The family of Ella Tomlinson, 14, of Leominster, had to raise £140,000 for the trip and operation.
Her father Steve said: "She's already been signed off, which is great news. I'm proud to bits of her."
Ella's family made the decision to travel for the surgery after St George's hospitals trust, in south London, put the procedures on hold.
The NHS trust, which had previously performed vertebral body tethering (VBT), said health advisory group NICE was looking into it more and apologised for any distress.
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Ella has scoliosis, an abnormal twisting of the spine which is usually noticed by a change in appearance of the back, or one shoulder or hip being more prominent than the other.
Mr Tomlinson said: "The [US doctors] are extremely pleased with her. They say it's one of the best operations they have done.
"She is in agony at times but she can walk. The aim is to keep her walking, little by little, so she gets better and better. It's a long, long journey but she's incredible.
"[We've been] resigned to the fact that we've had to cash pensions and remortgage in order to raise the money [for the operation]."
"But there's no option... She has to have it [this operation] before April or May when her spine stiffens up with age and she's no longer... able to have it."
Ella had previously said: "I just want it done, out the way, so I can get back to having a normal life."
A Herefordshire teenager is flying home after a major operation to fix a severe curvature in her spine.