You might be able to knit English with the left needle in a holder. Continental might still work if you have a brace and can run the yarn through your left fingers. I'd think the easiest would be what I've seen called "cottage knitting" where you hold a very long needle under one arm. There's a site just for disabilities and knitting, but I forget where it is right now. Crochet's a little more problematic, but that's entirely possible as well.
Don't worry--you can knit. It's just a matter of finding what works for you.