Justin Hartley "tore [his] bicep off" while working out at home

Speaking in an upcoming appearance on 'The Ellen DeGeneres Show', he said: "I was working out and I ended up doing something really ridiculous. I tore my bicep off my arm. It was nasty. The tendon that holds it to the bone came off. It sounded like someone ripped your shirt. It was bad.

“[The exercise] was something that I made up. It was something that I shouldn’t have done. It was like a bicep curl, but I think I jerked the weight or maybe it was too much weight.”

The 43-year-old star was "in shock" when the injury occurred and the pain quickly began to spread.

He continued: "I heard it. I think I was in shock, but it felt like… the way I would describe it is, I stopped because I heard it. It was an awful sound.

"I felt like a little grain of sand [near my bicep]. Then it turned into like a pea, then a marble, then a golf ball, then a tennis ball, then a softball, and then a watermelon. It just feeling like it was huge, like a human head was in there."

Justin was taken to hospital and later got the chance to watch a "disgusting" video of his surgery.

He said: "They put it back. The doctor cut me open, I'm totally healed now, I'm fine. The doctor showed me the video of the surgery. They were literally able to grab the tendon and pull it out of my arm. They showed me the video, it's pretty disgusting."

And fortunately, the star is now almost fully healed.

He said: "It took like three months to heal, I'm 95% now. It's a little tight but I'll be alright, I'm lifting weights again."