A biomechanical investigation of dual growing rods used for fusionless scoliosis correction

, , , , , & (2015) A biomechanical investigation of dual growing rods used for fusionless scoliosis correction. Clinical Biomechanics, 30(1), pp. 33-39.

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Background The use of dual growing rods is a fusionless surgical approach to the treatment of early onset scoliosis (EOS), which aims of harness potential growth in order to correct spinal deformity. The purpose of this study was to compare the in-vitro biomechanical response of two different dual rod designs under axial rotation loading. Methods Six porcine spines were dissected into seven level thoracolumbar multi-segmental units. Each specimen was mounted and tested in a biaxial Instron machine, undergoing nondestructive left/right axial rotation to peak moments of 4Nm at a constant rotation rate of 8deg.s-1. A motion tracking system (Optotrak) measured 3D displacements of individual vertebrae. Each spine was tested in an un-instrumented state first and then with appropriately sized semi-constrained growing rods and ‘rigid’ rods in alternating sequence. Range of motion, neutral zone size and stiffness were calculated from the moment-rotation curves and intervertebral ranges of motion were calculated from Optotrak data. Findings Irrespective of test sequence, rigid rods showed significantly reduction of total rotation across all instrumented levels (with increased stiffness) whilst semi-constrained rods exhibited similar rotation behavior to the un-instrumented (P<0.05). An 11% and 8% increase in stiffness for left and right axial rotation respectively and 15% reduction in total range of motion was recorded with dual rigid rods compared with semi-constrained rods. Interpretation Based on these findings, the semi-constrained growing rods do not increase axial rotation stiffness compared with un-instrumented spines. This is thought to provide a more physiological environment for the growing spine compared to dual rigid rod constructs.

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12 citations in Scopus
8 citations in Web of Science®
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ID Code: 79923
Item Type: Contribution to Journal (Journal Article)
Refereed: Yes
ORCID iD:
Grant, Carolineorcid.org/0000-0002-5128-9903
Adam, Claytonorcid.org/0000-0002-3948-2217
Askin, Geoffreyorcid.org/0000-0002-1734-0082
Pearcy, Markorcid.org/0000-0002-1108-6503
Measurements or Duration: 7 pages
Keywords: biomechanical, fusionless correction, growing rod, in vitro, intervertebral, multi-segment unit, porcine, range of motion, scoliosis, stiffness
DOI: 10.1016/j.clinbiomech.2014.11.008
ISSN: 0268-0033
Pure ID: 32864025
Divisions: Past > Institutes > Institute of Health and Biomedical Innovation
Past > QUT Faculties & Divisions > Science & Engineering Faculty
Copyright Owner: Consult author(s) regarding copyright matters
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Deposited On: 09 Jan 2015 04:19
Last Modified: 10 Feb 2025 15:14