Hosannah last featured for City in Stuart McCall’s final game in charge at Oldham on December 12 , having been sidelined with a serious hamstring injury.
The 21-year-old, who joined the club on a season-long loan in the autumn, has made just eight appearances.
Sellars, speaking before Tuesday’s League Two trip to Scunthorpe United, said: “Bryce is injured at the minute and we have looked at where he is in his rehab and things like that.
“It is a setback we are trying to monitor and get to the bottom of. We will possibly have some news on that early next week.
“You have always got that chance when you are not really sure what the problem is. If something is not healing the way it needs to heal, then there are ways and means you can help that and it may require surgery and there’s things like that.
“Fingers crossed that it is not. But it has not healed as well as we have expected and we will have to wait and see.
“Everybody has got the best interests at heart."
Billy Clarke could be back in the fray tomorrow following a muscular injury, with Sellars reporting no fresh injuries for the trip to Glanford Park.
Callum Cooke (hip) is also still sidelined.”
City look destined for a mid-table finish after a four-match winless streak has hit their outside hopes of making a push for the play-offs, but Sellars is making no predictions.
He said: “You don’t know because of how unpredictable the league is. Teams have gone on crazy runs and it’s hard to say.
“Our aim is to get as many points as possible and see where that takes us and get better as a team and develop. If we do those things, we are going to put ourselves in a better position.”