Horner told reporters at the Dutch Grand Prix that the AlphaTauri driver had several screws and a plate fitted in the operation in Barcelona.
“It went well, it was successful. The bone was broken in multiple places but it was a fairly straightforward procedure,” he said.
“Now it’s all about recovery. For a normal human being that would be a couple of months, for a grand prix driver it’s often a lot shorter.
“We need to see how that recovery process goes in the end but certainly not Italy,” he added when asked about the timeframe.
Singapore follows on Sept. 17 and Japan on Sept. 24.
Ricciardo posted a picture on Instagram of himself lying in a hospital bed with his left arm bandaged and in a sling.
“Hey everyone. Had surgery this morning, got my first bit of metal work so that’s pretty cool,” he said. “Big thanks to everyone who reached out and kept my spirits up. This ain’t a setback, just all part of the comeback.”
He flew to Barcelona on Saturday to see a specialist after suffering a break to a metacarpal on his left hand in a crash during Friday practice at Zandvoort.
The 34-year-old was three races into his comeback with Red Bull-owned AlphaTauri after leaving McLaren at the end of last year intending to take time out.
Barcelona-based MotoGP traumatology specialist Javier Mir operated on Aston Martin’s Lance Stroll when the Canadian broke his wrists before the start of the season.
Stroll was able to race in Bahrain two weeks later.
(Writing by Alan Baldwin in London, editing by Pritha Sarkar)