For two years Hamish Prasad's knee and groin pain was wrongly diagnosed by doctors.
When it was discovered he had slipped capital femoral epiphysis (SCFE), where the top of the thigh bone has been pressured off the joint, he needed to urgently have his femur bone removed, grafted and reinserted with four screws.
The operation took two-and-a-half hours.
"It was scary," the 14-year-old says, "it was a big relief."
Three weeks on from the operation, Hamish is confined to a wheelchair and crutches.
"They said six weeks without touching the ground, then after six weeks you slowly have to start walking but on crutches until 12 weeks."
It will be at least a year before he can play hockey and soccer again.
The Auckland teen is not slim, but neither is he obese. Many boys his age are outside the optimum weight range of 36kg to 58kg.
Hamish is 64kg, and doctors have not prescribed weight loss as part of his rehabilitation.
"They say it is a big thing, but I am not overweight," Hamish says.
The problem has become common among teens and pre-teens, even those like Hamish. But now, it is emerging as a problem for primary-aged children as well - most often caused by obesity.
It's so widespread, it's become known as a "New Zealand disorder".
Hospitals nationwide are seeing primary school-aged children with SCFE. The early ages at which children are being wheeled into the operating theatre has alarmed surgeons.
"That's huge. You wouldn't see that anywhere else in the world," said Starship hospital orthopaedic surgeon Andrew Graydon, who is performing one three-hour operation - reserved for the most acute cases - every month.
"Kiwi kids get more of them, and they get more of them at a younger age. It's a New Zealand disorder, in that we see such a lot of it here."
In a study set for publication in an international medical journal, Starship surgeons found more than 463 children in Auckland alone needed operations in a seven-year period. It is a rate five times higher than in the United States, and around 10 times higher than Korea, consultant orthopaedic surgeon Haemish Crawford said.
One of the more common developmental conditions of the hip joint, SCFE usually affects teens and pre-teens. But children are being hospitalised ever-younger, as hip joints collapse under the burden even before they hit puberty.
"Children can be very debilitated by a severe slip and need a hip replacement at a young age," Graydon said. "It's a terrible deformity, they walk with their leg sticking to one side and when they sit their legs are wide apart, they can't pull them together."
Auckland mum Meleita Manu was taking her daughter Ofa, 12, to a physio for more than a year to treat a limp. But when it got too painful, they went to hospital - and found Ofa had been walking around with a displaced thigh bone.
"I kept like complaining at night, I couldn't sleep, I had to sleep crooked because I was too sore, I couldn't walk properly and all my friends were laughing at me," Ofa said.
Since surgery in February 2013, she has lost weight and now plays netball and dances. Her sister, Liliana, now 25, had needed the same operation in her teens but had not seen the same results as she didn't make changes to her diet and activity, Meleita Manu said.
According to research by Waikato Hospital orthopaedic surgeon Dr Richard Willoughby, Maori children have the highest rate of SCFE in the world. "It is likely that rising obesity has influenced the overall trend towards younger children developing SCFE," he wrote in an article in The Journal of Pediatric Orthopedics in 2012.
Middlemore Hospital orthopaedic surgeon Paul Eaton said 95 per cent of the children he saw were overweight.
He has been working at Middlemore for 21 years, and said he was performing more operations and on younger kids.
"The trouble with these children is they're not a little overweight, I mean they are majorly overweight. My youngest patient was a six-year-old who was 95 kilos.
"I'm sure if these kids were a normal weight, SCFE would be a vanishing problem."
SCFE often disguised itself as knee pain, so some children weren't diagnosed for six months or more. Post-operation, they would struggle with arthritis for the rest of their lives.
Endocrine problems were a partial cause, but the relationship to growing childhood obesity "must be of concern," another study in the New Zealand Medical Journal found.
Diabetes New Zealand dietitian Teresa Cleary said obesity was in danger of becoming a way of life. "People are more inclined to see overweight in themselves or their children as just normal, rather than recognise it as a problem." Changes to diet and activity needed to be family-wide, she said.
Auckland University professor of population nutrition Dr Boyd Swinburn said SCFE was just one of the increasing side-effects of obesity, with Ministry of Health figures showing a third of all kids are overweight or obese. "New Zealand children are now fatter than all European countries . . . we are virtually doing nothing.
"The hands-off approach and pandering to industry has served New Zealand children very poorly, and we need a fundamentally different approach."
This included Government-led initiatives including the regulation of the marketing of fatty foods, and extra funding for programmes in low-income communities.
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