An in vitro biomechanical comparison of single-rod, dual-rod, and dual-rod with transverse connector in anterior thoracolumbar instrumentation

Chandan G Reddy; Michael Magnetta; Nader S Dahdaleh; Matthew Demmer; Kingsley Abode Iyamah; Tae-Hong Lim; James C Torner; Patrick W Hitchon

doi:10.1227/NEU.0b013e31823cf254

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An in vitro biomechanical comparison of single-rod, dual-rod, and dual-rod with transverse connector in anterior thoracolumbar instrumentation

Journal article

Peer reviewed

An in vitro biomechanical comparison of single-rod, dual-rod, and dual-rod with transverse connector in anterior thoracolumbar instrumentation

Chandan G Reddy, Michael Magnetta, Nader S Dahdaleh, Matthew Demmer, Kingsley Abode Iyamah, Tae-Hong Lim, James C Torner and Patrick W Hitchon

Neurosurgery, Vol.70(4), pp.1017-1023

04/2012

DOI: 10.1227/NEU.0b013e31823cf254

PMID: 22009252

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Abstract

After thoracolumbar corpectomy, standard anterolateral instrumentation may consist of dual rods with cross-connectors. However, when the vertebral bodies are small or involved with disease, only 1 rod may be possible. To compare the biomechanics of an in vitro L1 corpectomy model using 1 rod, 2 rods, or 2 rods with 2 cross-connectors. Eight fresh frozen human cadaveric spines were potted from T9 to L3. Pure moments of 1.5, 3, and 4.5 Nm were applied, and the motion of the spine was measured using 3 infrared cameras. Loads were applied in flexion and extension, right and left lateral bending, and right and left axial rotation. Each spine was first tested in the intact state. After performing an L1 corpectomy and replacement with a carbon fiber reinforced polymer cage, 3 constructs were tested: single rod (1R), dual rod (2R), and dual rod with 2 transverse connectors (CC). Analysis of variance suggests significant main effects of load (P < .0001), axis (P = .022), construct (P =.0019), and individual spine (P < .0001). Overall, the single-rod construct is significantly less rigid than the intact spine in axial rotation. There is no significant difference between the intact spine and either the dual-rod construct or the dual-rod cross-connector construct. In our in vitro model of anterior spinal stabilization after corpectomy and grafting, a single-rod construct is significantly less rigid than the intact spine. Addition of a second rod returns the rigidity of the spine to the intact state. A dual-rod cross-connector construct is significantly more rigid than a single-rod construct.

Spinal Fusion - methods

Humans

Middle Aged

Male

Spinal Fusion - instrumentation

Thoracic Vertebrae - surgery

Biomechanical Phenomena

Lumbar Vertebrae - surgery

Internal Fixators

Range of Motion, Articular

Aged, 80 and over

Adult

Female

Aged

In Vitro Techniques

Cadaver

Details

Title: Subtitle: An in vitro biomechanical comparison of single-rod, dual-rod, and dual-rod with transverse connector in anterior thoracolumbar instrumentation
Creators: Chandan G Reddy - Department of Neurosurgery, University of Iowa, Iowa City, Iowa, USA
Michael Magnetta
Nader S Dahdaleh
Matthew Demmer
Kingsley Abode Iyamah
Tae-Hong Lim
James C Torner
Patrick W Hitchon
Resource Type: Journal article
Publication Details: Neurosurgery, Vol.70(4), pp.1017-1023
DOI: 10.1227/NEU.0b013e31823cf254
PMID: 22009252
NLM abbreviation: Neurosurgery
ISSN: 0148-396X
eISSN: 1524-4040
Publisher: United States
Language: English
Date published: 04/2012
Academic Unit: Roy J. Carver Department of Biomedical Engineering; Epidemiology; Surgery; Injury Prevention Research Center; Neurosurgery
Record Identifier: 9983995178302771

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