Barnes is highly unlikely to be fit in time for Derby's Championship opener against Doncaster on August 9, but Jewell is hopeful he will be available well before October.
He told the Evening Telegraph: "We've had good news with Giles, really good news.
"He went over to the States this weekend. He doesn't need another operation.
"Dr Steadman is absolutely delighted with his progress. He's coming back to this country to start his rehab to try and be fit.
"There's no time frame on it but it's really good news for Giles and really good news for us."
Jewell added: "He won't be fit for the start of the season but it's as good a news as we could have expected when he went to see the surgeon.
"We thought Giles might have to go over there and have another operation - which the surgeon also thought might happen.
"But he's made great progress and great credit has to go to Giles and the medical staff here."




