A teenager born with the condition known as pigeon chest is now standing taller than his twin brother after undergoing an innovative new treatment to correct the condition.
James Jack Stark has pectus carinatum, a deformity of the sternum and rib cartilage that causes the chest to protrude outwards, giving it a bowed-out appearance similar to that of a pigeon.
Last year the 14-year-old was two inches shorter than his twin, Harry, but after undergoing a new technique to treat it, he now stands a whole inch taller than him at 5ft 5in.
The deformity is often seen at birth but is more noticeable as the child gets older, during growth spurts when the ribcage has grown and protruded further. The most common symptom is pain, but it can also often lead to harmful psychological effects such as low confidence and self esteem.
James Jack used to hate the way his body looked so much that he threatened to smash his chest with a hammer, but his mother, Jacquie Stark, said that since having the treatment, he now "walks with a swagger" and hopes to join the armed forces one day.
He was treated at Spire St Anthony's Hospital in North Cheam, Surrey, where consultant thoracic surgeon Ian Hunt and his colleague Joe Porcello have developed a new, non-surgical technique that involves a combination of treatments.
After being assessed to make sure the patient is suitable, they undergo careful and skilled manipulation of the breastbone, ribs and cartilage while receiving pain killing gas and air, before being fitted with a special, custom-made brace, which the patient then wears for up to a year.
James Jack, from Hemel Hempstead, Hertfordshire, underwent the treatment in January and was told at his four-month check-up that his progress is so good he can already start reducing the amount of hours he wears the brace each day.
The only time he currently takes it off is when he is at school, and he puts it back on when he gets home in the evening and wears it at night.
The non-identical twin, whose loves include being a cadet and playing computer games, said he was delighted to look "normal" straight away.
"It was amazing and so exciting to see the difference right from the first consultation," he said.
"The manipulation was uncomfortable but not painful. The brace is the same and now I'm four months into wearing it, it doesn't bother me."
Housewife Mrs Stark, 42, said: "The results were immediate - right from that first appointment he could see the difference.
"He instantly became a different child in terms of confidence and physical stature.
"The manipulation has not only corrected his pigeon chest but it has improved his posture. He is so confident, walks with a swagger and his head held high. You would not recognise him as the same child."
She added: "Previously he hated his chest, his confidence was at rock bottom and it could really upset him.
"I once found him in the garage in tears with a hammer in his hand threatening to break his own chest bones to sort it out. Now he is excited about his future and wants to be in the armed forces."
Between one and three in every 1,000 people have a pectus anomaly, which are more common in males.
Traditionally children underwent extensive, open chest surgery involving the breaking and realignment of the chest bones and ribs, but this alternative technique involves no surgery and leaves no scars.
The cause of pectus carinatum is not known, but it is thought to be genetic.
Mr Hunt said: "Being able to offer a non-surgical treatment is of incredible importance.
"Not only is it a cost effective treatment, but it is also so much less aggressive for the patient as it avoids fairly extensive surgery, the potential complications of surgery and long-term scarring.
"The difference it makes to the young patients we treat is amazing. Pectus anomalies are a congenital problem and can lead to some young people suffering serious body dysmorphia.
"Being able to see these low confidence, crushed teenagers recover emotionally as well as physically is quite remarkable and very rewarding."