The effect of soft tissue properties on spinal flexibility in scoliosis: biomechanical simulation of fulcrum bending

& (2009) The effect of soft tissue properties on spinal flexibility in scoliosis: biomechanical simulation of fulcrum bending. Spine, 34(2), pp. 76-82.

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Biomechanical analysis of the scoliotic thoracolumbar spine and ribcage using a three-dimensional finite element model. OBJECTIVE: To explore how the mechanical properties of spinal ligaments and intervertebral discs affect coronal curve flexibility in the fulcrum bending test. SUMMARY OF BACKGROUND DATA: Preoperative coronal curve flexibility assessment is of key importance in the surgical planning process for scoliosis correction. The fulcrum bending radiograph is one flexibility assessment technique which has been shown to be highly predictive of potential curve correction using posterior surgery; however, little is known about the extent to which soft tissue structures govern spinal flexibility. METHODS: CT-derived spinal anatomy for a 14-year-old female adolescent idiopathic scoliosis patient was used to develop the three-dimensional finite element model. Physiologic loading conditions representing the gravitational body weight forces acting on the spine when the patient lies on their side over the fulcrum bolster were simulated. Initial mechanical properties for the spinal soft tissues were derived from existing literature. In 6 separate analyses, the disc collagen fiber and ligament stiffness values were reduced by 10%, 25%, and 40% respectively, and the effects of reduced tissue stiffness on fulcrum flexibility were assessed by comparison with the initial model. Finally, the effect of discectomy on fulcrum flexibility was simulated for thoracic levels T5-T12. RESULTS: Reducing disc collagen fiber stiffness resulted in a greater change in segmental rotations in the fulcrum bending test than reducing ligament stiffness. However, reductions of up to 40% in disc collagen fiber stiffness and ligament stiffness produced no clinically measurable increase in fulcrum flexibility. By contrast, after removal of the discs, the simulated fulcrum flexibility increased by more than 80% compared with the initial case. CONCLUSION: Homogeneous reduction in either the disc collagen fiber or ligament stiffness had minimal influence on scoliotic curve reducibility. However, discectomy simulation shows that the intervertebral discs are of critical importance in determining spinal flexibility.

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31 citations in Web of Science®
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ID Code: 17344
Item Type: Contribution to Journal (Journal Article)
Refereed: Yes
ORCID iD:
Little, Paigeorcid.org/0000-0001-8377-5343
Adam, Claytonorcid.org/0000-0002-3948-2217
Measurements or Duration: 7 pages
Keywords: Finite element model, Flexibility assessment, Fulcrum bending radiograph, Scoliosis biomechanics, Scoliosis surgery
DOI: 10.1097/BRS.0b013e31818ad584
ISSN: 0362-2436
Pure ID: 31927874
Divisions: Past > QUT Faculties & Divisions > Faculty of Built Environment and Engineering
Past > Institutes > Institute of Health and Biomedical Innovation
Past > QUT Faculties & Divisions > Science & Engineering Faculty
Current > Research Centres > Australian Research Centre for Aerospace Automation
Copyright Owner: Consult author(s) regarding copyright matters
Copyright Statement: This work is covered by copyright. Unless the document is being made available under a Creative Commons Licence, you must assume that re-use is limited to personal use and that permission from the copyright owner must be obtained for all other uses. If the document is available under a Creative Commons License (or other specified license) then refer to the Licence for details of permitted re-use. It is a condition of access that users recognise and abide by the legal requirements associated with these rights. If you believe that this work infringes copyright please provide details by email to qut.copyright@qut.edu.au
Deposited On: 03 Feb 2009 03:04
Last Modified: 08 Feb 2025 07:40