Method and apparatus for injecting an elastic spinal implant
First Claim
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1. An insertion device for inserting an elastic prosthetic spinal nucleus 12 into an intervertebral disc space, said device comprising:
- (a) a tapered cannula 14 having a straight zone 48 with a cross-sectional area which approximates the cross-sectional area of said prosthetic spinal nucleus 12 and said tapered cannula 14 having a tapered zone 34 which tapers from said straight zone 48 to a proximal opening 50, wherein the cross-sectional area of said straight zone 48 divided by the cross-sectional area of said proximal opening 50 is a ratio lying between about 3 and about 8; and
(b) a force transmitting element 16 for acting on said elastic prosthetic nucleus 12 at its distal end 13 when said nucleus 12 is positioned within said straight zone 48 of said tapered cannula 14, said force transmitting element 16 causing said nucleus 12 first to move into said tapered zone 34 and then out of said proximal opening 50, the force transmitted by said force transmitting element 16 varying directly with the ratio between the cross-sectional area of said straight zone 48 and the cross-sectional area of said proximal opening 50 so that the speed at which said nucleus 12 passes through said proximal opening 50 is so fast as to avoid permanent deformation of said elastic prosthetic nucleus 12.
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Abstract
A method and apparatus for injecting an elastic spinal implant into a cavity in a spinal disc so as to treat disc degeneration are given. The method and apparatus can be used in a variety of surgical approaches with respect to the patient. An elastic spinal nucleus prosthesis is very quickly inserted into the cavity through a small opening in the disc so that permanent deformation of the prosthesis is avoided.
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11 Claims
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1. An insertion device for inserting an elastic prosthetic spinal nucleus 12 into an intervertebral disc space, said device comprising:
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(a) a tapered cannula 14 having a straight zone 48 with a cross-sectional area which approximates the cross-sectional area of said prosthetic spinal nucleus 12 and said tapered cannula 14 having a tapered zone 34 which tapers from said straight zone 48 to a proximal opening 50, wherein the cross-sectional area of said straight zone 48 divided by the cross-sectional area of said proximal opening 50 is a ratio lying between about 3 and about 8; and (b) a force transmitting element 16 for acting on said elastic prosthetic nucleus 12 at its distal end 13 when said nucleus 12 is positioned within said straight zone 48 of said tapered cannula 14, said force transmitting element 16 causing said nucleus 12 first to move into said tapered zone 34 and then out of said proximal opening 50, the force transmitted by said force transmitting element 16 varying directly with the ratio between the cross-sectional area of said straight zone 48 and the cross-sectional area of said proximal opening 50 so that the speed at which said nucleus 12 passes through said proximal opening 50 is so fast as to avoid permanent deformation of said elastic prosthetic nucleus 12. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for implanting an elastic prosthetic spinal nucleus 12 into an intervertebral disc space comprises:
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(a) making a small opening in the annulus of said disc; (b) removing a portion of spinal disc tissue; and (c) inserting a nucleus implant 12 made of elastic material through a tapered cannula 14 with a taper which tapers from a straight zone 48 to a proximal opening 50, with the ratio of the cross-sectional area of straight zone 48 to the cross-sectional area of the proximal opening 50 lying within the range from about 3 to about 8, and at a fast speed so that permanent deformation of said elastic prosthetic nucleus 12 is avoided. - View Dependent Claims (10, 11)
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Specification