Does index-level pedicle screw instrumentation affect cage subsidence after vertebral body replacement? - A biomechanical study in human cadaveric osteoporotic specimens

Maximilian Weber; Nikolaus Kernich; Max J Scheyerer; Andreas Prescher; Sebastian Walter; Vincent J Heck; Peer Eysel; Krishnan Sircar

doi:10.1016/j.clinbiomech.2023.106075

Does index-level pedicle screw instrumentation affect cage subsidence after vertebral body replacement? - A biomechanical study in human cadaveric osteoporotic specimens

Clin Biomech (Bristol, Avon). 2023 Oct:109:106075. doi: 10.1016/j.clinbiomech.2023.106075. Epub 2023 Aug 20.

Authors

Maximilian Weber¹, Nikolaus Kernich², Max J Scheyerer³, Andreas Prescher⁴, Sebastian Walter², Vincent J Heck², Peer Eysel², Krishnan Sircar²

Affiliations

¹ University of Cologne, Faculty of Medicine and University Hospital, Center for Orthopedic and Trauma Surgery, Kerpener Str. 62, 50937 Cologne, Germany. Electronic address: maximilian.weber1@uk-koeln.de.
² University of Cologne, Faculty of Medicine and University Hospital, Center for Orthopedic and Trauma Surgery, Kerpener Str. 62, 50937 Cologne, Germany.
³ Department of Trauma and Spine Surgery, Heinrich Heine University Hospital Düsseldorf, Düsseldorf, Germany.
⁴ Institute of Molecular and Cellular Anatomy (MOCA), Wendlingweg 2, 52074 Aachen, Germany.

PMID: 37651900
DOI: 10.1016/j.clinbiomech.2023.106075

Abstract

Background: Vertebral body replacement is a common surgical procedure for treatment of disorders associated with spinal instability. Therefore, pedicle screws are usually inserted in adjacent vertebrae for stabilization of the posterior column, however, there is lack of evidence whether implantation of index-level pedicle screws is beneficial or not. This biomechanical study aims to investigate the effect of pedicle screw instrumentation on axial stability following vertebral body replacement.

Methods: Unstable fracture at L3 level was simulated in lumbar spines from six human cadaveric specimens. Then instrumentation was performed one level above / one level below index level in three specimens and further, three specimens were instrumented at index-level (L3) additionaly. Then we used a testing protocol for biomechanical evaluation of axial loading on human cadaveric lumbar spines until cage subsidence occurred.

Findings: Our results show that index-level instrumented spines endured significantly higher load until cage subsidence occurred compared to non-index-level instrumented specimens (p = 0.05).

Interpretation: Our results demonstrate pedicle screw instrumentation at index-level vertebra should be considered when possbile as it may have a protective effect against cage subsidence in patients undergoing vertebral body replacement surgery.

Keywords: Biomechanics; Complications; Index level; Obelisc; Pedicle screw; Spine surgery; Vertebral body replacement.