I had the same problems after my L5/S1 fusion. Found out by posting on forums like this that the tingling is very common.
Two things cause it. One we are in bed so much more and in the same position most of the time and this irritates the ulnar nerve. The ulnar can also be irritated during the surgery. Guess that the position they have us in does this.
I woke up in the middle of the night the very night after my surgery and many, many, many nights after that for about 8 months with my pinky and ring fingers completely numb.
It has been a little over a year now and I rarely notice it. Did scare the **** out of my sometimes though.
I don't think it has anything to do with your spinal fusion. My mom had a similar thing happen to her. It was caused by her resting her arm on the arm of her computer chair for so long. The nerve was right under her elbow. She could not have any surgery done at the time of discovering her problem due to circulation problems. So she had to wait a long period of time, and ended up losing her use of those two fingers!
So be careful and have it looked at. It could be because of your fall...if it did some kind of damage to your elbow area. But I am not a Dr, so you need some advice from them.