Planning the Surgical Correction of Spinal Deformities: Toward the Identification of the Biomechanical Principles by Means of Numerical Simulation

Abstract

In decades of technical developments after the first surgical corrections of spinal deformities, the set of devices, techniques, and tools available to the surgeons has widened dramatically. Nevertheless, the rate of complications due to mechanical failure of the fixation or the instrumentation remains rather high. Indeed, basic and clinical research about the principles of deformity correction and the optimal surgical strategies (i.e., the choice of the fusion length, the most appropriate instrumentation, and the degree of tolerable correction) did not progress as much as the implantable devices and the surgical techniques. In this work, a software approach for the biomechanical simulation of the correction of patient-specific spinal deformities aimed to the identification of its biomechanical principles is presented. The method is based on three-dimensional reconstructions of the spinal anatomy obtained from biplanar radiographic images. A user-friendly graphical user interface allows for the planning of the desired deformity correction and to simulate the implantation of pedicle screws. Robust meshing of the instrumented spine is provided by using consolidated computational geometry and meshing libraries. Based on a finite element simulation, the program is able to predict the loads and stresses acting in the instrumentation as well as those in the biological tissues. A simple test case (reduction of a low-grade spondylolisthesis at L3–L4) was simulated as a proof of concept, and showed plausible results. Despite the numerous limitations of this approach which will be addressed in future implementations, the preliminary outcome is promising and encourages a wide effort toward its refinement.

Biomechanical study of rod stress after pedicle subtraction osteotomy versus anterior column reconstruction: A finite element study

“…Prior studies and cadaveric investigations demonstrated that sagittal correction with an ACR and posterior column osteotomies was comparable to that of a PSO. [ 13 26 27 ] Pedicle screw fixation two levels above and below the interbody has been shown to provide adequate biomechanical stabilization. [ 14 ] Traditional PSOs have been supplemented with a variety of construct techniques to help improve their biomechanical stability and minimize rod fracture.…”

Biomechanical Evaluation and the Assisted 3D Printed Model in the Patient-Specific Preoperative Planning for Thoracic Spinal Tuberculosis: A Finite Element Analysis

“…There are some limitations to the present study. First, similar to many individual models, it is difficult to fully validate the finite element models due to the limited clinical or experimental data and standardized methods ( Jones and Wilcox, 2008 ; Galbusera et al, 2015 ; Robinson et al, 2018 ). In the present study, simulations only focused on the difference in implant stress under flexion-extension conditions and emphasized the physical soundness of conceptual models rather than direct or indirect validation.…”

Computational modelling of the scoliotic spine: A literature review

“…Scoliotic models have been widely applied to simulate surgical corrections, and to investigate surgical techniques and instrumentation. Some FEMs with a software platform to aid the development of surgical devices and methods for the correction of scoliosis have been developed 73,75,83 . Aubin et al developed a MBM spine surgery simulator capable of simulating five different manoeuvres and designed to be used by clinicians 128 .…”