Town boss Kieran McKenna has confirmed that striker Kayden Jackson and winger Kyle Edwards will play no further part this season due to their injuries, while Kane Vincent-Young is back in training after a knock.
Jackson, who is out of contract in the summer but understood to be close to signing a new deal, suffered a hamstring problem in the Portsmouth match, while Edwards has been out of action since February with a quad injury.
Lee Evans and George Edmundson also remain sidelined with knee and ankle issues respectively.
"Asked about the injury position going into Saturday’s game at Rotherham, McKenna said: "Same situation, George, Lee Evans, Kayden and Kyle still not returned or training with the group, some are obviously further away than others but none of them have managed to get towards full training yet. The situation is pretty similar.
"Kane Vincent-Young hasn’t been training with us for the last couple of weeks with an issue but he returned to training the back end of this week so we have to take a view on Saturday or Tuesday when his first involvement might be.”
Quizzed on whether any of the four long-term absentees will now be able to return before the end of the season, McKenna added: "For most of them no, I think their deadline has passed that.
"But I’m not prepared to leave anyone out of the games who can be fit, so if their rehab process, done in the right way and with the right level confidence can be completed before the Charlton game, then I’d like to see them on the pitch and we’ll continue to push towards that and the medical team is pushing towards that.
"And if we can get any of the four fit and available before the end of the season that would be a big bonus, but certainly for Kayden and Kyle that’s pretty much ruled out completely.”
Town will also be without Cameron Burgess for the trip to the New York Stadium following the centre-half’s red card at Shrewsbury last week.