On Monday, Zahnee will undergo a 10-hour complex surgery at Starship Hospital to realign her lower spine to allow her to walk without pain.
It won't be the first time she has undergone surgery.
In 2011, Zahnee had a life-changing operation in New York to reposition her eyes due to damage from a rare facial vascular haemangioma that she was born with.
The teenager, who celebrated her 13th birthday last month, has missed almost two terms of school because of her back pain and says she misses her friends.
"I just needs my peeps," she says.
Mum Jade Riley says her teenage daughter has been struggling socially.
Zahnee hasn't been able to jump on the new trampoline she got last Christmas, ride horses, or go rock climbing - and her dreams of one day going skydiving and riding a rollercoaster were fading.
"She is a daredevil," Jade says. "Fear doesn't worry her at all."
But it was missing out on hanging with friends and being able to kick the soccer ball around with her younger brother Zandon, 11, that the teenager was finding difficult.
"She's got a lot of catching up to do," Jade says. "She's had a bit of a rough year."
Jade said Zahnee has been on the surgery's waiting list for about three months and has been doing intensive physiotherapy and hydrotherapy to help strengthen her spine.
"She can walk, but very slowly, and she is in a lot of pain," Jade says.
So Jade rallied help from the community to throw Zahnee a surprise 13th birthday party on Labour Weekend.
Zahnee was whipped away on the Saturday morning to get her nails done by good friend Nicola Dowdall, who works at the Bay of Plenty Times.
"My anxiety was going through the roof," Zahnee says. "I had no idea what was going on."
While Zahnee was out, her friends and family arrived to decorate the house in a Grammy Awards theme complete with red carpet, photo booth and balloons.
The teen, who arrived in a sparkly pink dress, was also treated to a tour of the town with her friends in a limousine.
"We also got to meet the Bay of Plenty Volcanix women's rugby team," she says.
Zahnee was making thank you cards for her birthday guests and it was this that inspired a fundraising idea for Ronald McDonald House, where the teenager will stay while she has her surgery.
She is encouraging schools, pre-schools, retirement villages or anyone who likes arts and crafts to send her a get well soon card, which could be left for her at the Bay of Plenty Times on Cameron Rd.
For each card Zahnee gets, she will donate 50 cents to the Ronald McDonald House.
"Not only does it give Zahnee words of encouragement, it also helps to support the Ronald McDonald House," Jade says.
What is spondylolisthesis?
Spondylolisthesis is a spinal condition that affects the lower vertebrae (spinal bones). This disease causes one of the lower vertebrae to slip forward on to the bone directly beneath it. It's a painful condition but treatable in most cases. Both therapeutic and surgical methods may be used. Proper exercise techniques can help you avoid this condition. Source: www.healthline.com
