U.S. patent application number 15/260561 was filed with the patent office on 2016-12-29 for facet joint prosthesis.
The applicant listed for this patent is GLOBUS MEDICAL, INC.. Invention is credited to Michael Lee Boyer, II, Andrew Iott, Daniel Laskowitz, Andrew Lee, David C. Paul, William Rhoda.
Application Number | 20160374732 15/260561 |
Document ID | / |
Family ID | 39616588 |
Filed Date | 2016-12-29 |
United States Patent
Application |
20160374732 |
Kind Code |
A1 |
Boyer, II; Michael Lee ; et
al. |
December 29, 2016 |
FACET JOINT PROSTHESIS
Abstract
A facet joint prosthesis comprising an inferior prosthetic
portion and a superior prosthetic portion is disclosed. Inferior
prosthetic portion includes a first anchor member and a first
articulating member and superior prosthetic portion includes a
second anchor member and a second articulating member. The first
articulating member comprises a support portion and first
articulating surface and the second articulating member comprises a
second articulating surface, and first and second articulating
surfaces are configured and dimensioned to contact or engage one
another. A flexible element is positioned between the support
portion and the first articulating surface.
Inventors: |
Boyer, II; Michael Lee;
(Phoenixville, PA) ; Laskowitz; Daniel;
(Lancaster, PA) ; Paul; David C.; (Phoenixville,
PA) ; Rhoda; William; (Media, PA) ; Iott;
Andrew; (Newtown Square, PA) ; Lee; Andrew;
(Santa Rosa, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
GLOBUS MEDICAL, INC. |
AUDUBON |
PA |
US |
|
|
Family ID: |
39616588 |
Appl. No.: |
15/260561 |
Filed: |
September 9, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13849246 |
Mar 22, 2013 |
9463051 |
|
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15260561 |
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|
11634242 |
Dec 6, 2006 |
|
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13849246 |
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|
60742527 |
Dec 6, 2005 |
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Current U.S.
Class: |
606/247 |
Current CPC
Class: |
A61B 17/7064 20130101;
A61F 2/4405 20130101; A61F 2002/3055 20130101; A61F 2220/0025
20130101; A61F 2220/0075 20130101; A61F 2002/30563 20130101; A61F
2002/30565 20130101; A61F 2002/305 20130101; A61B 17/8605 20130101;
A61F 2002/30649 20130101; A61F 2310/00011 20130101; A61F 2310/00179
20130101; A61B 17/7067 20130101; A61F 2002/30378 20130101; A61F
2002/30331 20130101; A61F 2220/0033 20130101; A61F 2002/30462
20130101; A61B 17/7059 20130101 |
International
Class: |
A61B 17/70 20060101
A61B017/70; A61B 17/86 20060101 A61B017/86 |
Claims
1. A spinal implant comprising: a first support member; an inferior
prosthetic segment attached to the first support member; a second
support member; and a superior prosthetic segment attached to the
second support member; wherein the inferior prosthetic segment and
the superior prosthetic segment are configured to articulate
relative to one another.
2. The implant of claim 1, wherein the inferior prosthetic segment
comprises a planar, plate-like member.
3. The implant of claim 2, wherein the superior prosthetic segment
comprises a cup-feature for receiving the planar, plate-like
inferior prosthetic segment.
4. The implant of claim 3, wherein the cup-feature comprises a
rectangular socket.
5. The implant of claim 1, wherein the superior prosthetic segment
comprises one or more ramped surfaces that extend from a
socket-like structure.
6. The implant of claim 1, wherein the superior prosthetic segment
comprises a partial rectangular cup or socket-like structure.
7. The implant of claim 1, wherein the inferior prosthetic segment
and the superior prosthetic segment are made of titanium.
8. The implant of claim 1, wherein the inferior prosthetic segment
comprises a hook member.
9. The implant of claim 8, wherein the superior prosthetic segment
comprises a receiver member or head for receiving the hook
member.
10. The implant of claim 9, wherein the hook member comprises a
gusset that is received into a cut-out formed in the receiver
member.
11. A spinal implant comprising: a first support member; a first
inferior prosthetic segment attached to the first support member; a
second inferior prosthetic segment attached to the first support
member; a second support member; a first superior prosthetic
segment attached to the second support member; and a second
superior prosthetic segment attached to the second support member;
wherein the inferior prosthetic segment and the superior prosthetic
segment are configured to articulate relative to one another.
12. The implant of claim 11, wherein the first inferior prosthetic
segment comprises a planar, plate-like member.
13. The implant of claim 12, wherein the first superior prosthetic
segment comprises a cup-feature for receiving the planar,
plate-like first inferior prosthetic segment.
14. The implant of claim 13, wherein the cup-feature comprises a
rectangular socket.
15. The implant of claim 11, wherein the first superior prosthetic
segment comprises one or more ramped surfaces that extend from a
socket-like structure.
16. The implant of claim 11, wherein the first superior prosthetic
segment comprises a partial rectangular cup or socket-like
structure.
17. The implant of claim 11, wherein the first inferior prosthetic
segment and the first superior prosthetic segment are made of
titanium.
18. The implant of claim 11, wherein the first inferior prosthetic
segment comprises a hook member.
19. The implant of claim 18, wherein the first superior prosthetic
segment comprises a receiver member or head for receiving the hook
member.
20. The implant of claim 19, wherein the hook member comprises a
gusset that is received into a cut-out formed in the receiver
member.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This Patent Application is a continuation application
claiming priority to U.S. Ser. No. 13/849,246, filed Mar. 22, 2013,
which is a continuation application claiming priority to U.S.
patent application Ser. No. 11/634,242, filed Dec. 6, 2006, which
claims priority to U.S. Provisional Application 60/742,527, filed
Dec. 5, 2005, the entire contents of which are incorporated by
reference.
FIELD OF THE INVENTION
[0002] The present invention generally relates to devices and
methods for treating spinal stenosis or for alleviating pain or
discomfort associated with the spinal column. More specifically,
the present invention is directed to several different types of
spinal joint replacement prostheses.
BACKGROUND OF THE INVENTION
[0003] The facet joints can deteriorate or otherwise become injured
or diseased, causing lack of support for the spinal column, pain,
and/or difficulty in movement.
[0004] Facet joint degeneration and disc degeneration frequently
occur together, although one may be the primary problem and the
other a secondary phenomenon due to altered mechanics of the spine.
Central and lateral spinal stenosis, degenerative
spondylolisthesis, and degenerative scoliosis may all result from
the abnormal mechanical relationship between the anterior and
posterior column structures of the spine resulting from such joint
and/or disc degeneration.
[0005] Proper spinal motion requires normal function of both the
disc and facet joints. Currently, surgical approaches for spinal
stenosis do not restore normal function. In some instances,
decompression with removal of soft tissue restraints and portions
of the facet joints may actually cause instability, or, at a
minimum, alter normal mechanics. As a result, instability that has
inadvertently been induced by medical treatment can lead to further
degeneration and pain
[0006] Spinal fusion puts stress on adjacent structures, and
accelerates transitional degeneration and may cause stenosis at the
adjacent segment. Secondary operations for hardware removal are
occasionally required, and bone graft donor site pain can be a real
problem for many patients.
[0007] A facet joint replacement would allow spinal alignment and
mobility to be preserved. Also, there would be less stress placed
on adjacent levels, and normal anatomic structures (lamina, spinous
process, ligaments) could be preserved. Therefore, a need exists
for an improved facet joint prosthesis to provide an adjunct to
anterior column disc replacement, or as a stand-alone treatment for
patients with isolated posterior column disease.
SUMMARY OF THE INVENTION
[0008] Various facet joint prostheses are disclosed. In one
embodiment, a facet joint prosthesis comprising an inferior
prosthetic portion and a superior prosthetic portion is disclosed.
Inferior prosthetic portion includes a first anchor member and a
first articulating member and superior prosthetic portion includes
a second anchor member and a second articulating member. The first
articulating member comprises a support portion and first
articulating surface and the second articulating member comprises a
second articulating surface, and first and second articulating
surfaces are configured and dimensioned to contact or engage one
another. In one embodiment, a flexible element is positioned
between the support portion and the first articulating surface.
[0009] In another aspect of the invention, a facet joint prosthesis
having first prosthetic portion, second prosthetic portion, and a
flexible element is disclosed. The first prosthetic portion
includes a first anchor member and a first articulating member and
the second prosthetic portion includes a second anchor member and a
second articulating member. A flexible element is interconnected
between the first and second articulating members.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention will be more readily understood with reference
to the embodiments thereof illustrated in the attached figures, in
which:
[0011] FIG. 1 is a lateral view of a representative vertebra;
[0012] FIG. 2 is a superior view of the vertebra of FIG. 1;
[0013] FIG. 3 is lateral view of a representative motion segment of
the spine;
[0014] FIG. 4 is a lateral view of one embodiment of a facet joint
prosthesis constructed in accordance with the present
invention;
[0015] FIG. 5 is a dorsal view of the facet joint prosthesis of
FIG. 4;
[0016] FIG. 6 is a dorsal view of another embodiment of a facet
joint prosthesis constructed according to the invention;
[0017] FIG. 7 is a dorsal view another embodiment of a facet joint
prosthesis constructed in accordance with the present
invention;
[0018] FIG. 8 is a dorsal view of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention;
[0019] FIG. 9 is a lateral view of the prosthesis of FIG. 8;
[0020] FIG. 10 is a dorsal view of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention;
[0021] FIG. 11 is a partial cross-sectional view of another
embodiment of a facet joint prosthesis constructed according to the
present invention;
[0022] FIG. 12 is a partial cross-sectional view of another
embodiment of a facet joint prosthesis constructed according to the
present invention;
[0023] FIG. 13 is a lateral view of the prosthesis of FIG. 12;
[0024] FIG. 14 is a lateral view of another embodiment of a facet
joint prosthesis constructed according to the present
invention;
[0025] FIG. 15 is a lateral view of another embodiment of a facet
joint prosthesis constructed according to the present
invention;
[0026] FIG. 16 is a partial cross-sectional view of another
embodiment of a facet joint prosthesis constructed according to the
present invention;
[0027] FIG. 17 is an exploded view of the prosthesis of FIG.
