Knee pain when bending? 6 common causes and how to find relief

Perhaps you’re starting to notice a familiar twinge when you squat down to pick up something. Sometimes it’s an uncomfortable ache when climbing stairs. Or you may feel a sharp pain when you're trying to get out of your car. If you're experiencing knee pain when bending, you're not alone—it's one of the most common joint complaints that can affect people of all ages and activity levels.

Whether you're an active gym-goer, weekend warrior or simply someone trying to go about your daily activities without discomfort, knee pain can be incredibly frustrating. The good news? Many causes of knee pain when bending can be addressed with the right approach. Here’s how.

Why does my knee hurt when I bend it?

The knee is like a sophisticated hinge with specific parts working together—the thighbone, shinbone and kneecap connected by strong bands of tissue (ligaments), cushioned by shock-absorbing pads (cartilage), moved by tough cords (tendons) and lubricated by joint fluid.

When any of these parts becomes damaged, inflamed or worn down, you may start to feel pain with everyday movements like bending. Here are six common causes of knee pain when bending:

1. Osteoarthritis: The most common type of arthritis occurs when the protective cartilage cushioning the ends of your bones wears down over time. This "wear and tear" condition typically develops gradually and can cause pain, stiffness and swelling, especially during and after movement.
2. Meniscus tears: Your meniscus is a C-shaped piece of cartilage that acts as a cushion between your thighbone and shinbone. Sudden twisting movements while bearing weight—like pivoting during sports—can tear this crucial cushion. Even everyday activities can cause tears in older adults with worn menisci.
3. Patellar tendinitis: Often called "jumper's knee," this condition involves inflammation in the tendon connecting your kneecap to your shinbone. It's common in athletes who jump frequently but can affect anyone who puts repetitive stress on their knee joint.
4. Patellofemoral pain syndrome: This condition, sometimes called "runner's knee," causes pain around and behind the kneecap. It often worsens when climbing stairs, sitting for extended periods or—you guessed it—bending your knee.
5. ACL injuries: The anterior cruciate ligament (ACL) helps stabilize your knee joint. Tears often occur during activities involving sudden stops, changes in direction or direct impacts.
6. Bursitis: Small fluid-filled sacs called bursae cushion the outside of your knee joint. When these become inflamed due to repeated pressure or overuse, bending can become painful.

What exercises help relieve knee pain when bending?

Exercise might seem counterintuitive when you're experiencing pain, but strengthening the muscles supporting your knee is actually one of the most effective treatments. Here are some gentle exercises for the knees that can help:

• Straight leg raises: Lie on your back with one knee bent and the other leg straight. Tighten the quadriceps muscle of your straight leg and slowly raise it to the height of the opposite knee. Hold for 5 seconds, lower slowly and repeat 10-15 times before switching legs.
• Wall slides: Stand with your back against a wall and feet shoulder-width apart, about 2 feet from the wall. Slowly bend your knees and slide down the wall until they're bent at about 45 degrees (avoid going into deeper bends if painful). Hold for 5-10 seconds, then slowly slide back up. Repeat 10 times.
• Hamstring stretches: Sit on the floor with one leg extended and the other bent. Reach toward your extended foot until you feel a gentle stretch in the back of your thigh. Hold for 30 seconds and switch legs. Repeat three times per leg.
• Calf raises: Stand near a wall or chair for support. Lift your heels off the ground, rising onto your toes. Hold briefly, then lower. Repeat 15-20 times.
• Swimming or water exercises: The buoyancy of water reduces pressure on your joints while allowing you to strengthen muscles. Walking in chest-deep water or gentle swimming can be particularly beneficial.

Remember: start slowly with any exercise routine and stop if you experience increased pain. Consistency is more important than intensity—gentle daily movement often yields better results than occasional intense sessions.

When should you see a doctor for knee pain when bending?

While many cases of knee pain when bending improve with rest, ice and over-the-counter pain relievers, some situations warrant professional medical attention.

Contact your healthcare provider if:

• Your knee pain is severe or keeps you from performing daily activities.
• Your knee is visibly swollen.
• You cannot fully bend or straighten your knee.
• You have significant instability or a feeling like your knee might "give out."
• You have a fever along with knee pain and swelling.
• Your pain persists for several days despite rest and at-home treatments.
• You heard a popping sound at the time of injury.
• You have a history of knee problems and are experiencing new symptoms.

Early intervention often leads to better outcomes and may prevent chronic issues from developing. Don't hesitate to seek care if your symptoms concern you.

Taking control of your knee health

Living with knee pain when bending doesn't have to be your new normal. By understanding potential causes, implementing the right exercises and knowing when to seek care, you can take meaningful steps toward healthier, happier knees.

Not sure where to start? Take our knee health quiz to get personalized recommendations based on your specific symptoms. For ongoing joint comfort and mobility support, discover our specialized Muscle and Joint Care program, designed to complement your knee health journey.