Why Does My Knee Hurt When I Bend It?

The knee controls flexibility and mobility. If you're asking yourself, “Why does my knee hurt when I bend it?” it could be time to talk to a doctor about what could be causing you this pain or discomfort.

Knees are constantly in motion due to strenuous physical activity such as sitting, walking, running, exercising, and work-related tasks. Joints prone to inflammation are more likely to cause you pain when bending.

Symptoms that cause knee pain are usually caused by sudden trauma, age-related wear and tear, or damage to part of the joint.

Knee pain can feel achy and dull, cause burning sensations, or create a stabbing pain.

You may experience various types of pain, such as shooting or tingling due to a chronic condition, or sharp and burning pain due to injury or surgery.

It could occur while bending your knee when walking or sitting.

Reasons People Experience Knee Pain When Bending   

If bending the knee causes pain, it can disrupt daily activities. Let's look at the most common reasons your knee might hurt while bending:

Arthritis   

Arthritis of the knee joints is a chronic inflammation that may cause stiffness, pain, and swelling when bending the knee joints. Several varieties of arthritis can impact the knee, including:

• Osteoarthritis
• Rheumatoid arthritis
• Post-traumatic arthritis

Bursitis   

Bursitis is the inflammation of the bursa – cushions that help knee joints move easily against muscles, ligaments, and tendons.

Symptoms of bursitis include pain, swelling, and warmth in the knee when bending.

Tendonitis

Tendonitis causes swelling and can be painful when bending the knee. It occurs when a tendon – a flexible tissue that attaches muscles to bones to enable movement – becomes inflamed from overuse.

This condition weakens the tendons and makes the knee more prone to injury. Mild tendonitis improves with rest and withdrawal from the activity that caused it.

Meniscus Tears

Damage to the meniscus cartilage in the knee can cause pain when you flex the knee. The thick cartilage lies between the tibia and femur and allows the knee joint to bend and move freely.

Although it’s elastic cartilage, injury or trauma can tear or damage it. Low squatting, kneeling, or bending the knees may also be the cause.

Common symptoms are swelling, pain, popping, or stiffness when stretching or bending your knee. Athletes are most at risk for a meniscus tear of the knee.

Treatment depends on the severity but includes steroid injections, the RICE method, and, in many cases, surgery.

Preventing Knee Pain When Bending

It’s possible to prevent some knee pain or reduce it. Begin by eliminating or limiting bending your knee when doing so hurts beyond mild discomfort. It could be an indication that something more serious could be wrong.

You’ll also want to:

• Engage in low-impact activities, such as swimming or biking
• Lose weight (if you’re overweight)
• Perform warm-up and cool-down exercises
• Incorporate weight training
• Regularly stretch
• Protect your kneecaps

When to See a Doctor About Your Knee Pain

Mild to moderate pain in the knee when bending isn't usually a cause for concern. However, you may want to see a doctor if you experience any of the following:

• Chronic or severe knee pain
• Inability to straighten or bend your knee
• Knee weakness
• Swelling or redness in your knee
• Popping noises associated with pain
• Limping
• Fever

We also recommend seeking medical attention if you recently had a knee injury accompanied by swelling, a popping noise, or an inability to bear weight on your leg.