• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
bone and spine logo

Bone and Spine

Your Trusted Resource for Orthopedic Health Information

  • Home
  • About
  • Contact Us
  • Policies
  • Show Search
Hide Search
You are here: Home / Spine disorders / Lenke Classification System for Scoliosis

Lenke Classification System for Scoliosis

Dr Arun Pal Singh ·

Last Updated on March 17, 2025

Lenke classification is a comprehensive radiographic classification of Adolescent Idiopathic Scoliosis named after Dr Lawrence Lenke who was instrumental in devising it.

Adolescent idiopathic scoliosis is the most common types of scoliosis encountered.

Though originally intended to be include factors in 3 planes, it eventually included two saggital and coronal plane.

The classification was published in 2001 and is being widely used.

The Lenke Classification System provides surgeons with a simple, accurate and reproducible way to measure and communicate about scoliosis.

It evaluates the x-rays used in different positions [the front, side, and in bending positions.]

For classification, the following things are used

  • By the curve type
  • Lumbar spine modifier
  • Sagittal thoracic modifier.

The Lenke Classification System recognizes and measures scoliosis as a multi-dimensional problem. It thus helps to devise a focused treatment.

Contents hide
1 Details of The Lenke Classification System
1.1 X-rays Required
1.2 Step 1 – Determination of curve type
1.3 Step 2 – Assignment of Lumbar modifiers (A,B,C)
2 Step 3: Assignment of Sagittal thoracic modifier (-, N, +)
3 References

Details of The Lenke Classification System

Lenke classification system for scoliosis
Lenke classification system for scoliosis

The Lenke classification is a triad classification system consisting  of:

  1. curve type (1-6)
  2. lumbar spine modifier (A, B, C)
  3. sagittal thoracic modifier (-, N, +)

X-rays Required

The final classification mentions all three factors. Thus an example of the classification may be Lenke 2A-

To determine the components of the triad the following radiographs of the spine are required:

  • Upright AP view
  • Upright lateral view
  • Left supine bending
  • Right supine bending

Step 1 – Determination of curve type

The spine is divided into 3 regions.

  • Proximal thoracic – Apex at T3, T4 or T5
  • Main thoracic – Apex between T6 and the T11-T12 disc
  • Thoracolumbar/Lumbar – Thoracolumbar apex between T12 and L1, and lumbar apex between the L1-L2 disc and L4

Proceed as follows

Measure regional curves

  • Proximal thoracic (PT)
  • Main thoracic (MT)
  • Thoracolumbar/lumbar (TL/L)

Identify major curve

Cobb angles are measured from cranial end vertebra to caudal end vertebra. End vertebra is the vertebra that is most tilted from the horizontal apical vertebra. For a given curve the cranial end plate is used for the proximal end vertebra while the caudal end-plate is used for the distal end-vertebra.

The curve with the largest cobb angle is by definition the major curve.

Other curves are by definition minor curves.

A major curve is

  • The biggest curve
  • Has largest cobb angle and is always structural.
  • Always either
    • MT (Type 1-4)
    • MT/L (Type 4,5,6)

[If PT is the largest curve, then by default major curve is assigned to MT]

Determine if a minor curve is structural or not

This is done by evaluating the left and right supine bending and lateral x-rays. Following criteria are used for marking the curves structural. Only one of the two criteria needs to be met

  • Minor Proximal thoracic
    • Residual coronal curve greater than or equal to 25 ° on supine bending radiograph
    • Kyphosis T2 – T5 of greater than or equal to 20 °
  • Minor main thoracic curve
    • Residual coronal curve greater than or equal to 25 ° on supine bending radiograph
    • Kyphosis T10 – L2 greater than or equal to  20 ° (regardless of coronal flexibility)
  • Minor thoracolumbar/lumbar curve
    • Residual coronal curve greater than or equal to 25 ° on supine bending radiograph
    • Kyphosis T10 – L2 greater than or equal to  20 ° (regardless of coronal flexibility)

