The experienced Brentford midfielder landed awkwardly when he slipped while jumping over a barrier at the Azteca Stadium on Sunday, and video footage showed his forearm buckling.
After leaving the field on a stretcher and receiving oxygen, Henderson was taken to hospital in Mexico City and did not travel back to England's training base in Kansas City with the rest of Thomas Tuchel's squad.
A member of England's medical staff stayed behind with him.
The 36-year-old Henderson was an unused substitute against Mexico, but the former Liverpool captain is among the squad's most respected figures, providing leadership, experience and a calming influence.
England's Football Association has not said anything officially about Henderson's participation in the rest of the tournament.
FIFA World Cup 2026
The 2026 World Cup is taking place from June 11th to July 19th in the United States, Canada and Mexico. The tournament features 48 national teams and is played at 16 modern stadiums.
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