You’re halfway into a squat or lunge, and your knees start spazzing out. They crack, pop and pretty much create their own less-than-pleasant workout soundtrack.
Called crepitus, this crackling can freak out anyone who doesn’t want to destroy his or her knees, or perhaps has some existing knee issues like runner’s knee, IT Band syndrome or osteoarthritis to contend with.
If your knees are cracking and popping away during workouts, you’re not alone. “Cracking of the knees is very common,” says Dr. Kelly Weselman, a rheumatologist with Wellstar Rheumatology in Smyrna, Georgia. “That’s probably something I get asked about pretty close to every day.”
What’s That Sound?
Crepitus can be totally benign and is very similar to popping your knuckles or back. During exercises like squats and lunges, the force on your knee joint can squish any gas that’s hanging out in the synovial fluid surrounding your knee (synovial fluid works to protect and lubricate your joints), causing a popping sensation or maybe even an audible “crack,” explains Minnesota-based exercise physiologist and certified strength and conditioning specialist Mike T. Nelson.
While it can be unnerving if you don’t know what it is, this form of crepitus is generally not painful or harmful. It’s common in people of all ages, and a 2013 Clinical Orthopaedics and Related Research study determined that, even in patients who experience crepitus after undergoing knee surgery, pain-free popping isn’t cause for worry.
“If you’re in your 30s and you’re at the gym and doing some weightlifting, or you’re doing your squats and you hear popping noises and creaking in your knees, that doesn’t mean anything’s wrong,” says Dr. Rebecca Shepherd, chief of rheumatology at Lancaster General Health/Penn Medicine. “But, if you’re 65 and your knees hurt when you go up and down stairs, and you feel a grinding sensation, that might be a sign of osteoarthritis,” which is the regular, ‘wear-and-tear’ form of arthritis.
In many people, crepitus can actually be the sound of your joint structures grating against each other – and that’s a sign of potential knee problems to come, explains physical therapist and certified strength and conditioning specialist Tony D’Angelo, senior vice president of clinical operations for Professional Physical Therapy in New York.
“Cracking or ‘crepitus’ can develop from poor alignment of the knee cap, called the patella, within the groove formed by the bones of the knee joint,” D’Angelo says. “It can result in the progressive wearing away of the protective cartilage within the joint. Over time, the wearing gradually worsens, and when the soft cartilage is worn away enough, it becomes very painful and leads to an arthritic joint.”
People who initially experienced more knee crepitus – but without any other symptoms – were more likely to eventually develop knee osteoarthritis than people who experienced less or no crepitus, in a study of nearly 3,500 participants published May 4, 2017, in the journal Arthritis Care & Research.
Among people who have knee arthritis, those with knee crepitus reported slightly lower physical function and knee-related quality of life than those without crepitus, in a study in the November-December 2019 issue of the Brazilian Journal of Physical Therapy.
Moreover, 2014 research published in Osteoarthritis and Cartilage, the official journal of the Osteoarthritis Research Society International, determined that, when coupled with knee cap pain, crepitus is an early indication of patellofemoral joint (where your knee cap meets your thigh bone) lesions and future osteoarthritis in the area.
Knee osteoarthritis, which affects about 13% of women and 10% of men age 60 and older, is one of the leading causes of disability in the U.S., according to a review of knee osteoarthritis published in the Caspian Journal of Internal Medicine.
How to Deal With the Crackling
With crepitus, related pain is the red flag. “The main indicator whether it’s something to be concerned about is whether there’s pain associated with the cracking,” Weselman says. “So, cracking without any discomfort or pain is really nothing to be concerned about. Most of us have a least one joint that cracks, if not multiple joints.”
If you experience pain along with crepitus, it’s important to stop what you’re doing and seek medical attention from a qualified orthopedist, physical therapist or sports medicine physician, Nelson says. They can help determine exactly what’s going on within your knee joint, as well as the best course of treatment for knee pain, if needed.
In cases of knee issues, crepitus is generally coupled with pain ranking as more than a 2 on a scale of 1 to 10, D’Angelo says. Discomfort can last even after you’ve left the gym and up to 24 hours or more, and often accompanies joint swelling, he says.
“If the person is in pain, there may be something else going on that needs to be addressed – like inflammation of a joint or tendon,” Weselman says. “It can be any type of pain, discomfort or ache. Certainly, a sharp pain is concerning.”
A routine exam can usually get to the root of your knee-related issue. “Generally speaking, it’s talking to the patient and getting the history,” Weselman says. “Details of the pain and symptoms, as well as a thorough physical example, probably give us 90% of the information we need.” In some cases, supporting tests such as X-rays or lab testing to rule out inflammatory arthritis or systemic inflammatory conditions may be done.
