Barcelona are allowed to sign a replacement for Vidal

Aleix Vidal is expected to be out for five months with the ankle injury he sustained against Alaves on Saturday. The length of his injury means FC Barcelona are allowed to sign a player to replace him. 

The restrictions on transfers are the following: It has to be a player either currently playing in La Liga or without a contract, i.e unattached to a club. He will be able to play in La Liga, the Copa del Rey, but not the Champions League.