Here's an interesting idea for some "practice" you can do while lying in bed.
Check out the Indian vocalization system. Steve Smith is big into (check out his new DVD, Standing On The Shoulders, for a little dip in the water). I believe it's called konakkol?
Here's a thread about it.
And a drum teacher i had raved about a book on it, specifically for drummers? Don't know what it was called, or who it was buy.
Not even sure if you're interested, but good luck with the surgery, I hope it all goes well.