Quasi-static and cyclic compressive loading studies of the intervertebral disc with combined flexion and torsion

Abstract

Bovine caudal motion segments were used to investigate the loss of load-bearing ability of the intervertebral disc (IVD) under both quasi-static and cyclic compressive loading combined with torsion and flexion. While the response of the disc to both compressive hyper-flexion and hyper-torsion has been previously investigated much less is known about their individual and combined influence on compressive failure. Eighty motion segments dissected from 41 bovine tails were subjected to quasi-static and cyclic compression with added components of flexion and torsion. The four different combinations of flexion and torsion were 0º torsion/0º flexion, 10º torsion/15º flexion, 10º torsion/0º flexion and 0º torsion/15º flexion. Quasi-static compression failed to show any significant difference among the different combinations of torsion and flexion for failure stress, failure strain and compressive tangent modulus. Cyclic compression indicated a significant influence of torsion in reducing the disc's load-bearing ability. Cyclic loading provides a more sensitive tool for the assessment of potentially damaging mechanical parameters for the IVD.Keywords Intervertebral disc, Quasi-static compression, Cyclic compression, Torsion, Flexion.Estudo da compressão monotônica e cíclica associada à flexão e torção do disco intervertebral

Replication of annulus fibrosus through fabrication and characterization of polyurethane and cellulose nanocrystal composite scaffolds

“…Each stress-strain curve for the ringed samples, as well as the natural AF and IVD, exhibited a toe region, linear elastic region, yield, plateau region, and incompressible region, where stress exponentially increases. 63 This shows the capability of the ringed structures to mimic the same compressive trends as the natural AF and IVD, however the actual mechanical properties need to be further tailored to more closely agree with literature values. It should also be noted that compression tests performed on natural IVDs within the stress range of this study showed no permanent compromise to the mechanical properties nor did it lead to any changes in the structure, suggesting that biological changes occur before structural damage occurs.…”

On the importance of retaining stresses and strains in repositioning computational biomechanical models of the cervical spine

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