I think this problem depends on the level your child has, as almost everything when it comes to Spina Bifida. : )
When your child is crawling he/she can't seem to get their knees up in the right place. Their legs are dragging to the sides or behind them. Kind of where their legs are spread apart. If your child has this problem then you should totally know what I'm talking about.
Take an old pair of panty hose, or better yet you could buy a new pair! : ) Cut off the legs right at the crotch so that you have a stretchy tube. Slip it over your child's legs up onto his lower hips and upper thighs. This help keeps the legs together and the knees up underneath. It worked like a charm for us. Or if you have an extra chunky baby you can try a child's size girl's swimsuit. Cut off the top and bottom and again you should have a stretchy tube. Slip it over and.....TAADDAAA! Really within about 3 to 5 times of doing this Toby was crawling much better.