Charlie, if you've got a badder back than I've got, you've got my sympathy. The vets (I call 'em 'vets' because they treat me like a beef critter when I walk into the office) have found 8 discs in my spine that are either ruptured or herniated, along with bone spurs growing into the nerve roots. And that's just my lumbar and cervical spine. They gave up and never got to my thoracic spine, but they're sure there are more problems to be found there.
So, someone with a bad back definitely CAN shoot a traditional bow. In fact, a trad bow is easier on my back than a compound is. Holding a compound weighing 5 pounds or so out at shoulder height, with your arm extended, puts a good bit of strain on the spine. A 3 pound recurve, or a longbow at 1 1/2 pounds is just that much less stressful, especially after an hour or so of walking around the 3D course.
As for draw weight, I'm shooting 50 pounds and really should drop down to 45 (can you say 'bullheaded stubborness?
). But what poundage you can handle depends entirely on your condition. If you're shooting a 60 pound compound, I'd bet you could do a 45 pound stick. The only way to find out for sure is to go and pull some bows and see how they feel.
The reflex/deflex longbows that are so popular now shoot pretty much the same arrow speed as recurves. They have much less recoil and handshock than the old Hill style straight limb bows, but still more than a recurve does. The shock and recoil are more harmful than the bow's draw weight, IMO. So, for someone with back, neck or shoulder problems, I'd recommend a recurve.
The extra mass in the riser of a takedown recurve helps soak up a lot of what recoil recurves do produce, so that's a good thing. And, of course, arrows from 9-10 grains per pound produce less recoil than lighter ones.
If you decide to give it a go, ease into it. Don't go out and shoot 200 arrows a day at first. Shoot maybe 20 or 30 arrows, then quit for the day. Increase the number of arrows you shoot every second or third outing and slowly get your muscles accustomed to the different draw cycle.