Once back-to-back, Joshua and Jacob Spates are now face-to-face after 13 hours of surgery.
The 7-month-old boys were conjoined at the rump -- pelvis and lower spine -- until a rare procedure separated them August 29 and was announced Tuesday.
The Daily Mail reports Dr. Max Langham, one of the surgeons at Le Bonheur Children's Hospital in Memphis, saying: 'Joshua's doing great, and hopefully he'll be up and going and have a pretty normal lifespan.
He told TODAY that while Jacob has more serious heart problems 'our cardiology team has very high hopes his treatment… will be successful'.
'If they had not been separated, sometime in the next year or two, they probably would have passed,' Dr Langham said.
Watch the Today Show report:
Only once in the past 11 years have pygopagus twins, which represent 15 percent of conjoined twins, been successfully separated with both children surviving, said Giancarlo Mari, director of the Le Bonheur Children’s Hospital fetal center and a professor at the University of Tennessee Health Science Center.
According to this video interview with the hospital's neonatologist Marilyn Robinson, the boy’s mother Adrienne said she knew Joshua “needed to be free”:
The doctors and parents decided to wait till the boys were seven months old to separate them. Even though Jacob was born with a serious congenital heart problem and high blood pressure in the lungs and waiting increased his risks, Joshua needed more time to grow.
Anesthesiologists came up with a novel way to practice flipping the patients during the surgery without tangling the various lines attached to them: They rehearsed it on a pair of Cabbage Patch dolls sewn together.
"Everyone laughed about the dolls ... but by the time the day of the surgery came, you would have thought we'd been doing it a long time," said Joel Saltzman, director of pediatric anesthesiology at the hospital.
Doctors involved in the procedure spoke to reporters Wednesday about the challenges, which included avoiding injury to the spine.
Bill Warner, an orthopedic surgeon in the hospital's spine clinic, said the boys have health problems that will require ongoing treatment, but he expects Joshua will be able to walk with braces and hopes that Jacob will do the same.
"The outlook is bright as far as them being functional in the community," Warner said.
Jacques Samson, a maternal fetal medicine fellow with the health science center and the fetal center, delivered the babies Jan. 24. He said the surgical teams were prepared at the time for the possibility that the twins would have to be separated immediately.
Fortunately, they were healthy enough to wait.
"You prepare for the worst and you're ready," he said. "You have a plan B and a plan C. You have to prepare and you have to simulate. We had our dolls sewn together, too."
Samson said he became close with Adrienne during months of counseling before the babies were born.
"It was a long journey," he said. "I'm happy for her and happy for the twins. She was always poised, always had it together. I'm amazed at her and her strength.
"She has great support. We're all ecstatic for her and her family."
One of the challenges the boys will face is walking, but doctors expect they'll both be able to do so with braces. The boys each had their own head, heart and lungs.
Watch this 3-D reconstruction of 320 slice CT Scan images of the conjoined twins:
The Associated Press contributed to this report.