"This is a problem of lifestyle in children across the social classes," Southampton orthopaedic surgeon Prof Nicholas Clarke reflects on the rise in cases of rickets.
For years rickets was seen as a problem of poverty.
Children growing up in Victorian slums suffered from bone deformities, such as bowed legs and curvature of the spine.
It was discovered to be caused by a lack of vitamin D - manufactured when the skin is exposed to sunlight.
The condition was thought to have been consigned to history in the 1940s - when it was added to everyday foods such as margarine and cereal.
However rickets is making a comeback.
More than 20% of children tested
for bone problems at Southampton General Hospital have showed signs of the crippling disease.
Teenager Tyler Attrill suffered from pain in her hips
Twelve-year-old Tyler Attrill lives on the Isle of Wight, one of the sunniest parts of Britain, but she has been treated for the symptoms of vitamin D deficiency.
Speaking to the BBC's Inside Out programme, she said: "It would make your legs feel all heavy, you couldn't move them."
Having been reduced to tears by the pain in her joints, she was eventually referred to Southampton's Children's Orthopaedic Unit where Professor Nicholas Clarke and his colleagues have seen an "astonishing" increase in admissions of children with the condition.
In advanced cases, surgery is needed to correct the bone deformity.
Prof Clarke said: "This is quite unbelievable - in a part of the country with more sunshine than anywhere else - it is honestly shocking.
Prof Nicholas Clarke says modern lifestyles contribute to the increase
"It's not about poverty or ethnicity, its simply about the reduction in exposure to sunlight," he said.
With modern lifestyles meaning children are taken to school in cars and spend more leisure time indoors, they are not going outside as often as previous generations.
Doctors say 20-30 minutes of direct sunshine a day, five days a week, is necessary to maintain healthy levels of vitamin D. Any sun cream over factor eight blocks the ultra violet light the body needs to create vitamin D.
Tyler's mother, Lisa, followed advice to protect children from skin cancer by putting on factor 50 sun cream on her daughter.
She admits to feeling guilty, as well as confused. "I thought I was doing the right thing," she said.
Ed Yong, head of health information and evidence at Cancer Research UK, said: "The amount of time you need to spend in the sun to make enough vitamin D varies as it depends on individual skin type as well as time of day, time of year, and where you are in the world.
"It should be enough to regularly go outside for a matter of minutes around the middle of the day without sunscreen. But it's important for everyone to know their skin so they can ensure they don't risk burning.
"When it comes to sun exposure, little and often is best."
Tyler's condition is now healing. A new family dog has given her a reason to get out of the house and increase her exposure to sunlight.
More on the return of rickets on Inside Out South - Monday, 17 January at 1930 GMT on BBC One and