The 49-year-old star, who serves as a judge alongside Simon on Britain’s Got Talent, confirmed her pal is doing “really well” as she shared a throwback snap of the duo from the ITV talent show’s auditions on her official Instagram page.
Simon, 60, came within “one-centimetre of being paralysed” when he fell from his electric bicycle earlier on Saturday, and was forced to undergo an operation which saw a metal rod placed in his back.
Former Wild at Heart actress Amanda penned: “I’ve been thinking about my dear friend all day and luckily I’m able to say (with blessing) that he’s had his operation and he’s doing really well.
“Chris, Lexi, Hollie and me wish you a speedy recovery and send you, Lauren and Eric all our love.”
Simon and Amanda have been close pals ever since he hired her to star as a panellist on the ITV competition series’ first edition in 2007.
The music mogul was operated on Saturday night after the accident at his Malibu home earlier in the afternoon.
A close friend has claimed to The Mirror that although Simon’s back was broken in several places, he narrowly missed breaking his spinal cord “by a centimetre” which would may have meant he was unable to walk again.
A source told the publication: “I spoke to him before the surgery and he was in incredible, ridiculous amounts of pain and also in shock. His back was broke in several places, but he is actually very lucky.
“He fell flat on his back and the doctors say the impact missed his spinal cord by about a centimetre and it could have been a lot, lot more serious.
“He was in surgery for six hours and they had to put a metal rod in his back and fix a number of things. He is recovering in hospital now and we expect him to be there for a few days and then he will take things from there.
“It is too early to say when he will be back on TV.”
Simon had been set to record first live America’s Got Talent show on Tuesday at Universal Studios but will now be resting for the foreseeable future; first in hospital and then at home wth his family.
A statement from Simon’s representative confirmed he broke his back and had surgery to fix it.
The spokesman said: “Simon has broken his back in a number of places in a fall from his bike whilst testing a new electric bike in the courtyard of his home in Malibu with his family.
“He was taken to hospital where they operated overnight, he’s under observation and is doing fine.”
The dad of one had been at home with his six-year-old son Eric and his partner Lauren Silverman when the accident happened.