Abstract
Study Design
Biomechanical analysis of the spinal cord and nerves during scoliosis correction maneuvers through numerical simulations.
Objective
To assess the biomechanical effects of scoliosis correction maneuvers and stresses generated on the spinal nervous structures.
Background Data
Important forces are applied during scoliosis correction surgery, which could potentially lead to neurologic complications due to stresses exerted on the nervous structures. The biomechanical impact of the different types of stresses applied on the nervous structures during correction maneuvers is not well understood.
Methods
Three correction techniques were simulated using a hybrid computer modeling approach, personalized to a right thoracic adolescent idiopathic scoliotic case (Cobb angle: 63°): (1) Harrington-type distraction; (2) segmental translation technique; and a (3) segmental rotation—based procedure. A multibody model was used to simulate the kinematics of the instrumentation maneuvers; a second comprehensive finite element model was used to analyze the local stresses and strains on the spinal cord and nerves. Average values of the internal medullar pressure (IMP), shear stresses, nerve compression, and strain were computed over three regions and compared between techniques.
Results
Harrington distraction maneuver generated high stresses and strains over the thoracolumbar region. In the main thoracic region, the segmental translation maneuver technique induced 15% more shear stress, 25% more strain, and 62% lower nerve compression than Harrington distraction maneuver. The segmental rotation—based procedure induced 25% lower shear stresses and 18% more strain, respectively, at the apical level, as well as 72%, 57%, and 7% lower IMP, nerve compression, and strain in the upper thoracic region, compared with Harrington distraction maneuver.
Conclusion
This study quantified the relative stress induced on the spinal cord and spinal nerves for different correction maneuvers using a novel hybrid patient-specific model. Of the three maneuvers studied, the Harrington distraction maneuver induced the most important stresses over the thoracolumbar region.
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JH (grants from Natural Sciences and Engineering Research Council of Canada, grants from Institut Français des Sciences et Technologies des Transports, de l’Aménagement et des Réseaux [IFSTTAR], grants from Aix-Marseille University Foundation AMIDEX, during the conduct of the study); HL (other from Spinologics Inc., grants from DePuy Synthes, other from Scoliosis Research Society, grants from Canadian Institutes of Health Research [CIHR], outside the submitted work); PJA (grants from Institut Français des Sicences et Technologies des Transports, de l’Aménagement et des Réseaux [IFSTTAR], grants from Aix-Marseille Foundation AMIDEX, during the conduct of the study); CÉA (grants from Orthopedic Research and Education Foundation, grants from Natural Sciences and Engineering Research Council of Canada [Discovery Grant & Industrial Research Chair with Medtronic of Canada], during the conduct of the study; grants from Medtronic, other from Medtronic, outside the submitted work).
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The authors receive a research grant from the NSERC-industrial research chair program with Medtronic of Canada for the realization of this study.
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Henao, J., Labelle, H., Arnoux, PJ. et al. Biomechanical Simulation of Stresses and Strains Exerted on the Spinal Cord and Nerves During Scoliosis Correction Maneuvers. Spine Deform 6, 12–19 (2018). https://doi.org/10.1016/j.jspd.2017.04.008
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DOI: https://doi.org/10.1016/j.jspd.2017.04.008