Pes anserine bursitis occurs when the pes anserine bursa (a fluid-filled sac on the inside of the lower leg just below the knee joint) becomes inflamed and swollen. This happens when the bursa ...

This injury usually results in almost immediate swelling or pain. Inflammation of the pes anserine bursa may lead to inner knee pain. This can be due to an acute injury or overuse of the knee joint.