I saw my third patient today with space between their second and third toes.  It seems to be related to a shift in weight bearing from the great (big) toe to the second or third toe.  I made no progress when I diagnosed this issue with the paient laying on thie back, but if I made them stand up and tested them, I noticed the weight shift.  I then treated what I found and have been getting pretty good results by approaching the feet in this manner.