Title: Multiaxial spine testing apparatus: system characterisation by evaluation of analogue and cadaveric lumbar spines

Authors: Zachary A. Dooley; Alexander W.L. Turner; G. Bryan Corwall

Addresses: NuVasive Inc., 7475 Lusk Blvd., San Diego, CA 92121, USA ' NuVasive Inc., 7475 Lusk Blvd., San Diego, CA 92121, USA ' NuVasive Inc., 7475 Lusk Blvd., San Diego, CA 92121, USA

Abstract: A custom 6 degrees-of-freedom test system was developed to collect unconstrained pure-moment biomechanical data from excised multi-segmental human spines. In this study, two characterisation methods were utilised. First, a polyethylene analogue model was created to establish test system baseline performance. Second, 22 lumbar spines (L1-L5) were tested to understand system operation under actual usage accounting for specimen stiffness and coupled motions. Each lumbar spine was tested in the anatomical planes (flexion-extension, lateral bending, and axial rotation) under two different conditions (intact and after implantation with an interbody cage at L3-L4). Specimen range of motion, neutral zone, and force/torque component errors generated by the test system were similar to previously reported data. Pure-moments were repeatable throughout the experiment in both cadaveric conditions, indicated by consistency in range of motion and neutral zone at the non-index levels. This characterisation will assist with interpretation of experimental data generated by the test system.

Keywords: spine testing apparatus; lumbar spine; multiaxial; experimental biomechanics; evaluation; kinematics; pure moments; system characterisation; cadaveric; in vitro; human spines; polyethylene analogue model; modelling.

DOI: 10.1504/IJECB.2013.056544

International Journal of Experimental and Computational Biomechanics, 2013 Vol.2 No.2, pp.189 - 203

Received: 26 Sep 2012
Accepted: 30 Jun 2013
Published online: 12 Jul 2014 *

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