How to calculate the rod geometry of a pedicle screw system for spinal fixation

Abstract

1. A method for calculating a shape of a rod of a pedicle screw system, comprising: a) acquiring (10) at least one two-dimensional image of a spine; b) acquiring (20) a three-dimensional image of the spine; c) obtaining a three-dimensional model of the spine (30, 40, 50); d) performing a sagittal balance analysis (60) to calculate spinopelvic parameters and comparing them with predefined values; e) applying the corrections to the three-dimensional model (70); f) calculating (80) corrected spinopelvic parameters on the corrected three-dimensional model of the spine and checking whether they are within a predetermined range of values; g) if negative, repeating steps e)-f); i) in the affirmative, obtaining (90) a three-dimensional corrected model of the spine based on such three-dimensional simulated correction including a plurality of virtual screws; j) calculating (100) the shape of the rod as a mathematical function approximating a curve through the virtual screw.

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