According to this article on WWE.com, CM Punk is cleared to return to the ring for Monday's TLC match against Ryback. Here is an excerpt from the article…
"As WWE Champion CM Punk’s potential title defense against Ryback approaches on the Jan. 7 edition of Monday Night Raw, WWE.com sources indicate that The Straight Edge Superstar has been medically cleared for in-ring competition several weeks after his undergoing knee surgery. The decision, if confirmed, returns Punk to action effective immediately, meaning he will defend his championship as scheduled in a Tables, Ladders & Chairs Match against Ryback.
The bout had originally been scheduled for the WWE TLC: Tables, Ladders & Chairs pay-per-view, but Punk’s sudden trip under the knife suspended that contest until the champion was fully recuperated. His status was in doubt as recent as Dec. 31, when his recovery timeline from the procedure was called into question by Punk's personal physician. WWE Chairman Mr. McMahon had gone so far as to schedule a potential replacement match of Ryback vs. Paul Heyman should Punk prove unable to compete, but pending approval, it appears The Chairman’s worries are assuaged.
Our sources also indicate that a final decision on the champion's status will be presented to the WWE Universe on WWE Main Event tonight at 8/7 CT on ION Television."
WWE is expected to make an official announcement on tonight's edition of WWE Main Event. They'll likely insert some commentary or a video package in post-production. The same will likely be done on this week's WWE SmackDown telecast.