New Study Tests Reliability of Lin/Lenke Classification System for Adult Idiopathic Scoliosis

A 2020 study has determined the classification system has high reliability, and may drive future treatment plans for adult scoliosis.

Peer Reviewed
Known as the benchmark radiographic standard for classifying adolescent idiopathic scoliosis, the Lin/Lenke classification method may be applicable to adult idiopathic scoliosis, too. 

Lin Lenke classification scoliosis adultsThe Lin/Lenke classification system may be applicable to adults, too.

A new study from the creators in Spine Deformity details the expanded three-component classification system, which consists of:

  • Curve type
  • A lumbosacral modifier
  • A global alignment modifier

The study has concluded that the new Lin/Lenke classification system has high reliability when used in patients with  adult idiopathic scoliosis, promoting acceptance to guide a future standard of care.

Method founder and one of the study’s authors, Lawrence G. Lenke, MD, Surgeon-in-Chief at the  Och Spine Hospital at New York-Presbyterian/Allen, Professor and Chief of Spinal Surgery, Chief of Spinal Deformity Surgery, Co-Director, Adult and Pediatric Comprehensive Spine Surgery Fellowship, Columbia Univ. Dept. of Orthopedic Surgery, spoke with SpineUniverse about the expanded classification system, and how it could affect future diagnoses and treatment.

A Classification Challenge

Developed in 2001, the Lenke classification system is the comprehensive radiographic classification for adolescent idiopathic scoliosis widely utilized worldwide. The system involves X-ray evaluation to guide surgeons in classifying scoliosis curves in three ways:

  • By curve type (1-6,) based on the curve’s location in the proximal thoracic, main thoracic or thoracolumbar/lumbar spines
  • The lumbar spine modifier (A, B, or C), in relation to the distance to the center of the lumbar spine to midline of the sacrum
  • A sagittal thoracic modifier (-, N, +), which identifies the amount of lateral curvature to the thoracic region

Despite the level of detail within the Lenke system, it posed a significant limit: the system only designated classifications for adolescents up to the age of 18. However, as Dr. Lenke explains, it became apparent that an adult classification was necessary because many cases of adolescent idiopathic scoliosis often go undiagnosed and untreated—until those adolescents become adults whose symptoms prompt them to seek medical attention. 

“In adults, it’s the same disease processes that are untreated as teens, but then present as adults,” Dr. Lenke notes.

According to Dr. Lenke, between 5 and 10% of adults will have some form of scoliosis—a number that increases with age—although the true incidence is most likely even higher.  

In contrast to adolescents, however, adults are more heterogeneous in their presentation, due to the factors of aging that add on additional and often complicated features, such as advanced curve degeneration, stenosis, and osteoporosis of the spine. Thus, the challenge to build upon the Lenke classification system for adolescent idiopathic scoliosis to encompass the multiple variables seen in adult presentations was born.

Now Accepting: Adults

To meet that challenge, Dr. James Lin, a past Spine Fellow at Columbia Univeristy, and Dr. Lenke used a similar three-component radiographic classification system—complete with curve types and lumbosacral and global alignment modifiers—in adult patients for the purposes of classifying adult idiopathic scoliosis. 

Twelve spine surgeons reviewed 30 pre-marked sets of X-rays twice, with case orders altered between the week of review, with the end result being “near perfect agreement” for both inter- and intraobserver reliabilty Dr. Lenke notes that despite a potential limitation of using pre-measured X-rays—in that the surgeons weren’t evaluating and measuring patients radiographs themselves—the results still revealed that the classification system had “excellent reliability.” 

And to further ensure the system’s reliability for adults, he adds that they are bringing in other surgeons  not involved in developing the system for additional evaluation.

“We’re biased because we developed this system,” he says. “So we have some non-developers also prospectively classifying curves by the system and identifying how they treat patients to see if it’s is driving appropriate treatment measures based on the curves.”

Targeting Treatment

Dr. Lenke hopes that the updated classification system will lead to more efficient and targeted treatments for adults with idiopathic scoliosis in the future.

“It will help organize surgeons’ thought processes of the evaluation and potential treatment of these patients,” he notes. “These classifications are somewhat treatment-based in that how you classify the curve will determine some of the treatments.”

He also tells SpineUniverse that the Lin/Lenke classification system may also someday expand even further to include a fourth classification component for an MRI evaluation—something he believes will add additional value in diagnosing adults, who often present with multiple degeneration and even spinal stenosis issues that require MRI assessment.

Despite the fact that a lumbar spine MRI evaluation is usually needed in adults, Dr. Lenke was cautious to add a fourth component too early, noting that the more components you have, the more difficult adoption and ensuring reliability becomes. He hopes that maintaining the three-component system will allow surgeons to adopt it for standard use in classifying adult idiopathic scoliosis and lay the groundwork for future modifications. And thanks to the Lin/Lenke’s classification system modular design, any future components can be added in a straightforward fashion.

“We do anticipate adding a fourth component to evaluate the MRI exam of the spine with the additional processes occurring in the adult patient,” he says. “That will be an exciting add-on.” 

 

Updated on: 09/10/20
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Severe Progressive Adult Idiopathic Scoliosis
Lawrence G. Lenke, MD
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