But Byrne has made a speedy recovery to claim his place in the Wales side that take-on South Africa.
"When I went to the hospital and had the x-ray and was told I was out for the autumn I thought, 'Here we go again. It it's going to be another autumn sitting on the sidelines'," said Byrne.
"I was devastated when I heard the news. But even when I did it I had good movement and felt I could get back for the Fiji game.
"It has healed quickly. The surgeon said that if I wanted to play last weekend I probably could have. But this week it's totally healed and I'm looking forward to getting back on the field. It's as good as new and everyday it gets better.
"So I'm really pleased to get another chance and hopefully go out there on the weekend to get a victory."
And after watching the defeat to the Wallabies from the sidelines, Byrne believes it is time Wales secured an historic win over the Springboks.
"This week is a must win game for us," continued Byrne.
"We have the best facilities, coaches and staff and as players we must start taking responsibility. We can't let the coaches take the flack all the time.
"All the Southern Hemisphere sides are really good and hopefully we can break the cycle of losing to them. As soon as we can do that we can look forward to the World Cup."
Byrne's return to fitness sees James Hook move into the centre in the place of Andrew Bishop, while George North is set to win his first cap with a place on the wing.
"George is a big bloke, only 18-years-old. I think every 18-year-old would wish they were his size.
"He has all the attributes, he's skilful, quick and has the size. He will certainly be a handful and it's great for him to have the opportunity.
"He has shown he has something about him in the Magners League. It's a big step up but I'm sure he will stand up to the challenge.
"I thought James did a great job at 15 and I was a little bit worried they might have left me out.
"But to have James back in midfield is great, he can put people in space and is the type of player you want to play with."