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.