"A small operational procedure has taken place to repair the damage, and the Sports Science team advise a 10-week recovery period, prior to any form of training," said a statement on the club's website.
Ruiz suffered the injury during the 3-0 away win over Bolton Wanderers on Saturday that left Fulham ninth in the 20-team standings with 43 points from 33 games.
Meanwhile, Russia striker Pavel Pogrebnyak, who joined Fulham on a six-month loan from VfB Stuttgart in January, has started talks about a permanent move to the West London club.
Pogrebnyak, who scored five goals in his first three games including a hat-trick in a 5-0 win over Wolverhampton Wanderers, has missed the last two matches due to an ankle injury.
Fulham boss Martin Jol has said he wants the 28-year-old to stay and Pogrebnyak is also keen to remain with the club.
"Yes, the negotiations about my contract with Fulham have already begun," Pogrebnyak was quoted as saying by Russian sports website sport.mail.ru earlier this week.
"My agent has already talked to the management of the club. I think there's a big chance that I will stay in England.
"Me, the coach and the management, we are all solid on the question regarding my future."
