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Updated: Nov 19, 2025
Minimally Invasive Treatment for Thoracolumbar Burst Fracture Using Sagittal Alignment Screws and A Trauma Reduction Device
Published on: November 8, 2024
Correction objectives have higher impact than screw pattern and density on the optimal 3D correction of thoracic AIS:
Luigi La Barbera1,2,3, A Noelle Larson4, Carl-Eric Aubin5,6
1Department of Mechanical Engineering, Polytechnique Montreal, Downtown Station, P.O. Box 6079, Montreal, QC, H3C 3A7, Canada. luigi.labarbera@polimi.it.
Study Design:
Assessment of screw pattern, implant density (ID), and optimization of 3D correction through computer-based biomechanical models.
Objective:
To investigate how screw pattern and ID affect intraoperative 3D correction of thoracic curves in adolescent idiopathic scoliosis, and how different correction objectives impact the optimal screw pattern. Screw pattern, ID, correction objectives and surgical strategies for posterior fusion of AIS are highly variable among experienced surgeons. The "optimal" instrumentation remains not well defined.
Methods:
10 patient-specific multibody models of representative adolescent idiopathic scoliosis Lenke 1A cases were built and used to compare alternative virtual correction surgeries. Five screw patterns and IDs (average: 1.6 screws/instrumented level, range: 1.2-2) were simulated, considering concave rod rotation, en bloc derotation, and compression/distraction as primary correction maneuvers. 3D correction descriptors were quantified in the coronal, sagittal and transverse planes. An objective function weighting the contribution of intraoperative 3D correction and mobility allowed rating of the outcomes of the virtual surgeries. Based on surgeon-dependent correction objectives, the optimal result among the simulated constructs was identified.
Results:
Low-density (ID ≤ 1.4) constructs provided equivalent 3D correction compared to higher (ID ≥ 1.8) densities (average differences ranging between 2° and 3°). The optimal screw pattern varied from case to case, falling within the low-density screw category in 14% of considered scenarios, 73% in the mid-density (1.4 < ID < 1.8) and 13% in the high-density. The optimal screw pattern was unique in five cases; multiple optima were found in other cases depending on the considered correction objectives.
Conclusions:
Low-density screw patterns provided equivalent intraoperative 3D correction to higher-density patterns. Simulated surgeon's choice of correction objectives had the greatest impact on the selection of the optimal construct for 3D correction, while screw density and ID had a limited impact.
Level Of Evidence:
N/A.
