Evidence map›Paper›PMID 39827360›Full record

ArticleJournal of orthopaedic surgery and research2025

Superior biomechanical stability of pedicle screws compared to lateral mass screws: recommendations for bicortical positioning and enhancing bone contact in geriatric C1 vertebrae.

Leon-Gordian Leonhardt, Leonie Rörup, Anna Lena Kammal, Michael Hahn, Marc Dreimann, Benjamin Ondruschka, Felix Nikolai von Brackel, Tim Rolvien, Lennart Viezens, Simon von Kroge

Abstract readComparative Study
In one paragraph

Article in Journal of orthopaedic surgery and research, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.

0numbers the graph read from it
0cells of the map it votes in
3citing papers in PubMed
–field-weighted citation impact
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

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Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

3 citing papers in PubMed.

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4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

10 authors.

Leon-Gordian LeonhardtDepartment of Trauma and Orthopaedic Surgery, University Medical Center Hamburg- Eppendorf, Martinistraße 52, 20246, Hamburg, Germany. l.leonhardt@uke.de.
Leonie RörupDepartment of Trauma and Orthopaedic Surgery, University Medical Center Hamburg- Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Anna Lena KammalInstitute of Legal Medicine, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529, Hamburg, Germany.
Michael HahnDepartment of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestraße 59, 22529, Hamburg, Germany.
Marc DreimannDepartment of Trauma and Orthopaedic Surgery, University Medical Center Hamburg- Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Benjamin OndruschkaInstitute of Legal Medicine, University Medical Center Hamburg-Eppendorf, Butenfeld 34, 22529, Hamburg, Germany.
Felix Nikolai von BrackelDepartment of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Lottestraße 59, 22529, Hamburg, Germany.
Tim Rolvien *Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg- Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Lennart Viezens *Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg- Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.
Simon von Kroge *Department of Trauma and Orthopaedic Surgery, University Medical Center Hamburg- Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundIn atlantoaxial instabilities, posterior C1/C2 fusion using lateral mass screws (LMS) or pedicle screws (PS) in a mono- or bicortical position in the atlas is a typical treatment. The bone microstructure and positioning of the screw trajectories appear to be of significant relevance for stability. PURPOSE: The aim of this study was a comparative analysis of the mechanical durability of screw fixation concerning microstructural characteristics of the trajectories of LMS and PS in mono- and bicortical position.

methodsHuman C1 from geriatric body donors (n = 28; 50% female, age 80.8 ± 13.9 years) were collected and characterized based on their bone microstructure. Additionally, the mechanical stability of LMS and PS fixation in mono- and bicortical positioning was tested by mechanical loading. High-resolution quantitative computed tomography was used to analyze the bone microstructure of cylinders corresponding to the trajectories of PS and LMS in mono- and bicortical locations in each C1. After instrumentation with both screw types and types of fixation, the mechanical stability was tested by increased cyclic loading in cranio-caudal direction.

resultsTrajectories of PS presented with more bone volume and a higher contact length to cortical bone. Simultaneously, a higher number of cycles and a higher maximum force was needed to loosen PS compared to LMS, while the loose by torque at the experiment end was still greater in PS. Differences between mono- and bicortical positioning of PS and LMS have only been observed in the initial stiffness of screws. When comparing microstructural and mechanical properties, the cortical contact length and bone volume in screw trajectories were strongest associated with a high loose and cycle count.

conclusionsThis study suggests that mono- and bicortical positioning of PS is similarly efficient in creating a stable basis for screw fixation in the atlas. While PS are superior to LMS, the contact with cortical bone is of major relevance for a stable foundation.

Indexed as

Atlanto-Axial JointBone ScrewsCervical AtlasJoint InstabilityPedicle ScrewsSpinal FusionAgedAged, 80 and overBiomechanical PhenomenaFemaleHumansMaleBone microstructureC1Cervical spine surgeryLateral mass screwMechanical testingPedicle screw

Identifiers

PMID39827360
PMCPMC11742196

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.