What is the Lenke classification system for scoliosis?

The Lenke classification assigns each AIS curve a type (1-6) based on the location and structural status of major and compensatory curves, a lumbar modifier (A, B, or C) based on the position of the lumbar apex relative to the central sacral vertical line, and a thoracic sagittal modifier (hypokyphosis, normal, or hyperkyphosis) based on T5-T12 kyphosis. These combine into a complete descriptor such as Lenke 1AN or Lenke 5CN.

What is a Lenke 5C scoliosis curve?

Lenke Type 5 describes a structural thoracolumbar or lumbar major curve with non-structural proximal thoracic and main thoracic compensatory curves. The C lumbar modifier indicates the apex of the lumbar curve is fully lateral to the central sacral vertical line. Dick JM et al. (Cureus, 2026) published a case report of non-surgical multimodal management for AIS Lenke 5C using an intensive CLEAR Institute protocol.

Lenke Classification -- Scoliosis Definition

Dr. Justin M. Dick, DC - Clear Life Scoliosis and Chiropractic Center - Charlotte, NC

Definition

The Lenke classification was developed by Dr. Lawrence Lenke and published in Spine in 2001. It is the most widely used system for characterizing adolescent idiopathic scoliosis (AIS) curves, now applied broadly in both surgical planning and conservative care.

Three components: curve type (1-6), lumbar spine modifier (A, B, C), and thoracic sagittal modifier. A complete descriptor looks like: Lenke 1AN or Lenke 5CN. The Lenke classification complements the Cobb angle measurement by capturing the three-dimensional curve pattern that a single angle cannot describe.

Curve Types 1-6

Type 1 - Main Thoracic (MT): Structural main thoracic curve; most common AIS type.
Type 2 - Double Thoracic (DT): Structural proximal thoracic and main thoracic.
Type 3 - Double Major (DM): Structural main thoracic and thoracolumbar/lumbar.
Type 4 - Triple Major (TM): All three curve regions structural.
Type 5 - Thoracolumbar/Lumbar (TL/L): Structural thoracolumbar or lumbar curve only.
Type 6 - TL/L-MT: Structural thoracolumbar/lumbar major with structural main thoracic minor.

A compensatory curve is structural if it fails to correct to less than 25 degrees on supine side-bending, or has a lateral Cobb of 25 degrees or more at T10-L2, or thoracic kyphosis of 20 degrees or more.

Lumbar and Sagittal Modifiers

Lumbar modifier A: CSVL falls between the pedicles of the lumbar apical vertebra(e). B: CSVL touches the lateral edge of the apical vertebral body. C: CSVL is completely lateral to the apical vertebral body, indicating significant decompensation.

Thoracic sagittal modifier: Hypokyphosis: T5-T12 less than 10 degrees. Normal: 10-40 degrees. Hyperkyphosis: greater than 40 degrees.

Lenke 5C - Research and Clinical Significance

Lenke Type 5C describes a structural thoracolumbar or lumbar major curve with non-structural proximal thoracic and main thoracic components, combined with a C lumbar modifier indicating the apex is fully lateral to the CSVL.

Published case report: Dick JM et al. (Cureus, 2026) documented a non-surgical multimodal approach to AIS Lenke 5C using an intensive two-week CLEAR Institute protocol, reporting measurable structural and functional improvements.

Application in Conservative Care

At Clear Life, Lenke typing informs:

ScoliBrace fabrication - the over-correction position is designed around the specific curve type
Exercise prescription - lumbar-dominant curves require different loading strategies than thoracic-dominant patterns
Treatment goal-setting - distinguishing true structural improvement from compensatory adjustment in serial Cobb angle comparison

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Lenke Classification — Scoliosis Definition