Our Danish midfielder was withdrawn in the second half of the 3-1 win, after being caught by a tackle from Reading striker Andy Carroll, who was later sent off for two bookable offences.
While investigations are continuing, initial assessments indicate that Eriksen is likely to be out until late April or early May.
The 30-year-old's absence will be a big disappointment to manager Erik ten Hag and fans, given the consistency of his performances throughout the season so far, making 31 appearances since arriving at Old Trafford.
However, there is hope that Christian can return in time to play a role in the final stages of the campaign.