Chanda Singh Chauhan, 49, was travelling in the second row of the ill-fated Smiler ride at Alton Towers in Staffordshire in the West Midlands region of England when it smashed into a stationary carriage at the speed of 80 kilometres per hour.
Singh's daughter Meera, 26, told 'Birmingham Mail' that her mother was being treated for a damaged liver and blood clots in hospital.
Amir Khan, medical director at Walsall Healthcare NHS Trust, said Chauhan underwent a surgery and is now recovering.
"Leah has suffered a life-changing injury and now has many months of rehabilitation ahead of her. Her leg was amputated above the left knee and she also suffered a fractured left hand," Washington's father David Washington from Barnsley said.
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In a statement, Alton Towers said it had written to all 16 of the injured or their families.
"Irrespective of the outcome of the current investigations into the causes of the accident, in these letters we have accepted full responsibility to those who had been injured in the accident and confirmed that we will ensure that compensation will be provided to them.
Alton Towers owners Merlin Entertainments said it had carried out "a thorough review" of safety procedures.
The UK's Health and Safety Executive inspectors have also been on site.
The site's owner Merlin Entertainments has closed down three rollercoasters at two other amusement parks as it deals with the fallout from last Tuesday's collision, which left four people seriously injured.