The Italy striker is currently in Colorado undergoing rehabilitation to heal the ligament damage that he suffered back in August.
The 27-year-old is expected to be back in training at the start of 2015.
"The assessment revealed the meniscus suture is healing in the correct way," read an official statement from the Serie A club. "There will be a gradual increase in weight loads until the next scheduled inspection in three-four weeks. After this period, the athlete will return to Florence."
Rossi scored 17 goals in 24 games for Fiorentina during the 2013-14 campaign.