Wright is expected to be ready for 2018.
"It's definitely disappointing to know that it's the beginning of the season and [my] season is over," Wright said. "But it's one of those things we tried to do whatever we could to get through it, and it just got to a point where it was just unbearable.
"That's one of the reasons we're doing it now is because it's a lengthy recovery process, and if I keep waiting to get it done and I get it done anyway, then next season is in question. But because we're doing it so soon and getting on it, there's no reason I shouldn't be ready for the start of next season."
Kyle Kendrick, who started Thursday night against the Orioles, is replacing Wright in the rotation. The veteran sinkerballer had his contract purchased from Triple-A Pawtucket prior to the game.
The Red Sox still feel good about their starting pitching, which includes Chris Sale, Rick Porcello, Eduardo Rodriguez and Drew Pomeranz.
David Price hasn't pitched yet this season due to a left elbow strain, but he could be back by late May or early June if he stays on his current path.
This injury comes one season after Wright went 13-6 with a 3.33 ERA and was an All-Star. Perhaps because he was pitching through discomfort in his knee, Wright got off to a tough start this season, going 1-3 with an 8.25 ERA.
"Very tough," said Red Sox manager John Farrell. "Any time you see a guy go down for the remainder of a year, that, in and of itself, is an unfortunate thing. You love the fact that there's a knuckleballer in your rotation for obvious reasons. A contrast of style, quality innings that he pitched for us a year ago, and he seemingly couldn't get on track this season."
Wright first started experiencing some discomfort in his knee in Spring Training. But the Red Sox checked him out at that time, and the images looked nothing like what was seen in the MRI the club performed last weekend.
"The injury that he had with his cartilage, which was small in Spring Training, [became] significantly larger," said Red Sox president of baseball operations Dave Dombrowski. "And the doctor doesn't really know why. He said normally there'd be a specific incident that would cause that. When we asked Steven if he had anything specific, he said not really. He said, 'I'm not really sure what took place.' It's a hard one to understand, totally."
It is equally hard to comprehend for Wright how a minor injury in Spring Training turned into this.
"No idea," said Wright. "The loose bodies [of cartilage] weren't in there in Spring Training. It was literally a small tear that was still attached to the bone. The second MRI I thought was going to be the same. Then all of a sudden, I come in and see Dave and John, the doctors and trainers, and I thought this was definitely something that was not just a little tear. That's when they told me about the floating bodies."