16;
[0028] FIG. 18 is a lateral view of another embodiment of a facet
joint prosthesis constructed according to the present
invention;
[0029] FIG. 19 is a partial exploded view of another embodiment of
a facet joint prosthesis constructed in accordance with the present
invention;
[0030] FIG. 20 is a dorsal view of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention;
[0031] FIG. 21 is a dorsal view of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention;
[0032] FIG. 22 is an exploded view of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention;
[0033] FIG. 23 is a perspective view of another embodiment of a
facet joint prosthesis constructed in accordance with the present
invention;
[0034] FIGS. 24-25 are views of another embodiment of a facet joint
prosthesis constructed in accordance with the present
invention;
[0035] FIG. 26 is an exploded view of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention;
[0036] FIGS. 27A-27B are front and rear perspective views of
another embodiment of a facet joint prosthesis constructed in
accordance with the present invention;
[0037] FIGS. 28A-28B are front and rear perspective views of
another embodiment of a facet joint prosthesis constructed in
accordance with the present invention;
[0038] FIGS. 29A-29B are front and rear perspective views of
another embodiment of a facet joint prosthesis constructed in
accordance with the present invention;
[0039] FIGS. 30A-30B are front and rear perspective views of
another embodiment of a facet joint prosthesis constructed in
accordance with the present invention;
[0040] FIGS. 31A-31B are front and rear exploded perspective views
of another embodiment of a facet joint prosthesis constructed in
accordance with the present invention;
[0041] FIGS. 32A-32B are front and rear exploded perspective views
of another embodiment of a facet joint prosthesis constructed in
accordance with the present invention;
[0042] FIGS. 33A-33C are front, rear, and front exploded
perspective views, respectively, of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention; and
[0043] FIGS. 34A-34C are front, rear, and front exploded
perspective views, respectively, of another embodiment of a facet
joint prosthesis constructed in accordance with the present
invention
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0044] Embodiments of the invention will now be described. The
following detailed description of the invention is not intended to
be illustrative of all embodiments. In describing embodiments of
the present invention, specific terminology is employed for the
sake of clarity. However, the invention is not intended to be
limited to the specific terminology so selected. It is to be
understood that each specific element includes all technical
equivalents that operate in a similar manner to accomplish a
similar purpose.
[0045] FIGS. 1 and 2 are lateral and axial views, respectively, of
an exemplary vertebra of a vertebral column. Each vertebra includes
a vertebral body 1, which is the anterior, massive part of bone
that gives strength to the vertebral column and supports body
weight. The vertebral arch 2 is posterior to the vertebral body 1
and is formed by the right and left pedicles 3 and lamina 4. The
pedicles 3 are short, stout processes that join the vertebral arch
2 to the vertebral body 1. The pedicles 3 project posteriorly to
meet two broad flat plates of bone, called the lamina 4. Together
with the pedicles on the side and the vertebral body and discs in
the front they form a canal, called the vertebral foramen 5, in the
middle of the vertebrae through which the spinal cord and other
structures pass.
[0046] Seven other processes arise from the vertebral arch. The
spinous process 6 and two transverse 7 processes project from the
vertebral arch 2 and afford attachments for back muscles, forming
levers that help the muscles move the vertebrae. The remaining four
processes, called articular processes, project superiorly from the
vertebral arch (and are thus called the superior articular
processes 8) and inferiorly from the vertebral arch (and are thus
called the inferior articular processes 9). The superior and
inferior articular processes 8 and 9 are in opposition with
corresponding opposite processes of vertebrae superior and inferior
adjacent to them, forming joints, called zygapophysial joints or,
more regularly, the facet joints or facets. The facet joints permit
gliding movement between the adjacent vertebrae. Facet joints are
found between adjacent superior and inferior articular processes
along the spinal column. Generally, a facet joint has a superior
half and an inferior half. The superior half of the joint is formed
by the vertebral level below the joint, and the inferior half of
the joint is formed by the vertebral level above the joint. The
facets have different orientations at different parts of the spine.
This allows for different motions. For example the facet
orientations at the lumbar spine primarily allow for flexion
(forward bending) and extension (backward bending). Where as in the
cervical spine the facets allow for flexion, extension, and a much
larger amount of rotation, and side bending. The facets are
surrounded by cartilage (joint capsule) that is innervated and
capable of producing pain.
[0047] Referring to FIGS. 4 and 5, one exemplary embodiment of a
facet joint prosthesis 10 according to the invention is shown. In
general, prosthesis 10 comprises an inferior prosthetic segment,
element, or portion 12 and a superior prosthetic segment, element,
or portion 14. Segment or portion 12 is designated as "inferior"
because it creates an artificial facet surface or portion in the
inferior half of the facet joint. Similarly, segment or portion 14
is designated as "superior" because it creates an artificial facet
surface or portion in the superior half of the facet joint. Similar
nomenclature is used throughout this description, however, as an
alternative to the "inferior" and "superior" nomenclature
designation, "cephalad" and "caudal" may be used.
[0048] In one embodiment, prosthetic portions 12, 14 comprise an
anchor member 16, 18 and an articulating member 20, 22,
respectively. In this regard, inferior prosthetic segment 12
comprises a first or inferior anchor member 16 and a first or
inferior articulating member 20. Similarly, superior prosthetic
segment 14 comprises a second or superior anchor member 18 and a
second or superior articulating member 22. Anchor members 16, 18
are configured and dimensioned to engage, anchor, or otherwise fix
to a vertebra. Articulating members 20, 22 are configured and
dimensioned to contact or engage adjacent articulating members such
that the articulating members can move relative to one another, for
example, by pivoting or by sliding towards, or away from, each
other.
[0049] As shown in FIG. 4, the left inferior facet of superior
vertebra 24 and left superior facet of inferior vertebra 26 have
been resected and/or removed and prosthesis 10 has been attached to
vertebrae 24, 26 to replicate the natural anatomy. Articulating
member 20 of inferior prosthetic segment 12 engages articulating
member 22 of superior prosthetic segment 14. In this regard,
articulating member 20 comprises a generally convex articulating or
bearing surface 28, and articulating member 22 comprises a
generally concave articulating or bearing surface 30, and surfaces
28, 30 are configured and dimensioned to contact or engage one
another, as described above. When the total facet joint is
replaced, as shown in FIGS. 4-5, then surface 28 articulates with
surface 30 to recreate the natural biomechanics of the spine motion
segment made up of vertebra 24, vertebra 26, and intervertebral
disc 32. In one embodiment, superior bearing surface 30 is sized to
be larger than the articulating inferior bearing surface 28, to
allow for motion of the joint. In alternate embodiments,
alternative shapes and configurations of articulating surfaces 28,
30 may be utilized. For example, surface 30 may be any appropriate
concave shape including, but not limited to, rectangular, disc
shaped, trough shaped, or cup shaped, and inferior surface 28 may
have a corresponding convex shape to mate, engage, or otherwise
contact surface 30.
[0050] As best seen in FIG. 4, in one embodiment, first and second
anchor members 16, 18 comprise bone screws. In one variation, the
bone screws may be polyaxial screws. One type of polyaxial screw
that may be used is disclosed in U.S. patent application Ser. No.
11/146,147, filed Jun. 7, 2005, the entire contents of which are
incorporated by reference. In this regard the articulating members
20, 22, may include features to facilitate connection with the
corresponding anchor or screw. In one exemplary embodiment, the
articulating member 20 comprises a rod portion 34 configured and
dimensioned to engage anchor 16. In this regard, a standard or
typical pedicle screw may be utilized without modifying the
connection means on the head of the screw, as pedicle screws are
generally configured to accommodate a cylindrical or rod-like
structure such as a spinal rod. As shown in FIG. 5, anchor or screw
16 may be implanted in a pedicle and articulating member 20 is
sized and shaped to span the distance between a pedicle and an
inferior articular process on the same side of a vertebral body. In
one variation of articulating member 20, a flexible element 36 may
be positioned between the anchor 16 and articulating surface 28.
One type of flexible element that may be used is disclosed in U.S.
patent application Ser. No. 10/762,533, filed Jan. 23, 2004, the
entire contents of which are incorporated by reference. In
alternate embodiments, a spring or other resilient or elastomeric
element may be used.
[0051] In another exemplary embodiment, articulating member 22 may
comprise a modified screw cap or top configured to engage the screw
head. In this regard, a standard or typical pedicle screw may be
utilized with a modified cap. In another embodiment, superior
articulating member 22 may comprise a connector portion 38 to allow
lockable angulation and provide the optimum position of bearing
surface 30. Referring to FIG. 23, in one embodiment articulating
caps 22 may have a generally flat or plate like shape and include a
bearing surface 30 to engage a similar adjacent cap. In the
aforementioned embodiments, the superior articulating member may be
positioned such that it has the appropriate cephalad and caudad
directions as well as the appropriate medial/lateral angulation for
the given level of the spine where the prosthetic is implanted.
[0052] The articulating members 20, 22 may be made of various
materials commonly used in the prosthetic arts including, but not
limited to, polyethylene, rubber, titanium, titanium alloys, chrome
cobalt, surgical steel, or any other total joint replacement metal
and/or ceramic, bony in-growth surface, sintered glass, artificial
bone, any uncemented metal or ceramic surface, or combination
thereof.
[0053] In the embodiment of FIGS. 4-5, a prosthetic device 10 is
shown wherein the inferior and/or superior halves of facet joints
are replaced on one side of a given vertebra (unilateral). Those
skilled in the art will appreciate that facet joints may be
replaced on both sides of a given vertebra (bilateral) utilizing
prosthetic device 10, as shown in FIG. 6, or a combination of each
along a length of the spinal column.
[0054] Referring to FIG. 7, another embodiment of a facet joint
prosthesis 40 according to the invention is shown. In general,
prosthesis 40 comprises a bilateral device and facet joints may be
replaced on both sides of a given vertebra. Prosthesis 40 is
similar to prosthesis 10 described above and generally comprises an
inferior prosthetic segment 42 and a superior prosthetic segment
44. In this embodiment, inferior segment 42 comprises bilateral
anchor members 46, 48 and a single bilateral articulating member
50. Articulating member 50 may be a single unitary piece or may
comprise two or more separate pieces that may be assembled in-situ.
Superior prosthetic segment generally comprises bilateral anchor
members 52, 54 and bilateral articulating members 56, 58, similar
to articulating member 22 described above with respect to FIGS.
4-5. Articulating member 50 comprises a pair of generally convex
articulating or bearing surfaces 60 separated laterally on both
sides of a given vertebra. Articulating members 56, 58 comprise
generally concave articulating or bearing surfaces 62, and surfaces
60, 62 are configured and dimensioned to contact or engage one
another, as described above. When the total facet joint is
replaced, as shown in FIG. 7, then surfaces 60 articulate with
surfaces 62 to recreate the natural biomechanics of the spine
motion segment made up of vertebra 41, vertebra 43, and
intervertebral disc 45.
[0055] In one exemplary embodiment, the articulating member 50
comprises bilateral rod portions 70, 72, each configured and
dimensioned to engage an anchor, such as a pedicle screw, in a
similar manner as described above with respect to prosthetic 10.
Articulating member 50 is sized and shaped to span the distance
between a pedicle and the inferior articular processes and provide
space or an opening for the spinous process. In this regard, facet
prosthesis 40 extends from its anchor point in a manner that does
not require contact with, or mating to, the complex geometry of the
lamina or posterior arch. Also, articulating member 50 is
configured and dimensioned to be implanted without removal or
resection of the spinous process. In one variation of articulating
member 50, a flexible element 74 may be positioned between the
anchors 46, 48 and articulating surfaces 60. One type of flexible
element that may be used is disclosed in U.S. patent application
Ser. No. 10/762,533, filed Jan. 23, 2004, the entire contents of
which are incorporated by reference. In alternate embodiments, a
spring or other resilient or elastomeric element may be used.
[0056] Referring to FIGS. 8-9, another embodiment of a facet joint
prosthesis 80 according to the invention is shown. In general,
prosthesis 80 comprises a bilateral device to replace facet joints
on both sides of a given vertebra. Prosthesis 80 is similar to
prosthesis 40 described above, except inferior prosthetic segment
82 is configured to attach to the spinous process 86 on the
superior vertebral body 81. In this regard, articulating member 88
of inferior segment 82 comprises a connecting portion 90 configured
to contact, engage, or otherwise connect to spinous process 86. In
one variation, shown in FIGS. 8 and 9, connecting portion 90
comprises a trough or H-shaped cross-section configured and
dimensioned to extend upward from the underside of the spinous
process 86 along either side of the spinous process. A slot or
through-hole 92 extends laterally through connecting portion 90 to
accommodate a trans-spinous fixation element 94, including, but not
limited to, an anchor, pin, screw, or other device to fix
articulating member 88 to spinous process 86. In all other
respects, prosthesis 80 functions in a similar fashion as
prosthesis 40 described above.
[0057] Referring to FIG. 10, an alternate embodiment of a bilateral
prosthesis 100 to replace facet joints on both sides of a given
vertebra is shown. Prosthesis 100 is similar to prosthesis 40, 80
described above, except inferior prosthetic segment 102 and
superior prosthetic segment 104 are configured to attach directly
to the superior vertebral body 101 and inferior vertebral body 103,
respectively, as opposed to the pedicles, or spinous process. In
this regard, articulating member 106 of inferior segment 102, and
articulating member 108 of superior segment 104 comprise one or
more holes, slots, or openings 110 extending therethrough
configured receive or accommodate one or fixation elements 112. Any
type of fixation element 112 may be used, including, but not
limited to, an anchor, pin, screw, staple or other device to fix
articulating members 106, 108 to vertebral bodies 101, 103. In all
other respects, prosthesis 100 functions in a similar fashion as
prosthesis 40, 80 described above.
[0058] Referring to FIG. 11, an alternate embodiment of
articulating surfaces 28, 30 of a facet joint prosthesis 120 is
shown. In this embodiment, superior bearing surface 30 and inferior
bearing surface 28 may be at least partially interlocked to provide
constrained articulation. In this regard, superior bearing surface
30 may be grooved, cupped, or otherwise generally concave and may
include capture arms 122 to at least partially enclose superior
bearing surface 30 to define a general keyhole cavity. Inferior
bearing surface 28 has a key shaped cross-sectional profile and is
configured and dimensioned to be received or captured within the
partially enclosed superior bearing surface 30 to provide
"captured" or constrained articulation or movement. In that regard,
when surface 28 engages surface 30, capture arms 122 are configured
and dimensioned to extend inward about an indented profile portion
of inferior surface 28 such that inferior articulating member 20 is
captured within articulating member 22. The outer perimeter of
inferior bearing surface 28 is smaller than the inner perimeter of
the superior surface 30 such that inferior bearing surface 28 can
move with respect superior bearing surface 30. In one variation,
surfaces 28, 30 may directly contact each other, and in other
embodiments, a polyethylene insert 124 may be interposed between
the surfaces.
[0059] Referring to FIGS. 12-13, an alternate embodiment of
articulating surfaces 28, 30 of a facet joint prosthesis 130 is
shown. In this embodiment, superior bearing surface 30 and inferior
bearing surface 28 provide a protrusion 132 and track 134
configuration to provide at least partially constrained
articulation.
[0060] Referring to FIG. 14, another embodiment of a prosthesis 140
is shown having an alternative joint interface 142. In this
embodiment, inferior segment 144 and superior segment 146 of
prosthetic 140 are joined or connected by a flexible member 148.
Flexible member 148 comprises a soft material such as an elastomer
or rubber that is attached to articulating members 150, 152 and may
encapsulate the articulating surfaces. In operation, flexible
member 148 of joint interface 142 provides constrained relative
movement between articulating members 150, 152 as well as glide and
cushioning ability to replicate the natural biomechanics of the
spine.
[0061] Referring to FIG. 15, another embodiment of a facet joint
prosthesis 160 is shown having an alternative joint interface 162.
In this embodiment, inferior segment 164 and superior segment 166
of prosthetic 160 are joined or connected by linkages 168. In one
embodiment, linkages 168 may comprise surgical cable, suture,
elastomer or rubber bands, or any other suitable linkage. In
operation, linkages 168 of joint interface 162 provide constrained
relative movement between articulating members 170, 172 to
replicate the natural biomechanics of the spine.
[0062] Referring to FIGS. 16-17, another embodiment of a facet
joint prosthesis 180 is shown. In this embodiment, superior segment
182 and inferior segment 184 are inter-connected by a flexible
sleeve 186. In one embodiment, sleeve 186 is made from an elastomer
material. Superior and inferior segments 182, 184 comprise
articulating members 190, 192 having a ball or spherical shaped
head portion 194. Sleeve 186 has sockets 196 to accommodate head
portions 194 and link articulating member 190 to articulating
member 192. Sockets 196 permit rotational movement of articulating
members 190, 192 with respect to the sleeve 186. Also, the
resiliency of sleeve 186 permits distraction and compression
between articulating members 190, 192. In operation, sleeve 186
provides constrained relative movement between articulating members
190, 192 as well as glide and cushioning ability to replicate the
natural biomechanics of the spine.
[0063] Referring to FIG. 18, another embodiment of a facet joint
prosthesis 200 is shown. In this embodiment, superior member 202
comprises an anchor portion 204 and an integrated articulating
portion 206. Inferior member 208 comprises an anchor portion 210
and an integrated articulating portion 212. Articulating portion
206 comprises a ball or spherical shaped head member 214 and
articulating portion 212 of inferior member 208 generally comprises
a socket or slot 216 to receive head member 214 and link
articulating portion 206 to articulating portion 212. Slot 216
permit rotational movement of articulating portion 206 with respect
to articulating portion 212. A spring 218 may be housed within slot
216 to provide resiliency and allow distraction and compression
between articulating portions 206, 212. In operation, slot 216
provides constrained relative movement between articulating
portions 206, 212 as well as glide and cushioning ability to
replicate the natural biomechanics of the spine.
[0064] Referring to FIG. 19, another embodiment of a facet joint
prosthesis 220 is shown including an alternate embodiment of
articulating surfaces 28, 30. In this embodiment, superior bearing
surface 30 comprises a cylindrical convex surface and inferior
bearing surface 28 comprises a matching cylindrical concave surface
to provide at least partially constrained articulation about one
arcuate or cylindrical path in a single plane. Movement of inferior
prosthetic member 222 about superior prosthetic member 224 in all
other planes is constrained or limited by side walls 226 of
superior surface 30. In one embodiment inferior and superior
members 22, 224 are angularly lockable to adjust and/or the plane
of action. In one variation, members 222, 224 may be locked post
operatively via a percutaneous procedure.
[0065] Referring to FIG. 20, an alternate embodiment of a facet
joint prosthesis 230 is shown. In this embodiment, cables 232, 234
may extend from a first anchor member 236 attached to the superior
vertebra 238 to anchor members 240, 242 attached to the inferior
vertebra 244. In one embodiment, first anchor member 236 comprises
a pin extending through the spinous process or a ring or clip
extending around the spinous process of vertebra 238. In another
embodiment, anchor members 240, 242 comprise clips or rings
extending about the transverse process of vertebra 244. Cables 232,
234 extend between anchor 236 to anchors 240, 242 to link the
superior and inferior vertebral bodies to mimic the natural
biomechanics of the spine.
[0066] Referring to FIG. 21, another embodiment of a facet joint
prosthesis 240 is shown. In this embodiment, bilateral superior
articulating members 242, 244 may be anchored to a vertebra or
sacrum 248 to a central anchor 246. A pair of inferior articulating
members 250, 252 may be anchored bilaterally on the superior
vertebral body 254. Flexible elements 247 may be interposed between
anchor 246 and articulating members 250, 252. Flexible elements 247
may be similar to the flexible elements 36 and 74 of previously
described embodiments.
[0067] Referring to FIG. 22, another embodiment of a facet joint
prosthesis 260 is shown. In this embodiment, superior member 262
comprises an anchor portion 264 and an integrated articulating
portion 266. Inferior member 268 comprises an anchor portion 270
and an integrated articulating portion 272. Articulating portion
272 comprises a ball or spherical shaped head member 274 and
articulating portion 266 of superior member 262 generally comprises
a socket 276 to receive head member 274 and link articulating
portion 266 to articulating portion 272. Socket 276 permits
rotational movement of articulating portion 272 with respect to
articulating portion 266. In operation, socket 276 provides
constrained relative movement between articulating portions 266,
272 to replicate the natural biomechanics of the spine.
[0068] Referring to FIGS. 24-25, another embodiment of a facet
joint prosthesis 280 according to the invention is shown. In
general, prosthesis 280 comprises a device attached to the spinous
processes of a motion segment to replace or replicate the facet
joint(s) on one or both sides of a given vertebra. Prosthesis 280
generally comprises a straddle or yoke portion 283 configured to
attach to the spinous processes 286 on the superior vertebral body
281 and a post or fin protrusion portion 284 configured to attach
to the spinous processes 288 on the inferior vertebral body 282. As
best seen in FIG. 24, yoke portion 283 comprises a trough or
U-shaped cross-section configured and dimensioned to extend from
the underside of the spinous process 286 along either side of the
spinous process. Fin protrusion portion 284 comprises a straight
cross-section configured and dimensioned to extend from the topside
of the spinous process 288 and fit within the U-shaped
cross-section of yoke portion 283. In this regard, fin protrusion
284 may articulate within yoke 283 to replicate the constrained
movement of a natural facet joint. One or more slots or
through-holes 292 may extend laterally through yoke portion 283 and
fin portion 284 to accommodate a trans-spinous fixation element
294, including, but not limited to, an anchor, pin, screw, or other
device to fix yoke portion 283 and fin portion 284 to spinous
processes 286, 288 respectively.
[0069] Referring to FIG. 26, another embodiment of a facet joint
prosthesis 300 according to the invention is shown. In general,
prosthesis 300 comprises a device that functions similar to
prosthesis 280, described above, except that it is attached to the
adjacent vertebral bodies of a motion segment by, for example,
pedicle screws. Prosthesis 300 generally comprises a straddle or
yoke portion 303 attached to a superior vertebral body 301 and a
post or fin protrusion portion 304 on the inferior vertebral body
302. As best seen in FIG. 26, yoke portion 303 comprises a trough
or U-shaped cross-section adjacent the underside of the spinous
process 306. Fin protrusion portion 304 comprises a straight
cross-section configured and dimensioned to extend adjacent the
topside of the spinous process 308 and fit within the U-shaped
cross-section of yoke portion 303. In this regard, fin protrusion
304 may articulate within yoke 303 to replicate the constrained
movement of a natural facet joint. One or more slots or
through-holes 312 may extend through yoke portion 303 and fin
portion 304 to accommodate a fixation element 314, including, but
not limited to, an anchor, pin, screw, or other device to fix yoke
portion 303 and fin portion 304 to vertebral bodies 301, 302,
respectively.
[0070] Referring to FIG. 27-29, alternative embodiments of facet
joint prostheses 400, 420, and 440 according to the invention are
shown. In general, prosthesis 400, 420 and 440 comprise bilateral
devices and facet joints may be replaced on both sides of a given
vertebra. Prostheses 400, 420 and 440 generally comprise an
inferior prosthetic segment 402 and a superior prosthetic segment
404. According to one variation, inferior and superior segments
402, 404 may be attached to adjacent vertebral bodies respectively,
to mimic the natural facet joints and the natural biomechanics of
the spine.
[0071] Referring to the embodiment of FIGS. 27A-27B, inferior
segment 402 of device 400 comprises a pair of bilateral
articulating members 406, 408 extending in a downward or inferior
direction from a lateral cross-member or support 410. Support 410
generally comprises a bar, rod, or other like structure, extending
generally along a lateral axis 412. In one embodiment, articulating
members 406, 408 generally comprise thin-walled straight, planar,
plate-like members extending generally transverse to the axis 412
of support 410. Articulating members 406, 408 are generally spaced
laterally a sufficient distance to be positioned on either side of
the spinous process of the vertebral body to which the inferior
segment 402 is attached. Articulating members 406, 408 are
generally configured and dimensioned to fit within, interact with,
or otherwise engage the superior articulating members 416, 418. In
one embodiment, articulating members 406, 408 have a generally
triangular shape with a ramped or angled surface or edge 417 along
the anterior side thereof. The angled surface 417 generally tapers
from a wider base portion at the top to a narrow tip at the bottom.
One skilled in the art may appreciate, in operation such a ramped
anterior facilitates a gliding or smooth movement rather than a
dead stop, particularly in cases of forward translation.
[0072] Superior prosthetic segment 404 generally comprises a pair
of bilateral articulating members 416, 418 extending in an upward
or superior direction from a lateral support 414. Articulating
members 416, 418 are generally spaced laterally a sufficient
distance to be positioned on either side of the spinous process of
the vertebral body to which the superior segment 404 is attached.
Support 414 is similar to support 410 and generally comprises a
bar, rod, or other like structure, extending generally along a
lateral axis 415. In one variation, supports 410, 414 may comprise
cylindrical rods which may be readily attached to the vertebral
structure of a patient using known tools and techniques, including
but not limited to, using pedicle screws and pedicle screw
insertion techniques known to those skilled in the art. In one
embodiment, shown in FIGS. 27A-27B, articulating members 416, 418
generally comprise a rectangular cup or socket-like structure, each
configured and dimensioned for receiving an articulating member
406, 408. The interior or inner portion of articulating members
416, 418 generally comprise articulating or bearing surfaces
configured to contact or engage articulating members 406, 408 to
guide and limit motion of the superior and inferior prosthetic
segments with respect to each other. In the embodiment of FIG.
27A-27B, the articulating members 416, 418 comprise rectangular
wall members substantially surrounding articulating members 406,
408 laterally and posteriorly. In this regard, when device 400 is
assembled or installed, articulating members 416, 418 generally
limit or constrain rotation and lateral translation of the inferior
segment 402 with respect to the superior segment 404. According to
one variation, inferior and superior segments 402, 404 may be
attached to adjacent vertebral bodies respectively to replace the
facet joints and members 406, 408 may articulate with members 416,
418 to recreate the natural biomechanics of the spine motion
segment. According to one embodiment, one or more through-holes 419
may extend through articulating members 416, 418 to accommodate a
fixation element, including, but not limited to, an anchor, pin,
screw, or other device to fix articulating members 406, 408 to
articulating members 416, 418 and prevent relative movement between
the inferior and superior segments 402, 404, respectively. As with
previous embodiments, prosthetic 400 and inferior and superior
segments 402, 404 may be made of various materials commonly used in
the prosthetic arts including, but not limited to, polyethylene,
rubber, titanium, titanium alloys, chrome cobalt, surgical steel,
or any other total joint replacement metal and/or ceramic, bony
in-growth surface, sintered glass, artificial bone, any uncemented
metal or ceramic surface, or combination thereof. In one particular
embodiment, inferior and superior segments 402, 404 may be made
from a titanium or metal material and may include polyethylene
bearing or mating surfaces.
[0073] Referring to FIGS. 28A-28B, another embodiment of a facet
joint prosthesis 420 is shown. Prosthesis 420 is similar to
prosthesis 400 except articulating members 416, 418 generally
comprise a partial rectangular cup or socket-like structure. The
interior or inner portion of articulating members 416, 418
generally comprise articulating or bearing surfaces configured to
contact or engage articulating members 406, 408 to guide and limit
motion of the superior and inferior prosthetic segments with
respect to each other. In the embodiment of FIG. 28A-28B, the
articulating members 416, 418 comprise partial rectangular wall
members that are positioned to contact or engage articulating
members 406, 408 along the medial lateral and anterior walls. In
this regard, when device 420 is assembled or installed,
articulating members 416, 418 is generally less limiting or
constraining to extension and anterior-posterior translation of a
patient's vertebrae and allows relative movement of the inferior
segment 402 with respect to the superior segment 404.
[0074] Referring to FIGS. 29A-29B, another embodiment of a
bilateral facet joint prosthesis 440 is shown. Inferior segment 402
of device 440 comprises a pair of bilateral articulating members
446, 448 extending in a downward or inferior direction from a
lateral cross-member or support 450. In this embodiment,
articulating members 446, 448 are generally hook shaped and
comprise articulating or bearing surfaces 452 along the anterior
side thereof. Articulating members 446, 448 are generally
configured and dimensioned to fit around, interact with, or
otherwise engage the superior articulating member 456.
