Darmian had to be replaced by Donald Love after 36 minutes played at the Stadium of Light when the Italian defender landed awkwardly on his shoulder.
Darmian had not had the best of games up until that point and it was an afternoon to forget for him. Van Gaal confirmed that the player is set for a lengthy absence.
Louis van Gaal confirms Matteo Darmian has a dislocated shoulder and will be out for "several weeks". #mufc
— Manchester United (@ManUtd) February 13, 2016
United have had to contend with a number of injuries at the back this term, with Luke Shaw, Antonio Valencia, Ashley Young, Marcos Rojo and Phil Jones spending time at the treatment table.
Van Gaal has been forced to throw the likes of Love and Cameron Borthwick-Jackson into the mix and results have suffered as a result.
The defeat against Sunderland has left United’s top four hopes hanging by a thread and it is hard to see them qualifying for the Champions League next season.