Bane doesn't break Batman's back - he breaks Gordon's.
We know that RISES begins with Batman on the run. Officially, the Gotham Police Department has always been searching for him, but unofficially, they've supported him. Especially Gordon.
One of the major plot points in THE DARK KNIGHT was that Batman acquired a new ally: Harvey Dent. Along with Gordon, the three formed a conspiracy to take down the mob in Gotham. But by the end of THE DARK KNIGHT, the Joker has succeeded in destroying Dent, and while Batman and Gordon do what they can to preserve Dent's image, it is still a major blow to them.
The setup for RISES seems to be that Batman has disappeared from public view since the events of THE DARK KNIGHT. Dialogue in the trailer implies that Bruce Wayne has lost faith in his alter-ego's ability to be a force for good; alternatively, he may believe that he has done all he can for Gotham in the guise of Batman, and that Batman can no longer protect them.
When Bane was introduced in the "Knightfall" arc, the centrepiece was him breaking Batman's back. Critics claimed that this was little more than Mola Ram Syndrome, giving a villain a super-evil power to give them instant credibility (it's named after Mola Ram in INDIANA JONES AND THE TEMPLE OF DOOM who was largely non-threatening, and so given the ability to tear a man's still-beating heart from his body). However, Bane has always been characterised as being as cunning and as intelligent as he is strong.
This is important for RISES because if Batman has already retreated to self-imposed exile, Bane would not be able to break his back until later in the film, once Batman has emerged to confront him. It would likely happen in their first fight, and would reek of giving Bane instant credibility. Rather, I trust Nolan to play up the other aspects of Bane's character, most notably his intelligence. The exact plot details for the film remain unknown, but his goal will likely be the ultimate destruction of Batman.
The "Knightfall" storyline has Bane all too aware that rushing to a confrontation with Batman will not end well for him. So he instead frees the inmates of Arkham Asylum, wearing Batman down as he is forced to re-capture each and every one of them. Bane is able to break Batman's back by ambushing him when Batman is exhausted. And this could be implemented into RISES in a figurative - rather than literal - way.
We know that Jim Gordon has always been Batman's ally, and with Harvey Dent's death and the blow the Joker dealt their little conspiracy, Batman is going to be depending on Gordon more than ever. Bane is intelligent enough to work this out - he knows that the Gotham police could capture Batman if they wanted to. And be extension of that, he will know that Batman has to have supporters inside GCPD. I believe he will work out that Batman and Gordon are allies, and so will attack Gordon early in the film, breaking his back. This will be to force Batman out into the open. It would have the same effect as Bane's action in "Knightfall" when he released the inmates of Arkham Asylum: mentally and physically wearing him down, increasing Bane's chances in the confrontation.
It also explains why Gordon is in hospital, and why he implores Bruce Wayne to return as Batman (Gordon was always intelligent enough to work out who Batman really is, but chose not to).