Why does an old scar still hurt?

I fell down a set of stairs about a year ago and gashed my calf open. The wound was treated by a doctor and did not require stitches or hospitalization. It has long since scared over and does not show any sign of infection. However, the scar hurts to touch and standing for long periods of time causes a pain like a shin splint to gather in that area. Why is this? Is there any way to make it go away?