Now it’s time to be worried about Rob Gronkowski.
The Patriots’ star tight end has had four surgeries on his broken left forearm since December, but that injury is expected to be healed by the time training camp opens in August.
But an upcoming back surgery is a much bigger issue, and might knock Gronkowski out for an extended period of time, perhaps as much as the first six games of the regular season.
A league source confirmed Wednesday that Gronkowski, 24, will undergo surgery in mid-June to repair a herniated disk. It will be performed by noted spine surgeon Dr. Robert Watkins in Los Angeles, who did similar surgery on Gronkowski in 2009, which forced him to miss the entire 2009 college season at Arizona. The current injury is not to the disk that was repaired four years ago.
While the surgery is relatively routine, and Gronkowski should be out of the hospital that day, the rehab is lengthy, according to Dr. Stephen Parazin, chief of spinal surgery at New England Baptist Hospital. Parazin does not know the specifics of Gronkowski’s injury, but said he performs 70 to 100 such surgeries each year (called a microdiscectomy, which Gronkowski had in 2009) and estimated that Gronkowski’s recovery will be a minimum of 12 weeks.
The Patriots open their season Sept. 8 in Buffalo; a 12-week recovery could keep Gronkowski out until mid-to-late September. The Patriots likely will consider putting Gronkowski on the physically unable to perform list before the start of training camp in late July.
Gronkowski could come off the PUP list any time during training camp and return to practice. But if he remains on the list after training camp, he must sit out the first six games of the season.
At that point, the Patriots have three weeks to allow Gronkowski to return to practice, and another three weeks from the date of his first practice to activate him to the 53-man roster. If Gronkowski is not ready to play at that point, he will be placed on injured reserve and miss the entire season.
Parazin said the rehab from a microdiscectomy is similar for world-class athletes and regular people. Gronkowski will need about six weeks to heal the scar and muscles, and another six weeks to regain the strength and conditioning.
In the first six weeks, he will be allowed to do light cardio work, “but he really can’t jog, run, or lift,” said Parazin. “You can’t do a lot of straining, or things where they have to hold their breath and grunt.”
The second six weeks will be about regaining his strength. Gronkowski may be tempted to return to the field sooner, but the Patriots are likely to be careful with the tight end, a vital weapon on offense who regularly slams into 250-pound defenders.
“These guys that are going to get smashed by other big guys, you have to take a little extra time,” Parazin said. “The last thing you want is for him to be out of shape and then get injured somewhere else.”
Gronkowski’s back injury in college caused him to slip to the second round of the 2010 draft, but he played in all 32 games his first two seasons with the Patriots and the first 10 of 2012 before breaking his forearm.
June’s surgery will be Gronkowski’s sixth in 16 months: He had four on his forearm, the last on May 20, and surgery on his ankle after the 2011 season.
Parazin hypothesized that Gronkowski had to wait for his forearm injury to heal, and the infection to be completely cleared from the area, before undergoing back surgery.
“Maybe they want to make sure the forearm heals a little more, because it gets infected and then the back surgery gets infected,” Parazin said.
Gronkowski signed a six-year, $54 million contract extension before the 2012 season that paid him more than $18 million guaranteed. If he is unable to play the first part of the season, the Patriots will rely on a handful of tight ends to replace him: Aaron Hernandez, who is recovering from shoulder surgery; Jake Ballard, back from a torn ACL; Michael Hoomanawanui; Daniel Fells; and perhaps undrafted rookies Zach Sudfeld and Brandon Ford.Ben Volin can be reached at Ben.Volin@globe.com. Follow him on Twitter @BenVolin.