Spine specialists at HSS have been using a 30-camera array, called 3dMD, in the lab for several years, but the new study shows that the system produces clinically meaningful information. Because 3dMD does not rely on ionizing radiation, the technology may help adolescents with scoliosis avoid many of the repeated and potentially harmful x-rays that conventional care requires.

“Determining spinal range of motion is a lot more difficult than it sounds,” said Roger Widmann, MD, chief of the Pediatric Orthopedic Surgery Service at HSS and co-principal investigator on the new study. The conventional gold standard has been the use of x-ray imaging; however, x-ray tests are expensive, and long-term exposure to radiation from the scans has been linked to cancers.

The new technology provides a “safe, repeatable, inexpensive measurement of spinal range of motion that can be used in both a research and clinical setting,” Dr. Widmann said.

Information from the 3dMD scans can help spine surgeons determine the optimal approach to operative treatments and allow them to better track the progress of scoliosis patients following surgery. “The technology gives you objective measures of range of motion so you can improve your surgical decision-making,” Dr. Widmann said.

The HSS team presented their findings today at the 2023 Annual Meeting of the American Academy of Orthopaedic Surgeons (AAOS) in a poster titled “3D Surface Topographic Optical Scans Yield Highly Reliable Spine Range of Motion Measurements in Adolescents.”

The 30-camera array can generate a whole-body image of a standing person in under 2 milliseconds – fast enough to eliminate any blurring from even the slightest movement in any direction.

In previous studies, the HSS team and their colleagues have shown that images generated with the ultrafast cameras match the anatomy beneath the skin. That alignment is critical for 3dMD to be useful in the clinic as a way to guide treatment for scoliosis, which affects between 2% and 3% of youth in the United States, or 6 to 9 million people.

Treatment for scoliosis frequently involves physical therapy or the use of braces to correct the curvature of the spine – a measurement called the “Cobb angle” – but in the most severe cases, surgery may be necessary.

For the new study, Dr. Widmann’s group used 3dMD to image 254 boys and girls with scoliosis and 53 without the spinal deformity as they underwent several exercises designed to work the torso in various directions.

“This is teaching us which parameters are more useful and which are not,” says Howard Hillstrom, PhD, a biomechanical engineer at HSS, senior director of the Leon Root, MD Motion Analysis Laboratory and co-principal investigator on this project.

The new study found two movements that were reliably able to differentiate youth with scoliosis from those with normal spines: bending as far to the left and right as possible while standing, and bending toward the floor as if to touch the toes.

In the first case, patients with scoliosis show significant asymmetry between one side and the other in terms of how far to each side they can bend. Meanwhile, scoliosis patients are not able to bend as far toward the floor – as measured from a point on their collarbone – as those with unaffected spines, Dr. Hillstrom said. “That’s good enough to distinguish healthy kids from those with scoliosis because most kids are so flexible they can get to the floor and those with scoliosis probably can’t.”

Although the assessments make sense both intuitively and clinically, the latest study shows that they are also an objective measure of scoliosis. The entire process, from the start of the scan to the generation of results, takes under 10 minutes, Dr. Hillstrom added.

“And now we have this system that acquires these variables and doesn’t require ionizing radiation to do so,” he said, noting that this is critically important because scoliosis patients have a significantly greater incidence of cancer, breast cancer, and cancer mortality than those without the condition – an increase many experts attribute to the radiation they receive from x-rays and CT scans.

The process of diagnosing scoliosis starts early. “The first time someone notices that a child may have scoliosis is usually when the school nurse sees it during a routine examination,” Dr. Hillstrom said. “The nurse tells the parent to take the child to a doctor, and the first thing a physician will do is order an x-ray.”

The HSS team now has imaging studies of more than 300 adolescent patients with scoliosis in its 3dMD database. “Of those, approximately 50 are a year out from surgery and 30 are two years out, providing the ability to look at the long-term benefits of the technology on range of motion and other parameters [such as angle of trunk rotation, back surface rotation, and asymmetry in lateral bending and twisting”, Dr. Widmann said. 

Authors: Alon Wolf, PhD; Ankush Thakur, MS,BS (HSS); Benjamin N. Groisser, BA, (Technion); Caroline C. Gmelich, BA; Don Li, MD,PhD; Hila Otremski, MD; Howard J. Hillstrom, PhD; Jessica H. Heyer, MD; Kira Page, BA; Kyle Morse, MD; Matthew E. Cunningham, MD, PhD, FAAOS, (HSS); Michael T. Hresko, MD,FAAOS, (Boston Children's Hospital); Roger F. Widmann, MD, FAAOS, (HSS); Ron Kimmel, DPHIL (OXON)

The findings, presented today at the American Academy of Orthopaedic Surgeons (AAOS) 2022 Annual Meeting, shows that the ultrafast cameras produce scans of the surface of the body that complement internal images generated by low-dose x-ray. Because 3dMD does not rely on ionizing radiation, the investigators believe the technology may help scoliosis patients avoid many of the repeated and potentially harmful x-rays that conventional care require.

