The new Lions coach downplayed the significance of the surgery and did not provide a timetable for recovery, saying he's "not certain" Fairley will return for OTAs.
"He's got a medical issue he's dealing with," Caldwell said. "He'll be back as soon as he's recovered."
Dave Birkett of the Detroit Free Press notes that Fairley has been treated for sleep apnea in recent months.
Fairley's absence is notable in that the defensive lineman is now entering his contract season after general manager Martin Mayhew surprisingly declined to pick up the fifth-year option on the first-round pick.
Fairley has been inconsistent through his first three seasons, but along with Suh makes up the most vital chunk of the Lions defense. Missing workouts in May isn't a huge deal, but missing any time in October would be for the slow-to-improve Lions' defense.