Austin, accompanied by his parents and grandmother, Sandy, flew out to the America on May 11 and underwent the selective dorsal rhizotomy (SDR), on May 19.
The procedure involved sectioning (cutting) some of the sensory nerve fibres which come from the muscles and enter the spinal cord.
Because of all the hard work Austin had been doing before the operation the hospital was able to offer another operation too, Bilateral Gastroc Lengthening. This meant Austin would be able to walk in a straight line instead of his legs scissoring.
Austin's mum Helen Manning said she was a nervous wreck when her youngest child was wheeled away from her for the first operation.
"My legs were shaking, but him, he was just amazing. They made him so comfortable, on his way into surgery Austin and nurses were telling each other jokes."
Every half an hour a nurse from theatre called the private room Austin's family were waiting in to let them know everything was going according to plan. When the surgery was finished, Austin's doctor came into the room and talked them through how successful operation had been, she said.
"As soon as he was okay, they got him out of bed and put him into his wheelchair but that was one of the hardest and scariest things for me.
"When they sat him there he just slumped over. He couldn't even hold his head up, he had no strength at all. It was all gone and I thought, oh my God, what have we done."
They were warned of this though, she said.
"It happens because they have taken all the spasticity in his body. Before if he sat up or if he did anything he was held up by the spasticity in his muscles. That was been taken away and all of a sudden he had to use muscles that he has never used before."
While at the hospital Austin was also able to undergo another operation, a Bilateral Gastroc Lengthening, which would stop his legs from scissoring when he walked.
After the operations, Austin had daily one hour sessions of intense physio, as well as homework like having to do 20 sit to stands.
"He was quite weak when he started. We would make him walk from our motel room to the lifts, about 30 meters, which took him about 25 minutes to do. Mum and I had to hold his hands on the walker to keep him stable so he could walk when he first started, by the end of the trip he didn't need us to do that. He was able to walk it himself."
There were of course stressful times on the pair, she said.
"But we had to do it. We had to keep going, I knew that. I couldn't give in because then he would too. We saw other kids at the end of their stay and we saw them walking and that helped too. I knew Austin would do it."
Everyday Austin was able to do something which surprised her, she said.
"The first few days he would be lying on the bed, the next minute they go him to go on the bike and then he was walking."
Now his wheelchair was used as a treat, or for long distances. He was able to sit at the table in a normal chair. He sits in a bumper seat instead of a car seat.
Austin also has more movement in his hands, which he didn't have before. He is now able to grip and holds things in his right hands.
Mrs Manning said he can sit up at the table and eat a yogurt without spilling any. Where as before it would go everywhere because he could not control his hand to control the spoon and eat at the same time.
Mrs Manning said she is excited for what the future holds for her son.
"I cannot believe that we are eight weeks post op and he's walking, imagine what we are going to be like in six months time."