The latest update on WWE Champion CM Punk after his knee surgery today (Dec. 4, 2012) is that there have been no plans put in place to change or alter current storylines involving Punk and Ryback's pursuit of his title.
PWInsider has noted there is a belief internally that Punk will work their planned match at the TLC pay-per-view (PPV) on Dec. 16 in Brooklyn. The surgery was relatively minor, after all, and athletes have come back within two weeks and done far more rigorous work. Others believe Punk won't be working the show.
The reality is that he shouldn't.
Punk was always going to beat Ryback to retain the WWE championship so he could move on to a big money match against The Rock at the Royal Rumble next year. This could be a blessing in disguise. Ryback shouldn't be losing in another PPV match and there's no need to risk Punk's long term health when the outcome isn't exactly in doubt.
Punk vs. Rock is where the money is at, not banged up Punk vs. Ryback.
The other consideration here is that John Cena vs. Dolph Ziggler has enough on the line that it could pass as the main event of TLC. Cena possibly winning the Money in the Bank briefcase in a ladder match against one of the best wrestlers on the roster should sell just fine.
There are far too many variables at play here and Punk risking further injury simply isn't worth the risk. So even if he can work the match, he definitely shouldn't.