The Fulham stopper's stay with the Alex will expire on New Year's Day and boss Steve Davis is concerned that the 23-year-old may be unable to add to the three appearances he has already made.
Etheridge incurred the injury during his final clearance of the Alex's 1-0 win over Crawley last Saturday and the prognosis does not look good for the rest of his time at Gresty Road.
"We are disappointed for Neil because he was playing well and enjoying his loan," Davis told the club's official website.
"He had played three games and I thought he was getting better in every game.
"If he is unable to play for us again then I hope we could do something when he is fully fit again.
"I would certainly look at bringing him back and seeing if he can carry on where he left off. He is a super lad and a good goalkeeper."
Crewe are out of the FA Cup and so do not play this weekend but Davis must consider who to pick in goal against Coventry next weekend, with Steve Phillips and Alan Martin the most likely candidates.