Conor McGregor has claimed he already had "multiple stress fractures" to his shinbone before stepping into the octagon to fight Dustin Poirier on Saturday.

The 33-year-old broke his leg in the first round of the UFC 264 event in Las Vegas after stumbling backwards and trapping his foot beneath himself.

The fight was subsequently stopped by medics and Poirier claimed the victory by TKO – his second win against McGregor in their trilogy of fights.

McGregor has since undergone surgery to repair a break to the lower tibia in his left shin, which could potentially keep the Irishman out of action for the next year.

But in a six-minute video posted on Instagram on Thursday in which he rides around on a motorised scooter, McGregor insisted he had informed UFC chiefs of his injury problems prior to the bout.

"I was injured going into the fight," he said. "People were asking me when was the leg break – at what point did the leg break? Ask Dana White. Ask the UFC. Ask Dr Davidson, the head doctor of the UFC. They knew.

"My leg – I had stress fractures in my leg going into that cage. There was debate about pulling the thing out because I was sparring without shin pads, and I was kicking.

"I kicked the knee a few times, so I had multiple stress fractures in the shin bone above the ankle, and then I had trouble with the ankle anyway throughout the years of fighting all the time."

Former two-weight world champion McGregor also revealed how he now has a titanium rod inserted in his "unbreakable" leg, which he joked makes him feel like fictional cyborg The Terminator.

"I used to just train on my back, and that's how I developed those ground-and-pound shots from the back. That's why Dustin backed away when he was on top of me and I was landing the upkicks and the elbows," he said.

"It's a horrible place to be in when you're against someone like me. You can't land.

"You take so much effort to try and land shots from your top position, and while you're trying to do that and losing your energy, you're getting lumped out by downward elbows and vicious upkicks. 

"It was a skill I developed because I had the damaged leg, and I had to adjust my training.

"What I needed was a titanium shinbone and now I've got a titanium rod from the knee to the ankle. The doctor says it's unbreakable. Once I keep building back, playing with the balance, then build the strength, I have an unbreakable titanium leg. 

"I'm like Arnie [Arnold Schwarzenegger] in Terminator 2! I've got all the tools to do this and I'm going to do it – what a story it's going to be."