The 22-year-old moved to Loftus Road in a reported £5 million switch from fellow Championship outfit Blackpool in August, and has gone on to score three times in 21 appearances this season.
But his participation for the rest of the campaign is now doubtful after he was withdrawn after just six minutes of the 3-3 thriller with fellow promotion hopefuls Burnley on Saturday.
Redknapp remains hopeful he can play a part in the promotion run-in, but he is not optimistic.
"It looks like a long-term injury," he said.
"We hope that we can get him back before the end of the season, but it's a serious one."
QPR are currently second in the Championship standings with 56 points.
Next up for Redknapp's charges is a crunch encounter with Derby County at Pride Park, with just four point separating the two sides.
