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Modified Lenke Classification System for Infantile and Juvenile Idiopathic Scoliosis: Poster #4

Mishiro, Takuya PhD (Takamatsu Redcross Hospital); Lenke, Lawrence G. MD; Koester, Linda A. BS; Bridwell, Keith MD; Luhmann, Scott J. MD

Spine: Affiliated Society Meeting Abstracts: September 2009 - Volume 10 - Issue - p 137
Traditional Poster Abstracts

Introduction: There is no universally acceptable system for the classification of infantile and juvenile (age 0 to 9+11) idiopathic scoliosis (IIS, JIS). We developed a new system for the classification of IIS & J IS by modifying the Lenke Classification System for adolescent idiopathic scoliosis (AIS).

Methods: 114 IIS/JIS patients (66 operative/48 nonoperative; 86 females/28 males) were included. Upright AP/lateral x‐rays were obtained and measured. The proximal thoracic (PT), main thoracic (MT), and thoracolumbar/lumbar (TL/L) regions were designated as either the major curve (largest Cobb measurement, always structural) or minor curves which are determined to be either structural or nonstructural. Minor curve criterion for the MT curve‐the apex is completely off the plumbline; and for the TL/L curve‐the apex is completely off the center sacral vertical line (CSVL). Structural characteristics of the PT curve are designated by a Cobb angle of >35°and the height of the bilateral 1st ribs (1st rib opposite the MT curve >3mm elevation for PT Cobb angle between 10–35°). If the PT Cobb angle is <10°, the curve is always nonstructural regardless of the 1st rib height.

Results: This produced the triad classification of curve types (1–6) combined with a coronal lumbar modifier (A, B, C) and a sagittal thoracic modifier (‐, N, +) similar to the AIS classification system. Type 1 MT curves were found in 43.9% of cases (n=50), type 2 DT in 23.7% (n=27), type 3 DM in 2.6% (n=3), type 4 TM in 4.4% (n=5), type 5 TL/L in 21.1% (n=24) type 6 TL/L‐MT in 4.4% (n=5). Lumbar modifier A was found in 64.0% of cases, B modifier in 17.5% C modifier in 18.4%. Sagittal modifier “‐” was found in 11.4% of cases, “N” in 82.5% “+” in 6.1%. The 5 most common classifications include: 1AN (27.2%), 2AN (15.8%), 5AN (7.9%), 5CN (7.9%) 1 A‐ (7.0%).

Conclusion: The classification system of IIS & JIS is based on a modified Lenke Classification System allowing for the classification from only upright AP and lateral x‐rays, side‐bending x‐rays are not needed. The frequency of curve patterns is remarkably similar to the AIS population. The ultimate goal of this modified system is to allow the inclusion and organization of IIS & JIS curve patterns and objectively evaluate various treatment methods.

© 2009 Lippincott Williams & Wilkins, Inc.