When Trevor Johnson was 11, his growing spine took a detour from the normal straight path. Instead of stacking neatly one atop the other, his vertebrae began to drift sideways into an S-shape and his rib cage started torquing to the left.

This spinal deformity, called idiopathic adolescent scoliosis, is common, affecting nearly 6 million Americans. In its early stages, the long-accepted approach is to wait and see whether the curve worsens.

Trevor's parents had been down this road before and were not alarmed. His older sister has scoliosis, too. By the time she finished her growth spurt, the slight swerve in her back was hardly noticeable and posed no health problems.

But Trevor would not be so lucky. Periodic X-rays showed his spine bending and twisting like a sapling surrendering to gale-force winds.

"First the curve was 11 degrees," said his mother, Amy. "It went to 19, then 25, then 34, then panic."

In February, the Johnsons were told Trevor needed surgery to straighten his spine so he could breathe properly and enjoy an active life. "Isn't there anything else we can do?" they asked.

There was.

Only a few months earlier, Lisa Angioli, a physical therapist in Exton, had been trained in the Schroth method, which uses posture correction, resistance training, and breathing exercises to stabilize the spine.

The method was developed in the 1920s and has been used in Europe for decades, but until three years ago, few places in the United States offered the treatment other than a small clinic in Wisconsin.

With pressure from an increasing number of parents like Trevor's who are loath to subject their children to major back surgery, more physical therapists are training in variations of the Schroth technique and more doctors are willing to consider its merits.

"Five or six years ago, I first started hearing parents ask me about it," said Suken Shah, the pediatric orthopedic surgeon who evaluated Trevor. As division chief of the Nemours Spine and Scoliosis Center in Wilmington, Shah said he had always encouraged patients to get exercise and stay active. Although many studies have been published in Europe about Schroth, no solid work has appeared in the top U.S. journals supporting claims that Schroth and similar therapies can help stop a scoliotic curve from progressing or actually reverse it, as many advocates claim.

That does not mean, however, the method is ineffective, Shah said.

"I'm open," he said. "We're interested in really good outcomes, whether that's operative or nonoperative. And nonoperative care is not optimal right now. We may not be acting early enough. And we may not be taking advantage of things available elsewhere."

John P. Dormans, chief of orthopedic surgery at Children's Hospital of Philadelphia and president of the Scoliosis Research Society, said the buzz about Schroth had been growing.

"There is still a lot of skepticism," he said. "But there is mounting evidence that specific exercises can be effective. As thoughtful surgeons, we support better, high-quality research to see if it really does work."

Nearly a century ago, Schroth, a German teacher who had worn a steel brace as a teenager to straighten her spine, developed exercises to treat scoliosis. She discovered that by assessing the back in three dimensions, practicing deep breathing, strengthening weak muscles, and training herself to reposition her shoulders, hips, and torso, she stood straighter and expanded her lung capacity.

She opened several clinics and began working with her daughter, Christa. After her mother's death in 1985, Christa treated patients in Germany, then went on to join forces with a doctor in Barcelona, fine-tuning the technique.

The treatment was brought to the U.S. in 2003 by Beth Janssen, a physical therapist from Wisconsin. Janssen's son had scoliosis and after two years in a rigid brace, still had problems with his posture and breathing. After hearing about the clinic in Barcelona, she took him there for treatment, then trained as a practitioner.

Janssen's clinic, Scoliosis Rehab, and one in Milwaukee, Spinal Dynamics of Wisconsin, were the two main sites offering treatment and training therapists in the method until 2012, when the Hunter College School of Physical Therapy launched a program.

So far, only two physical therapists in this region are certified to practice the method: Johan van Schalkwyk in Cherry Hill and Lisa Angioli in Exton.

Like most physical therapists, Van Schalkwyk, 46, said that in his 16 years of practice, all his training, and continuing education, no one ever suggested patients with scoliosis needed specialized care.

A few years ago, when a patient asked him about Schroth, he looked into it and was struck by its logic. Last year, he took the course at Hunter, which has now certified more than 60 therapists, said Gary Krasilovsky, chair of the physical therapy department.

Scoliosis normally starts early in puberty and occurs equally in boys and girls, although girls are eight times more likely to have a curve progress to the point that they need a brace or surgery.

The catch-22 is that there is a higher probability of preventing a curve from getting worse when patients are braced early on, before they enter the peak of their growth spurt. But because it is impossible to predict whose curve will progress enough to require intervention, and it is impractical - and from a public-health perspective, too costly - to brace every child at the first sign of scoliosis, doctors do not recommend doing anything until the curve reaches 25 degrees.

