Observational Study
Copyright ©The Author(s) 2021. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. May 18, 2021; 12(5): 310-319
Published online May 18, 2021. doi: 10.5312/wjo.v12.i5.310
Potential contribution of pedicle screw design to loosening rate in patients with degenerative diseases of the lumbar spine: An observational study
Andrey Bokov, Svetlana Pavlova, Anatoliy Bulkin, Alexandr Aleynik, Sergey Mlyavykh
Andrey Bokov, Svetlana Pavlova, Anatoliy Bulkin, Alexandr Aleynik, Sergey Mlyavykh, Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, Nizhniy Novgorod 603000, Russia
Author contributions: Bokov A and Mlyavykh S finished study design, data mining, statistical analysis; Mlyavykh S finished manuscript editing; Pavlova S, Bulkin A and Aleynik A finished data collection, data mining; Bulkin A finished preparation of manuscript.
Institutional review board statement: The study was reviewed and approved by the Privolzhskiy Medical Research University Institutional Review Board, web: https://pimunn.ru/dissertation#rec62878046.
Informed consent statement: All study participants, provided informed written consent prior to study enrollment.
Conflict-of-interest statement: The authors declare that they have no competing interests.
Data sharing statement: No additional data are available.
STROBE statement: The authors have read the STROBE Statement—checklist of items, and the manuscript was prepared and revised according to the STROBE Statement—checklist of items.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Andrey Bokov, PhD, Senior Researcher, Department of Oncology and Neurosurgery, Federal State Budgetary Educational Institution of Higher Education “Privolzhsky Research Medical University” of the Ministry of Health of the Russian Federation, 603000, Russia. andrei_bokov@mail.ru
Received: January 10, 2021
Peer-review started: January 10, 2021
First decision: February 15, 2021
Revised: February 15, 2021
Accepted: March 28, 2021
Article in press: March 28, 2021
Published online: May 18, 2021
Processing time: 121 Days and 12.9 Hours
Abstract
BACKGROUND

The majority of published data report the results of biomechanical tests of various design pedicle screw performance. The clinical relevance and relative contribution of screw design to instrumentation stability have been insufficiently studied.

AIM

To estimate the contribution of screw design to rate of pedicle screw loosening in patients with degenerative diseases of the lumbar spine.

METHODS

This study is a prospective evaluation of 175 patients with degenerative diseases and instability of the lumbar spine segments. Participants underwent spinal instrumentation employing pedicle screws with posterior only or transforaminal interbody fusion. Follow-up was for 18 mo. Patients with signs of pedicle screw loosening on computed tomography were registered; logistic regression analysis was used to identify the factors that influenced the rate of loosening.

RESULTS

Parameters included in the analysis were screw geometry, type of thread, external and internal screw diameter and helical pitch, bone density in Hounsfield units, number of levels fused, instrumentation without anterior support, laminectomy, and unilateral and bilateral total facet joint resection. The rate of screw loosening decreased with the increment in outer diameter, decrease in core diameter and helical pitch. The rate of screw loosening correlated positively with the number of fused levels and decreasing bone density. Bilateral facet joint removal significantly favored pedicle screw loosening. The influence of other factors was insignificant.

CONCLUSION

Screw parameters had a significant impact on the loosening rate along with bone quality characteristics, the number of levels fused and the extensiveness of decompression. The significance of the influence of screw parameters was comparable to those of patient- and surgery-related factors. Pedicle screw loosening was influenced by helical pitch, inner and outer diameter, but screw geometry and thread type were insignificant factors.

Keywords: Degenerative diseases; Lumbar spine; Pedicle screw design; Pedicle screw loosening

Core Tip: The published data on the contribution of pedicle screw design to pedicle screw stability remain controversial. According to the study results, the influence of screw parameters was comparable to that of patient- and surgery-related factors. The rate of pedicle screw loosening was influenced by helical pitch, inner, and outer diameter, but the influence of screw geometry and thread type was not significant.