Spinal energy balance can predict post-operative spine alignment in Lenke 1 Adolescent Idiopathic Scoliosis.

Abstract

The preoperative planning of adolescent idiopathic scoliosis (AIS) remains largely debated. We hypothesized that adopting a biomechanical energetic framework could provide valuable insights for exploring the impact of spinal arthrodesis. Using this approach, we conducted a comparative analysis to quantify discrepancies between in silico simulations derived from preoperative radiographs and the actual three-dimensional spinal alignment obtained from post-operative imaging. Fifty-two consecutive patients with Lenke Type 1 AIS (mean age: 16 years; mean thoracic Cobb angle: 52°) who underwent posterior spinal fusion were included in the analysis. All patients had complete biplanar radiographs at three time points: preoperatively, post-operatively and at two-year follow-up. Discrepancies between in silico simulated surgery, calculated using preoperative radiographs and a biomechanical model, and actual clinical outcomes were quantified using two metrics: maximum coronal/sagittal deviations (MaxC/MaxS) from T1 to L5, and a comprehensive predictability factor ( <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mtext>a</mtext> <mtext>c</mtext></msub> </math> and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mtext>a</mtext> <mtext>s</mtext></msub> </math> ) measuring cumulative 3D position discrepancies across 17 vertebral levels, normalized by total spinal length. Mean MaxC was 4.7 mm (SD=4.9) and MaxS was 5.7 mm (SD=3.8). Mean values of <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>a</mi> <mtext>c</mtext></msub> </math> were 3.4% (SD=3.8) and <math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mi>a</mi> <mtext>s</mtext></msub> </math> were 4.1% (SD=2.6). Of the cohort, 44 patients (90%) showed very good or good agreement in the coronal in silico simulation and 43 patients (88%) in the sagittal in silico simulation. When the coronal and sagittal results were combined, 38 patients (78%) showed very good or good agreement. The distribution of biomechanical energy obtained from preoperative radiographs is reliable to simulate spine alignment after arthrodesis in a Lenke 1 AIS cohort.