He fought his way back to fitness and starred for the Dragons once again this season, only to brake the same leg against Benetton Treviso on April 3 - just seven games after his comeback.
To make matters worse the fracture was caused by the metal plate put in Thomas' leg after the first injury.
Thomas, 24, said: "It was basically a freak accident. I rebroke my leg about an inch above the plate they put in last time.
"The Treviso prop fell on my leg and it fractured. Had the pressure come an inch either way of the plate it wouldn't have happened.
"To rebrake it almost a year after the first time was extremely frustrating. I just thought a career in rugby wasn't meant to be for me.
"I had worked so hard to comeback, it was at a real low-point."
But while Thomas admits he thought his career was over following a second devastating blow within 12 months, after the initial disappointment subsided, he knew he could overcome the injury.
The west Walian spent five weeks in a protective moon boot before having the plate and screws from the previous injury removed in May.
Thomas then spent a further five weeks in the boot before taking the first steps in a lengthy rehabilitation process.
Thomas added: "I quickly realised it was a minor injury compared to the first one, I knew mentally that I could deal with it.
"I'm now at the stage where I'm running again. My rehab is progressing week in week out and I hope to be fit for the beginning of the season.
"I've managed to get away a couple of times and I'm going out to Parma on my mate 'Papa Rich's' yacht for a week after pre-season so I will be feeling fresh and hopefully ready to go.
"All I'm aiming to do this year is stay injury free and get a run of games under my belt. But before I can do that I have to get back in the team.
"The boys did well at the end of the season and there's a bit more strength in depth following the signing of Jamie Smith from Ulster.
"There's a real buzz about the place at the moment. The future's looking bright and everyone wants to be a part of it.
"As a team it's important that we start well. We'll be missing a couple of players at the World Cup but it's vital that we win our home games.
"It's also important to win on the road. Our away form wasn't good enough last year and we have to improve on that even if it's just picking up bonus-points.
"We have young coaches who know what they want to do and if we can implement their game-plan correctly I'm sure we can be successful."