Del Horno had a problem with his Achilles tendon in training last week and national team doctor Genaro Borras said the player would be out of action for around three weeks, therefore a last minute change was required.
Pernia, who had set a wedding date for June 20 after he was left out of the squad, will fly back from Buenos Aires and join up with the side in time for the warm-up game against Egypt in Elche on Saturday.
"My wife's happy for me although a bit disappointed about having to postpone the wedding," Pernia told Spanish television station Antena 3.