An in vitro study to identify worst-case parameters for assessing mechanical performance of anterior vertebral body tethering (AVBT) systems.

Daksh Jayaswal, Junfei Tong, Snehal Shetye, Vijay Goel, Vivek Palepu

Abstract read

In one paragraph

Article in Spine deformity, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

0numbers the graph read from it

0cells of the map it votes in

0citing 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

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

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

0 citing papers in PubMed.

No citing paper in PubMed yet.

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

5 authors.

Daksh JayaswalDepartment of Bioengineering and Orthopaedic Surgery, Engineering Center for Orthopaedic Research Excellence (E-CORE), University of Toledo, 2801 West Bancroft Street, Toledo, Ohio, 43606, USA.ORCID http://orcid.org/0000-0002-7568-5329

Junfei TongCenter for Devices and Radiological Health, Office of Science and Engineering Laboratories, Division of Applied Mechanics, U.S. Food and Drug Administration, Silver Spring, Maryland, 20993, USA.

Snehal ShetyeCenter for Devices and Radiological Health, Office of Science and Engineering Laboratories, Division of Applied Mechanics, U.S. Food and Drug Administration, Silver Spring, Maryland, 20993, USA.ORCID http://orcid.org/0000-0001-7469-3039

Vijay GoelDepartment of Bioengineering and Orthopaedic Surgery, Engineering Center for Orthopaedic Research Excellence (E-CORE), University of Toledo, 2801 West Bancroft Street, Toledo, Ohio, 43606, USA.ORCID http://orcid.org/0000-0002-9175-5366

Vivek PalepuCenter for Devices and Radiological Health, Office of Science and Engineering Laboratories, Division of Applied Mechanics, U.S. Food and Drug Administration, Silver Spring, Maryland, 20993, USA. vivek.palepu@fda.hhs.gov.ORCID http://orcid.org/0000-0002-0407-079X

Funding

Intramural FDA HHS FD999999

6 · The paper itself

Abstract

purposeAnterior vertebral body tethering (AVBT) is a novel surgical option for scoliosis patients that preserves spinal mobility. However, tether-related failures such as tether breakage are common, and cause of these failures is unknown. Furthermore, there is a lack of data on how different design and surgical factors influence the subsequent in vivo performance of these AVBT systems. This study aims to examine the mechanical durability of a mock AVBT system under various mechanical loading scenarios resulting from important surgical factors.

methodsA mock AVBT system was designed using Titanium screws and Polyethylene Terephthalate (PET) tether to evaluate mechanical performance under various clinically relevant loading conditions. Static and dynamic tensile tests assessed the effects of screw angulation (0°/40°), tether gauge length (length between the vertebral anchors: 25/76 mm), setscrew torque (5/6/7 Nm), and retightening. Constructs were tested using Instron equipment; measuring stiffness, yield, and failure loads. Statistical analyses compared configurations to identify factors influencing AVBT durability.

resultsFor this mock AVBT system, failure primarily occurred at the tether/setscrew junction due to slippage. Greater screw angulation (40°) increased yield and runout loads compared to 0°. Changing the gauge length had minimal effect on failure loads. Furthermore, the higher setscrew torque (7 Nm) improved strength and fatigue resistance, while setscrew retightening also increased yield and runout loads.

conclusionsDue to the infancy of this technology, there is a need for deeper understanding of the failure mechanics of AVBT systems. These findings identify testing parameters that affect mechanical performance and suggest future research directions for assessing the mechanical integrity of AVBT devices.

Indexed as

Adolescent idiopathic scoliosisDynamic tensile testingStatic tensile testingTether breakageVertebral body tethering

Identifiers

PMID42337182

DOI10.1007/s43390-026-01395-x

PMCPMC13470553

What OpenQuestion holds

Textmetadata

Read underepoch 390

Registered trials

None linked

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.