U.S. patent application number 11/181782 was filed with the patent office on 2005-12-01 for inflatable intervertebral disc replacement prosthesis.
Invention is credited to Suddaby, Loubert.
Application Number | 20050267580 11/181782 |
Document ID | / |
Family ID | 33298562 |
Filed Date | 2005-12-01 |
United States Patent
Application |
20050267580 |
Kind Code |
A1 |
Suddaby, Loubert |
December 1, 2005 |
Inflatable intervertebral disc replacement prosthesis
Abstract
An intervertebral disc replacement prosthesis which can be
implanted in a collapsed state, then expanded within the disc space
such that minimally invasive surgical techniques may be employed
for its insertion, and, by virtue of its expandable nature,
ligaments can be restored to proper tension, facet joints can be
unloaded posteriorly to inhibit degenerative changes, and
functional mobility of the intervertebral segment can be
restored.
Inventors: |
Suddaby, Loubert; (Orchard
Park, NY) |
Correspondence
Address: |
SHOEMAKER AND MATTARE, LTD
10 POST OFFICE ROAD - SUITE 110
SILVER SPRING
MD
20910
US
|
Family ID: |
33298562 |
Appl. No.: |
11/181782 |
Filed: |
July 15, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11181782 |
Jul 15, 2005 |
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10420803 |
Apr 23, 2003 |
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Current U.S.
Class: |
623/17.12 ;
623/17.14 |
Current CPC
Class: |
A61F 2/4425 20130101;
A61F 2002/30583 20130101; A61F 2002/30841 20130101; A61F 2210/0085
20130101; A61F 2/441 20130101; A61F 2002/30649 20130101; A61F
2002/30586 20130101; A61F 2220/0091 20130101; A61F 2002/30579
20130101; A61F 2002/443 20130101; A61F 2002/30624 20130101; A61F
2002/30471 20130101 |
Class at
Publication: |
623/017.12 ;
623/017.14 |
International
Class: |
A61F 002/44 |
Claims
1. An intervertebral disc replacement prosthesis comprising at
least one chamber which can be inflated to conform to various
intervertebral spaces.
2. The prosthesis of claim 1, comprising a pair of end plates on
opposite sides of said chamber, each having a generally convex
surface adapted to engage a respective cranial or caudal surface of
neighboring vertebrae.
3. The prosthesis of claim 2, wherein each of said end plates has
plural projections or corrugations for engaging said surfaces, to
prevent movement of the end plates relative to said surfaces.
4. The prosthesis of claim 1, wherein each of said end plates is
rigid.
5. An intervertebral disc replacement prosthesis comprising a pair
of independently inflatable chambers, each adapted to engage a
respective cranial or caudal surface of neighboring vertebrae.
6. The prosthesis of claim 5, wherein each of said inflatable
chambers has an end plate adapted to engage a respective cranial or
caudal surface of neighboring vertebrae.
7. The prosthesis of claim 5, wherein each of said end plates has
plural projections or corrugations for engaging said surfaces, to
prevent movement of the end plates relative to said surfaces.
8. The prosthesis of claim 5, wherein said chambers have
complementary structures which interengage to provide limited
universal movement between said chambers.
9. The prosthesis of claim 6, wherein each of said end plates is
formed of at least two parts having hinges therebetween so that the
prosthesis can be folded prior to insertion through minimally
invasive techniques.
10. The prosthesis of claim 6, wherein each of said chambers has a
flexible wall.
11. The prosthesis of claim 10, wherein said wall is made of a
polymeric material.
12. The prosthesis of claim 10, wherein said wall is made of a
fabric.
13. The prosthesis of claim 12, wherein the fabric is Kevlar.
14. The prosthesis of claim 12, wherein the fabric is not
substantially stretchable, and the chamber is made is a shape
conforming to the space to be filled.
Description
[0001] This application is a division of application Ser. No.
10/420,803, filed Aug. 23, 2003.
BACKGROUND OF THE INVENTION
[0002] This invention relates to orthopedic surgery, more
particularly to a prosthetic intervertebral disc replacement system
which can be implanted into a suitably prepared intervertebral disc
space via minimally invasive surgical techniques to provide for and
restore substantial functional normalcy.
[0003] The normal intervertebral disc is in essence a complex joint
which allows for various articular motions between adjacent
vertebral segments. These articular motions, in turn, account for
the flexibility and functional mobility of the normal human spine.
In the course of a day, the normal intervertebral disc encounters a
variety of compressional, rotations and associated flexion or
extension movements. In these day to day activities, movements in
varying and repetitive combinations accumulate and contribute to
the deterioration of natural discs that occurs over time. As with
other joints in the human body that deteriorate over time, it would
be desirable to have disc replacement prostheses which could be
inserted in place of a failed or worn normal disc when it is
determined the disc is irreparably damaged and that preservation of
functional mobility is required. The time honored method of
addressing debilitating symptoms and signs of a degenerative disc
is to remove the disc and fuse the two adjacent vertebral bones
together. Fusion eliminates motion at the abnormal segment, and
while useful at improving debilitating symptoms, the consequence of
eliminating natural motions at a single segment is that greater
degrees of stress occur above or below that segment. This in turn
accelerates degeneration of neighboring intervertebral discs, often
necessitating additional fusion surgeries. It would be desirable,
therefore, to preserve motion at every disc space and thus retain
natural motion and eliminate the adjacent level degeneration that
discectomy and fusion seems to produce. Toward this end, an
intervertebral disc replacement prosthesis ought ideally to restore
and preserve disc space height while permitting sufficient natural
motion (flexion, extension, rotation and lateral bending) to
prevent excessive stresses on spinal segments above and below the
prosthesis.
[0004] Several intervertebral disc replacement prostheses are now
in production, but none has the capacity to be implanted
posteriorly through traditional exposures of the spine, or through
smaller incisions, known collectively as minimally invasive
surgical techniques.
SUMMARY OF THE INVENTION
[0005] An object of the invention is to provide for a complete and
functional disc replacement that simultaneously restores sufficient
disc space height and mobility to provide for functional normalcy,
while allowing for a variety of surgical approaches and the use of
minimally invasive surgical techniques.
[0006] To achieve this objective, the component parts of the
replacement disc are bonded to the surface of sacks or chambers
which are distensible or inflatable. In this manner, the
replacement discs can be inserted through a small opening and then
inflated within a disc space thereby assuming its final functional
configuration. The sacks are nonporous and allow no escape of their
contents. The sacks, or chambers, are initially inflated with a
radio opaque liquid contrast material under fluoroscopic guidance
to check for functional positioning and anatomic alignment, as well
as functional integrity of the chambers themselves. Once ideal
placement is confirmed, the radio opaque contrast material is
removed and replaced with a hardenable material or resin which
forms a solid construct once suitably mature. In this fashion,
infinite anatomic variation of disc heights and configurations can
be accommodated, and insertion of the replacement disc can be
facilitated through a small annulotomy favoring minimally invasive
surgical techniques.
[0007] The preferred embodiment contains at least two inflatable
chambers, although one, or any number of chambers might be
conceived and created, depending on specific needs.
[0008] For example, in the two component version, one chamber sits
atop the other with the disc space between the vertebral end
plates. On the cranial or superior surface of the cranial chamber,
teeth, digits, or corrugations are found which impress themselves
into the end plate when the sack or chamber is inflated. A similar
set of components is found on the caudal or inferior surface of the
caudal or inferior chamber. These teeth or digits transgress the
end plate surface and fixate the replacement disc in situ when the
chambers are inflated. The juxtaposing surface between the cranial
and caudal chambers contain mating surfaces that allow for
functional motion between the cranial and caudal chambers when they
are inflated to their final size. The mating surfaces are formed of
male and female components that interdigitate, largely in a ball
and socket fashion, but other similar functional relationships may
be considered, provided that the adjacent surface interaction
provides for the cardinal movements of a functioning intervertebral
disc. These cardinal movements will allow for approximately 15
degrees of flexion, 5 degrees of extension, 5 degrees of lateral
bending, 2 degrees of axial rotation and 1-5 mm of translation.
When fully expanded, the fulcrum of movement on flexion and
extension is located near the junction of the posterior one third
and anterior two thirds of the vertebral body. The relationship
between the components is such that it allows for varying degrees
of rotation, flexion, extension and translational movements while
simultaneously retarding the extremes of these motions to prevent
disengagement of the cranial and caudal components at the extremes
of functional movement. The mating surfaces are lined with
polyethylene or similar materials suited for long term frictional
wear. These linings may include plastics, ceramics, metals, carbon
composites or combinations thereof.
[0009] The male and female component of the mating surface is
bonded to the surface of its adjacent inflatable chamber such that
proper union is assured when both chambers are inflated to their
final proportions. Because the chambers are inflatable, they can be
inserted into the disc in a collapsed state through a small opening
and then inflated once they are appropriately positioned within the
disc space.
[0010] As the chambers are inflated, teeth or digits on the
superior or cranial and inferior or caudal surface of the chambers
dig into the adjacent end plate and lock the prosthesis in
position. The mating surface between the two inflated chambers in
turn contains a ball and socket or male and female interacting
component that permits functional movement between the cranial and
caudal chambers when they are suitably inflated. By inflating them
with a hardenable material, a solid, functional disc prosthesis can
be formed with a final size that is much larger than its component
parts. This allows not only for varying disc sizes and shapes, but
also provides for use of the prosthesis in minimally invasive
surgical techniques.
[0011] Suitable materials for the teeth or digits which bond to the
end plate are any of a variety of metal or plastics or ceramics
having sufficient strength to indent or puncture or bond with a
vertebral end plate. Fabrics permitting tissue ingrowth might also
be used.
[0012] Suitable materials for the walls of the inflatable chamber
include Kevlar, polypropylene or any of a variety of plastics or
fabrics having either elastic or non-elastic properties, but
sufficiently pliable and having sufficient tensile strength to
allow for deflated and inflated attitudes. The material should be
sufficiently non-porous so as to prevent leakage of injected
contents.
[0013] Suitable materials for the mating surfaces between the
cranial and caudal chambers include any materials presently used in
joint replacement having the capacity for long term frictional
wear. These include various synthetics, such as polyethylene,
plastics, ceramics and metal surfaces capable of long term cyclical
frictional interactions.
[0014] Suitable materials to inflate the chamber to allow them to
assume their final functional configuration include any hardenable
material capable of maintaining function integrity under a variety
of loads during various combinations of flexion, extension,
rotation or translational movements. These materials include
polymethyl methacrylate, polycarbonate, various polymerizing resins
or indeed any material capable of being inject in a liquid or
semisolid state and then capable of assuming a solid structural
shape as determined by the recipient chamber into which it is
injected.
[0015] In the simplest embodiment, a single chamber sitting between
two metallic dishes conforming roughly to the shape of the
vertebral end plates could be inflated to allow a friction fit of
the metallic dishes to the end plates cranially and caudally. Once
the injected material hardened within the chamber, functional
mobility would be restored and retained.
[0016] In U.S. Pat. No. 3,875,595, Froning describes a bladder-like
prosthesis which is inflated with liquid or plastic, but requires a
valve as the material is non-hardenable and could potentially leak
from the retaining bladder, causing the prosthesis to collapse.
[0017] Kuslich, in U.S. Pat. No. 5,571,189, describes an expandable
porous fabric implant designed to stabilize a spinal segment. The
fabric is porous and packed with biologic material which favors
fusion of the interspace rather than functional mobility. It is
packed with material which stabilizes a spinal segment by allowing
ingrowth of bone and fibrous issues through pores on its
surface.
[0018] In U.S. Pat. No. 5,674,295, Ray describes a pillow-shaped
prosthetic spinal disc nucleus body made of a hydrogel core and a
flexible constraining jacket which permits the hydrogel core to
expand and contract. The constraining jacket is also porous,
allowing entry and egress of fluids. The jacket is not filled with
a hardenable material, since significant expansion and contraction
is a pivotal feature to the biologic function of the prosthesis he
describes.
[0019] These and other objects are attained by a inflatable
intervertebral disc replacement prosthesis as described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020] In the accompanying drawings,
[0021] FIGS. 1a-1f are diagrammatic front and side views of an
inflatable intervertebral disc replacement prosthesis embodying the
invention;
[0022] FIGS. 2a-2f are diagrammatic front and side views of a
second embodiment of the invention;
[0023] FIGS. 3a-3f are diagrammatic front and side views of a third
embodiment of the invention;
[0024] FIGS. 4a-4e are diagrammatic front and top views of the
first embodiment;
[0025] FIGS. 5a-5f are front, top and side views of the first
embodiment;
[0026] FIGS. 6a-6f are front and top view of a fourth embodiment of
the invention;
[0027] FIGS. 7a-7e are front and top views of the second embodiment
of the invention;
[0028] FIGS. 8a-8e are front, top and side views of a fifth
embodiment of the invention; and
[0029] FIGS. 9a-9e are front, top and side views of a sixth
embodiment of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0030] The drawings show several embodiments of the invention,
having the characteristic feature that each prosthesis has at least
one chamber 12 which can be inflated to conform to various
intervertebral spaces.
[0031] Preferably, each chamber 12 is provided with studs 14,
fingers, corrugations or other projecting structures designed to
dig into the cranial and caudal surfaces of the vertebrae "V"
against which they bear, to keep the prosthesis in place. The
chamber 12 is at least partially made of a flexible material, not
only so that it can expand, but also so that is can be collapsed to
a small size, so that it can be inserted by minimally invasive
techniques. The chamber wall 20 may be a strong fabric material,
for example Kevlar, or it may be made of a strong polymeric film
such as polypropylene. In the case of Kevlar, which is not
substantially stretchable, the chambers may advantageously be
formed in a particular shape, which will be attained on inflation,
corresponding to the particular space being filled.
[0032] The chambers 12 may have rigid end plates 22 made, for
example, of metal. FIGS. 2, 7 and 8 lack such end plates, and have
the projecting structures 14 formed integrally with the flexible
wall material 20. In the other embodiments, the projecting
structures are formed on the rigid end plates 22. Where the end
plates are rigid, they may advantageously be formed in two or more
parts 24, 26 interconnected by hinges 28, so that they can be
folded up to small size prior to insertion. Such constructions are
suggested in FIGS. 3, 6 and 9.
[0033] In the embodiments where two chambers 12, 12' are used
(FIGS. 2, 3 and 6-9), the chambers may have an articulating joint
30 between them, formed of cooperating rigid articular plates 32,
32'. The plates have complementary geometries, such as a ball 34
and socket 36, to provide limited universal movement between the
chambers. In embodiments having a single chamber 12 (FIGS. 1, 4 and
5), there may be articular plates 38 or portions designed to
cooperate with correspondingly shaped recesses 40 formed in the end
plates.
[0034] In any case, the prosthesis is placed by first preparing the
intervertebral space, then inserting the prosthesis in the space,
and then inflating its chamber(s) via valve(s) 42. The inflating
fluid may be a liquid such as a gel or a hardenable material.
Inflation is done to a degree determined by the surgeon to restore
the space to its original height.
[0035] Since the invention is subject to modifications and
variations, it is intended that the foregoing description and the
accompanying drawings shall be interpreted as only illustrative of
the invention defined by the following claims.
* * * * *