In a Facebook post on Wednesday, Weidman said that he did not want to pull out of the fight, but he found out that he has a "large extrusion herniation" in his neck and will need surgery.
"To all the people bad-mouthing me right now, I understand it and you're entitled to your opinion," Weidman's post said. "Just wanna make sure you know this is a fight I refused to pull out of no matter what. I was never in better shape, more healthy, motivated, confident and excited for a fight in my life. I also felt I was the best fighter I have ever been and made some great improvements."
Weidman said that he has experienced neck stiffness for years, and after he sparred Thursday, his neck stiffened up on Friday and grew progressively worse. By Saturday, Weidman said he was experiencing vertigo and not walking straight. He said an MRI revealed the injury.
The fighter said that he initially thought that an epidural would alleviate his symptoms and allow him to fight, but the injection did not solve the problem.
"I am being told I'm going to need surgery," the Facebook post said. "Either they take the disc out or they fuse it and I have to meet with surgeons today to figure out what they will do."
Weidman said that since the injury is lower in his neck, he will regain full motion and hopes to fight in UFC 205 on Nov. 12 in New York.Weidman fights out of New York, where a ban on professional MMA was recently lifted.
"I promise I'll be back and I will get that belt back," he wrote.
The UFC is currently seeking a replacement to keep Rockhold on the card, which will take place at the Forum in Inglewood, California. It is expected to make an announcement about the fight in the next 24 to 48 hours.
Rockhold is looking to defend his 185-pound title for the first time since he claimed the belt in a fourth-round finish of Weidman via TKO at UFC 194 in December.
Weidman (13-1) will have to wait a little longer to avenge the first loss of his professional career. Following the loss, Weidman admitted that he went into the Rockhold fight with a broken foot, but he was adamant that he didn't view the injury as an excuse. Rockhold, for his part, fought with a staph infection.
Rockhold (15-2), meanwhile, is on a five-fight win streak. He is unbeaten since he suffered a first-round knockout loss to Vitor Belfort in his UFC debut in May 2013. ESPN.com ranks Rockhold the No. 3 pound-for-pound fighter in the world.
Options for a potential replacement opponent would appear to includeRonaldo "Jacare" Souza(23-4), who is coming off a one-sided first-round finish of Belfort at UFC 198 last weekend.
Souza, a former Strikeforce champion, has fought Rockhold once, dropping a unanimous decision in a Strikeforce title fight in September 2011.
Longtime middleweight contender Michael Bisping (28-7) would also be an obvious option. Bisping is on a three-fight win streak and has never fought for a UFC title. He is coming off a win against Anderson Silva in February and has a loss to Rockhold on his record.
Bisping took to social media to express his interest in the fight.
A bantamweight championship trilogy bout between Dominick Cruz and Urijah Faber is currently scheduled to co-headline UFC 199.
Weidman out of UFC 199 with injury
Brett Okamoto reports on Chris Weidman's undisclosed injury that has forced him to withdraw from a middleweight title rematch against Luke Rockhold at UFC 199, and takes a look at Weidman's future, possibly at Madison Square Garden in UFC 205.
Stepping in for Weidman: Jacare or Bisping?
ESPN MMA reporter Brett Okamoto recaps the co-main event of UFC 198, a first-round TKO win for Jacare Souza (23-4, 1 NC) over Vitor Belfort (25-12). With Chris Weidman's withdrawal from UFC 199, who is next in line?