Amelia Seiga, 12, from Colwyn Bay, north Wales was treated for sprained wrists after going on the newly-opened Rita, Queen of Speed ride in April.
Her mother, Jane Seiga, said x-rays taken a week later showed fractures in both wrists.
The 60mph ride has been given the all-clear by safety officials.
Ms Seiga said the force of the ride was so strong it peeled Amelia's hands off the guard rail and bent her wrists back.
She is now asking for the ride's height restriction to be raised to prevent it happening to other children.
An Alton Towers spokeswoman said: "A full and thorough investigation of Rita, Queen of Speed was completed both internally by Alton Towers and externally by the Health and Safety Executive.
"The investigation concluded the ride is safe and no changes to the ride, height restrictions or operating procedures are deemed to be necessary."
A Health and Safety spokesman confirmed no faults had been found.
"However, as it is a new ride Alton Towers will continue to monitor it closely and will report any further incidents," he said.
If there were further incidents the investigation would be reopened, he added.
Source : BBC News