NFL Network's Ian Rapoport just reported that three weeks ago, Aldon Smith underwent surgery for a torn labrum suffered during the 2012 season. There is no timetable on his return, but Rapoport said Smith was recently seen without a brace.
As for when the injury occurred? Well, as Rapoport pointed out, Aldon was on the 49ers injury report starting in Week 12 with a shoulder injury. He was listed as probable through the end of the season and the playoffs with that shoulder injury. The 49ers likely will not be confirming any details on this, but one has to imagine that labrum was an issue during this period. I suppose he could have aggravated a smaller injury, but either way, he was playing hurt.
Aldon put together 19.5 sacks on the season, with all of them coming through December 9. If the labrum was torn before Week 12, that means he grabbed at least 4.5 sacks once injured. We discussed his decline over the close of the season, and Justin Smith's injury was always brought up. Now it is possible a combination of Justin Smith's injury AND Aldon Smith's own injury were the cause of Aldon's decline in sacks.
Whatever the case, this would seem to indicate the right side of the 49ers defensive front made it to the Super Bowl basically with one arm apiece. We'll keep an eye on this situation as the team gets ready for OTAs in May. You can learn more about torn labrums at the Johns Hopkins website.