Both were injured during Saturday's trip to London.
James Ryan and Ryan Baird have been ruled out of Ireland's Six Nations clash with Scotland this weekend.
Ryan is going through the return to play protocols after sustaining a head injury against England on Saturday, while Baird has a back issue.
Leinster pair Ross Molony and Joe McCarthy have been drafted in by Andy Farrell to train with the squad.
Ireland play the Scots in their final match on Saturday - with a win enough to secure the Triple Crown.