Ask an Expert: Knuckle cracking and arthritis

Q: Does cracking my knuckles increase my risk of arthritis?

Answer from Peter Bonafede, M.D., medical director of the Providence Arthritis Center at Providence Portland Medical Center:

Likely not. I'm not saying "definitely no" because, while cracking knuckles is common, research on its effects is not. We have only a handful of studies on the subject. None shows a definite link between knuckle cracking and arthritis.

However, cracking your knuckles is neither harmless nor desirable. The arthritis connection may be an old wives' tale, but cracking your knuckles can hurt your hand in other ways, and there's no benefit to it. Some students crack their knuckles after writing a great deal, but cracking knuckles isn't a solution for writer's cramp. Instead, take a  break, and bend and stretch out your fingers a few times.

Kids may develop a habit of cracking their knuckles because they like the sound. The "crack" comes because of a change in the synovial fluid, the lubricant that bathes the joints. When finger bones are suddenly stretched apart, the space between the joints widens, and an air bubble forms in the synovial fluid. The bubble quickly bursts and makes a sharp sound.

Nature did not intend us to repeatedly stretch the ligaments of the finger joints. I found two medical articles that talked about patients who had injured their hands from knuckle cracking. One over-stretched his ligaments and dislocated his fingers. Another partially tore the ligament in her thumb.

In 1990, a researcher looked at the hand function in 200 adults, age 45 and above. He didn't find a greater tendency toward arthritis in the 74 habitual knuckle crackers, but the knuckle crackers were more likely to have swollen hands and reduced hand strength. However, an accompanying editorial posed this idea: Perhaps a person must have looser-than-average ligaments in order to crack knuckles in the first place. And those loose ligaments and joints may set the person up for other sorts of joint damage.

In another study, published back in 1975, the researcher visited an old age home and asked patients whether or not they had cracked their knuckles when they were young. He found 15 who remembered they had, and 13 who remembered they had not. When the researcher X-rayed their hands, and compared the two groups, he found no difference in arthritis rates.

What does cause arthritis? There are many kinds of arthritis, but the most common, osteoarthritis, is a function of age and genetic predisposition. If you X-ray hands of people age 65, 70 percent will have arthritis. Osteoarthritis tends to be a bit worse in the dominant hand.

The bottom line: While cracking knuckles may not get you arthritis faster, it won't win you many fans and might injure those fingers in other ways. So it's best not done.