Prosthetic spinal disc nucleus
First Claim
1. A prosthetic disc nucleus for implantation into a human spinal disc having a nucleus area defined generally in a horizontal plane by an anulus and generally in a vertical plane by two vertebral end plates, the nucleus area having a sagittal diameter and a traverse diameter, the prosthetic disc nucleus comprising:
- a hydrogel core having a length approximating the sagittal diameter of the nucleus area and a width less than half of the transverse diameter of the nucleus area, wherein the hydrogel core is configured such that it will consistently return to a predetermined shape following removal of a load; and
a jacket surrounding the hydrogel core, wherein the jacket is configured to have a horizontal limit in the horizontal plane of the nucleus area such that the jacket directs expansion of the hydrogel core to only the vertical plane of the nucleus area after expansion of the hydrogel core reaches the horizontal limit of the jacket.
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Accused Products
Abstract
An elongated, pillow shaped prosthetic spinal disc nucleus body for implantation into a human intervertebral spinal disc, made of a hydrogel core and a flexible constraining jacket surrounding the hydrogel material core that permits the hydrogel core to expand and contract. The hydrogel core has a length approximating the sagittal diameter of a nucleus of the human disc, a width less than the length, and a height less than the length or width. The hydrogel core will expand and contract in a desired fashion as it imbibes and expels fluids in response to various loads placed upon the spinal tract. The constraining jacket is porous to allow fluids to pass through to the hydrogel core, but prevents the hydrogel from escaping, thus fostering the natural physiology of the human intervertebral disc. By implanting two prosthetic spinal disc nucleus bodies side-by-side into a damaged disc of a human spine, both height and motion can be maintained.
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Citations
23 Claims
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1. A prosthetic disc nucleus for implantation into a human spinal disc having a nucleus area defined generally in a horizontal plane by an anulus and generally in a vertical plane by two vertebral end plates, the nucleus area having a sagittal diameter and a traverse diameter, the prosthetic disc nucleus comprising:
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a hydrogel core having a length approximating the sagittal diameter of the nucleus area and a width less than half of the transverse diameter of the nucleus area, wherein the hydrogel core is configured such that it will consistently return to a predetermined shape following removal of a load; and a jacket surrounding the hydrogel core, wherein the jacket is configured to have a horizontal limit in the horizontal plane of the nucleus area such that the jacket directs expansion of the hydrogel core to only the vertical plane of the nucleus area after expansion of the hydrogel core reaches the horizontal limit of the jacket. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 17)
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14. A prosthetic disc nucleus for implantation into a human spinal disc having a nucleus area defined by an anulus, the nucleus area having a sagittal diameter and a transverse diameter, the prosthetic disc nucleus comprising:
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a hydrogel core having a cylindrical body and a frontal cross-section which is a flattened oval, wherein the flattened oval cross-section defines a major axis and a minor axis; and a jacket surrounding the hydrogel core, wherein the jacket is configured to have a horizontal limit in a plane defined by the major axis of the hydrogel core such that the jacket directs expansion of the hydrogel core to only the minor axis of the hydrogel core after expansion of the hydrogel core reaches the horizontal limit of the jacket. - View Dependent Claims (15, 16)
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18. A prosthetic disc nucleus for implantation into a human spinal disc having a nucleus area with a generally horizontal plane, a sagittal diameter and a transverse diameter defined by an anulus, and a generally vertical plane defined by two vertebral end plates, the prosthetic disc nucleus comprising:
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a hydrogel core having a length approximating the sagittal diameter of the nucleus area and a width less than half of the transverse diameter of the nucleus area, wherein the hydrogel core is dehydrated prior to implantation and hydrated after implantation and the hydrogel core is configured such that it will maintain a predetermined shape after hydration; and a jacket surrounding the hydrogel core, wherein the jacket is configured to have a horizontal limit in the horizontal plane of the nucleus area such that the jacket directs expansion of the hydrogel core to only the vertical plane of the nucleus area after expansion of the hydrogel core, reaches the horizontal limit of the jacket.
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19. A prosthetic disc nucleus for implantation into a human spinal disc having a nucleus area defined by an anulus, the nucleus area having a sagittal diameter and a transverse diameter, the prosthetic disc nucleus comprising:
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a hydrogel core having a length approximating the sagittal diameter of the nucleus area, a width less than half of the transverse diameter and a frontal cross-section which is a flattened oval having a major axis and a minor axis, wherein the hydrogel core has a water content of 25-65% when fully hydrated and is subjected to a plurality of compressive cycles prior to implantation so that the hydrogel core is configured such that it will consistently return to a predetermined shape following removal of a load; and a substantially inelastic woven tube surrounding the hydrogel core, wherein the woven tube is configured to have a horizontal limit in a plane defined by the major axis of the hydrogel core such that the jacket directs expansion of the hydrogel core to only the minor axis of the hydrogel core after expansion of the hydrogel core reaches the horizontal limit of the jacket.
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20. A method of manufacturing a prosthetic disc nucleus for implantation into a human disc having a nucleus area defined by an anulus, the nucleus area having a sagittal diameter and a transverse diameter, the method including:
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forming a cylindrical hydrogel core having a flattened oval-shaped frontal cross-section which defines a major axis and a minor axis; forming a woven jacket having a limit in a plane defined by the major axis of the hydrogel core, wherein the jacket is configured to direct expansion of the hydrogel core only to a direction defined by the minor axis once expansion of the hydrogel core reaches the limit of the jacket; inserting the hydrogel core into an open end of the woven jacket; and closing the open end of the woven jacket to surround the hydrogel core. - View Dependent Claims (21, 22, 23)
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Specification