Tshimanga, who has scored 24 goals in 27 league games this season, has been out since February with a dislocated ankle and fractured leg.
It had previously been said that the forward might have a ‘slim chance’ of returning towards the end of the campaign but manager Paul Cook has revealed his season is over.
"He will not make the play-offs at all,” Cook told the DT.
"He is back on the grass and he is training but we are in no position to want to risk him or feel the need to risk him.”
The Spireites will also have to end the season without key man Oyeleke.
Cook said: "He has got a knee problem at the minute, he is seeing a specialist this week and he is likely not to play again this season which is really disappointing for the lad.
"Our thoughts are totally with the lad because he is a good young man, he wants to play for the club and he wants to do well. But unfortunately his body is not allowing him to do that at the moment.”
But he could be back fit if Town qualify for the play-offs, Cook said.
"He still has not trained this week so the likelihood is he won’t have any involvement in the game on Sunday,” Cook added.