NEW YORK (AP) – Twin boys, born joined at the top of their heads, celebrated their improbable fifth birthdays Saturday, 2½ years after doctors separated them in a series of difficult surgeries.

Until 2004, Carl and Clarence Aguirre couldn’t sit up, stand straight or look each other in the eye because of their unusual link.

But at a party at Montefiore Medical Center in the Bronx on Friday, they romped like healthy kids. Carl stuck his hand in the birthday cake. Clarence hung on his mother, Arlene Aguirre, and ran about with a toy.

“We were shooting for independence and I guess we got it,” Dr. David Staffenberg, a leader of the surgical team that separated the children, told the Journal News of Westchester.

The brothers still aren’t done with what will likely be years of treatment for problems associated with their former link.

Both wear helmets to protect holes in their skulls where they were once attached. They will eventually have reconstructive surgery to replace the missing bone. Both also continue to lag behind children of a similar age in terms of their physical and verbal development, because of the time they spent on their backs.

Still, the boys, who arrived in the United States from the Philippines in 2003 weighing just 18 pounds, are improving constantly, doctors said.

Experts usually give twins, joined in such a fashion, only a 1 in 10 chance of surviving to age five, said Dr. James Goodrich, another leader of the surgical team.

“I’m still pinching myself,” Arlene Aguirre said. She said she planned to register the brothers in the Scarsdale public schools this spring.

The family, which was allowed to come to the U.S. so the boys could receive treatment, relies on charitable donations to cover many of their health care and living expenses, in part because Arlene Aguirre’s travel visa does not allow her to work in this country.

Montefiore and its surgeons have donated millions of dollars worth of free care to the twins, and the Blythedale Children’s Hospital in Valhalla has given the family free housing and therapy.