The news was first reported by the NFL Network.
A second-round selection by the Chargers in last year's draft, the Western Kentucky product missed all of his rookie season after tearing the ACL in his right knee during the first week of training camp in August.
Lamp said at the end of last season he was hopeful to begin running and working out with the team when the Chargers' offseason program began in April, but has not been visible on the field during practice sessions open to reporters.
Lamp was penciled in to start at right guard for the Chargers in 2018. However, the Bolts re-signed offensive lineman Michael Schofield to a two-year, $5 million deal that includes $2.5 million in guaranteed money during free agency in March, and the Michigan product has been working with the starters at right guard.
Once Lamp is cleared for practice, he's expected to compete with Schofield for time at that spot.
"Losing Forrest last year was big," Chargers coach Anthony Lynn said at the NFL Scouting Combine in February. "I saw enough in a week to know what he could've done for the rest of the season. He's working his way back right now.
"He's not quite back yet. With him back in the lineup at that right guard position, I'm expecting him to pick up where he left off last year."