The Celtics said Tatum is expected to make a full recovery and no timetable was given for his return, but players who have suffered similar injuries are typically sidelined for about one season. “Jayson has a warrior mentality like the rest of his teammates,” Celtics lead governor Wyc Grousbeck said in a text message to the Globe. “He will work very hard to get back, and in the meantime the Celtics will fight hard for every game.”