You can’t keep a determined girl down.

Two summers ago, Addilyn Cook, then 6, wore two casts—right arm, left leg—and refused to let them get in her way.

“She said, ‘Why can’t I go off the diving board?’” her mom, Melinda Cook, said. “She’s not afraid of anything.”

Addilyn spent much of her life in casts, having broken her left leg more than once as a young child in an Ethiopian orphanage.

Those fractures hadn’t healed well. Even before her adoptive family met her for the first time in the summer of 2016, they knew from pictures she would need surgery to straighten her leg. The bones had grown back together at an awkward angle.

Path to diagnosis

After arriving at her new home in Holland, Michigan, Addilyn soon visited Lisa Maskill, MD, a pediatric orthopedic surgeon at Spectrum Health Helen DeVos Children’s Hospital.

Dr. Maskill consulted with Melinda and her husband, Kevin, before they traveled to Addis Ababa to pick Addilyn up. In the three years since, Dr. Maskill has become a significant person in Addilyn’s life.

“Dr. Maskill could probably join us at the Thanksgiving table—I mean, we know her so well,” Kevin said.

Since that first office visit in September 2016, Addilyn, now 9, has had five orthopedic surgeries and spent countless months in wheelchairs, walkers, braces, walking boots and colorful casts.

First she underwent surgery to straighten and stabilize her left leg by having a rod inserted in her femur.

From the start, Dr. Maskill could tell something was different about Addilyn’s bones.

“Her leg is much shorter on the side that seems to be the weakest, and it was very obvious that she had multiple fractures throughout her life that had healed improperly. She also has a lot of curve in her thigh bone and her shin bone,” Dr. Maskill said. “But she hadn’t broken anywhere else, and so we were still on the fence with (her) true diagnosis.”

A pediatric endocrinologist ran tests and recommended good nutrition as the best way to build stronger bones.

The next summer, Addilyn broke her right arm and had surgery to repair it. The following winter, she broke her left leg—again.

“She just slipped on the floor,” said her mom, who works as a NICU nurse at Helen DeVos Children’s Hospital. That’s all it took to end up with a break.

Osteogenesis imperfecta

When Addilyn fractured her right leg for the first time four months later, Dr. Maskill sent her for genetic testing. By this time, she was convinced Addilyn had a genetic bone disorder called osteogenesis imperfecta, commonly known as brittle bone disease.

“Most kids that have osteogenesis imperfecta have pretty symmetric involvement—meaning both arms, both legs,” Dr. Maskill said.

“Hers really seemed to be concentrated on one leg. It wasn’t until … she started having breaks in other bones that we were able to say, ‘OK, this is for sure osteogenesis imperfecta; it just doesn’t act like the typical presentation.’”

Genetic testing confirmed the diagnosis.

It also confirmed an unrelated bleeding disorder, von Willebrand disease, which Dr. Maskill discovered during the first surgery and her colleagues in pediatric hematology later verified. Now Addilyn’s doctors know to give her medication before any surgery to prevent excessive bleeding.

In June 2018, Addilyn had what her family calls “the big surgery”—more than 10 hours long. To keep her bones stable as she grows, the surgical team inserted thin, telescoping rods in both legs.

“One end sticks in the growth plate at the top of the bone and one sticks below, and then as they grow… the rod telescopes and grows with them,” Dr. Maskill said.

Recovering from that surgery proved to be long and tedious.

“It was hard to swim then,” Addilyn recalled.

But the family has a backyard pool, so she didn’t let the waterproof casts keep her on the sidelines. With six brothers and sisters ranging in age from 4 to 20, she has plenty of playmates cheering her on.

“She’s a trouper. She just does it—takes it and goes with it,” her mom said. “And then as soon as she can get up and walk again, she just walks.”

This is what’s made the biggest impression on Dr. Maskill—Addilyn’s resilience.

“What really strikes me the most, and I think what has endeared her to a lot of people in our office, is that she has an unbreakable spirit. She is positive and smiling and engaged, no matter what’s going on,” Dr. Maskill said.

“(Despite) everything she’s been through, she is one of the happiest, most active kids that we have in our practice.”

‘One wrong slip’

Since her diagnosis, Addilyn has had to severely cut back on her activities. Running and jumping and playing sports are all risky because they quickly lead to fractures.

That’s the biggest challenge for the families of kids with osteogenesis imperfecta, Dr. Maskill said.

“You want to let them be a kid and run around and do things like all their friends and classmates and siblings, and yet, there’s always this … concern that one wrong move, one wrong slip, and they have a broken bone.”

Her parents agree that the restrictions are the toughest part.

“She likes to do everything,” Melinda said. “She’s super determined.”

Addilyn’s two most recent mishaps took place at a birthday party, where she slipped and bent one of the rods in her legs, and at home, where she fell and broke a wrist while dancing.

The leg injury required a rod replacement, while the wrist fracture earned her a new cast.

When her legs aren’t in a cast, Dr. Maskill keeps Addilyn in braces to protect her thin bones and prevent them from bowing.

This past March, when bone density scans showed minimal improvement from nutrition alone, Dr. Maskill started Addilyn on twice-yearly bisphosphonate infusions. Doctors have long used bisphosphonate to treat older women with osteoporosis, but using it in children is less common.

The hope, Dr. Maskill said, is that it will strengthen Addilyn’s bones over time and help prevent fractures—or at least lessen their severity.

‘Whatever she wants to do’

This summer, Addilyn’s third in West Michigan, has been her best yet.

She was up on her feet, without new fractures. She took voice lessons and swimming lessons, went to Vacation Bible School and traveled to Kentucky with her family.

She swam almost daily, resisting the lure of the diving board.

The next few years will be critical for Addilyn, Dr. Maskill said. Once she reaches her teenage years, osteogenesis imperfecta will become more of a nuisance than an everyday threat.

In the meantime?

“We need to try to help her grow, and grow straight, and get her bones as strong as we can for her adult life,” Dr. Maskill said, “and then I think she’s going to do great.

“She’s smart and bright and determined—so she’s going to do whatever she wants to do.”