Bradley Davies and Lesley Klim will be sidelined into 2019 after both players underwent surgery.
Davies was released back to the Region from the Welsh camp last weekend for further investigations on a knee problem while Klim has yet to play since joining the Ospreys this summer after injuring his hamstring on international duty with Namibia in August.
Chris Towers, Medical Performance Manager, said:
“Lesley has failed to recover from a hamstring injury he suffered playing against Zimbabwe in August, despite our best attempts at rehabilitation.
“Subsequently, following discussions with specialists the decision was made to proceed with surgery, with a tentative return to play of four months post surgery.
“Bradley underwent surgery for a cartilage problem in the knee last week. Taking on board guidelines, he is looking at being available for selection in three to four months time.”