The 26-year-old picked up the knock in the second half of Tuesday's Champions League defeat by Paris St-Germain, a game the Reds lost on penalties after losing 1-0 on the night thanks to an early Ousmane Dembele goal. Both Conor Bradley and Joe Gomez are still recovering from injuries, which means Slot is without a recognized right back.
"Trent is not available. He will not be there at the final," said head coach Arne Slot.
"But he is still to be assessed for how long it will take but we do expect him back before the end of the season.
"Maybe Curtis (Jones) can play (right-back). Trent is not available, he won't be there, he is still to be assessed but we do expect him back before for the season's end."
Alexander-Arnold will likely be replaced by Jarell Quansah who was called up by England manager Thomas Tuchel on Friday morning. Slot praised the young defender and said he deserves to play for his country after his impressive performances for the side this season.
"It says a lot about his mentality (England call). I changed him v Ipswich and Virgil and Ibou (Konate) are such a strong combination, so every time he plays everyone can see he is a talent. He has had some setbacks and he has reacted and shown in recent performances, he has outgrown being called just a talent so that is what Tuchel has seen.
"He has done well for us in a position he is not used to, at right-back. He is strong, fast and comfortable on the ball. And he gives us something different on set-pieces too, you saw where he hit the post."