Effect of corrective stresses on rods in adult spinal deformity surgery-finite element analysis.
Adult spinal deformity
Adult spinal deformity surgery
Finite element study
Rod fracture
Spinal corrective fusion
Journal
Journal of orthopaedic science : official journal of the Japanese Orthopaedic Association
ISSN: 1436-2023
Titre abrégé: J Orthop Sci
Pays: Japan
ID NLM: 9604934
Informations de publication
Date de publication:
16 Mar 2023
16 Mar 2023
Historique:
received:
16
12
2022
revised:
02
03
2023
accepted:
05
03
2023
entrez:
18
3
2023
pubmed:
19
3
2023
medline:
19
3
2023
Statut:
aheadofprint
Résumé
The incidence of rod fracture after corrective surgery for adult spinal deformity (ASD) is high. Although many reports have investigated the effects of rod bending considering postoperative body motion, and countermeasures, there are no reports investigating the effects during intraoperative correction. The purpose of this study was to investigate the effect of ASD correction on rods by using finite element analysis (FEA) based on the rod shape changes before and after spinal corrective fusion. Five ASD patients (mean age 73 years, all female) who underwent thoracic to pelvic fusion were included in this study. A 3D rod model was created using computer-aided design software from digital images of the intraoperatively bended rod and intraoperative X-ray images after corrective fusion. The 3D model of the bent rod was meshed by dividing each of the screw head intervals into 20 sections and cross-section of the rod into 48 sections. Two surgical fusion methods of stepwise fixation as the cantilever method and parallel fixation as the translational method were simulated to evaluate stress and bending moments on the rods during intraoperative correction. The stresses on the rods were 1500, 970, 930, 744, and 606 MPa in the five cases for stepwise fixation and 990, 660, 490, 508, and 437 MPa for parallel fixation, respectively, with parallel fixation having lower stresses in all cases. In all cases, maximum stress was found around the apex of the lumbar lordosis and near L5/S1. The bending moment was high around L2-4 in most cases. The external forces of intraoperative correction had the greatest effect on the lower lumbar region, especially around the apex of the lumbar lordosis.
Sections du résumé
BACKGROUND
BACKGROUND
The incidence of rod fracture after corrective surgery for adult spinal deformity (ASD) is high. Although many reports have investigated the effects of rod bending considering postoperative body motion, and countermeasures, there are no reports investigating the effects during intraoperative correction. The purpose of this study was to investigate the effect of ASD correction on rods by using finite element analysis (FEA) based on the rod shape changes before and after spinal corrective fusion.
METHODS
METHODS
Five ASD patients (mean age 73 years, all female) who underwent thoracic to pelvic fusion were included in this study. A 3D rod model was created using computer-aided design software from digital images of the intraoperatively bended rod and intraoperative X-ray images after corrective fusion. The 3D model of the bent rod was meshed by dividing each of the screw head intervals into 20 sections and cross-section of the rod into 48 sections. Two surgical fusion methods of stepwise fixation as the cantilever method and parallel fixation as the translational method were simulated to evaluate stress and bending moments on the rods during intraoperative correction.
RESULTS
RESULTS
The stresses on the rods were 1500, 970, 930, 744, and 606 MPa in the five cases for stepwise fixation and 990, 660, 490, 508, and 437 MPa for parallel fixation, respectively, with parallel fixation having lower stresses in all cases. In all cases, maximum stress was found around the apex of the lumbar lordosis and near L5/S1. The bending moment was high around L2-4 in most cases.
CONCLUSIONS
CONCLUSIONS
The external forces of intraoperative correction had the greatest effect on the lower lumbar region, especially around the apex of the lumbar lordosis.
Identifiants
pubmed: 36934060
pii: S0949-2658(23)00075-1
doi: 10.1016/j.jos.2023.03.004
pii:
doi:
Types de publication
Journal Article
Langues
eng
Sous-ensembles de citation
IM
Informations de copyright
Copyright © 2023 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.
Déclaration de conflit d'intérêts
Declaration of competing interest All authors declare that there are no other conflicts of interest.