Artificial pyramid

• US 20040082998A1
• Filed: 12/22/2003
• Published: 04/29/2004
• Est. Priority Date: 02/23/2001
• Status: Active Grant

• Current Assignee: Japan Science And Technology Agency, National Institute for Materials Science
• Original Assignee: Japan Science And Technology Agency
• Inventors: Tanaka, Junzo, Kikuchi, Masanori, Shinomiya, Kenichi, Itoh, Soichiro
• Granted Patent: US 6,887,272 B2
• Time in Patent Office: Days
• US Class Current: 623/17.11
• CPC Class Codes: A61B 17/80 Cortical plates , i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates
• CPC Class Codes: A61F 2/44 for the spine, e.g. vertebrae, spinal discs
• CPC Class Codes: A61L 2430/38 for reconstruction of the spine, vertebrae or intervertebral discs
• CPC Class Codes: A61L 27/46 with phosphorus-containing inorganic fillers
• CPC Class Codes: A61L 27/56 Porous materials, e.g. foams or sponges
• CPC Class Codes: C08L 89/06 derived from leather or skin , e.g. gelatin

Abstract

Disclosed is an artificial vertebra having a bone-marrow regenerating function, comprising a hydroxyapatite (HAp)/collagen (Col) composite body formed by pressure-dehydrating a coprecipitate of hydroxyapatite and collagen to have a nanocomposite structure in which HAp particles are conjugated along a Col fiber while aligned each of the c-axes of the HAp particles along the Col fiber. The HAp/Col composite body is formed with a perforated aperture for allowing a blood vessel and an osteogenic cell to intrude thereinto. The present invention also provides a biodecomposable/bioabsorbable support for fixing an artificial vertebra, comprising a polylactic acid plate prepared by injection-molding molten polylactic acid and then extrusion-molding the injection-molded polylactic acid in such a manner that it is draw-oriented in a uniaxial direction. The plate has four corner regions each formed with a screw hole for fixing the plate to vertebral bodies.

Claims

1. An artificial vertebra system having a bone-marrow regenerating function, comprising a hydroxyapatite (HAp)/collagen (Col) composite body formed by pressure-dehydrating a coprecipitate of hydroxyapatite and collagen to have a nanocomposite structure in which HAp particles are conjugated along a Col fiber while aligned each of the c-axes of said HAp particles along said Col fiber, said HAp/Col composite body being formed with a perforated aperture for allowing a blood vessel and an osteogenic cell to migrate thereinto.

2. The artificial vertebra as defined in claim 1, wherein the weight ratio of HAp to Col in said HAp/Col composite body is in the range of 70:

30 to 80;

20 which is equivalent to that of a bone.

3. The artificial vertebra as defined in claim 1 or 2, wherein said coprecipitate has a cross-linked surface.

4. The artificial vertebra as defined in either one of claims 1 to 3, wherein said HAp/Col composite body is formed as a block having a horseshoe shape in a section orthogonal to the long axis thereof, wherein a portion of said block to be located frontward relative to the front side of a human body has a curved surface having an analogous shape to that of a vertebral body, and a portion of said block to be inserted into vertebral bodies has rectangular planer surfaces to provide an increased contact area with the vertebral bodies.

5. The artificial vertebra as defined in either one of claims 1 to 4, wherein said aperture is perforated in the direction of the long axis of said HAp/Col composite body in a configuration analogous to that of a Haversian canal, wherein a plural number of said apertures are arranged at even intervals.

6. The artificial vertebra as defined in either one of claims 1 to 5, wherein said aperture is perforated in the frontward/rearward direction and rightward/leftward direction relative to the front side of a human body in a configuration analogous to that of a Volkmann'"'"'s canal, wherein a plural number of said apertures are arranged at even intervals.

7. The artificial vertebra as defined in either one of claims 1 to 6, wherein said HAp/Col composite body is adapted to receive a load in an early stage after implantation, wherein said HAp/Col composite body has a function of being transformed into an autologous bone in such a manner that new bone (bone marrow) is initially formed in said perforated aperture and the transformation is then extended from said new bone region to the periphery thereof.

8. The artificial vertebra as defined in either one of claims 1 to 7, which includes an osteogenic factor impregnated into said HAp/Col composite body.

11. An artificial vertebra assembly comprising in combination the artificial vertebra as defined in either one of claims 1 to 8, and the biodecomposable/bioabsorbable support as defined in claim 9 or 10.

9. A biodecomposable/bioabsorbable support for fixing an artificial vertebra, comprising a polylactic acid plate prepared by injection-molding molten polylactic acid and then extrusion-molding said injection-molded polylactic acid in such a manner that it is draw-oriented in a uniaxial direction, said plate having four corner regions each formed with a screw hole for fixing said plate to vertebral bodies.

10. The biodecomposable/bioabsorbable support as defined in claim 9, wherein said screw hole is perforated in an oblique direction.