What seemed like only a minute ago, Dr. Ed Kosnik was teaching his daughter how to ride a bike. The next, she was standing next to him in the operating room at the Medical University of South Carolina.

"It was a pretty awesome experience, when you think that someone whose diapers you changed is now capable of opening up your head and doing the right thing," Kosnik said. "You just sit there and shake your head and say, 'Oh, my God.' But Libby's always been one who has been ready to do something, in some ways."

His very capable, now 35-year-old daughter, Dr. Libby Kosnik Infinger, was, until graduation yesterday, the chief resident of MUSC's neurosurgery program. She leaves Charleston later this summer to complete a one-year fellowship at Cincinnati Children's Hospital, where she'll specialize in pediatric neurosurgery, just like her dad.

Certainly, this isn't the first time a daughter has followed in her father's footsteps, but this situation is special. The Kosniks are the only known father-daughter duo in the pediatric neurosurgery specialty across the country who regularly operate side-by-side. Kosnik, 69, suspended his retirement in 2013 and joined the neurosurgery department at MUSC, where Infinger had been training as a resident since 2007. He previously worked several decades as a pediatric neurosurgeon in Columbus, Ohio.

"It was great," Infinger said. "It's funny. We have very similar personalities. We've always done things together, gone fishing, projects around the house. It was different because, you know, you're operating, but we've always had a close relationship."

They operate on children together at least once a week: patients with spinal defects, brain tumors, babies born with water on their brain. Their last operation together, at least for the next year until Infinger returns to MUSC after her fellowship, was Friday.

"I think this is a very unique experience," Kosnik said. "I've known a lot of neurosurgeons and - you look at all the numbers of neurosurgeons - I don't think there are any other father-daughter combinations, certainly not in pediatrics."

Even as a child, Infinger remembers she was curious about what her dad did for a living.

"In second grade, there was a girl that sat in front of me that he did surgery on. Every day, I could look at her scar when she came back to school and that really got me interested in seeing what he did, and exactly what he did as a pediatric neurosurgeon."

Kosnik remembers the patient, but tells the story differently. "I asked (Libby) what the scar looks like and she said, 'Yucky!' "

The early aversion eventually wore off. While her dad never pushed her into neurosurgery, it turned out that's what she enjoyed most in medical school. She also saw firsthand the kind of lifelong impact pediatric neurosurgeons had on their patients.

Ed Kosnik's fan base is huge, she acknowledged. In 2011, when her dad spent several weeks in an intensive care unit after heart surgery, the Caring Bridge website the Kosnik family set up to keep friends up to date on his progress received 80,000 hits. He estimates he performed some 15,000 operations during his career in Columbus.

"I had one family tell me once, 'Thanks for giving up a little bit of your dad so he could be a dad to all these other kids out there,' " Infinger said. "But I never felt like he missed anything important. He was there whenever I needed him."

Reach Lauren Sausser at 937-5598.