Hearing cracking or popping from any part of your body is alarming, but many people report that their knees, in particular, make these sounds regularly. Think about it: Have you ever been in a low-squat position or sitting on the ground just to notice some cracking sounds erupt from your knees as you stand up?
Turns out, this is a pretty common occurrence, especially as we get older. But is it just age that causes this, or is there something deeper brewing? At what point ― if any ― should you be concerned?
We asked experts about knee cracking, and their insight was pretty surprising. Here’s what you should know:
In most cases, a popping or cracking sound from your knee is nothing to worry about.
“Everyone’s knees crack and pop, and [this] can be normal and doesn’t mean that there’s anything wrong with the knee,” Daniel Wiznia, an orthopedic surgeon at Yale School of Medicine and co-director of the avascular necrosis program, told HuffPost.
This is particularly true if you’re not struggling or in pain when it happens. “Some painless popping that doesn’t affect motion or function is usually not considered serious,” Constance Chu, a professor of orthopedic surgery at Stanford University, told HuffPost via email.
There are many potential reasons why your knee makes a cracking sound, both experts said. According to Wiznia, the main cause of this pain-free clicking is something called cavitation. “Cavitation is when you have two surfaces form a vacuum, and then they’re snapped apart,” he said. The sound is “produced as the two joint surfaces snap apart and the joint fluid forms almost like a little gas, and that makes the sound.”
Another explanation could have to do with how your kneecap tracks. “The kneecap, as it tracks on the end of your thigh bone, can sometimes find a path where there’s a little ridge or bump within the cartilage within that path. That causes a little bit of a snap, and that’s normal. A lot of people will have that,” Wiznia said.
Or you could be dealing with an issue called crepitus. “Crepitus occurs when the cartilage underneath the bone has been worn down and then you have two surfaces of bone grinding against each other,” Wiznia said, noting that you often see this in patients who have osteoarthritis.
It can be loud and sometimes you can even feel it when you put your hands over your knee, he said. “That means that the patient has arthritis. Not all arthritis needs to be treated surgically, a lot of the time, arthritis is actually not painful,” Wiznia added.
But it’s a red flag if you notice knee pain, swelling or stiffness.
“If a crack and pop is painful, or if a crack and pop coincides with instability of the joint or if it coincides with the knee locking and getting stuck, then that’s definitely something that you would want to see a doctor about,” Wiznia said.
There are a number of things that may cause knee pain or stiffness, including meniscus tears, cartilage damage, arthritis, thickened tissue from an injury and more, according to Chu.
In more rare instances, the clicking could be avascular necrosis, Wiznia said. “This is where the blood supply to the bone gets injured, and when the bone isn’t receiving a blood supply, it unfortunately dies.” This can lead to a collapse of the joint, which leads to a clicking sound and knee pain, he noted.
“If there is pain, swelling, an injury, something moving around inside the knee, or the knee gets stuck, the knee should be evaluated by a doctor as soon as possible,” Chu stressed.
Your doctor can do a physical exam and potentially order X-rays to determine what’s going on with your knee and what kind of treatment is needed.
skynesher via Getty Images
Cracking knees commonly happens with age, and exercise is an important way to manage it.
“Most of the time, the cracking and popping creeps up on people as a part of aging,” Chu said.
While knee cracking is a common occurrence, Chu noted that it may mean your knee is not totally healthy or strong enough to maintain certain positions — but this can be improved.
“Getting up from low positions puts more stress on the kneecap area, particularly if the person’s legs and body are not strong enough to maintain good body positions during the movement,” Chu said. “In this situation, knee health and function can be improved with learning how to properly strengthen the body and improve how the body moves, even if there is already some arthritis.”
You can make an appointment with a physical therapist to learn how to build your strength, or you can choose to get a little more active. For example, a recent study found that both indoor and outdoor bicycling can prevent knee pain and lower instances of arthritis.
Exercise in many forms can help folks manage arthritis pain. “Swimming, running, strength training help decrease what we call symptomatic arthritis. … You can have arthritis and you may not have as much pain from the arthritis with exercise,” Jessica Tomazic, a sports medicine doctor at the Cleveland Clinic, previously told HuffPost.
But, once again, pain-free knee cracking and popping is likely not serious — and exercise and strength-training is a good idea whether or not you deal with this phenomenon.
“Prioritizing knee health is important to maintaining mobility, which is critical to overall health and well-being,” Chu said.
