If you've ever crouched down or just bent your leg and heard your knee crack, you've probably wondered what exactly is going on – and whether this weird noise is something you should be concerned about. Is knee "popping" bad? When should you see a doctor? The good news is that, yes, this popping sound is normal and not usually a major cause for concern. Still, there are a few key things you'll want to know before you dismiss this weird phenomenon altogether.
Why Do My Knees Pop?
When your knee pops or cracks, the sound you're hearing actually comes from your cartilage, said Nirav Pandya, MD, an associate professor of orthopedic surgery at UC San Francisco. "Cartilage is typically a very smooth surface that allows for the knee to glide without any noise," he explained. Over time, though, the cartilage can grow rough. The knee joint won't glide as smoothly, which can result in a popping or cracking sound when you move. "The cartilage under the knee cap is particularly prone to have this happen," Dr. Pandya explained.
You may have also experienced your ankles and hips popping, which Dr. Pandya said can occur for similar reasons. The knee, though, "is typically the most common joint patients will complain about."
Why Do My Knees Pop When I Squat?
Many people experience knee popping or cracking when they squat or do lunges. This is common because you're putting more force on your knee joint, said exercise physiologist Mike T. Nelson, CSCS, in an interview with US News and World Report. The extra force can push out any gas in the lubricating synovial fluid around your knee, leading to that cracking sound.
Is Knee Popping Normal?
In the absence of pain or swelling, knee popping is normal and not something to worry about. However, if the popping sound does come with pain or swelling around the knee, "it can indicate a tear of the meniscus, a loose piece of cartilage, or a tight tendon rubbing over the bone," Dr. Pandya told POPSUGAR. That's when you'll want to see your healthcare provider, who'll give you an examination and potentially an MRI or X-rays to determine the cause.
Even though the popping sound isn't usually a major deal, you should still take good care of your knees to avoid more serious injury. Strengthening your core and improving the flexibility in your lower body can help by alleviating some of the jarring impact your knees take during activities like running and walking. Dr. Pandya also recommended avoiding overuse as much as possible (so, running or doing other repetitive, high-impact activities every day), so that you're not wearing away your cartilage or putting more stress than necessary on your knee joints.