Even with expertly done surgery, if you don't remove all the infected mucus it can quickly grow back. Antibiotics often don't work, because of the lack of blood circulation to the sinuses, and saline irrigation doesn't work well, because gravity pulls the saline out of your nose before it reaches the upper sinuses.
The technique I developed uses gravity, rather than fight it. It used to be the last resort after surgery, but now surgery is the last resort, because this works very well.
http://www.medhelp.org/user_journals/show/2322
The Flip-Turn Sinus Flush is mildly risky, because you have to bend over to do it, preferably in a shower, but you can also do it outside on soft ground.