Bairstow, who broke his leg and ankle, will not play again this year.
He walked to the tee box.
The last Test of England's home summer series was missed by the Yorkshireman.
In an interview with the Telegraph, Bairstow said he "heard it snap straight away".
Bairstow is a key part of England's white-ball teams, having scored over 1000 runs in 10 Tests and 6 centuries.
He told the Telegraph that it would have been fine if he'd fallen on his butt.
My left ankle turned right and my weight went through my left lower leg when I tried to regain my balance. It snapped right away.
I fell down after taking a couple of steps. I was three-quarters of the way down when I collapsed. It happened so fast.
I felt a pain. You hear uncontrollable screams when you play rugby. I knew I needed to go to the hospital. Without painkillers, the next three hours were not enjoyable.