The Velez Sarsfield full-back had a medical with the Black Cats last week but it has been revealed that he failed that due to ligament problems.
"We have to make sure about some situations but my club is not a club that can sign at the moment a player who is injured, even though it's not a crucial injury.
"We are not Manchester City, who can think about buying a talented player with an injury and wait for him.
"We are not very late [in the transfer window], but I would like a player ready to join the rest of the group because the process of integration is not just physical. They have to understand how we play, which is not easy."