthritis?

What to know: Cracking your knuckles does not cause arthritis based on current published scientific studies, including one in Arthritis & Rheumatism. The sound comes from harmless gas bubbles collapsing in the joint's synovial fluid. While excessive cracking might cause minor joint pain, it doesn’t lead to arthritis.

The association between cracking your knuckles and arthritis is a myth: 

• There is no evidence linking knuckle cracking to arthritis.
• A famous anecdotal study by Dr. Donald Unger involved him cracking the knuckles of one hand daily for over 60 years while leaving the other hand untouched – he found no difference in arthritis between the two hands.
• Additionally, a 1990 study published in the journal Arthritis & Rheumatism compared people who habitually cracked their knuckles with those who didn’t and found no major differences in the prevalence of arthritis.

Some studies suggest a possible association with hand swelling and weakness, although there isn’t enough definitive evidence to make a strong connection.

• The same study in 1990 found people who cracked their knuckles habitually had a weaker grip strength.
• However, a study in 2017 dispelled this evidence and found it doesn’t affect grip strength.

Don't let joint pain or stiffness slow you down. Visit INTEGRIS Health Orthopedics to learn more. 

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