"If you committed every kid with a 20-degree curve to a brace, you'd be overtreating," said Dormans. Studies have shown, he said, that people who enter adulthood with a curve of less than 40 degrees usually do not get any worse as they age.

For patients at risk of more serious curvature, reaching a consensus on the best treatment has been difficult for physicians.

In 2013, a large multicenter study was halted because researchers found bracing so effective in preventing curves from advancing that continuing with a control group would have been unethical.

"The benefit increased with longer hours of brace wear," the authors wrote in the New England Journal of Medicine.

Yet in the same issue, an editorial doubted the researchers' conclusions, saying the study wasn't big enough to evaluate a diverse group of patients.

It is no surprise, then, that an alternative therapy such as Schroth has been slow to gain acceptance among surgeons.

Advocates of Schroth and similar exercises say the central question is: Why not teach patients how to strengthen their backs, correct their posture, and breathe more effectively rather than passively waiting to see how far their curves progress?

"I believe in exercise as active observation," said Amy Sbihli, a Schroth-certified therapist in Burlington, Mass. She teaches the method at Hunter, which had a waiting list of 20 therapists for the course this fall.

"A lot of physical therapists who come to my courses tell me they're seeing so much scoliosis and don't know what to do with it," Sbihli said. "There's a world of unmet need."

Children's Hospital here is planning to offer Schroth therapy to patients in the spring, a spokesperson said.

At Nemours, Shah said, he is writing a business proposal to have two therapists trained in the method.

"It's hard to quantify the effect," he said, until larger, more rigorous studies are done. "But if we already assume it doesn't cause any harm and it might help, it's all good."

Exercise in general should be encouraged more, Shah said, noting that young ballet dancers with scoliosis benefit greatly from their keen awareness of posture, constant workouts, and stretching.

Among the most successful is Wendy Whelan, the exquisite dancer who retired Sunday after 30 years with the New York City Ballet. Diagnosed with severe scoliosis at 12, Whelan spent two years in a brace, but took ballet classes the entire time and continued, throughout her career, to practice breathing and stretching exercises to compensate for her asymmetrical back.

The advantage of Schroth over the standard physical therapy Shah said, is that it is customized to each patient's curve type and age. He cautions, however, against unrealistic expectations.

After traveling to Wisconsin and Barcelona for intensive and costly care, some of his patients with serious curves have returned to find they needed surgery anyway.

Schroth's expansion will be limited by insurance coverage and patients' self-discipline. Besides working with a therapist at least once a week for months, they must do exercises at home for 30 minutes five days a week or more.

Trevor Johnson believes the investment paid off.

Now 14, he has been working with Angioli once or twice a week since March and practicing at home nearly every day. During a recent session at Empower Physical Therapy, Angioli adjusted his posture and talked him through a series of subtle but challenging moves.

Angioli had been practicing for 25 years when a colleague told her about Schroth. The woman's sister was a ballet dancer who after being told she needed surgery for scoliosis opted for a brace and Schroth therapy. The results were dramatic.

Angioli received her Schroth certificate from Hunter on Oct. 8, 2013. "Are we totally against surgery?" she asked. "Absolutely not. In some cases, it's absolutely necessary." And for many patients, bracing is required.

"Check those ribs," she said as Trevor squared his shoulders. Gently tapping on his lower back, she coaxed, "Breathing here and here. Good!"

Later, Trevor hung by his arms from a special ladder, then, focusing on the weaker muscles in his shoulders and back, raised and lowered his body. In another exercise, he stretched sideways on the floor while Angioli slipped beanbags under his hip and neck, aligning his posture. He then lifted his top leg to strengthen targeted muscles, and, as before, drew breath into constricted spaces in his lungs.

"It was weird at first," Trevor said. "But then I got used to it."

At the time Shah recommended an operation, Trevor was in so much pain he could not sit through classes and his grades suffered.

"But I didn't want surgery. It would have taken me four months to recover and I would have needed more physical therapy after that. Plus, it was really expensive and they would have given me heavy drugs."

After he was put in a brace, he went for regular physical therapy, but "it made the pain worse."

Since he started with Angioli, he has doubled his lung capacity, is in much less pain, and can focus on his studies. When he was last X-rayed in August, his upper curve had fallen from 34 to 30 degrees and his lower curve from 35 to 27 degrees.

Trevor, who hopes to be an orthopedic surgeon one day, wonders why there is so much hesitation about Schroth. "It works," he said. "They ought to spread it further."

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