The Danish player, 30, had to be substituted during United's 3-1 win over Reading on Saturday in the FA Cup following a foul by Andy Carroll and a statement from the club on Tuesday said he was "likely to be out until late April or early May".
Eriksen has played 31 out of United's 32 matches in all competitions this season while scoring two goals and providing nine assists.
The midfielder joined United on a free transfer last year from fellow Premier League side Brentford, where he had re-established his career after having a cardiac arrest on the pitch during the European Championship in June 2021.
Reuters