Why Does My Knee Pop When Walking? Causes and Treatments

Have you ever taken a step and heard a sudden “pop” or “crack” in your knee? This common experience, medically known as crepitus, can be startling but is often harmless. In this guide, we'll explore why knees pop, what it means for your joint health, and when it might be a sign of something more serious.

What Causes Knee Popping When Walking?

Knee popping can stem from several sources, ranging from completely normal bodily functions to signs of an underlying joint issue.

Harmless Causes of Knee Popping

Most of the time, a popping knee without pain is not a cause for alarm. The most common benign causes include:

• Gas Bubbles (Cavitation): Your joints are lubricated by synovial fluid, which contains dissolved gases like nitrogen. When you move, the pressure in the joint can change, causing these gases to form bubbles that quickly collapse or "pop." This is the same process that occurs when you crack your knuckles and is generally harmless. As explained by experts at the Mayo Clinic, this type of noise does not damage the joint.
• Ligament and Tendon Movement: The knee is surrounded by tough bands of tissue—ligaments and tendons—that connect bones and muscles. As you walk or bend your knee, these tissues can momentarily stretch and snap over a bony prominence, creating a popping or clicking sound.
• Minor Alignment Changes: Sometimes, the surfaces within your knee aren't perfectly smooth. As you move, a slightly rough spot on the cartilage or kneecap might glide over another surface, causing a noise. This is especially common when walking up or down stairs.

Potentially Concerning Causes of Knee Popping

While most knee popping is benign, a pop accompanied by pain, swelling, or instability can signal an underlying problem.

1. Meniscus Tear: The meniscus is a C-shaped piece of cartilage that cushions your knee. A sudden twist can tear it, often producing a "pop" at the moment of injury. Afterward, a torn piece can catch during movement, causing clicking, pain, and a locking sensation.
2. Cartilage Wear and Osteoarthritis: Over time, the smooth cartilage covering the ends of your bones can wear down, leading to osteoarthritis. This creates rough surfaces that can grind or crackle during movement. This gritty, grinding form of crepitus is often a symptom of arthritis, especially in older adults.
3. Ligament Injuries (e.g., ACL Tear): A major injury, such as an anterior cruciate ligament (ACL) tear, often produces a loud, audible pop at the moment of impact. This is typically followed by immediate pain, significant swelling, and a feeling of instability, as if the knee is "giving out."
4. Patellar Tracking Problems: If your kneecap (patella) doesn't glide smoothly in its groove on the thigh bone, it can cause snapping or grinding noises. This condition, known as patellofemoral pain syndrome or "runner's knee," is often caused by muscle imbalances.
5. Loose Bodies: Small fragments of bone or cartilage can break off due to injury or arthritis and float within the joint. These "loose bodies" can get caught between moving parts, causing a hard clunk, locking, and pain.

When Should You Worry About a Popping Knee?

According to orthopedic specialists, noisy joints without other symptoms are generally not a cause for concern. However, you should consult a doctor if your knee popping is accompanied by any of the following:

• Pain: Sharp, persistent, or worsening pain during or after the popping.
• Swelling: The knee appears puffy, feels warm, or swells up after activity.
• Instability: A feeling that your knee might "give out" or buckle.
• Locking or Catching: The knee gets stuck in one position and must be jiggled to move again.
• Recent Injury: The popping began after a specific fall, twist, or impact.

Expert Insight: "If your knees pop or crack without any pain or swelling, it's usually harmless... But if a popping sound comes with pain, swelling, or instability, that’s when you should get it checked out." — Dr. Jenna Moore, DPT, Physical Therapist

For more information on determining if your knee issues require medical attention, watch this explanation:

How to Manage and Treat Knee Popping

Treatment depends entirely on the underlying cause. If your knee popping is painless, no treatment is needed. However, you can take steps to improve overall joint health. If there is an underlying issue, a doctor may recommend one of the following approaches.

At-Home Care and Lifestyle Adjustments

For minor discomfort or to reduce benign popping, these strategies can help:

• Strengthening Exercises: Building the muscles around your knee—specifically the quadriceps, hamstrings, and glutes—improves stability and can help the kneecap track properly.
• Stretching: Keeping your leg muscles flexible, especially the hamstrings and quadriceps, reduces tension on the knee joint.
• Low-Impact Activity: Activities like swimming, cycling, and using an elliptical machine keep your joints moving without the stress of high-impact exercises like running.
• Weight Management: Losing excess weight reduces the load on your knees, which can decrease strain and slow cartilage wear.
• Proper Footwear: Supportive shoes can improve your alignment and reduce stress that travels up from your feet to your knees.

Need some guidance on how to stop the popping? This video demonstrates effective methods to help stabilize your knees:

Medical Treatments

If your knee popping is caused by an injury or condition, a healthcare provider might suggest:

• Physical Therapy: A physical therapist can design a personalized program to address muscle imbalances, improve flexibility, and restore proper joint mechanics.
• Medication: Over-the-counter or prescription non-steroidal anti-inflammatory drugs (NSAIDs) can help manage pain and reduce inflammation.
• Injections: For pain from osteoarthritis, corticosteroid injections can reduce inflammation, while hyaluronic acid injections (viscosupplementation) can help lubricate the joint.
• Arthroscopic Surgery: In cases of a meniscus tear or loose bodies, a minimally invasive procedure may be used to repair the damage, remove debris, and smooth cartilage surfaces.

How to Promote Overall Knee Health

You may not be able to eliminate all knee noises, but you can take steps to keep your joints healthy and reduce the risk of problems:

• Stay Active: Regular, low-impact movement keeps joint fluid circulating and muscles strong.
• Warm Up and Cool Down: Always prepare your muscles for exercise with a warm-up and stretch afterward to maintain flexibility.
• Use Proper Form: Whether lifting weights or climbing stairs, using correct technique protects your knees from unnecessary strain.
• Eat a Balanced Diet: Nutrients like calcium, vitamin D, and omega-3 fatty acids support bone and joint health.

In summary, knee popping when walking is most often a harmless phenomenon. Pay attention to your body's signals—if the noise is accompanied by pain, swelling, or instability, it's time to seek a medical opinion. By focusing on strength, flexibility, and a healthy lifestyle, you can support your knees for years to come.