Nick Fairley sits out Lions' OTA
Lions coach Jim Caldwell said he did not know when Fairley would return or what procedure he had done.
"He's got a medical issue that he's dealing with," Caldwell said. "He'll be back as soon as he's recovered."
When that could be is uncertain, according to Caldwell.
Fairley's absence comes the same day Ndamukong Suh returned to the Lions for OTAs.
Detroit declined to pick up Fairley's fifth-year option earlier this year.