Vaughan has been ruled for the rest of the year after suffering a foot injury at training on Tuesday as he attempted to return for Jason Nightingale's farewell home match.

St George Illawarra Head of Athletic Performance Nathan Pickworth said that the new injury had ended the NSW front-rower's season.

"Paul suffered a season-ending injury to his foot in a freak incident at training," Pickworth told Dragons.com.au.

"Paul's foot injury occurred on the opposite leg to the one he previously suffered against the New Zealand Warriors in Round 21."

The 27-year-old said he was gutted to be ruled out for the remainder of the season.

"I'm devastated that my season has come to an end so suddenly today," Vaughan said.

"However, I'll continue to support the boys for the rest of the year, and I look forward to coming back bigger and better in 2019."