The County skipper and wicket-keeper was forced off the field on Saturday afternoon after suffering a finger injury while trying to take a catch.
Ripley admitted that Rossington will not keep wicket on the final day, with Ricardo Vasconcelos stepping in, but he will bat if needed.
Glamorgan go into the fourth and final day at the County Ground with a 248 run lead, closing day three of 205 for four after bowling Northants out for 364 in reply to their 407 all out.
Asked about the injury to Rossington, who scored a crucial 76 in the first innings, Ripley said: “It is a bit sore. I don’t think we’ll send him out to keep tomorrow.
"I guess he’ll have an x-ray on Monday to get the final detail of whether it is a fracture or not – at the moment it is 50/50 over what it looks like.
“As far as this game is concerned he can bat.
“It is a different finger [to the one he damaged against Kent], he is making his way through all ten!
“The bounce has got a little low but it comes with the territory.”
The draw is looking the most likely result on Sunday, with Northants indebted to half centuries from Wayne Parnell and Gareth Berg.
The pair steered Northants from a precarious 252 for seven overnight to 364 all out, with Parnell making 54 and Berg 69 not out.
That meant Northants conceded only a 43-run deficit, and means if Glamorgan want to set up a chance of winning on the final day they are likely going to have to set a total after a declaration.
“That partnership at the beginning of the day was vital," admitted Ripley.
"If we had surrendered there and conceded a big lead to Glamorgan then we are really struggling and there is only one winner in the contest.
“It was a quite cagey day’s play, but from what we set out to achieve I don’t think we could have done much more than we did.
“I think we need something special for us to win the game from here.
“It is early season so I would be surprised if they set something up, but it will depend on what Glamorgan are feeling.”