Henderson is scheduled to undergo left elbow surgery Wednesday, Derrick Goold of the St. Louis Post-Dispatch reports.
Henderson missed the first three months of the season with a flexor strain, only to go down with an elbow strain in his season debut in early August. It's unclear whether Wednesday's operation will be flexor tendon surgery or a different procedure, but it will end his 2026 campaign and could wipe out most, if not all, of his 2027 season.