What Causes Knees to Click or Pop?

The knee is a complex joint that supports a wide range of motion and bears much of your body weight. With bones, ligaments, tendons, cartilage, and fluid all working together, it's no surprise that occasional noises can come from your knees.

Here are the common reasons for those clicks or pops:

1. Gas Bubbles (Benign Crepitus)

Just like your knuckles crack when you stretch them, your knee can pop due to the formation or collapse of gas bubbles in the synovial fluid (the fluid that lubricates your joints). This is a normal, harmless occurrence and doesn’t indicate injury or damage.

Signs it's harmless:

• No pain or swelling
• Happens occasionally during motion
• Doesn’t limit your movement

2. Ligament or Tendon Movement

Sometimes, a ligament or tendon in the knee may shift slightly out of place and then snap back during movement, producing a clicking sound. This often happens during deep squats, lunges, or when rising from a seated position.

This type of noise is common in athletes or people with tight muscles around the knee. It’s generally not serious, though frequent popping combined with discomfort might indicate overuse or tightness.

3. Meniscus Tears

The meniscus is a C-shaped piece of cartilage that cushions your knee joint. A tear in the meniscus, often due to twisting injuries or degeneration with age, can cause the knee to click, pop, or even lock up.

Watch out for:

• Pain when moving or twisting
• Swelling
• Feeling like your knee might "give out"

4. Patellofemoral Pain Syndrome (Runner’s Knee)

When the kneecap (patella) doesn’t track properly over the thigh bone (femur), it can lead to friction and cause a clicking or grinding sound. This condition is often associated with overuse, weak thigh muscles, or improper alignment.

Common in:

• Runners
• Cyclists
• People who sit for long periods or squat frequently

5. Arthritis

In people over 40, knee clicking may be due to osteoarthritis, where the cartilage wears down, and bones start to rub against each other. This not only causes clicking or popping but may also lead to pain, stiffness, and inflammation.

Symptoms to watch for:

• Persistent clicking with pain
• Morning stiffness
• Swelling and reduced mobility

When Should You Be Concerned?

Not every click is a red flag. But you should consult a healthcare provider if the knee clicking or popping is accompanied by:

• Persistent pain
• Swelling or inflammation
• Instability or weakness
• Locking or inability to fully move the knee
• History of injury or trauma

How to Manage or Prevent Knee Clicking

Here are some tips to keep your knees healthy and quiet:

• Stretch regularly – Tight muscles, especially in the quads and hamstrings, can pull on the knee joint.
• Strengthen leg muscles – Build strength in your thighs, hips, and glutes to support proper joint movement.
• Use proper form – While exercising or lifting, ensure your knees track correctly over your toes.
• Warm up and cool down – This prepares the joints for movement and helps prevent injury.
• Stay at a healthy weight – Excess weight increases stress on your knees.