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Mount Sinai Spine Center
5 East 98th Street, 4th floor
New York, NY 10029

Mount Sinai Doctors Manhasset
1155 Northern Boulevard,
3rd Floor, Suite 300
Manhasset, NY 11030

Mount Sinai’s Baron Lonner, MD, Changes Young Lives with Advanced Scoliosis Surgery


Baron Lonner, MD, frequently receives videos from the parents of his young patients. In the clips, the children are dancing, golfing, swimming or doing competitive gymnastics. It is remarkable to watch them flip or twirl—sometimes just a few months after Dr. Lonner, Professor of Orthopedic Surgery and Chief of Minimally Invasive Scoliosis Surgery at The Mount Sinai Hospital, performed surgery to correct their twisted spines. He is inspired and gratified by every one of the videos.

Scoliosis, a sideways curvature of the spine, is common in adolescents. It occurs in 3 out of 100 people. Most cases are mild, but some children develop severe scoliosis as they grow. Without treatment, the condition causes pain, weakness, numbness and physical asymmetries such as uneven shoulders or a hump on the back. In severe cases, untreated scoliosis can interfere with a person’s breathing or affect their quality of life and ability to do daily activities, including recreation and work.

For many young people with scoliosis, the physical changes cause significant distress, says Dr. Lonner, a world leader in treating scoliosis. “It is not a cosmetic issue. Scoliosis affects their self-image, their interactions with peers, their whole life,” he said. And as they go through life, they are more likely to experience pain that limits their function. In some cases, external braces can prevent the curve from worsening or even partially straighten it. But in severe cases, Dr. Lonner uses a variety of surgical procedures to correct scoliosis.

Dr. Lonner treats patients through the Young Spine Program at Mount Sinai, which offers comprehensive, compassionate care to pediatric patients with spine conditions. As a member of the Young Spine Program, Dr. Lonner works closely with an expert team that includes orthopedic surgeons, pediatricians, anesthesiologists, plastic surgeons and physical therapists who work together to find the best treatment for each young patient.

The program draws patients of all ages from across the country and around the world, who consult with Dr. Lonner and his team because of his deep expertise in minimally invasive scoliosis surgery and other approaches for treating scoliosis and other spinal curve differences. In addition to performing a range of leading-edge procedures, he is actively involved in developing new devices for non-fusion and fusion approaches that can correct scoliosis with shorter recovery times, fewer complications and better long-term outcomes.

“These treatments are life-changing,” Dr. Lonner said. “We restore the patient’s body symmetry, ability to function, and self-image. The individual sees the change when they look in the mirror.”

Orthopedic Surgery: A Meeting of Hands and Mind

Dr. Lonner grew up on Long Island, the son of refugees whose families left Germany during World War II. His mother fled to Uruguay and then Argentina before reuniting with family in Pittsburgh as a teenager. His father arrived at Ellis Island at the age of 8. “My parents are survivors who came to the U.S. and gave so much to provide for me and my brother, who is also an orthopedic surgeon,” he said. “Their support set the tone for me to pursue medicine.”

From an early age, he had an innate interest in science and a deep desire to help people. When he was around 9, his beloved grandmother began experiencing a decline in health due to myasthenia gravis, a chronic neuromuscular disorder. “From that point on, I was tilted toward a career in medicine,” he said.

Dr. Lonner had always been athletic and was naturally drawn to orthopedic surgery. “I was interested in orthopedics because I appreciated the importance of restoring function at the highest level. And surgery, because I like to use my hands and my mind,” he said. “Orthopedic surgery requires a lot of judgment and decision-making. At the same time, there is a physicality needed to perform these long surgeries with intense focus and technical skill that I really enjoy.”

He went to medical school at Boston University School of Medicine. As a student, he became a research assistant to the late John Hall, MD, former Chief of Orthopedic Surgery at Boston Children’s Hospital and Professor at Harvard Medical School, a pioneer in pediatric scoliosis surgery. It was a time before digital X-rays, and Dr. Lonner painstakingly measured thousands of X-rays by hand over the next two years as he helped Dr. Hall with scoliosis research.

