It’s a common scenario: you bend your knee, and pop! Or maybe it’s more of a crackle, crunch, or grinding sound. If your knee is popping but there’s no pain, you might just shrug it off. But what if that popping is accompanied by pain? Should you be worried?
The good news is, not all knee popping is a cause for alarm. According to orthopedic surgeon Dr. Sabrina Strickland from HSS, “Most of the time, a popping sound is harmless.” This sound, officially known as “crepitus,” can stem from several benign reasons. However, when knee popping is paired with pain, it could signal an underlying issue that needs attention.
One common harmless cause of knee popping is simply the buildup of air or gas bubbles in the synovial fluid around your joints. When these tiny bubbles burst, it creates that cracking or popping sound you hear. Think of it like cracking your knuckles – often harmless and just a release of pressure.
However, knee popping that comes with pain can sometimes be a sign of early or even moderate osteoarthritis. Dr. Strickland explains, “As the cartilage wears down, the underside of the kneecap rubs against the front of the thighbone, and a bend in the knee can cause a crackly, crunchy, creaky, or even pop-like sound.” Osteoarthritis is a degenerative joint condition where the protective cartilage cushioning the ends of bones breaks down over time. This breakdown can lead to bone-on-bone friction, causing pain, stiffness, and those concerning noises.
If you suspect you might have osteoarthritis in your knee, especially if you’re experiencing persistent pain along with the popping, it’s wise to consult a sports medicine physician or an orthopedic surgeon for a proper diagnosis and guidance.
Knee injuries are another significant reason for popping and pain. Certain types of injuries are particularly known for causing a popping sensation. These include:
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ACL Tear: An Anterior Cruciate Ligament (ACL) tear is perhaps the most well-known injury associated with a distinct pop. The ACL is a crucial ligament in your knee, responsible for stability and preventing the shinbone from sliding too far forward. ACL tears are common in sports involving sudden direction changes like soccer, basketball, tennis, and skiing. Women who are active in these sports have a higher risk of ACL injuries due to biomechanical factors that can place more stress on their knees.
When an ACL tears, individuals often report hearing or feeling a loud pop right at the moment of injury. This is quickly followed by swelling and a feeling of instability in the knee. The severity of symptoms can vary; minor tears might present with milder symptoms, while complete tears can make it impossible to bear weight or perform pivoting movements.
While ACL tears won’t heal on their own, surgery isn’t always necessary. Dr. Strickland notes, “It really depends on which activities you want to get back to.” For activities that involve straight-line movement like swimming, walking, jogging, or cycling, you might manage without surgery. However, for sports requiring twisting and turning, like skiing or tennis, a repaired ACL is usually essential.
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Meniscus Tear: The meniscus is a C-shaped cartilage that acts as a cushion and shock absorber between your thighbone and shinbone. It prevents bone-on-bone contact and helps distribute weight evenly across the knee joint.
A meniscus tear can occur during twisting motions in sports like basketball or tennis, but surprisingly, it can also happen from simple actions like a deep knee bend. The inner part of the meniscus has poor blood supply, meaning it doesn’t heal well. As Dr. Strickland points out, “Every step that you take, every time you go running, every time you jump off a step, you wear it down, so it’s very common to tear it without any significant trauma, particularly if you’re over 40.”
Pain within the knee joint is the primary symptom of a meniscus tear. You might also experience swelling, bruising, or a sensation of locking or catching in the knee as torn fragments get trapped. Knee weakness or buckling can also occur.
Unfortunately, meniscus tears often don’t heal on their own due to limited blood supply. However, not everyone requires surgery. Non-surgical treatments such as anti-inflammatory medications and physical therapy can help manage pain, strengthen the knee, and restore range of motion. Surgery, involving trimming or repairing the meniscus, is sometimes necessary for more severe cases.
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MCL Tear: The Medial Collateral Ligament (MCL) is located on the inner side of your knee, connecting your thighbone to your shinbone. It provides stability to the inner knee. MCL tears often occur in skiing due to a “valgus force,” where the shinbone bends outward relative to the thighbone, explains Dr. Strickland.
Pain along the inner knee, along with swelling and bruising, are typical symptoms of an MCL tear. Fortunately, MCL tears usually heal without surgery. The initial treatment involves RICE – Rest, Ice, Compression, and Elevation. More severe tears may benefit from a hinged knee brace to prevent overstretching during healing.
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Baker’s Cyst Rupture: Baker’s cysts are fluid-filled sacs that develop behind the knee. Many people are unaware they even have one until it ruptures. Dr. Strickland says, “Out of the blue, these harmless cysts can pop, causing the calf to swell and become discolored.” This rupture can be accompanied by a sharp knee pain and a sensation of fluid running down the calf.
In most cases, a ruptured Baker’s cyst requires no specific treatment other than RICE. However, sometimes Baker’s cysts are related to underlying knee problems like arthritis or cartilage tears. In such instances, addressing the root cause is necessary.
If your knee keeps popping and hurting, it’s important to pay attention to your symptoms and seek medical advice. While occasional popping without pain is often benign, persistent pain, swelling, locking, or instability alongside the popping could indicate a more serious condition that requires diagnosis and appropriate management. Consulting a healthcare professional is the best step to determine the cause of your knee popping and pain and get you back on the path to healthy knees.
