Anatomic Maps May Offer New Technique for Calculating Spine Curvature
HSS researchers evaluating ‘3dMD' technology to reduce x-ray use and improve therapy for scoliosis patients
Researchers at Hospital for Special Surgery (HSS) in New York City are enrolling patients in a study using cutting-edge imaging technology to produce three-dimensional maps of the spine in people with scoliosis.
Currently, physicians monitor patients with scoliosis — an excessive curvature of the spine — using x-rays for a period of many years. This extensive exposure to radiation can be harmful, particularly as scoliosis primarily affects young people. HSS researchers hope the results of the study will lead to an algorithm to estimate the curvature of the spine without the need for x-rays.
At the heart of the approach is a highly accurate 30 camera whole body 3D surface imaging system manufactured by 3dMD, which acquires the patients shape using stereophotogrammetry. “You can take that image, flip it upside down, slice it and dice it at any level that you want because it’s a mathematical depiction of the surface of the patient,” said Roger F. Widmann, MD, Chief of the Pediatric Orthopedic Surgery Service at HSS.
“This technology is essentially producing the world’s most advanced selfie, and the benefit is that there’s nothing dangerous about it,” said Howard J. Hillstrom, PhD, director of the Leon Root, MD Motion Analysis Laboratory at HSS and the principal investigator of the study. “When you image with this system, you can count the number of hairs on a person’s leg.”
The new study combines two recently available imaging technologies: topographical mapping using 3dMD, a proprietary system of high-resolution cameras, and EOS imaging, a dual plane x-ray machine that determines spinal alignment while significantly reducing exposure to ionizing radiation. The 3dMD system combines information from 30 high-definition cameras to produce a full map of the torso in under a second. The speed of the process is a significant advantage over conventional imaging, according to Dr. Hillstrom, who noted that up to 10 to 20 percent of torso x-rays must be redone because inadvertent movements during the scans distort the picture. “3dMD is immune to that,” he said. In conjunction with collaborators from Technion (Alon Wolf, PhD, Ron Kimmel, PhD, and Benjamin Groisser), a leading scientific university in Israel, it is the long-term goal for HSS to improve the ability of estimating spinal malalignment with a minimum amount of radiation exposure to these patients.
Scoliosis affects an estimated 6 to 9 million Americans, or roughly 2 to 3% of the population; most patients are female. The condition typically is detected when children are in elementary school, during routine screening at school or at their pediatrician’s office. If scoliosis is suspected, clinicians will try to determine the extent of the curvature — mild, moderate or severe — using x-rays. Although mild and moderate cases can improve with physical therapy and bracing, severe cases may require surgery. “Severe scoliosis starts to affect the symmetry of the thoracic cavity and might then affect lung function,” Dr. Hillstrom said.
Restoring symmetry is a primary goal of scoliosis surgery, added Dr. Widmann. However, symmetry is difficult to determine using x-rays, which don’t necessarily reveal how changes to the skeleton affect the shape of the body. “One of the most important things to patients and families is appearance,” he said. “That’s what they see and what the world sees. This technology is showing you the surface, and we hope it will help us align the goals of surgery even more closely with what patients and families want from the procedure.” Anatomical mapping could improve bracing therapy in the same way, he added.
HSS researchers also will be gathering Patient Reported Outcomes Measures (PROMs), such as mobility, personal appearance, ability to participate in sports and other aspects of daily life and more.
So far, 30 children have enrolled in the study, which Dr. Hillstrom and colleagues hope will ultimately include 2,000 patients over the next five years, as well as roughly 500 people with normal spines to serve as comparisons.
“Being able to use this technology to screen patients for scoliosis would be a big improvement over the current method, which uses a carpenter’s level on a patient’s back and has a very high rate of false-positives,” Dr. Widmann said. In other words, many children initially suspected of having scoliosis don’t have the condition — but doctors don’t know that until they take an x-ray. “You’re taking x-rays on a lot of kids who don’t need them, so we need a very reliable technology that correlates with x-rays so that you can safely decide if you need one or not. We’d love to have a better tool for this,” he adds.
The technology might also prove useful for other orthopedic applications, such as creating better casts for custom orthoses and prostheses or estimating inequality in the length of limbs — a problem that can lead to issues with gait, back pain and other complications. One medical application that combines these two technologies is cranio-fascial reconstructive surgery where both the shape of the external surface and the underlying bony architecture must be matched for proper function. But the uses are potentially much broader, Dr. Hillstrom said. “I think when you turn a group of experts loose on a new technology, they’re going to come up with a list of applications that we never dreamed of at the outset.”
Portions of the data collected from 3dMD will also be a part of a 3-year competitive research grant that was just awarded to HSS from the Cotrel Foundation entitled, “Use of Surface Topography for Screening and Outcome Evaluation of Adolescent Idiopathic Scoliosis”. Dr. Widmann serves as the principal investigator and Dr. Hillstrom as a co-investigator along with a team of pediatric Orthopedic surgeons, scientists, engineers, radiologists, pediatric sports medicine specialists, physical therapists, prosthetists/orthotists, pediatricians, and trainees.
HSS is the world’s leading academic medical center focused on musculoskeletal health. At its core is Hospital for Special Surgery, nationally ranked No. 1 in orthopedics (for the 11th consecutive year), No. 4 in rheumatology by U.S. News & World Report (2020-2021), and named a leader in pediatric orthopedics by U.S. News & World Report “Best Children’s Hospitals” list (2020-2021). HSS is ranked world #1 in orthopedics by Newsweek (2020-2021). Founded in 1863, the Hospital has the lowest complication and readmission rates in the nation for orthopedics, and among the lowest infection rates. HSS was the first in New York State to receive Magnet Recognition for Excellence in Nursing Service from the American Nurses Credentialing Center five consecutive times. The global standard total knee replacement was developed at HSS in 1969. An affiliate of Weill Cornell Medical College, HSS has a main campus in New York City and facilities in New Jersey, Connecticut and in the Long Island and Westchester County regions of New York State, as well as in Florida. In addition to patient care, HSS leads the field in research, innovation and education. The HSS Research Institute comprises 20 laboratories and 300 staff members focused on leading the advancement of musculoskeletal health through prevention of degeneration, tissue repair and tissue regeneration. The HSS Global Innovation Institute was formed in 2016 to realize the potential of new drugs, therapeutics and devices. The HSS Education Institute is a trusted leader in advancing musculoskeletal knowledge and research for physicians, nurses, allied health professionals, academic trainees, and consumers in more than 130 countries. The institution is collaborating with medical centers and other organizations to advance the quality and value of musculoskeletal care and to make world-class HSS care more widely accessible nationally and internationally. www.hss.edu.