This question has been nagging at me as I've been reading some Batman comics for the first time. I cross-referenced my interpretation of various things we see her doing with a very informative Wikipedia article (Spinal Cord Injury), and came to a few conclusions.
Clearly, her paralysis affected only her legs. She obviously had use of her arms, and I believe there's plenty of canon evidence that she twisted around in her chair, so she had control of her trunk and abdominal muscles.
The damage (at least to her motor control) was clearly untreatable by conventional medical means (the procedure that she underwent in the New 52 continuity was, I believe, considered experimental). Otherwise, I have to believe that Commissioner Gordon and/or Bruce would have done everything possible to help her recover. It is, however, unclear to me how much sensory function she had in her legs.
Based on the original panel in The Killing Joke, I don't believe she should have been paralyzed at all: the bullet appeared to hit her in the hip, not remotely close to the spine. However, it is possible that the bullet ricocheted off her hip bone; I don't know enough about gunshot wounds to say for certain.
So my question is in the title, but there are a few specific things I'm particularly interested in:
- How much motor control did Barbara have in her legs? Could she move them at all (for example, at the hip but not at the knee)?
- How much sensory function did she have in her legs?
- (A somewhat broader question) Was there any medical, or pseudo-medical, description of her injury?