Image copyright Ryan Mcnamara Image caption Keilan's curved spine became so bad that it affected his breathing

Keilan, a 12-year old boy with scoliosis, a severe curvature of the spine, waited 47 weeks before being admitted to hospital for surgery.

Keilan's story is revealed in Hospital, the award-winning BBC Two series, which was filmed in January and February at Nottingham University Hospitals - one of the country's biggest and busiest trusts.

It is the story of the health service at an unprecedented time in its 70-year history.

Keilan's operation, aimed at correcting and straightening his spine, had been scheduled for the middle of the winter crisis when NHS England advised every hospital to suspend all routine operations.

Although paediatrics is usually protected from cancellations, the high number of patients being treated at the Queen's Medical Centre, where Keilan was taken for surgery, meant his operation had twice been put back.

Keilan's case highlights how growing pressure on the hospital can lead to delays which affect patients' conditions.

'Severely bent'

"As time goes on, his curve has gone from 35 to 80 degrees in less than two years", says Lee, Keilan's father.

Born at 28 weeks and weighing just over 1.5lb (600g), Keilan was given a 10% chance of survival and placed in an incubator for the first 19 weeks of his life.

After a few years his spine started to show some signs of scoliosis which eventually started to affect his breathing.

Mike Grevitt, one of the country's leading consultant orthopaedic spinal surgeons, said: "Keilan's spine was so severely bent on one side of his body that his ribs were crowded, which gave him the problems breathing."

Because of these breathing difficulties, there were concerns that once under anaesthetic, Keilan's lungs might not be able to cope with the surgery.

As a result, he would have to be placed in paediatric intensive care to recover after the operation.

But a shortage of beds in the unit put the surgery in doubt.

Limited resources

"It's a fact that on any winter's day, there may be only a handful of beds in the country for paediatric critical care," said Mr Grevitt.

Keilan's operation took a total of five hours and consisted of screwing metal rods alongside his spine.

The surgery enabled Keilan to gain 2.5 inches (6.5cm) in height and he was reassured afterwards that his scoliosis was permanently treated.

Mr Grevitt, who has treated a range of spinal disorders - many highly complicated - during his career, said: "This is certainly the most challenging [operation] we will do this year."

The series shows the extraordinary work of some of Nottingham's 15,000 staff as they push the boundaries of what is possible with cutting-edge treatments and life-saving operations, despite the pressures of limited resources and increasing patient numbers.

The six-part Hospital series returns on Monday 26 March at 21.00 on BBC Two and then on Tuesdays at 21.00.