His last post on Twitter read: “Some good advice… if you buy an electric trail bike, read the manual before you ride it.”
“I have broken part of my back. Thank you to everyone for your kind messages.”
Following this, the music mogul has remained unusually quiet, with not even a post about Britain’s Got Talent final.
His BGT co-star and good friend Amanda Holden said: “He’s doing well. I keep in touch with Lauren [Silverman, Cowell’s girlfriend] every week. His will and determination to get himself better is inspiring. He’s very determined, he’s a fighter.”