While there is no current research demonstrating that crepitus without pain is harmful, prioritizing proper exercise form, as well as integrating knee-stabilizing exercises into your workout routine, can help prevent misalignment of the knee cap and more serious causes of crepitus, such as osteoarthritis in the knee, down the road, D’Angelo says.
For improved knee function and health, he recommends strengthening the quadriceps (on the front of the thigh), hamstrings (on the back of the thigh) and gluteal muscles (which make up your butt). These muscle groups help center the patella within its groove.
Interestingly, squats and lunges are great for strengthening those muscles. This highlights the need to always prioritize proper form, as even great exercises like these can contribute to knee wear and tear when not performed properly, D’Angelo says. During these exercises, focus on not letting your knee cave in toward your opposite leg or out to the side; your shin should always stay perpendicular to the floor.
Similarly, if you commonly experience crepitus or slight discomfort when performing these exercises, you may need to work on sitting back into your butt, rather than dumping the weight forward into your knee, according to Nelson.
Within the gluteal muscles, the gluteus medius on the side of your hip is especially important in properly aligning and stabilizing your knee. “This muscle group is often very weak and extremely important when performing complex movements like squats and lunges,” D’Angelo says. To increase strength in the gluteus medius, turn to hip abduction exercises like lateral band walks and clamshells.
Lastly, while the knee extension machine will strengthen your quads, this machine is best avoided, especially for those with existing knee problems, he says. “Loading your knee in this position is something that does not occur naturally. The knee extension places more stress on the undersurface of the kneecap. In turn, that further irritates the soft cartilage and worsens pain and contributes to poor tracking of the knee cap.”
Depending on the cause of knee cracking, stretching exercises might help, Weselman says. “If there’s one specific problem joint, and it’s identified that maybe it’s a tight muscle or tight tendon, then stretching that particular joint – either from yoga or through physical therapy – can be helpful.”
Overall, “we encourage exercise,” Weselman says. “Exercise is very good for joint tissues.” But some type of exercise might be better than others. Low-impact exercises like walking, a stationary bike and swimming are great for the joint.
Other Ways to Improve Knee Health
For cracking without pain, “just maintain a good, healthy body weight, and maintain good muscle tone and exercise,” Weselman advises. “Low-impact exercise is good. Some kind of resistance programs is good to maintain good muscle support of the joints.”
Lifestyle changes can really help. “If you have weight loss of even 10 pounds that can significantly improve knee pain,” Shepherd says.
If pain is associated with cracking, a physician may be able to pinpoint a fixable cause requiring specific treatment with a physical therapist, Weselman says. “If somebody has osteoarthritis of the knee, oftentimes, wearing a knee brace during activity to support the joint can help. Physical therapy can be very important for protecting the joint, and talking with the patient about specific types of exercise that may be beneficial versus those that may be harmful.”
Creaking With Swelling
“Normal joints make noise,” says Dr. Nima Mehran, an orthopedic surgeon in Los Angeles and an American Academy of Orthopaedic Surgeons spokesperson. “It’s really as simple as that. So if it’s not associated with pain, swelling or inflammation, don’t worry about it”
If swelling does occur within a joint along with cracking, a variety of simple treatments can help. Some of Mehran’s patients prefer to take natural anti-inflammatories like turmeric, he says, either in food or as supplements. Anti-inflammatory medications such as over-the-counter ibuprofen (Motrin, Advil) or naproxen (Aleve, Naprosyn) are also options.
Remember RICE – rest, ice, compression and elevation – to reduce swelling, Mehran suggests. Wrapping the knee provides compression. “Elevation is actually one of the most underrated but important things,” he says. “What can happen is when people have fluid in their knee joint, when they stand up, gravity brings it down to their ankle. Now, their ankle is swollen and they’re kind of freaked out by it. So it’s important to elevate that fluid out, and you want to elevate that knee above your heart” for draining to occur.
That said, it’s important to not only treat symptoms beyond knee cracking, such as pain and swelling, but to also determine what’s causing the problem, Mehran says. For instance, an X-ray could reveal tricompartmental osteoarthritis of the knees, with hallmarks such as bone spurs, cysts and narrowing of the joint.
But if you’re experiencing creaky joints alone, don’t worry. And don’t be embarrassed if your knee cracks loudly at your workplace or gym. “Laugh it off, because it happens to the rest of us too,” Shepherd suggests. “Cracking knees can be completely normal – it happens in routine life.”
If you’re starting to have consistent knee pain and it’s affecting your quality of life, “that’s when you go see your primary care doctor and have them take a peek at you,” Shepherd says. “But we all do get a little bit of osteoarthritis as we get older. It’s very common.”