Biomechanical and morphologic evaluation of a three-dimensional fabric sheep artificial intervertebral disc: in vitro and in vivo analysis.
METHODS
We have developed a new artificial intervertebral disc consisting of triaxial three-dimensional fabric for the sheep lumbar spine. To clarify the characteristics of the new implant, a series of biomechanical tests and morphologic evaluations were conducted.


OBJECTIVE
To investigate the static, viscoelastic, and fatigue properties of the three-dimensional fabric disc in comparison with natural sheep disc and to evaluate their biomechanical and morphologic alteration in vivo.


BACKGROUND
In its human dimensions the three-dimensional fabric disc revealed mechanical properties similar to a natural human disc.


METHODS
The disc-body units from sheep spine and the sheep three-dimensional fabric discs underwent tensile-compressive (200 N), torsional (5 Nm), and creep-recovery tests (30 minutes-30 minutes, 200 N). After fatigue loading (2 million, compressive 200 N) the biomechanical changes and the debris were investigated. For in vivo evaluation after placing in the sheep psoas muscles for 6 months, the surface of the three-dimensional fabric disc was evaluated using macroscopy and scanning electron microscopy, followed by previous biomechanical tests.


RESULTS
The behavior of the sheep three-dimensional fabric disc was similar to that of natural sheep disc in tensile-compressive and creep-recovery tests. In torsional testing the behavior of natural sheep disc was more rigid than that of the sheep three-dimensional fabric disc. After fatigue loading there was no biomechanical change and no debris detected. Six months after surgery no morphologic deterioration was observed nor were there changes in biomechanical parameters.


CONCLUSIONS
The sheep three-dimensional fabric disc exhibited biomechanical and morphologic biostability, appropriate viscoelasticity, and excellent fatigue properties. The three-dimensional fabric disc has a potential for clinical application of human intervertebral disc replacement.
Kadoya
K
K
Department of Orthopaedic Surgery, Hokkaido University, Graduate School of Medicine, Sapporo, Japan.
Kotani
Y
Y
Abumi
K
K
Takada
T
T
Shimamoto
N
N
Shikinami
Y
Y
Kadosawa
T
T
Kaneda
K
K
D000818:Animals; D001672:Biocompatible Materials; D019245:Compressive Strength / Q000502:physiology; D005260:Female; D066298:In Vitro Techniques; D007403:Intervertebral Disc / Q000473:pathology* / Q000502:physiology* / Q000637:transplantation; D008159:Lumbar Vertebrae / Q000502:physiology / Q000601:surgery*; D008422:Materials Testing; D023421:Models, Animal; D011475:Prosthesis Failure; D012756:Sheep
D001672:Biocompatible Materials