'Popping' Knees Are Not a Sign of Early Arthritis, According to New Study

• The study included 112 young adults with a median age of 28 — The participants were all recovering from anterior cruciate ligament (ACL) surgery. According to research, this particular group of people has a higher risk of developing arthritis; about half of people who suffer an ACL rupture develop arthritis symptoms and structural joint changes within 10 years — that’s roughly 15 years earlier than those without knee injury.

• The study ran for over five years — The researchers used magnetic resonance imaging (MRI) scans and patient-reported outcomes to track osteoarthritis signs among the participants. And while the early results suggest a worrying trend, the longer-term follow-up told a different story.

• Knee crepitus is associated with cartilage damage but not long-term joint damage — According to the researchers, those with crepitus had 2.5 times greater rates of full-thickness cartilage defects in the kneecap region; they also reported worse pain and poorer function one year after surgery. However, over the next four years, there was no difference in pain or function between those with noisy knees and those with quiet knees.

• To put it simply, the sound did not predict continued joint decline — Instead, it was more of an early-phase marker of recovery stress rather than a permanent red flag. Despite starting out with more pain and functional limits after the surgery, those with crepitus caught up with the quiet-knee group over time. Their pain did not worsen, and their function did not keep declining. Instead, with proper rehab and activity, they improved just as much as their peers.

• These findings are reassuring especially for active young people who have undergone surgery after sustaining joint injuries — Having noisy joints and automatically associating them with disease could push you toward aggressive interventions or medications you do not need.

Dr. Adam Culvenor, head of the Knee Injury Research Group at La Trobe’s Sport and Exercise Medicine Research Centre (LASEM), said this study “also highlights the importance of staying active and engaged in rehabilitation to avoid or delay osteoarthritis.”⁴

• The specifics of crepitus are worth unpacking — The knee joint is complex, and is made up of bones, tendons, cartilage, ligaments, and synovial fluid. These mechanisms can play a role in why crepitus occurs. For example, the release of gas bubbles leads to knee sounds. These bubbles form and collapse inside the fluid that lubricates your joints. However, the popping sound that comes from it is no more dangerous than cracking your knuckles; it’s also painless.

• Another common cause is the movement of tendons or ligaments — Peng explains that when tendons and ligaments briefly shift over bones, they produce a snapping or clicking sensation. These mechanical shifts are often harmless and tend to happen during squats, lunges, or even when you stand up. “While this is usually not a sign of damage, it may be a concern if accompanied by pain or feelings of instability,” he added.

• Nevertheless, there are situations when crepitus is a sign of something serious — This is when crepitus occurs along with cartilage wear, meniscus (a crescent-shaped cartilage) tears, or loose fragments in the joint. In these cases, the noise is joined by pain, swelling, or locking. This is your body’s way of alerting you that the joint structure has been disrupted. If crepitus suddenly manifests after an injury, these tears within the joint could be the cause.

“Research has found that the presence of crepitus could signal that structural changes like cartilage damage or bone spurs are happening in the joint. In fact, 81% of people with diagnosed knee osteoarthritis experienced knee crepitus. That’s a significant number, which is why it’s so often discussed in relation to arthritis,” Peng explained.

• Time-related details also matter — If crepitus stems from normal joint function, the noise may persist but does not lead to degeneration. But if noise results from conditions like osteoarthritis, symptoms can worsen gradually, especially without joint care.

• Aside from knee popping or cracking, arthritis also causes painful stiffness and tightness in your knee — The pain usually worsens every morning or after prolonged sitting, as well as when there are temperature changes.

• Meniscus tears often appear because of sports injuries — Although they can also occur because of degenerative changes. They come with a cracking sound when the injury happens. Your knees may also lock or buckle when you walk or squat; pain may arise when you’re doing mundane activities like standing up from a chair or getting out of the car.

• Ligament injuries and tendon tears form because of sports or traumatic injuries, like a car accident — When the ligament or tendon ruptures, a sudden popping sound occurs. This comes with painful swelling and buckling of the knees when walking or pivoting.

With tendon tears, indentations can appear at the top or bottom of the kneecap. The kneecap may also be moving into the thigh, meaning the patellar tendon is torn and no longer attached to the shinbone. The kneecap may also sag, indicating the quadriceps tendon has been torn.

• If the popping or snapping sound comes from outside of the knee, it could be what’s called iliotibial (IT) band syndrome — This happens when the iliotibial band — a group of tissue that runs from the hip to your knee, located on the outside of your leg — becomes irritated due to constant rubbing. It often occurs in runners, and the pain worsens with activities that involve repetitive bending and straightening of the knee.

• Less common but still important are conditions like plica syndrome and loose bodies inside the joint — Plica syndrome causes snapping or popping inside the knee, paired with tenderness and swelling. Meanwhile, loose bodies — tiny pieces of cartilage or bone floating in the joint — cause a cracking or locking sensation, almost as if something is blocking your movement.

• Fractures of the kneecap are another cause, and require immediate medical attention — A fracture produces a sharp cracking sound at the moment of injury, along with bruising, swelling, and sometimes visible deformity. This type of noise is never benign and always requires immediate medical help.

• Surgery is rarely needed for knee crepitus — Instead, the biggest benefits were seen in people who stayed active, managed their weight, and followed knee-friendly strengthening routines.

• However, making modifications to your workout may be needed — This is important, especially if certain activities lead to pain or discomfort. Peng recommends reducing the weight load or switching to lower impact exercises like cycling or swimming, which will help protect your knees while retaining their strength.

• Strengthening the surrounding muscles and improving mobility are also essential — He advises focusing on workouts that target the quadriceps, hamstrings, glutes, and calves. Doing so will “help stabilize the knee joint and minimize excessive movement that may contribute to crepitus.” Stretching the hamstrings, hip flexors, and quadriceps will also ease knee popping.

• Peng recommends listening to your body to avoid unnecessary strain — Most low-impact exercises are safe, but doing high impact or high stress movements could lead to discomfort. Making modifications to movements like deep squats or full squats is advised.

“Resistance training supports the knee joint by reducing strain on cartilage and improving overall mechanics. However, overloading weak muscles too quickly or using poor technique can lead to discomfort,” Peng said.

“If certain movements cause pain, modifying them, such as reducing squat depth or lowering resistance, can help protect the joint while still building strength.”

• Collagen is a major component of cartilage — In fact, it accounts for about 30% of the total protein in your body. Collagen is crucial for repairing soft tissue, muscle and connective tissue, all of which tend to get weaker and less elastic with age.

• For knee problems, a high-quality organic and/or grass fed collagen supplement at a dose of 50 grams a day can be very beneficial — Collagen supplements can be either unhydrolyzed (undenatured) or hydrolyzed (denatured). The processing that most collagen supplements undergo to become hydrolyzed can result in questionable byproducts that are best avoided.

• Homemade bone broth is another great source of collagen — Bone broth contains several nutrients that are beneficial for joint health, including collagen, gelatin, glucosamine, and chondroitin. It also contains amino acids such as glycine and proline, which have anti-inflammatory properties that help reduce joint pain and inflammation.