MEMPHIS, Tenn. — Anesthesiologists who assisted in a rare, risky surgery to separate conjoined twins came up with a novel way to practice flipping the patients without tangling the various lines attached to them: They rehearsed it on a pair of Cabbage Patch dolls sewn together.

Doctors said the maneuver was key to the successful operation at Memphis’ Le Bonheur Children’s Hospital.

“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.

Joshua and Jacob Spates were joined back-to-back at the pelvis and lower spine, each with separate hearts, heads and limbs. The 7-month-old boys were separated Aug. 29 in a procedure announced Tuesday. Doctors spoke to reporters Wednesday challenges such as avoiding spinal injury.

Bill Warner, an orthopedic surgeon in the hospital’s spine clinic, said the boys have ongoing health problems, 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.

The way Joshua and Jacob were joined makes them pygopagus twins, which represent about 15 percent of all conjoined twins, according to the hospital. Only once in the past 11 years have pygopagus twins been successfully separated with both children surviving, said Giancarlo Mari, director of the hospital’s fetal center and a professor at the University of Tennessee Health Science Center.

One of the most critical decisions was when to deliver the babies, Mari said. Leaving them in the womb posed a risk because of a tangled umbilical cord. But the longer they could be allowed to develop in utero, the stronger they would be at delivery.

The team decided to deliver the babies by Caesarean section at 34 weeks.

Then came another tough decision: when to separate them.

Jacob was born with a serious congenital heart problem and high blood pressure in the lungs. Dr. Max Langham, who led the surgical team, said waiting to separate the two increased the risks for Jacob, but lowered the risks for Joshua, who needed time to grow.

Waiting also gave the surgery teams, consisting of more than 100 people, lots of time to practice.

Jacques Samson, a maternal fetal medicine fellow with the health science center and the fetal center, delivered the babies Jan. 24.

“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 mother Adrienne Spates during pre-birth counseling.

“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.”