That early experience, combined with a residency at Montefiore Medical Center and the Albert Einstein College of Medicine in New York City, cemented a lasting interest in spinal surgery. One of his mentors, Stanley Hoppenfeld, MD, was a leader in scoliosis surgery and education. He was instrumental in fostering Dr. Lonner’s interest. In 1999, Dr. Lonner took over Dr. Hoppenfeld’s practice. Today, most of Dr. Lonner’s patients are adolescents, though he also treats younger children and babies with spinal deformities, as well as adults living with the consequences of having scoliosis for decades. “Treating that spectrum of patients allows me to understand the impact of the treatments we offer today and what that might look like for patients 20 or 30 years down the road, whether they were previously treated or never had treatment before for their condition,” he said.

Innovations in Spine Surgery

Dr. Lonner’s drive to learn and improve has led him to publish more than 200 research papers. He is also pioneering the development of new devices for scoliosis treatment. In collaboration with other surgeons and engineers, he helped develop the Tether Vertebral Body Tethering System, a scoliosis treatment approved by the U.S. Food and Drug Administration in 2019. Traditionally, people with severe spinal curves needed spinal fusion, which permanently joins two or more vertebrae, the bones of the spine. Though it is an effective treatment, fusion limits normal spinal motion. It also increases the risk that the spinal discs below the fused area will develop wear and tear over time, leading to back pain and sciatica, a pain that radiates down the leg.

The Tether offers an alternative to spinal fusion for patients who are still growing. During the Tether procedure, the surgeon makes very small incisions and inserts a narrow scope to visualize and reach the spine. They place screws to the vertebrae in the curved portion of the spine, attach a flexible cord to the screws and then apply tension to partially straighten the curve. As the child grows, the cord continues to straighten the spine.

Compared to spinal fusion surgery, patients who receive the Tether have less bleeding, lower risk of infection and faster recoveries. They also maintain motion in their spines. Long-term studies are needed to reveal how these patients do over the decades, but Dr. Lonner believes they are less likely to experience the disc degeneration and back pain that are common with spinal fusion. “Their recoveries are remarkable,” he said. “Within six weeks, they can return to full activity.”

The Tether has become so successful that it is now the biggest part of Dr. Lonner’s practice. Over the last seven years, he has performed nearly 500 of these procedures. He has also been involved in designing other new treatments. He was a consultant on the development of a system called ApiFix, also known as posterior dynamic distraction correction. In this system, surgeons place a rod on the spine, which acts as an internal brace that corrects the curve when it is inserted. As the patient grows, the device ratchets open to correct the curve further. Like the Tether, ApiFix allows for a more natural range of movement than spinal fusion. “For the right patients, it has been a wonderful option. We see very quick recoveries and rapid return to activities,” Dr. Lonner says.

A Commitment to Patient Care

Every patient is unique, and Dr. Lonner spends a lot of time with patients and their families to learn about their lives, activities and aspirations. “A solution that is right for one person is not the best choice for another. I customize treatment to a patient’s goals and desires,” he said. “It is an exciting time in scoliosis treatment because we can give people options where there were not a lot of alternatives before.”

His commitment to advancing patient care aligns well with the values of Mount Sinai, he added. “I have practiced in many hospitals, and I can say this is absolutely a world-class institution,” he said. “There is really a team approach at Mount Sinai. Everyone on the team focuses on the well-being of each patient and strives to improve the patient experience.”

During his career, Dr. Lonner has performed more than 3,000 surgeries on children and adults. It is a physically demanding job, and when Dr. Lonner is not in the operating room, he heads to the beach to give his muscles a break. “Swimming is my passion, especially in the ocean. I take my swimsuit with me wherever I go,” he said. He has competed in long swims and triathlons, including the Escape from Alcatraz Triathlon, which includes a 1.5-mile swim through the San Francisco Bay and has done a six-mile, 4-hour swim off Coney Island in Brooklyn, New York.

He also enjoys spending time with his two sons and stepdaughter and traveling with his wife. His travels have taken him around the world on mission trips to Asia, Africa, the Caribbean and the Middle East to train local surgeons in spinal surgery techniques and perform surgeries on young patients. Those experiences have been gratifying. “We may have different accents and customs, but underneath we are all the same. Families want the best for their children. They want a safe operation that will relieve their suffering and free them from pain,” he said. “I have been blessed to have patients from all over the world. I am fortunate to be here at Mount Sinai and be able to offer my patients this innovative care.”