He played only 5:34 in the win and sat on the bench for the entire second and third periods.
After the game, Blues coach Ken Hitchcock was optimistic but did not offer details when asked about Backes and rookie Robby Fabbri, who played only two shifts in the third period.
"I'll let you know in a couple days," Hitchcock said when asked about their status. "Both guys, they should be good to go."
When asked why Backes remained on the bench the rest of the game, Hitchcock said it was to support his teammates.
"He was cheerleading," Hitchcock said. "He was doing a good job."
Near the conclusion of a 47-second shift with 5:14 remaining in the first period, Backes slid somewhat awkwardly into the boards skate-first, though it wasn't apparent if that was what caused his injury. He also had a hit on Sharks defenseman Brent Burns that could have shaken him up.
Backes is having the best postseason of his career, with seven goals in 17 games. Three of those goals have been game winners.