Vertebroplasty: Patient and treatment variations studied through parametric computational models

Vithanage N Wijayathunga,Robert J Oakland,Alison C Jones,Richard M Hall,Ruth K Wilcox

doi:10.1016/j.clinbiomech.2013.07.012

Vithanage N Wijayathunga, Robert J Oakland + Show 3 more

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https://doi.org/10.1016/j.clinbiomech.2013.07.012

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Journal: Clinical Biomechanics	Publication Date: Jul 27, 2013
Citations: 17	License type: cc-by

Affiliation: University of Leeds

Abstract

BackgroundVertebroplasty is increasingly used in the treatment of vertebral compression fractures. However there are concerns that this intervention may lead to further fractures in the adjacent vertebral segments. This study was designed to parametrically assess the influence of both treatment factors (cement volume and number of augmentations), and patient factors (bone and disc quality) on the biomechanical effects of vertebroplasty. MethodsSpecimen-specific finite element models of two experimentally-tested human three-vertebral-segments were developed from CT-scan data. Cement augmentation at one and two levels was represented in the respective models and good agreement in the predicted stiffness was found compared to the corresponding experimental specimens. Parametric variations of key variables associated with the procedure were then studied. FindingsThe segmental stiffness increased with disc degeneration, with increasing bone quality and to a lesser extent with increasing cement volume. Cement modulus did not have a great influence on the overall segmental stiffness and on the change in the elemental stress in the adjoining vertebrae. However, following augmentation, the stress distribution in the adjacent vertebra changed, indicating possible load redistribution effects of vertebroplasty. InterpretationThis study demonstrates the importance of patient factors in the outcomes of vertebroplasty and suggests that these may be one reason for the variation in clinical results.

Highlights

The estimated annual incidence of vertebral compression fractures in Europe is nearly 1.4 million (Anon, 2002), many of which lead to severe pain and a significant reduction in quality of life
The influence of the cement properties assigned to the augmented region on the overall segmental stiffness was found to be minimal, with changes of 0.7, 1.8 and 3.3% when the augmented region modulus was reduced by 50, 75 and 87.5% respectively
The disc condition was found to have a greater influence on the segmental stiffness than the cement volume

Summary

Introduction

The estimated annual incidence of vertebral compression fractures in Europe is nearly 1.4 million (Anon, 2002), many of which lead to severe pain and a significant reduction in quality of life. Notwithstanding differences in study designs, the results of recent randomised controlled trials have reported inconsistent patient outcomes and contrastingly different conclusions (Buchbinder et al, 2009; Kallmes et al, 2009; Klazen et al, 2010). One possibility for these differing results could be that, from the general cohort of back-pain patients identified for routine vertebroplasty, some subgroups gain more benefit from the procedure than others. This study was designed to parametrically assess the influence of both treatment factors (cement volume and number of augmentations), and patient factors (bone and disc quality) on the biomechanical effects of vertebroplasty. Interpretation: This study demonstrates the importance of patient factors in the outcomes of vertebroplasty and suggests that these may be one reason for the variation in clinical results

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