PhD Scientific Days 2023

Clinical Medicine III.

Semirigid Spinal Fixation Techniques Could Help Prevent Proximal Junctional Kyphosis – A Finite Element Study

Előadó neve

Turbucz, Mate

Neptun code

RMB8D9

Előadó munkahelye

National Center for Spinal Disorders

Előadó telefonszáma

+36306866662

Előadó e-mail címe

turbucz95@gmail.com

Az előadás címe

Semirigid Spinal Fixation Techniques Could Help Prevent Proximal Junctional Kyphosis – A Finite Element Study

Szerző(k) neve és munkahelye

Mate Turbucz1,2, Agoston Pokorni1,2, Aron Lazary2,3, Peter Eltes2,3

1 School of PhD Studies, Semmelweis University, Budapest
2 In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Buda Health Center, Budapest
3 Department of Spine Surgery, Department of Orthopaedics, Semmelweis University, Budapest

Bemutatás módja

Szóbeli

Szekció

Clinical Medicine III.

Language of the presentation

Hungarian

Preferred session

Clinical Medicine

Összefoglaló szövege

Introduction:
Proximal junctional kyphosis (PJK) is a common complication following long instrumented posterior spinal fusions, with an incidence rate ranging from 17% to 39% within two years after surgery. Biomechanical studies suggest that one of the leading causes is the sudden mobility change between the instrumented and healthy spinal segments.

Aims:
The aim of this study is to compare the biomechanical impact of two semirigid fixation techniques (SFTs) with conventional rigid fixation in terms of spinal mobility and pedicle screw loading, with the goal of reducing the risk of proximal junctional kyphosis (PJK).

Method:
Four T7-L5 finite element (FE) models were developed: 1) intact spine; 2) ⌀5.5mm titanium rods between T8 and L5 (TRF); 3) five ⌀1.9mm titanium rods between T8 and T9 connected with ⌀5.5mm titanium rods between T9 and L5 (MRF); 4) ⌀5.5mm PEEK rods between T8 and T9 connected with ⌀5.5mm titanium rods between T9 and L5 (PRF). A modified multidirectional hybrid test protocol was employed with two successive loading steps. The first step simulated flexion, extension, lateral bending, and axial rotation, and the intervertebral rotation (IVR) angles were recorded. The second step evaluated the von Mises stress values in the pedicle screws at the upper instrumented vertebra (UIV) using the motion of the TRF technique obtained from the first loading step.

Results:
In the load-controlled step, relative to TRF, at the uppermost instrumented segment, the IVR values increased by 46.8% and 99.2% for flexion, by 43.2% and 87.7% for extension, by 90.1% and 137% for lateral bending, and by 407.1% and 585.2% for axial rotation, in MRF and PRF, respectively. In the motion-controlled step, the maximum pedicle screw stress values at the UIV level were highest for TRF with 37.26 MPa, 42.13 MPa, 44.4 MPa, and 44.59 MPa for flexion, extension, lateral bending, and axial rotation, respectively. Compared to TRF, in the case of MRF and PRF, the screw stress values were reduced by 17.3% and 27.7% for flexion, by 26.6% and 36.7% for extension, by 6.8% and 34.3% for lateral bending, and by 49.1% and 59.8% for axial rotation.

Conclusion:
The findings of this study suggest that semirigid fixations increase the mobility at the upper instrumented segment, providing a more gradual transition in motion between the instrumented and healthy spinal segments. SFTs decrease the pedicle screw loads at the UIV level, and hence could help reduce the risk of PJK. Further investigations are recommended to evaluate the long-term clinical usefulness of SFTs.

Funding:
Project no. KDP-14-3/PALY-2021 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2020 funding scheme. The financial support from

University and Doctoral School

Semmelweis University, Károly Rácz Doctoral School of Clinical Medicine

Supervisor

Aron Lazary and Peter Eltes

Publication of my abstract

I do not give consent to the publication of my abstract on the website of the congress.

Kind

Szabad

Status

elfogadva

Accepted presentation method

szóbeli

Előadás fájl jóváhagyás

nem rendelkezett róla

Előadó

6039

Start

09:45

End

10:00

Authors (legacy)

Mate Turbucz1,2, Agoston Pokorni1,2, Aron Lazary2,3, Peter Eltes2,3

1 School of PhD Studies, Semmelweis University, Budapest
2 In Silico Biomechanics Laboratory, National Center for Spinal Disorders, Buda Health Center, Budapest
3 Department of Spine Surgery, Department of Orthopaedics, Semmelweis University, Budapest