ESPN's Adam Schefter reports Rob Gronkowski's back surgery recovery is expected to take ten weeks.
There are about 16 weeks left before Week 1. Profootballtalk has reported the back surgery will occur roughly 3-4 weeks following Gronkowski's Monday arm procedure, putting a tentative return timetable at 2-3 weeks before the season, assuming all healing proceeds without setbacks. At this point, we can't expect Gronk to participate at all in the preseason, but he still has a shot to be ready for Opening Day. The Pats open Sunday, September 8 at Buffalo.

A source with knowledge of the situation tells Profootballtalk.com that Rob Gronkowski will "probably" require back surgery after receiving a second opinion from Dr. Robert Watkins.
It's confirmation of NFL Network's previous report that the surgery "looks likely." Per PFT, the back surgery will take place in 3-4 weeks following Monday's surgery on Gronkowski's forearm. Doctors don't want to schedule the two surgeries too close together. Although the back surgery is considered "minor" in comparison to the operation that cost him the entire 2009 college season, Gronkowski's Week 1 availability is now very much in doubt.

ESPN's Adam Schefter reports Rob Gronkowski's potential back operation is considered "minor," and wouldn't necessarily sideline him any longer than his arm surgeries.
The back surgery is considered "likely," per NFL Net's Albert Breer, but Schefter reports the operation would take place within the timeframe of Gronk's absence due to a fourth arm procedure. "He is going to be fine long term," said a source close to Gronkowski. "(He is) not worried about the short term, i.e. start of training camp." Either way, multiple offseason surgeries on multiple body parts are cause for major fantasy football alarm. And the fact that Gronkowski is in line to have had two back surgeries since 2009 is absolutely a long-term worry.