Walk around the Gillette Children’s Specialty Healthcare hospital in St. Paul, and you are likely to see them — kids on their tummies, cruising headfirst down the hallways on colorful padded carts.

The kids in the carts are recovering from a complex lower-back surgery called a selective dorsal rhizotomy, which treats severe spasticity in the legs caused by some forms of cerebral palsy. Gillette is a national center for the surgery.

And the carts? They were conceived, tested, and patented by Gillette. Now the specialty children’s hospital is marketing the $9,995 Minnesota-made carts to the handful of other hospitals around the country that do rhizotomies.

The first Gillette Prone Cart for patients outside its namesake hospital rolled off the assembly floor last fall. Today Gillette is actively marketing the carts, which are manufactured at Oakdale Precision, a few miles down Interstate 94.

“The kids can move it by themselves. The old carts, the kids couldn’t move them,” said Sally Wulfing, a nurse manager at Gillette who was a member of the team that came up with the concept for the new cart, which is also much easier to clean than the old design.

Last week, 6-year-old Patience Wheaton of Portage, Wis., showed off her Mariokart skills on a Nintendo Wii U console while in her prone cart in a rec room at Gillette. She also posed for pictures, twisted around like an otter, and played a board game from the relative comfort of her stomach.

Asked if her back feels better after the surgery, she flashed a smile and gave a thumbs-up.

Patience received a rhizotomy at Gillette on Feb. 22 to treat the worsening spasticity in her legs. Cerebral palsy is a neurological disorder that can cause a wide spectrum of issues, one of which is continuous involuntary tightening of the leg muscles known as spasticity.

Patience’s mom, Bonnie Schehr, said they tried many less-invasive options first, but ultimately decided to go ahead with the rhizotomy because the spasticity from cerebral palsy was affecting Patience’s growing bones.

“She could walk and get around, but doctors said the more she grows, the worse it’s going to get. Her bones were starting to deform. So to prevent problems later in life, they wanted to do the rhizotomy,” Schehr said.

During the operation, Patience’s doctors opened an incision in her lower back and tested which nerve roots were sending the signals causing the spasticity. Then they precisely severed just those nerves, leaving the rest intact.

Now Patience is on doctor’s orders to spend at least one hour prone (i.e., on her stomach) three times per day, Schehr said.

Lying in that position helps to stretch out leg muscles and build strength in the core and upper body, while teaching the body how to function without involuntary muscle tightness. But getting a young child to lie on their tummy for hours on end is not easy.

“A child needs to be engaged to spend much time in that position. [In the prone carts,] they are able to move around, engage in activities,” said Dr. Angela Sinner, a pediatric rehabilitation physician at Gillette.

The wheels on the cart are similar to those on a wheelchair, so that a patient can move it herself, if she wants to. Gillette doesn’t expect to sell tens of millions of dollars’ worth of the carts, which is a sign of the deeper problem. Traditional med-tech companies often have a hard time making pediatric devices because the commercial markets for them are smaller and less lucrative than for adult-sized devices.

That’s not news to Gillette. The 119-year-old institution, which specializes in complex pediatric orthopedic and neurological conditions, has its own engineers and full-time design lab to make custom devices.

The lab builds scores of custom devices for kids, and the hospital has patents on several inventions, the OrthoCleft retainer for cleft lip and the Gillette CranioCap for flat head syndrome.

That can-do spirit helps explain why, when hospital staff realized in 2009 that they didn’t like any of the prone carts on the market, they set out to make their own.

The staff realized “there just isn’t a good one out there for our population,” said Dennis Jolley, vice president of institutional advancement at Gillette. “So why don’t we just design one ourselves and see if we can find a manufacturer who would help us build it?”