Gradient composite materials for artificial intervertebral discs.

Composites with the gradient of Young's modulus constitute a new group of biomimetic materials which affect the proper distribution of stresses between the implant and the bone. The aim of this article was to examine the mechanical properties of gradient materials based on carbon fibre-polysulfone composite, and to compare them to the properties of a natural intervertebral disc. Gradient properties were provided by different orientation or volume fraction of carbon fibres in particular layers of composites. The results obtained during in vitro tests displayed a good durability of the gradient materials put under long-term static load. However, the configuration based on a change in the volume fraction of the fibres seems more advantageous than the one based on a change of the fibres' orientation. The materials under study were designed to replace the intervertebral disc. The effect of Young's modulus of the material layers on the stress distribution between the tissue and the implant was analyzed and the biomimetic character of the gradient composites was stated. Unlike gradient materials, the pure polysulfone and the non-gradient composite resulted in the stress concentration in the region of nucleus pulposus, which is highly disadvantageous and does not occur in the stress distribution of natural intervertebral discs.

[1]  J. M. Garcı́a,et al.  Modelling bone tissue fracture and healing: a review ☆ , 2004 .

[2]  Modyfikacja Równania do Opisu Krzywych Wöhlera , 2010 .

[3]  G Van der Perre,et al.  Structural and material mechanical properties of human vertebral cancellous bone. , 1997, Medical engineering & physics.

[4]  Ming Zhang,et al.  Biomechanical responses of the intervertebral joints to static and vibrational loading: a finite element study. , 2003, Clinical biomechanics.

[5]  Damien Lacroix,et al.  In silico evaluation of a new composite disc substitute with a L3–L5 lumbar spine finite element model , 2012, European Spine Journal.

[6]  Nikolai Bogduk,et al.  Chapter 2 – Biomechanics of the Cervical Spine , 2002 .

[7]  W. C. Hayes,et al.  Multiaxial Structure-Property Relations in Trabecular Bone , 1990 .

[8]  N Yoganandan,et al.  Biomechanics of the cervical spine Part 2. Cervical spine soft tissue responses and biomechanical modeling. , 2001, Clinical biomechanics.

[9]  A. Minami,et al.  A biomechanical and histological evaluation of a bioresorbable lumbar interbody fusion cage. , 2005, Biomaterials.

[10]  Philippe K Zysset,et al.  A review of morphology-elasticity relationships in human trabecular bone: theories and experiments. , 2003, Journal of biomechanics.

[11]  Vijay K Goel,et al.  Artificial disc prosthesis: design concepts and criteria. , 2004, The spine journal : official journal of the North American Spine Society.

[12]  Marek Gzik,et al.  Experimental determination of cervical spine mechanical properties. , 2008, Acta of bioengineering and biomechanics.

[13]  Tsu-Wei Chou,et al.  Structure and properties of composites , 1993 .

[14]  M. Adams,et al.  The internal mechanical properties of cervical intervertebral discs as revealed by stress profilometry , 2007, European Spine Journal.

[15]  Seeram Ramakrishna,et al.  Development of nanocomposites for bone grafting , 2005 .

[16]  J. Iatridis,et al.  Mechanisms for mechanical damage in the intervertebral disc annulus fibrosus. , 2004, Journal of biomechanics.

[17]  M. Adams,et al.  Healing of a painful intervertebral disc should not be confused with reversing disc degeneration: implications for physical therapies for discogenic back pain. , 2010, Clinical biomechanics.

[18]  Pawel Borkowski.  Biomechanical analysis of artificial lumbar disc , 2006, Bio Algorithms Med Syst..

[19]  T. Keller,et al.  Mechanical behavior of the human lumbar spine. II. Fatigue strength during dynamic compressive loading , 1987, Journal of orthopaedic research : official publication of the Orthopaedic Research Society.

[20]  W C Hutton,et al.  The Effect of Posture on the Fluid Content of Lumbar Intervertebral Discs , 1983, Spine.

[21]  J. Chłopek,et al.  The influence of carbon fibres on the resorption time and mechanical properties of the lactide–glycolide co-polymer , 2007, Journal of biomaterials science. Polymer edition.

[22]  Paul Ducheyne,et al.  A three-dimensional nonlinear finite element analysis of the mechanical behavior of tissue engineered intervertebral discs under complex loads. , 2006, Biomaterials.