Does cracking your knuckles make you more likely to develop arthritis in your hands? And is it bad to “pop” other parts of your body, like the neck and shoulders?
Despite all the finger wagging about the ill effects of knuckle cracking, the evidence for harm is scant to nil—but not for a lack of scientific scrutiny. Studies looking at whether cracking your knuckles predisposes you to arthritis and other conditions go back at least 50 years. Admittedly, most are small and some not terribly well controlled, but they all point in the same direction.
In a 1975 study published in the Western Journal of Medicine that looked at 28 people (average age, 78.5), the 15 among them who reported a history of knuckle cracking were no more likely to show evidence of joint degeneration indicative of hand arthritis than the 13 who did not. The two groups were compared by both X-rays and clinical exams. The researchers concluded that the “chief morbid consequence of knuckle cracking would appear to be its annoying effect on the observer.”
A study in Annals of the Rheumatic Diseases in 1990 involved a larger group of people (300 in total) ages 45 and older (average age, 63), some of whom had been cracking their knuckles for as long as 60 years. It also found no association with arthritis. However, the knuckle crackers were more likely to have swelling of the hand and poorer grip strength. The habitual knuckle crackers were also more likely to be manual laborers who smoked and drank more frequently than those who had left their knuckles alone. How that might have affected the results is unclear, however.
Worth keeping in mind is that another study, published in Clinical Orthopaedics and Related Research in 2017, refutes those findings about swelling and grip strength. Looking at 30 knuckle crackers and 10 non-knuckle crackers and likewise relying on clinical exams and imaging, investigators found no difference between the two groups. In fact, the knuckle crackers were discovered to have a greater range of motion in the joints they cracked.
Still another investigation, in 2011, found that people ages 50 to 89 with a history of knuckle cracking were no more likely to develop arthritis in their hands than those who kept their knuckles quiet.
It has not even been nailed down what makes the cracking sound. When people crack a knuckle, they are manipulating one of the metacarpophalangeal joints—the five large joints in the hand that connect the five finger bones to the hand bones. (Make a fist, and you’ll see them.) Specifically, knuckle crackers are pulling apart the surfaces of joints. The synovial fluid between the joint surfaces moves in the process, the pressure between joint surfaces changes, and the crackle is sounded. There is debate about whether bubbles formed in the joint spaces during manipulation of the fingers contribute to the noise and, if so, how.
When it comes to the effects of cracking the neck, shoulders, and back, studies are lacking, perhaps because the knuckle-cracking habit is probably the most common. But rheumatologist and editorial board member Brian Kaye, M.D., says that popping the joints in those areas of the body is “a perfectly fine and normal thing to do.”
In fact, he says, “a lot of people find that occasionally, there’s some kind of internal tension they sense building up and that if they crack the area, it relieves the tension.”
Dr. Kaye does list some caveats. If it’s painful when you crack your neck, shoulder, or back, there may be some underlying pathology that should be looked into—starting with your primary care physician and then following up with an orthopedist or rheumatologist if that is warranted. He also points out that if you’re doing it every five minutes, it probably can lead to an overuse injury such as tendinitis.
Theoretically, Dr. Kaye adds, if you crack your neck, it could dislodge a clot in a blood vessel and cause a stroke. There’s at least one case described in the medical literature. Certainly, he says, if you’re 70 or older and know you’re at an increased risk for a stroke because you have been told there’s plaque in the carotid arteries, “it’s probably not a good idea to crack your neck.”
But for most people who crack a body part three or four times a day, Dr. Kaye says, “it’s probably not a bad or dangerous thing. The snapping sound is just the movement of ligaments or tendons as they move over bone.”
He adds that if you hear a cracking or crunching sound when you move your neck from side to side but didn’t intend to create one, that can just be a sign of osteoarthritis, and “it doesn’t mean you have to do anything about it.”
