The three-year-old from Hughes has cerebral palsy and recently returned from the United States after having an operation that has been shown to reduce spasticity in children with cerebral palsy, improving sitting, balance and mobility.

Ms Patch said Ollie had made remarkable progress since having the procedure, known as selective dorsal rhizotomy, at St Louis Children's Hospital, Missouri, in December.

"Our usual physio saw him for the first time since (the operation) and she was just blown away by the changes in him. I don't think neither she nor us expected that we were going to get such positive changes and good results so quickly," she said.

Ollie was able to have the operation thanks to the generosity of people who donated more than $74,000 through a hugely successful crowd-funding campaign.

Ms Patch said she was deeply grateful for the support.

"All along, we've been blown away by the generosity of people, people who don't know us but just know our story, donating really quite significant amounts," she said.

"We are so incredibly grateful to everyone who has supported Ollie and not only just through the monetary donations but while we were away, getting messages of support from family and friends and from people we don't know largely, it really lifted our spirits in those harder times.

"That encouragement and support was just fantastic. It really meant a lot to us."

The operation has also given the family hope Ollie will one day be able to run, walk and even ride a bike on his own like his siblings Elliott and Millie and other children his age.

"It means his potential in life is much greater than it was before," Ms Patch said.

"His walking is a lot better, he's not dragging his feet at all. He's a lot looser so even things like changing his nappy are a lot easier because he doesn't have tight hips any more.

"His mobility is so much better. Ollie is actually enjoying moving now and it's a lot easier for him to get around so that means his participation in his therapy sessions is really good."

Before having the procedure, Ollie had only ever taken four completely unaided steps.

But the three-year-old's progress has been remarkable since the operation and he recently took 101 steps on his own for the first time.

"We were just thrilled with that. We didn't expect him to be doing that well at this stage," Ms Patch said.

"He's also preferring to walk just holding one of our hands instead of even using his walker which is really good."

Ollie's surgeon, Dr T S Park, also told the family the three-year-old may one day no longer need therapy.

"To hear that, is just amazing... just to know that there's likely to be an end to this for him," Ms Patch said.