If you’re experiencing pain, discomfort, or limited movement in your knee, it’s time to talk to your doctor. One of the most common causes of knee pain is osteoarthritis, a degenerative joint disease that causes the cartilage in your bones to breakdown and wear away. When this happens, the bones under the cartilage rub together, leading to pain, swelling and overall loss of motion. Over time, this condition can cause your bones to lose their normal shape and bone spurs (small deposits of bone) to grow on the edges of the joint, resulting in even more pain.