Adam Schefter of ESPN first reported the news.
The Chargers will seek a second opinion Wednesday, but the non-contact injury is expected to be season-ending, according to Schefter.
Henry set career highs with 45 catches for 579 yards in 2017, although his touchdown total decreased from eight during his rookie season to four this past year. His season ended after 14 games when the Chargers placed him on injured reserve with a kidney laceration in mid-December.
The Arkansas product wasted little time surpassing future Hall of Famer Antonio Gates on the Chargers' depth chart, establishing himself as one of Philip Rivers' go-to options. At 6'5", he serves as a red-zone threat, and he has the athleticism to exploit the seams in man-on-man situations against linebackers.
Although the Chargers previously said they wouldn't re-sign Antonio Gates, Schefter noted the team will have to consider bringing him back if Henry is indeed sidelined for the entire 2018 season. Otherwise, former Denver Broncos stalwart Virgil Green will be the most established player on L.A.'s roster at tight end.