Defining criteria for optimal lumbar curve correction following the selective thoracic fusion surgery in Lenke 1 adolescent idiopathic scoliosis: developing a decision tree

  • Saba PashaEmail author
  • Jean-Marc Mac-Thiong
Original Article • SPINE - SCOLIOSIS



The aim of this study was to identify the range of optimal versus suboptimal rates of spontaneous lumbar Cobb correction (SLCC%) and the factors predicting such outcomes in a cohort of Lenke 1 adolescent idiopathic scoliosis (AIS) after posterior spinal fusion surgery.


Seventy-one consecutive Lenke1 B and C AIS patients with a fusion level to L1 and higher with two-year follow-up were included. Thoracic kyphosis (T1–T4 and T4–T12 TK), lumbar lordosis (L1-S1 LL), thoracic and lumbar Cobb angles, thoracic and lumbar apical vertebral rotations and translations (AVR and AVT), pelvic incidence, sacral slope, and sagittal and frontal balances were measured at preoperative, early postoperative, and two-year follow-up. The SLCC% was calculated between preoperative and two-year follow-up. A clustering analysis determined the subgroups of patients with significantly higher and lower (optimal versus suboptimal) rate of SLCC% in the cohort at two-year follow-up. The cutoff values of the preoperative and early postoperative radiographic parameters that significantly predicted the optimal and suboptimal SLCC% were determined using a decision tree.


The averages of the optimal versus suboptimal range of SLCC% in the cohort were 72% [55%, 105%] versus 39% [− 7%, 42%]. Preoperative and early postoperative spinal parameters predicted the optimal versus suboptimal SLCC% with an accuracy of 82%, 95%CI [0.73–0.94]. Preoperative AVTLumbar < 10 mm was a predictor of optimal SLCC%. In patients with a preoperative AVTLumbar > 10 mm, early postoperative T4–T12 TK < 24° (but not less than 17°) accompanied by − 5° < AVRThoracic < 5° were the main predictors of optimal SLCC% in our cohort.


Quantitative clustering of the SLCC% into optimal and suboptimal groups allowed identifying the cutoff values of preoperative (AVTLumbar) and early postoperative (T4–T12 TK and AVRThoracic) spinal parameters that can predict the optimal range of SLCC% at two-year postoperative in our cohort of Lenke 1 AIS.

Level of evidence



Adolescent idiopathic scoliosis Surgical planning Spine Three-dimentional Decision trees Machine learning 



Funding was received from Scoliosis Research Society in form of research Grant for this study.

Author contributions

SP designed the work and performed the acquisition and analysis of data and drafted the manuscript. SP and JM contributed to the interpretation of data for the work; revised the manuscript critically for important intellectual content; and approved the final version for publication.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Human and animal rights

Institutional review board approved the study.


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Copyright information

© Springer-Verlag France SAS, part of Springer Nature 2019

Authors and Affiliations

  1. 1.Division of Orthopedic SurgeryThe Children’s Hospital of PhiladelphiaPhiladelphiaUSA
  2. 2.Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaUSA
  3. 3.Hôpital du Sacré-Cœur de MontréalMontrealCanada
  4. 4.Sainte-Justine University Hospital Research CenterMontrealCanada
  5. 5.Department of Surgery, Faculty of MedicineUniversity of MontrealMontrealCanada

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