A bone spur is a painful bump on the top of the foot which is actually a bony enlargement. This bump is common where the first toe joint meets with the mid foot. This bump grows in response from friction or pressure from an imbalance. It often becomes irritated and painful. In addition, it may create a soft tissue bursae (sac of fluid) or Ganglion cyst.
If you are very flat-footed, pronate too much or if you are bow-legged and have excessive heel wear on the outsides of your shoes, this may lead to a bone spur on the top of the foot or possibly a bunion joint on the sides of the foot.