Why Do My Knees Hurt?

The knee is the largest joint in the body. A healthy knee moves easily, allowing you to walk, turn, and do many other activities without pain.

Every day, your knees must support your full body weight. Cartilage is the “shock absorber” of your knee joints, but over a lifetime it can start to wear away. This "wear and tear" arthritis (osteoarthritis) is the most common cause of knee pain.

Without your cartilage protecting your knees, your bones grind against each other, which causes you pain: Pain that you can feel climbing stairs, working in the garden, or just trying to sit down. It may even keep you up at night.

Symptoms of Osteoarthritis

Your first sign might be a bit of discomfort and stiffness in one or both of your knees. The aching pain can flare up when you are active, and gets better when you rest. Your knees may become stiff and swollen, making it difficult to bend or straighten them. You could feel weakness in your knee, like it’s locking or buckling. People also commonly report that cold weather or rainstorms can make their joint pain worse.