The popular Austrian stopper picked up the problem during Boro's pre-season tour of his homeland.
It was initially only seen as a minor problem, but Gareth Southgate has now admitted that Pogatetz may need to go under the knife.
"We sent Manny for scans and he went to see a specialist," said Southgate.
"It doesn't look good. Surgery is something we might have to consider. Obviously we have to make a quick decision."