Knees that “pop,” “click” or “crackle” may sometimes be headed toward arthritis in the near future, a new study suggests.
It’s common for the knees to get a little noisy on occasion, and hearing a “crack” during your yoga class is probably not something to worry about, experts say.
But in the new study, middle-aged and older adults who said their knees often crackled were more likely to develop arthritis symptoms in the next year.
Of those who complained their knees were “always” noisy, 11 percent developed knee arthritis symptoms within a year. That compared with 4.5 percent of people who said their knees “never” popped or cracked.
Everyone else fell into the middle. Of people who said their knees “sometimes” or “often” made noise, roughly 8 percent developed knee arthritis symptoms in the next year.
Doctors have a term for those joint noises: crepitus.
Patients commonly complain of it, said Dr. Grace Lo, the lead researcher on the study. She’s an assistant professor at Baylor College of Medicine in Houston.
But until now, it hasn’t been clear whether crepitus can predict symptomatic knee arthritis. That means people not only have evidence of cartilage breakdown on X-rays, but also suffer symptoms from it — namely, frequent pain and stiffness.
“Our study suggests crepitus is not completely benign,” Lo said. “It’s a sign that something is going on in the knee joint.”
Dr. Joseph Bosco, an orthopedic surgeon who wasn’t involved in the study, agreed that frequent crepitus should be checked out.
“A lot of people’s knees ‘snap’ and ‘pop,'” said Bosco, a professor at NYU Langone Medical Center in New York City. “Do they need to run out for knee replacements? No.”
But, he added, “if you experience crepitus regularly, get an evaluation.”
The findings, published May 4 in the journal Arthritis Care & Research, come with some caveats.
The nearly 3,500 study participants were at increased risk of developing knee arthritis symptoms to begin with, Lo explained.
The participants ranged in age from 45 to 79. Some were at risk of knee arthritis simply because of old age, while others had risk factors such as obesity or a history of a significant knee injury.
So it’s not clear, Lo said, whether the findings would translate to — for example — a 35-year-old whose knees crack when she runs.
Plus, even though the study participants were initially free of knee arthritis symptoms, some did have signs of arthritis damage on an X-ray.
And it was in that group where crepitus was a red flag: People who “often” or “always” had noisy knees were nearly three times more likely to develop knee arthritis symptoms as those who “never” had crepitus.
According to Lo, the findings could be useful in everyday medical practice. “If patients are complaining of frequent cracking or popping in the knees,” she said, “get an X-ray.”
If that turns up signs of arthritic damage, Lo said, then the risk of progressing to symptoms in the near future is probably significant.
Unfortunately, there is no magic pill that can stop arthritis in progress. But, Lo said, for patients who are heavy, weight loss can help.
Some, she added, might benefit from strengthening the muscles that support the knees.
If you’ve ever heard a loud pop as you bent down to pick something up, you’ll be relieved to know that it’s normal for your joints to make popping and cracking noises.
These sounds can be caused by a number of things, including when soft tissues — such as tendons and ligaments — rub or snap over other tissues and bones, explained Dr. Aman Dhawan. He is an orthopedic sports medicine specialist at Penn State Health’s Milton Hershey Medical Center.
“Our joints are mobile, so there are a lot of things that slide over or run past each other. When they move, there is the potential for anatomy to intersect,” he said in a Penn State news release.
The sounds can also be caused by pockets of nitrogen gas within the fluid that helps lubricate joints and provides nutrition to cartilage, Dhawan added.
According to Dr. Robert Gallo, another orthopedic sports medicine specialist at Hershey Medical Center, the only time you need to be concerned about noisy joints is if you also have swelling or pain.
There’s no link between joint sounds and arthritis, both doctors agreed. And cracking your joints does not make them swell up or become arthritic, they added.
“Joint sounds are not really an indicator of health or lack of health,” Dhawan said. He pointed out that the cracking or popping sounds “may be irritating to the listener, but that’s a separate issue. There is really no evidence that it causes any damage.”
Some people believe chondroitin and glucosamine supplements or injections help lubricate joints. But there is little evidence to prove they are effective, Gallo said.
Your joints can benefit from stretching and strengthening exercises, low-impact workouts (such as swimming and bicycling), maintaining a healthy weight and not smoking, the doctors advised.
“There is good data to support getting rid of excess weight because it does improve pain in the joints of the lower extremities, as well as decreases your risk of getting arthritis or of having it progress,” Dhawan said. “The joints carry the weight of our bodies, so the less stress you put on them, the longer they will stay healthy.”