Evidence map›Paper›PMID 36872418›Full record

ArticleSpine deformity2023

Is lower screw density associated with mechanical complications in adult spinal deformity surgery?

Hani Chanbour, Matthew E LaBarge, Soren Jonzzon, Steven G Roth, Amir M Abtahi, Byron F Stephens, Scott L Zuckerman

Abstract read
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In one paragraph

Article in Spine deformity, 2023. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.

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0cells of the map it votes in
2citing papers in PubMed
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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

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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

2 citing papers in PubMed.

  1. Machine learning clustering reveals risk factors of mechanical complications requiring revision in adult spinal deformity surgery: a 2-year follow-up study.European spine journal : official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society · 2026
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4 · The record

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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

7 authors.

Hani ChanbourDepartment of Neurological Surgery, Vanderbilt University Medical Center, Medical Center North T-4224, Nashville, TN, 37212, USA.
Matthew E LaBargeDepartment of Orthopedic Surgery, Vanderbilt University Medical Center, Nashville, TN, USA.
Soren JonzzonDepartment of Neurological Surgery, Vanderbilt University Medical Center, Medical Center North T-4224, Nashville, TN, 37212, USA.
Steven G RothDepartment of Neurological Surgery, Vanderbilt University Medical Center, Medical Center North T-4224, Nashville, TN, 37212, USA.
Amir M AbtahiDepartment of Neurological Surgery, Vanderbilt University Medical Center, Medical Center North T-4224, Nashville, TN, 37212, USA.
Byron F StephensDepartment of Neurological Surgery, Vanderbilt University Medical Center, Medical Center North T-4224, Nashville, TN, 37212, USA.
Scott L ZuckermanDepartment of Neurological Surgery, Vanderbilt University Medical Center, Medical Center North T-4224, Nashville, TN, 37212, USA. scott.zuckerman@vumc.org.ORCID http://orcid.org/0000-0003-2951-2942

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

purposeTo assess the impact of screw density on: (1) rod fracture/pseudarthrosis, (2) proximal/distal junctional kyphosis/failure (PJK/DJK/PJF), and (3) deformity correction judged by sagittal vertical axis (SVA) and T1-pelvic angle (T1PA).

methodsA single-center, retrospective cohort study of patients undergoing adult spinal deformity (ASD) surgery from 2013 to 2017 was undertaken. Screw density was calculated by dividing the number of screws placed by the total instrumented levels. Screw density was then dichotomized at our calculated mean density to ≥ 1.65 and < 1.65. Outcomes consisted of mechanical complications and the amount of correction obtained.

results145 patients underwent ASD surgery with 2-year follow-up. Mean screw density (range) was 1.6 ± 0.3 (1.00-2.00). The most common levels with missing screws were L2 (n = 59, 40.7%), L3 (n = 57, 39.3%) and L1 (n = 51, 35.2%), located mainly along the concavity in 113(80.0%) patients and apices in 98 (67.6%) patients. Rod fracture/pseudarthrosis: 23/32 (71.8%) patients with rod fracture and 35/46 (76.0%) with pseudarthrosis had missing screws within two levels of the rod fracture/pseudarthrosis. Logistic regression showed no significant association between screw density and rod fracture/pseudarthrosis. PJK/F: 15/47 (31.9%) patients with PJK and 9/30 (30.0%) with PJF had missing screws within three levels of the upper instrumented vertebra (UIV). Logistic regression showed no significant association between screws density and PJK/F. Correction obtained: linear regression failed to show any significant association between screw density and SVA or T1PA correction.

conclusionThese findings showed that no significant association was found between screw density and mechanical complications or the amount of correction obtained, though approximately 3 out of 4 patients with rod fracture/pseudarthrosis had missing screws at or within two levels of the pathology. The prevention of mechanical complications is likely multifactorial and subject to both patient's characteristics and surgical techniques. LEVEL OF EVIDENCE: III.

Indexed as

Fractures, BonePseudarthrosisAdultBone ScrewsHumansPostoperative ComplicationsRetrospective StudiesSpineAdult spinal deformityMechanical complicationsProximal junctional kyphosisPseudarthrosisRod fractureScrew density

Identifiers

PMID36872418

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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.