“They’d say, ‘Oh, look at the cripple,’ and that was so hard for me because, already, I was doing gymnastics and I was short, and I was doing a girls’ sport,” he said. “So a lot of times, I would sit at the kitchen window and watch all the kids running around the park and playing football, and I’d get pretty emotional. All I wanted to do was be an ordinary kid again.”

Doctors warned him that the damaged nerves might never regenerate. A psychiatrist told him to prepare him for life in a wheelchair. They were wrong.

Although it took 15 months, Behan did become an ordinary kid again. And he went back to gymnastics.

But about eight months after he returned from his leg injury, disaster hit again. In what he calls a freakish accident, he smacked the back of his head on the metal horizontal bar during a routine and tumbled to the ground in a lump.

The accident caused a traumatic brain injury and severe damage to the vestibular canal of his inner ear, which affected his balance so much that even the slightest movement could cause Behan to black out. And black out he did, hundreds of times, maybe thousands of times, his mother said, as Behan struggled to turn his head, feed himself and walk without stumbling and looking as if he were dead drunk.

Frustrated by his slow progress after two months in the hospital, Bernie Behan went home with her son in her arms because doctors would not discharge him. She quit her job as an aerobics instructor to care for him.

“He kept telling the doctors, ‘I can walk — tell them, Mom, that I can walk,’ and my heart was breaking,” she said. “I’d go to the car park and cry my eyes out, then walk back and say: ‘Yes, Kieran, you can do this. We can do this. I believe you, son.’ ”

Nearly two years after his accident and after unrelenting physical therapy, Kieran Behan — the miracle boy, doctors said — regained his hand-eye coordination and got back onto his feet again.