Leg swelling can also be caused by inflammation in leg joints or tissues — either a normal response to injury or disease or due to rheumatoid arthritis or another inflammatory disorder. You'll usually feel pain with inflammatory disorders.

Inflammation: It happens when the tissues in your legs get irritated and swollen. It’s a natural response if you break a bone or tear a tendon or ligament, but it also may be a sign of a more serious inflammatory illness, like arthritis. Several things can lead to extra fluid, or edema, in one leg, or both: