Nearly two months after a groundbreaking surgery, 18-month-old Garrett Peterson is full of energy.

He plays with the toys hanging over his bed, smiles for nearly 45 straight minutes and gives his mom’s hair a sharp tug while she pats and tickles him.

“He has more energy than I do,” Garrett’s mom Natalie Peterson said. “Yesterday I really wanted to take a nap but if I even left the room for a second to talk to my mom on the phone he would start getting agitated.”

The procedure that Peterson underwent Jan. 31 — the second of its kind ever attempted — was made possible by advancements in 3-D printing technology and the collaboration of a number of doctors and engineers from the University of Michigan and across the country.

Garrett Peterson suffers from a rare disorder called tetralogy of Fallot with absent pulmonary valve. Because of the pressure put on his airways by the condition, he developed severe tracheobronchomalacia, a softening of the bronchi that led to difficulty breathing.

Peterson’s bronchi were so weak that they would often collapse and eventually were only the size of small slits even with the help of a ventilator. Natalie said that she frequently would be terrified by the sight of her son changing color after the most mundane of activities.

“A lot of the time he couldn’t have physical therapy because if you moved his head he’d turn blue, you change his diaper he’d turn blue,” she said. “So we couldn’t make him do anything because he always had to be happy. It was just unrealistic.”

In 2012, University of Michigan doctors and engineers worked together to print a biodegradable splint and implant it into the airway of Kaiba Gionfriddo. It was the first time that a 3-D printed splint had been implanted into a human. Natalie and her husband Jake Peterson read about the surgery and reached out to Dr. Glenn Green, the pediatric ears, nose and throat specialist who oversaw the operation at U-M.

“We went from talking about it and yes it could be a possibility and maybe it will happen to being here within a matter of 48 hours,” Natalie said.

Garrett’s operation was more extensive than Kaiba’s, requiring the splinting of both bronchi. Once the surgery is completed, the hope is that naturally occurring tissue will form around the molds so that by the time the material dissolves, the child will have replaced it with a fully functioning airway.

Approximately one in 2,200 babies are born with tracheobronchomalacia, but severe cases are rare and most children grow out of the condition by the age of 2 or 3.

“The kids that are as sick [from this] as Garrett and Kaiba are in the dozens,”. Green said. “Kaiba and Garrett in that group of dozens are among the sickest.”

For the second time, the doctors at C.S. Mott Children’s Hospital were able to obtain Food and Drug Administration clearance to perform the surgery, and Green said that the next step is to get the procedure approved by the FDA.

“The results are dramatic enough that we expect a trial to not need a lot of patients and should be accomplished fairly quickly,” Dr. Green said. “When you see something that has this much of an effect, it’s not that hard to prove that it works.”

Green said that some parts of the procedure were more streamlined during the second operation, but that it still is an intensive project that requires a lot of collaboration. After Garrett was flown to Mott Hospital on a Survival Flight plane, radiologists carefully scanned his airways.

The results of the scans were hand delivered to the engineering department, where Scott Hollister, a biomedical engineer, designed the splints. Hollister has been working on designing the 3-D printed splints, also known as scaffolds, for years and along with Green has a patent pending on the technology.

With one operation under their belts, Green said that the team working on the splints was able to move more quickly and efficiently to print out the necessary splints.

“The first one we printed several hundred different models. We had four or five backups to every last thing,” he said.

“On this one we made maybe 20 or 30. We didn’t know exactly how things would fit, so we had different contingencies. We knew how it looked in the model, but we had contingencies in case it didn’t fit just right.”

Once the splints were printed, they were flown to Peterson’s home state of Utah for sterilization. Green said that sterilizing the scaffolds is difficult because normal sterilization techniques that use lasers and heat would melt the delicate splints.

Once the splints were ready and safely back in Michigan Green assisted Dr. Richard Ohye, head of pediatric cardiovascular surgery, in performing the operation.

Since the procedure, Peterson’s airways have remained open and his ventilator levels have decreased by 75 percent.

There are still some obvious signs that Garrett is not your average 18-month-old boy. The child — who has spent his entire life in hospitals — is still hooked up to the ventilator, a feeding tube, intravenous medication and a number of monitors.

Peterson has started to eat some baby foods, is expected to be removed from the IV medication Tuesday and could be on his way home to Salt Lake City, Utah within a month.

“He’ll stay in long-term care for a bit longer so that his parents can learn to manage his care at home,” Green said Monday. “But very soon there will be nothing medical keeping him in the hospital.”

Garrett has never seen his parents' house, and the couple held off decorating the room that he’ll live in to see how old he would be when they arrived.

“I didn’t want to make it all up for a baby and have him come home as a toddler or even older,” Natalie said. “But now we’ve begun to look at decorations and it’s been fun.”

The move home will be a big one for the whole family, as Jake pointed out that he and Natalie have effectively been living in hospitals for the last year and a half as well.

“So It’s great for him but it’s great for us also,” he said. “There’s still a lot for us to do to take care of him, but there will be some sense of normalcy.”

Green said that other institutions have already reached out to him and Hollister about the possibility of using the procedure to help children with similar problems.

“I’ve had maybe five other hospitals ask how much it costs to set it up,” Dr. Green said. “I tell them it’s not the cost to set it up it’s having the right people.”

Michigan had the right people for the Petersons, and Jake said that the family has been converted to lifelong U-M fans. As the family prepares to head back to Utah, Natalie said that she and her husband have been spreading the word about the procedure and how it changed their son’s life.

“We want to reach families that feel like their child will be on a ventilator or in a care center their entire life and there’s no other option,” she said. “We know now that there is another option and we want other people to be able to find it as well.”

Ben Freed is a general assignments reporter for The Ann Arbor News. Email him at benfreed@mlive.com and follow him on twitter at @BFreedinA2. He also answers the phone at 734-623-2528.