Scrum-half Kieran Marmion is facing a battle to be title defence.
Marmion, 26, began Ireland’s 16-9 triumph from New Zealand in Dublin but he was replaced in the 59th minute.
The Connacht participant will have surgery this week and the province say he will be out of action until February.
Grand Slam champions Ireland begin their 2019 Six Nations campaign.
Flanker Sean O’Brien can be targeting a Six Nations return because he recovers from the shoulder he continued against the Pumas.
Leinster’s Luke McGrath and Ulster’s John Cooney will compete for the beginning role in Ireland fall international against the USA after Marmion had started the games against Argentina and the All Blacks in the absence of first-choice amount nine Conor Murray.
In a further blow to Connacht, while Conor McKeon, Craig Ronaldson and Eoin McKeon are long-term absentees prop Conan O’Donnell has had a surgery on a hand injury and will be sidelined until next month.
Connacht head coach Andy Friend has obtained a group of 25 players to South Africa because of their back Pro14 matches against Southern Kings and Cheetahs with fit-again Paul Boyle, Matt Healy and Peter McCabe all part of the traveling squad.