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In vitro simulation of intraoperative vertebroplasty applied for pedicle screw augmentation. A biomechanical evaluation
Affiliations- Department of Neurosurgery, Independent Public Clinical Hospital No. 7 of the Medical University of Silesia in Katowice, Professor Leszek Giec Upper Silesian Medical Centre, Katowice, Poland
- IBeMT Institute of Bioengineering and Medical Technologies/LfC Medical, 65-364 Kożuchowska 41, Zielona Góra, Poland
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Abstract
The purpose of this study was to evaluate the effect of an in vitro simulation of intraoperative vertebroplasty on embedded pedicle screws resistance to pullout. This method involved an application of acrylic cement into the vertebral bodies only after pedicle screws implementation.
Materials and methodsFor the purpose of conducting this research, the authors used the spines of fully-grown pigs. The procedure was as follows: firstly, the pedicle screws were bilaterally implemented in 10 vertebrae; secondly, cancellous bone was removed from vertebral bodies selected for screws augmentation and lastly it was replaced by polymethylmethacrylate (PMMA). Six vertebrae with implemented pedicle screws served as a control group. The pullout strength of thirty-two screws (20 augmented and 12 control) was tested. All screws were pulled out at a crosshead speed of 5mm/min.
ResultsThe PMMA-augmented screws showed a 1.3 times higher average pullout force than the control group: respectively 1539.68N and 1156.59N. In essence, no significant discrepancy was determined between average pullout forces of screws which were pulled as first when compared with consecutive contralateral ones.
ConclusionsAn in vitro simulation of intraoperative injection of PMMA in the vertebral body instrumented with screws (intraoperative vertebroplasty) resulted in enhancing its pullout strength by 33%. Pulling of one of the pedicular screws from the augmented vertebral body did not affect the pullout resistance of the contralateral one.
Abstract
The purpose of this study was to evaluate the effect of an in vitro simulation of intraoperative vertebroplasty on embedded pedicle screws resistance to pullout. This method involved an application of acrylic cement into the vertebral bodies only after pedicle screws implementation.
Materials and methodsFor the purpose of conducting this research, the authors used the spines of fully-grown pigs. The procedure was as follows: firstly, the pedicle screws were bilaterally implemented in 10 vertebrae; secondly, cancellous bone was removed from vertebral bodies selected for screws augmentation and lastly it was replaced by polymethylmethacrylate (PMMA). Six vertebrae with implemented pedicle screws served as a control group. The pullout strength of thirty-two screws (20 augmented and 12 control) was tested. All screws were pulled out at a crosshead speed of 5mm/min.
ResultsThe PMMA-augmented screws showed a 1.3 times higher average pullout force than the control group: respectively 1539.68N and 1156.59N. In essence, no significant discrepancy was determined between average pullout forces of screws which were pulled as first when compared with consecutive contralateral ones.
ConclusionsAn in vitro simulation of intraoperative injection of PMMA in the vertebral body instrumented with screws (intraoperative vertebroplasty) resulted in enhancing its pullout strength by 33%. Pulling of one of the pedicular screws from the augmented vertebral body did not affect the pullout resistance of the contralateral one.
Keywords
Vertebroplasty, Transpedicular stabilization, Screw augmentation, Polymethylmethacrylate, Biomechanics
About this articleTitle
In vitro simulation of intraoperative vertebroplasty applied for pedicle screw augmentation. A biomechanical evaluation
Journal
Neurologia i Neurochirurgia Polska
Issue
Pages
64-69
Published online
2017-12-08
Page views
403
Article views/downloads
681
DOI
10.1016/j.pjnns.2017.12.001
Bibliographic record
Neurol Neurochir Pol 2018;52(1):64-69.
Keywords
Vertebroplasty
Transpedicular stabilization
Screw augmentation
Polymethylmethacrylate
Biomechanics
Authors
Krzysztof Zapałowicz
Agnieszka Kierzkowska
Lechosław F. Ciupik
