Significant Differences Among Patients in Lenke Curve Types: Paper #12

Sponseller, Paul D. MD; Flynn, John M. MD; Newton, Peter O. MD; Lonner, Baron S. MD; Marks, Michelle C. PT, MA; Bastrom, Tracey MA; Petcharaporn, Maty BS; Betz, Randal R. MD

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Summary: Lenke 3 and 4 curves have largest magnitude; 5 are oldest and smallest. Males have more thoracic curve types (Lenke 1‐4) and less lumbar apical translation. Larger curves are seen in younger surgical patients.

Introduction: The use of Lenke curve types (for surgical planning, research and perhaps future genetic study) raises an important question: do Lenke types distribute in a homogeneous way, or are there significant differences in gender, age, frequency, magnitude at surgery, etc? We studied nearly 2000 surgical patients to answer this.

Methods: Methods: Parameters of 1912 AIS patients <21 y/o at operation were studied. Lenke type (LT) was verified. Curves were stratified as <50°, 50‐75°, and >75°. Age, primary curve magnitude and gender were compared among types.

Results: LT vary by gender: males were more likely to have a major thoracic curve (types 1‐4, 22% male) than major TL/L (5 & 6; 15% male) (p=0.005); Males also had fewer lumbar C modifiers (32 vs 44%, p=0.001) and less apical lumbar translation (1.1 vs 1.7 cm, p=0.001). LT vary by frequency: 50% were Lenke 1; least common were Lenke 3(5%) and 4(4%). LT vary by magnitude at surgery (Fig 1): Type 4 had the greatest % of large curves (52% > 75°); most smaller curves were LT 1 & 5.The largest mean curve was Type 4 (78°)*, followed by 3 (63°), 2 (60°), 6(59°), 1 (52°)* and 5(46°)*(* comparisons p<0.001). LT vary by age at surgery: patients with Lenke 5 curves were oldest (15.4 yrs vs. 14.6 for all others) despite lowest mean magnitude (p=0.001). Curve size was negatively correlated with age at surgery (r=‐0.16, p=0.001); Mean age at surgery was 14.2 for curves >75°, 14.6 for curves 50‐75°, and 15.2 for curves < 50°. LT vary by patient self image: Lenke 4 patients had lower preop SRS scores for self image than Lenke 1 (p=0.005) and a trend toward lower total scores than most other LT (p<0.079).

Conclusion: Lenke curve types do not distribute among patients homogenously. Instead, this careful analysis of surgical AIS patients reveals that each Lenke type has its own “personality”, characterized by age, gender, severity at surgery and patient self‐image.

Significance: These differences should be considered in research design.

© 2010 Lippincott Williams & Wilkins, Inc.