Effect of Axial Load on the Flexural Properties of an Elastomeric Total Disc Replacement.

Aziza Mahomed, Parshia Moghadas, Duncan Shepherd, David Hukins, A Roome, S Johnson

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)

Abstract

Study Design. Twelve Cadisc-L devices were subjected to flexion (0° to 6°) and extension (0° to -3°) motions at compressive loads between 500 N and 2000 N, at a flexural rate between 0.25 °/s and 3.0 °/s.Objective. To quantify the change in flexural properties of the Cadisc™-L (elastomeric device), when subjected to increasing magnitudes of axial load and at different flexural rates.Summary of Background Data. The design of motion preservation devices, used to replace degenerated intervertebral discs is commonly based on a low friction, ball and socket articulating joint. Recently, elastomeric implants have been developed, that attempt to provide mechanical and motion properties that resemble those of the natural disc more closely.Methods. Twelve Cadisc-L devices (MC-10mm-9° and MC-10mm-12° size) were supplied by Ranier Technology Ltd (Cambridge, CB5 8AA, UK). The devices were hydrated and tested using a Bose spinal disc testing machine (Bose Corporation, ElectroForce Systems Group, Minnesota, USA) in Ringer's solution at 37 °C. A static load of 500 N was applied to a device and it was then subjected to motions of 0° to 6° to 0° (flexion) and 0° to -3° to 0° (extension) at a flexural rate of 0.25 °/s, 0.5 °/s, 1.0 °/s, 1.5 °/s, 2.0 °/s and 3.0 °/s. Tests were repeated at 1000 N, 1500 N and 2000 N.Results. Regression analyses showed: a significant (R > 0.99, p <0.05) linear increase in bending moment and flexural stiffness with flexion and extension angles (at 1000 N and higher loads); a significant (R > 0.994, p <0.05) linear decrease in flexural stiffness in flexion and extension as flexural rate increased.Conclusion. The bending moment of the Cadisc™-L increased linearly with flexion and extension angles at 1000 N and higher loads. Flexural stiffness increased with compressive load, but decreased with flexural rate.
Original languageEnglish
Pages (from-to)E908-E912
Number of pages5
JournalSpine
Volume37
Issue number15
DOIs
Publication statusPublished - 13 Feb 2012

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