Crowell had been on the road to recovery after picking up the injury a month ago, but the 22-year-old has now been told he needs corrective surgery.
The Bridgend-born Wales Under-21 international was due to go under the knife on Monday.
Meanwhile, Wrexham reserve striker Alex is beginning his long rehabilitation after breaking his leg last week.
The 18-year-old broke his tibia and fibula following a last minute tackle in Wednesday night's Pontin's League victory over Chester City at the Deva Stadium.
"Everyone at the club wishes Alex a speedy return to action," said a statement on the Wrexham website.
BBC