The Italian failed to cement a first-team place at Anfield following his £20m move from Roma in 2009.
After a successful spell with Juve it was expected that Aquilani would compete for a place at Liverpool, but Kenny Dalglish brought in a host of midfielders this summer such as Charlie Adam and Jordan Henderson.
The Scottish manager has now admitted that a return to the Reds is unlikely.
"For Alberto, it was an opportunity for him to go back home. If he does well, then [AC Milan] will purchase him," Dalglish said.
Liverpool take on rivals Manchester United a week on Saturday in their next Premier League fixture.