Here is an example of a patient of mine and you can see in the x-ray there is a "V" between the 3rd and 4th digit. There are many things that can cause the toes to spread but one common problem is a neuroma. A neuroma is a thickening of the nerve that feeds the adjacent sides of the 3rd and 4th digits. When this nerve gets squished between the bones in that area it gets thicker and thicker with scar tissue. Soon the nerve takes up more space and causes the toes to spread out. This is call the "V" sign. By this time most patients need surgery to remove the nerve if it is painful. However, for many people this doesn't even hurt but only looks funny.
To learn more about neuromas look at this webpage:
To your health,
Dr. Donald Pelto