It’s suggested his condition is worse that first anticipated and he could now miss the Africa Cup of Nations.
“Traore is not [back] yet back, he’s in London,” Bosz told reporters.
“Chelsea striker Bertrand Traore is on loan at Ajax”
“He’s still being treated. The injury was worse than the symptoms suggested.
“With the injury I can’t be sure whether Traore will be with Burkina Faso to participate in the Africa Cup.
“If he can’t play with us, he will not be able to play there.
“There’s contact between Chelsea, Ajax and Burkina Faso.”
The 21-year-old impressed for Chelsea last season, scoring four goals in 16 appearances in all competitions.
He also played several pre-season games and looked set for a full Premier League campaign under Antonio Conte this term.
However, the Italian opted to ship the Burkina Faso international out on loan to gain more experience.