Assign Type 1-6 based on the chart below

 

Curve Type Curve Name PT MT TL/L
Type 1 MT – Structural (major*) –
Type 2 Double thoracic (DT) Structural Structural (major*) –
Type 3 Double major (DM) – Structural (major*) Structural
Type 4 Triple major (TM) Structural Structural (major*) Structural (major*)
Type 5 TL/L – – Structural (major*)
Type 6 TL/L-MT – Structural Structural (major*)

Step 2 – Assignment of Lumbar modifiers (A,B,C)

  • Identify apical lumbar vertebrae (ALV)
    • Inferior lumbar body that falls outside of the curve
  • Draw  vertical line from the center of the sacrum [Centeral sacral vertical line (CSVL)]
  • See its relationship to pedicles of apical lumbar vertebra
  • Assign modifier
    • A –  CSVL passes between pedicles of apical lumbar vertebrae
    • B –  CSVL touches pedicle of apical lumbar vertebrae
    • C –  CSVL does not touch apical lumbar vertebrae

Step 3: Assignment of Sagittal thoracic modifier (-, N, +)

  • Measure sagital Cobb from T5 to T12
  • Assign modifier
    • hypokyphotic (-) if < 10°
    • normal if 10-40°
    • hyperkyphotic (+) if >40°

Combine the three values to provide final triad.

References

  • Lenke Classification of AIS
  • Lenke Classification AO foundation

Spine disorders This article has been medically reviewed by Dr. Arun Pal Singh, MBBS, MS (Orthopedics)

About Dr Arun Pal Singh

Dr. Arun Pal Singh is a practicing orthopedic surgeon with over 20 years of clinical experience in orthopedic surgery, specializing in trauma care, fracture management, and spine disorders.

BoneAndSpine.com is dedicated to providing structured, detailed, and clinically grounded orthopedic knowledge for medical students, healthcare professionals, patients and serious learners.
All the content is well researched, written by medical expert and regularly updated.

Read more....

Primary Sidebar

Know Your Author

Dr. Arun Pal Singh is an orthopedic surgeon with over 20 years of experience in trauma and spine care. He founded Bone & Spine to simplify medical knowledge for patients and professionals alike. Read More…

Explore Articles

Anatomy Anatomy Fractures Fractures Diseases Diseases Spine Disorders Spine Disorders Patient Guides Patient Guides Procedures Procedures
featured image for orthopedics traction

Orthopedic Traction – Principles, Types, and Uses

Traction is a fundamental concept in orthopedics for managing …

featured image of gower sign for segmenatal instability of lumbar spine

Clinical Tests for Lumbar Segmental Instability

Lumbar segmental instability may not always be visible on standard …

mesurement of scoliosis for braces

Braces for Scoliosis- Types, Uses and Results

Braces for scoliosis are recommended to prevent the scoliotic curve …

discogenic back pain

Discogenic Back Pain Causes, Diagnosis and Treatment

Discogenic back pain is a common cause of axial low back pain [the …

Elbow arthrodesis using internal fixation

Elbow Arthrodesis- Indications, Methods and Complications

Elbow arthrodesis refers to the surgical fusion of the elbow joint. It …

Popular articles

Carpal Tunnel Syndrome Presentation and Treatment

Carpal tunnel syndrome refers to …

Olecranon Bursitis

Olecranon Bursitis Presentation and Treatment

Olecranon bursitis is inflammation of …

Parsonage Turner Syndrome

Parsonage Turner Syndrome

Parsonage Turner syndrome or brachial …

Lateral View of United Fracture of Talus In A Child

Fractures of Talus Bone

Fractures of the talus include a broad …

Bone and Spine

© 2025 BoneAndSpine.com · All Rights Reserved
The content provided on BoneAndSpine.com is intended for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Read Disclaimer in detail.