Materials and design concepts for an intervertebral disc spacer. II. Multidurometer composite design.
The main function of the intervertebral disc is to transmit and attenuate compressive and torsional forces, and stabilize the intervertebral joint. Unfortunately, the disc may be displaced or damaged due to trauma or disease causing the nucleus to herniate and protrude into the vertebral canal or intervertebral foramen. Pressure on the spinal nerve may cause pain or paralysis in the area of its distribution. At present, the surgical procedures used to alleviate this condition include disc excision, and/or spinal fusion. A more desirable situation would involve removing the nucleus pulposus and part or all of the annulus fibrosis and implanting a suitable biofunctional equivalent. Such a prosthesis should attenuate stresses and prevent abnormal stress at adjacent intervertebral joints. Maintenance of normal disc height would prevent impingement of the posterior facet joints and facet joint syndrome. In a previous companion paper (J. Applied Biomat. 5:125-132; 1994), the mechanical behavior of disc prostheses manufactured from fiber reinforced, elastomeric thermoset resins were examined. In order to develop devices which were more practical from a manufacturing standpoint and extremely reproducible, the fiber reinforced thermoset resins were replaced by multi-durometer thermoplastic elastomeric materials. In the present paper, the mechanical properties of thermoplastic multicomponent designs have been investigated.
Vuono-Hawkins
M
M
University of Medicine and Dentistry of New Jersey, New Jersey Medical School, Section of Orthopaedic Surgery, Newark 07103, USA.
Langrana
N A
NA
Parsons
J R
JR
Lee
C K
CK
Zimmerman
M C
MC
D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D001705:Bioprosthesis; D006801:Humans; D007403:Intervertebral Disc / Q000601:surgery*; D008962:Models, Theoretical
D001672:Biocompatible Materials