Powerhouse Canberra back-rower Joe Tapine is suspected to have broken the same thumb that ended his 2018 season as the Raiders went down to the Storm on Friday night.
Tapine played just 19 minutes of the first half before being replaced. He did not return after the Storm had jumped out to an early 14-0 lead.
The Raiders said Tapine would undergo scans on Monday.
"He had a bad thumb last week, he played on and it could be a fracture," Stuart said after his side's 22-10 loss at GIO Stadium.
"Scans will tell the story tomorrow, we just hope that he's okay, he's a very important part of our team.
"We lost an international player but that's not an excuse, we have to carry on and move forward and they did that."
If Tapine is ruled out, it will continue a spate of hand injuries for the 24-year-old over the last 12 months. A broken finger kept him out for a month before a broken thumb in round 24 ended his 2018 campaign.
Match Highlights: Raiders v Storm
After impressing in their round one shut-out of the Gold Coast Titans, the Raiders defence was found wanting at crucial times as Suliasi Vunivalu scored a first-half hat-trick.
Some of the 42 missed tackles for the match came early and allowed the Storm to get on a roll and open up what would prove to be an unassailable lead.
Stuart said the causes for the defeat were fixable.
"There was a couple of little team errors rather than team structure and they're easily fixed," Stuart said.
"Nicky [Cotric] wasn't in the line or Charnze [Nicoll-Klokstad] came up out of the line, they're young guys, so those things are easily fixed.
"Structurally overall our defence [was good], take away a couple of those tries the one off the bomb where Jack [Wighton] threw the intercept like that is against the run of play.
"There's two of three tries there I think we can fix quickly."
Josh Papalii again showed off his work rate with 138 metres and 29 tackles in the middle while John Bateman showed off his versatility by shifting to the centres for much of the match.
Despite the loss, Stuart was buoyed by the heart shown by the side in the second half.
"It was a huge effort against a very good football team, so we didn't go away," he said.
"I'm okay where we are at the moment, we're playing against Melbourne who I see as one of your benchmark teams.
"So, for us to come back into that game and score that try or get a bounce off one of those bombs and put it back to six points difference it's a big of heart coming back against a very good footy team."