Supplementation or replacement of a nucleus pulposus of an intervertebral disc
A degenerated nucleus pulposus located in a central core region of an intervertebral disc within the annulus fibrosus is supplemented or replaced by a method wherein an amount of a biocompatible material is introduced into the central core region by a process including the steps of 1) forming a channel through a vertebral body adjacent to said intervertebral disc, extending from an exterior surface of the vertebral body to the central core region of the annulus fibrosus; 2) introducing an amount of a biocompatible material through the channel into the central core region of the annulus fibrosus; 3) pressurizing the biocompatible material through the channel to a postsurgical pressure sufficient to alleviate symptoms caused by the degenerated nucleus pulposus; and 4) sealing the channel while maintaining the sufficient postsurgical pressure. After sealing the channel, a vertebroplasty may optionally be performed in the vertebra.
1 . A method for replacing or supplementing a nucleus pulposus in an intervertebral disc, said intervertebral disc having an annulus fibrosus with a central core containing said nucleus pulposus, said method comprising:
forming a channel through a vertebral body adjacent to said intervertebral disc, said channel extending from an exterior surface of said vertebral body to said central core of said annulus fibrosus;
introducing an amount of a biocompatible material through said channel into said central core of said annulus fibrosus;
exerting pressure on said biocompatible material through said channel; and
sealing said channel while maintaining said pressure.
2 . The method of claim 1 , wherein said pressure is sufficient to at least approximately restore natural function of said intervertebral disc.
3 . The method of claim 1 , wherein said pressure is sufficient to at least approximately restore natural intervertebral spacing.
4 . The method of claim 1 , wherein said biocompatible material is pressurized to a pressure approximating natural pressure of the nucleus pulposus.
5 . The method of claim 1 , wherein said biocompatible material has a compressional modulus not greater than about 4 Mpa.
6 . The method of claim 1 , wherein said biocompatible material is a hydrogel.
7 . The method of claim 6 , wherein said hydrogel is comprised of a material selected from the group consisting of poly(vinyl alcohol) and an associating hydrogel that is a blend of poly(vinyl alcohol) and poly(vinylpyrrollidone).
8 . The method of claim 1 , wherein said biocompatible material is selected from the group consisting of a polyurethane and a silicone.
9 . The method of claim 1 , wherein said channel is sealed with a plug of a biocompatible sealing material.
10 . The method of claim 9 , wherein said biocompatible sealing material is selected from the group consisting of a bone cement, an autograft, an allograft, and a xenograft.
11 . The method of claim 10 , wherein said bone cement is selected from the group consisting of poly(methylmethacrylate), calcium phosphate, calcium sulfate, calcium carbonate, and hydroxyapatite
12 . The method of claim 1 , wherein said channel is sealed with a plug of biocompatible sealing material and a mechanical plug.
13 . The method of claim 12 , wherein said mechanical plug is selected from the group consisting of a bone screw and a barbed plug.
14 . The method of claim 1 , wherein said implant is pressurized by inserting a bone screw or a barbed plug into said channel.
15 . The method of claim 1 , additionally comprising a step of performing a vertebroplasty in said vertebral body after sealing said channel.
16 . A restorative implant for an intervertebral disc comprising:
a quantity of a biocompatible material implanted in a central core of a human intervertebral disc replacing or supplementing a nucleus pulposus, said quantity of biocompatible material being accessible through a channel formed in an adjacent vertebra; and
a plug positioned in said channel and exerting pressure on said quantity of implanted low modulus material.
17 . The implant of claim 16 , wherein said postsurgical pressure is sufficient to at least approximately restore natural function of said intervertebral disc.
18 . The implant of claim 16 , wherein said postsurgical pressure is sufficient to at least approximately restore natural intervertebral spacing.
19 . The implant of claim 16 , wherein said biocompatible material is pressurized to a pressure approximating natural pressure of the nucleus pulposus.
20 . The implant of claim 16 , wherein said biocompatible material has a compressional modulus not greater than about 4 Mpa.
21 . The implant of claim 16 , wherein said biocompatible material has a Poisson ratio in a range of from about 0.30 to 0.50.
22 . The implant of claim 26 , wherein said biocompatible material is a hydrogel.
23 . The implant of claim 22 , wherein said hydrogel is a comprised of a material selected from the group consisting of poly(vinyl alcohol) and an associating hydrogel that is a blend of poly(vinyl alcohol) and poly(vinylpyrrollidone).
24 . The implant of claim 16 , wherein said biocompatible material is selected from the group consisting of a polyurethane and a silicone.
25 . The implant of claim 16 additionally comprising a predetermined quantity of a generally incompressible material positioned in said channel between said implanted material and said plug.
26 . The implant of claim 25 wherein said generally incompressible material is selected from the group consisting of bone cement, an autograft, an allograft, and a xenograft.
27 . The implant of claim 16 wherein said plug is selected from the group consisting of a bone screw and a barbed plug.
28 . A restorative implant for an intervertebral disc implanted by the method of claim 1.