I would definately ask your surgeon and doctors about actually getting back in the saddle, though i would imagine they can't give you a definate answer till you have healed enough to see what kind of movement and flexion etc you have after surgery, i would definately be worried about the possibility of more serious damage in another fall however i also worry about a car accident each time i drive so i guess common sense should be your guide, follow doctors recommendations, make sure your horse is a VERY calm nature ( especially the horse you fell off of, if it is the same horse why did you come off? pure accident or horse spook etc) if it was a case of hard to handle horse maybe look into getting a quiet calm horse instead and don't allow yourself to go into a possibly dangerous situation, again common sense, walking a boring trail calmly slowly and safely on a horses back to me is still much better than not getting on at all.
if you are not ably to actually get on the back of a horse there is still a lot you can do that is gratifying from the ground, just grooming, and playing games, teaching tricks, taking in a retirement horse and just loving it to death, all worth it just to get the love back that they offer. I wish you the best of luck with this and hope you don't lose your love of such a wonderful animal.