Scoliosis: Research to improve patient treatment

Mayo Clinic Children's Center has a comprehensive spine deformity treatment program with state-of-the-art spinal care for children from birth to adulthood. This clinical care is supported by an extensive research program aimed at improving treatment and quality of life for children with scoliosis.

"We are involved in many projects to learn about the etiology of scoliosis, to advance treatment and to understand how our treatments are impacting families," says A. Noelle Larson, M.D., an orthopedic surgeon at Mayo Clinic Children's Center in Rochester, Minnesota. "There's a significant need for novel approaches in the treatment of scoliosis and other growth-plate disorders."

Dr. Larson and colleagues at Mayo Clinic Children's Center participate in a number of nationwide study groups and registries for pediatric spinal disorders. "We have a good sense of what's being done in the world of pediatric orthopedics," she says. "Coming to Mayo Clinic Children's Center gives patients and their families access to that global knowledge and the opportunity to enter into clinical trials."

Among other groups, Mayo Clinic is a member of the Children's Spine Study Group, which compiles a registry of patients with early-onset scoliosis, and works to improve their quality of life. "The advantage is that, in our own practice, we might see 100 to 200 patients with early-onset scoliosis. But the registry has 3,800 patients," Dr. Larson says. "We can use that combined experience to improve treatments for our patients and look into specific rare conditions."

The registry facilitated a recent study of 200 patients with congenital rib fusions. "The registry gave us access to that larger group so we could ask relevant clinical questions," Dr. Larson says.

Seeking optimal outcomes

The options for treating pediatric scoliosis include casting, traditional and magnetic growing rods, and other methods of surgical correction. Each approach poses challenges for young, growing patients and for physicians striving for optimal outcomes that avoid complications and the need for future surgery.

At Mayo Clinic Children's Center, early-onset scoliosis in children under age 4 is often treated with elongation, derotation and flexion casting — also known as Mehta casting. The treatment utilizes a custom-made thoracolumbar cast that acts simultaneously in the frontal, sagittal and coronal planes. Outcomes are often excellent, but early diagnosis is critical.

"There is a high rate of cure for children under the age of 2 who have a curve under 60 degrees," Dr. Larson says. "Unfortunately, we also see children who were braced or had no treatment at a young age. Suddenly, we have missed the treatment window and the child has a very large curve that is frequently too big to cure with casting."

If surgery is required, Mayo Clinic Children's Center has highly specialized orthopedic pediatric teams. Those specialists are researching improved surgical techniques. Mayo was one of 14 centers that enrolled patients in the Minimum Implants Maximum Outcomes Clinical Trial, which randomized patients to groups having scoliosis surgery with fewer or more pedicle screws to determine how many surgical implants are needed to have a successful surgical result.

"Some surgeons like to use two pedicle screws for every single level of the spine that's fused, while other surgeons will use far fewer," Dr. Larson says. "Fewer screws might offer advantages. Once two-year follow-up data is available, we will be comparing factors such as blood loss, curve correction, operative times and complications between the two surgical groups."

Orthopedic surgeons at Mayo Clinic Children's Center also have access to the low-dose intraoperative CT-guided navigation technology. The system provides real-time, multidimensional intraoperative imaging of a patient's anatomy. In a study published in the April 2016 issue of Clinical Spine Surgery, Mayo Clinic researchers found that intraoperative image-guided navigation resulted in a 97.8 percent rate of accurate screw placement in patients age 10 years or younger. Previous studies have noted that up to 15 percent of freehand pedicle screws in children are reported to be malpositioned.

"More recently, we have had a zero percent return to the operating room for malpositioned screws using the CT-navigation system compared with the 0.3-1.0 percent return reported in the literature," Dr. Larson says.

To minimize radiation exposure from intraoperative CT, Mayo Clinic Children's Center developed a protocol for pediatric patients using a lower radiation dosage than that recommended by the manufacturer. In the September 2016 issue of Journal of Pediatric Orthopaedics, Mayo researchers reported successful clinical use of the pediatric protocol that reduces radiation from intraoperative CT to less than one-fourth the mean annual natural background radiation compared with 2 times the annual background radiation at the settings recommended by the manufacturer.

One current project is studying the level of activity before and after surgery of patients with scoliosis. Patients wear activity trackers for four days before treatment and then again a year after bracing and surgery.

"Unfortunately, we're finding that patients with scoliosis are less active compared with controls, and potentially even less active after treatment," Dr. Larson says. "Our treatments probably have effects on children's lives that we're not fully aware of. But now that we know this, we can develop treatment plans for children undergoing scoliosis treatment to bring patients back to a healthy level of activity."

A longer term target for Dr. Larson is the epigenetics of scoliosis. That research is facilitated by a Mayo Clinic Children's Center biobank that collects waste tissue from scoliosis surgeries for laboratory analysis.

"We do high-throughput RNA sequencing, which allows us to identify genetic factors that might make children susceptible to idiopathic scoliosis," Dr. Larson says. "If we can find a gene that is malfunctioning — a druggable target — we could have a big impact on patients' lives. My dream is to develop pharmacologic treatments for scoliosis — hopefully I will see this come to pass during my lifetime."

For more information

Luo TD, et al. Accuracy of pedicle screw placement in children 10 years or younger using navigation and intraoperative CT. Clinical Spine Surgery. 2016;29:E135.

Su AW, et al. Switching to a pediatric dose O-arm protocol in spine surgery significantly reduced patient radiation exposure. Journal of Pediatric Orthopaedics. 2016;36:621.