The Boston Celtics will be without Kyrie Irving for the remainder of the regular season and the entire playoffs. ESPN's Adrian Wojnarowski reported the news on Thursday afternoon, and the team confirmed that Irving will have a second knee surgery that will sideline him for four-to-five months:

Irving took to Instagram on Thursday to address his fans, adding that he had an infection in his surgically repaired knee:

The hardest thing to do sometimes is accept the uncontrollable things life throws at you. You try consistently to learn, grow, and prepare everyday to equip your mind, body, and spirit with tools to deal with some of those things, but I feel when those moments arise they all give you a sense of unfulfillment, simply because it puts some of your professional journey and goals on a brief hold. It's simply a test of your perseverance and Will, to be present, even in the wake of what's going on. In this case, finding out I have an infection in my knee is definitely a moment that I now accept and move past without holding on to the all the what ifs, proving the nay-Sayers completely f***ing wrong, and accomplishing the goals I've set out for the team and myself. This season was only a snapshot of what's to come from me. Trust Me. "The journey back to the top of Mt. Everest continues." #StandingRockSiouxTribe Let's go Celtics!! Celtics fans, I look forward to hearing how loud it gets in the TD Garden during the playoffs and experiencing how intense the environment gets. Thank you all!

A post shared by Kyrie Irving (@kyrieirving) on

Irving underwent surgery on his left knee on March 24 to remove a tension wire that was causing discomfort. He initially had a timeline of three-to-six weeks, which meant he would be out for the rest of the regular season, but there was hope he could possibly return in the playoffs depending on how far the Celtics went. 

Following the surgery, Celtics GM Danny Ainge said that Irving's knee was "structurally sound." He also noted, however, that Irving may at some point require an additional procedure. Via NBC Sports Boston:

"We tried to do a minimal amount of surgery at this moment," Ainge, the Celtics president of basketball operations, said on his weekly call-in to 98.5 the Sports Hub's Toucher & Rich show. "And it might require some more. We don't know any of that. I don't know."

"When I say it shouldn't affect his career, I'm saying his knee is very structurally sound," Ainge said. "It isn't like a long-term thing. There could still be some challenges."

According to SportsLine data scientist Stephen Oh, the Celtics' already-slim chances of winning the NBA title have dwindled to almost zero now that Irving is out for the playoffs. Assuming Irving would have been back on April 20 prior to Thursday's news, Boston had a 1 percent chance of winning the title -- that now stands at 0.6 percent. The Celtics are also no longer favored to even make it out of the first round.

Celtics playoff chancesRound 1Round 2Conference finalsChampionship

With Irving back on April 20

52.4%

16.8%

4.0%

1.0%

Without Irving

48.6%

13.5%

3.0%

0.6%

Difference

-3.8%

-3.3%

-1.0%

-0.4%

The Celtics, following their loss to the Raptors on Wednesday night, are all but locked into the No. 2 seed. Irving, of course, is not the only key member of the team who has had to undergo surgery this season. Gordon Hayward (ankle) and Daniel Theis (knee) will not play in the playoffs, and it's likely that Marcus Smart (thumb) will miss out on the entire postseason as well.