Surface topography and internal imaging work together to provide a much fuller picture of how scoliosis affects the body, according to Roger F. Widmann, MD, chief of the Pediatric Orthopedic Surgery Service at HSS and the senior researcher on the study. “When you see someone with a spinal deformity, you’re not necessarily visualizing the shape of the spine underneath,” he said. “Three-dimensional (3-D) surface scanning is analogous to what you see visually, whereas x-rays or MRI are often much different from what you see on the surface. Both approaches are important, but the information they provide is quite different.”

Howard J. Hillstrom, PhD, a biomechanical engineer at HSS and co-principal investigator on the project, says the 30-camera array can generate a full image of a standing person in under two milliseconds—fast enough to eliminate any blurring from even the slightest movement in any direction. “It gives us very accurate information to begin with, and it’s important to start with sound data,” Dr. Hillstrom noted.

What was previously unknown was how well these images of the body’s surface conform to the anatomy beneath the skin. This relationship is critical for 3dMD to be useful in the clinic as a way to guide treatment for scoliosis, which affects between 2% and 3% of youth in the United States, or 6 to 9 million people.

Treatment for scoliosis frequently involves the use of braces to correct the curvature of the spine—a measurement called the Cobb angle—but in the most severe cases, surgery may be necessary.

Dr. Hillstrom, who describes the image as a “large, 3-D selfie,” said these results “give us the green flag to study spinal pathology and the effects of treatments for different severities of scoliosis” in ways that weren’t possible previously.

For clinicians, he added, “It’s great to have objective tools to support the patient-reported outcomes that we use.”

For the study, the researchers compared images gathered by 3dMD with those produced by a next-generation x-ray system called EOS. A total of 46 youths participated in the study, 26 of whom had been diagnosed with adolescent idiopathic scoliosis (mean age, 14.7 years; 14 female, 12 male) and 20 who did not have the condition (mean age, 14.6 years; 9 female, 11 male).

The 3dMD images demonstrated extremely high reliability, particularly for linear geometric measurements of the surface of the subjects. “The measurements generated from the 3-D scans were used to create unique volumetric measures of truncal asymmetry, which demonstrated very high correlations with patient-reported self-image,” Dr. Widmann said.

Dr. Hillstrom noted the post-processing software that employs artificial intelligence (AI) is the secret behind the accuracy of the camera array. “AI fills in the blanks very quickly. It helps to identify anatomical regions and provide a mathematical approach to organizing the topographic data showing you the head, neck, trunk and pelvis—from outside of the body. You can uncover details you wouldn’t normally be able to see with the naked eye or with the use of conventional radiology.”

As the 3dMD system moves into the clinic, the technology will help surgeons better predict both the cosmetic and functional outcomes of the various procedures for scoliosis. “You can use the system to assess the efficacy of different surgical techniques based on how well you’re creating symmetry of the surface of the torso,” Dr. Widmann said. “This technology offers a quick and easy way to objectively assess surface symmetry as well as global spine range of motion, and both measures are really important to assess after scoliosis surgery.”

Authors: Alon Wolf, PhD; Ankush Thakur, MS, BS, (HSS), Benjamin N. Groisser, BA (Technion), Howard J. Hillstrom, PhD (HSS), Kyle Morse, MD, Matthew E. Cunningham, MD, PhD, FAAOS (HSS), Michael T. Hresko, MD, FAAOS (Boston Children's Hospital), Roger F. Widmann, MD, FAAOS (HSS), Ron Kimmel, DPHIL (OXON).

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 sports medicine surgeon and Team Physician for the New York Knicks Answorth A. Allen, MD, said "one of the fantastic things about working at Hospital for Special Surgery is that you're never alone. You're part of something bigger than yourself.

"There's always very good communication between the trainers, the managers and the owners who are all trying to do the right thing for the individual - which is first a patient and an athlete second," added Dr. Allen.

Lisa R. Callahan, MD, primary care sports medicine physician at HSS; Chief Medical Officer and Senior Vice President of Player Care at Madison Square Garden Sports, said "that it is important to assess a player from a variety of angles."

The Leon Root, MD, Motion Analysis Laboratory offers advanced technology to record a patient's movement for assessment.

"Little reflective markers are put on bony landmarks around the body. We can study your jumps, your running, your walking, your cutting. We get these 3D motions... we're applying it to understand the biomechanics of the athlete," said Howard J. Hillstrom, PhD, director of the motion analysis lab.

"It's very important to know what's normal for that individual athlete, so after they've had an injury, you know what their baseline is that you can compare the return to," said Dr. Callahan.

Also featured is HSS rehabilitation specialist Theresa Chiaia PT, DPT, who conducted an athletic performance assessment and fitness tests with a patient utilizing video. As part of the athlete's education in injury prevention, Chiaia reviews the playback with a patient to determine where adjustments need to be made.

Watch the full video at msgnetworks.com. This segment aired during the January 14, 2018 broadcast.