[0075] Superior prosthetic segment 404 generally comprises a
superior articulating member 456 extending from a lateral
cross-member or support 454. Articulating member 456 generally
comprises a T-shaped body 458 attached to support 454. Body 458
generally comprises articulating surfaces 460, 462 spaced laterally
about a central posterior extending nose portion 461. Articulating
surfaces 460, 462 are configured to contact or engage articulating
or bearing surfaces 452 of members 446, 448 to guide and limit
motion of the superior and inferior prosthetic segments 402, 404
with respect to each other. In this embodiment, when device 440 is
assembled or installed, nose portion 461 is positioned to contact
or engage articulating members 446, 448 along the inner lateral
portion thereof and generally limit or constrain rotation and
lateral translation of the inferior segment 402 with respect to the
superior segment 404. According to one variation, inferior and
superior segments 402, 404 may be attached to adjacent vertebral
bodies respectively to replace the facet joints and members 446,
448 may articulate with member 456 to recreate the natural
biomechanics of the spine motion segment. In this embodiment,
articulating member 456 may be made from a polyethylene
material.
[0076] Referring to FIGS. 30A-30B, another embodiment of a facet
joint prosthesis 480 is shown having an alternative articulating
joint interface 482. In this embodiment, inferior segment 484 and
superior segment 486 of prosthetic 480 are joined or connected by a
hook/hinge configuration. The inferior segment 484 generally
comprises a hook-like structure 485 extending from the end of a
support portion 487. In one variation, support portion 487 may
comprise a cylindrical structure such as a rod extending upward for
screw attachment. Hook 485 generally comprises a curved portion 489
transitioning to a generally flat plate portion 491 and plate
portion 491 is generally perpendicular to support portion 487.
Superior segment 486 generally comprises a receiver member or head
488 extending from a support portion 490. In one variation, support
portion 490 may comprise a cylindrical structure such as a rod
extending downward for screw attachment. In one embodiment, head
488 generally comprises a hollow rectangular or box like structure
that only has top, bottom and side walls, with no front or back
wall. In operation, plate portion 491 fits into the hollow interior
portion of receiver 488. In one embodiment, plate portion 491 may
be strengthened by adding a gusset 492 that may mate into a cutout
494 in the top of receiver 488 when installed. As best seen in FIG.
30B, in another embodiment, a rounded transition portion 496 may be
provided adjacent one of the posterior or anterior sides of
receiver 488 to accommodate engagement with curved portion 489 of
hook 485. In operation, hook 485 may rotate with respect to
receiver 488 and curved portion 489 may contact or engage
transition portion 496 to facilitate such rotational movement.
According to one embodiment, when prosthesis 480 is installed,
transition portion 496 and curved portion 489 may be positioned in
a posterior facing orientation to facilitate articulation during
flexion and extension of a patient's spine. As with previous
embodiments, inferior and superior segments 484, 486 of prostheses
480, 510, and 520 may be made of various materials commonly used in
the prosthetic arts including, but not limited to, polyethylene,
rubber, titanium, titanium alloys, chrome cobalt, surgical steel,
or any other total joint replacement metal and/or ceramic, bony
in-growth surface, sintered glass, artificial bone, any uncemented
metal or ceramic surface, or combination thereof. In one particular
embodiment, inferior and superior segments 484, 486 may be made
from a titanium or metal material.
[0077] Referring to FIGS. 31-32, alternative embodiments of facet
joint prostheses 500, 510 according to the invention are shown.
Prostheses 500, 510 are similar to prosthesis 480 described above,
except an alternative articulating joint interface 482 between the
inferior and superior segments is provided. In one variation of
prosthesis 500, shown in FIGS. 31A-31B, the distal end of hook 485
may be altered to include a generally cylindrical tip 502 instead
of a flat plate portion 491. The interior of receiver 488 may have
a generally matching or mating interior shape to accommodate tip
502 therein and facilitate constrained movement between the
inferior and superior segments 484, 486. In operation, hook 485 may
rotate or articulate with respect to receiver 488 and cylindrical
tip 502 may contact or engage the cylindrically shaped interior to
facilitate rotational movement in a single plane. According to one
embodiment, when prosthesis 500 is installed, cylindrical portion
may be orientated to facilitate articulation during flexion and
extension of a patient's spine.
[0078] In another embodiment, shown in FIGS. 32A-32B, the distal
end of hook 485 of prosthesis 510 may be altered to include a
generally spherical tip 512. The interior of receiver 488 may have
a generally matching or mating interior shape to accommodate tip
512 therein and facilitate constrained movement between the
inferior and superior segments 484, 486. In operation, hook 485 may
rotate or articulate with respect to receiver 488 and cylindrical
tip 512 may contact or engage the spherically shaped interior to
facilitate rotational or articulation movement in multiple planes.
According to one embodiment, when prosthesis 510 is installed, the
inferior and posterior segments 484, 486 may rotate or articulate
during flexion, extension, or torsion of a patient's spine.
[0079] In another embodiment, shown in FIGS. 33-34, alternative
embodiments of facet joint prostheses 520, 530 according to the
invention are shown. Prostheses 520, 530 are similar to prosthesis
510 described above, except an alternative articulating joint
interface 482 between the inferior and superior segments is
provided. In general, prostheses 520, 530 may include a sleeve or
insert member 522 inserted into the inner of receiver 488 and
generally interposed between the hook member 485 and receiver 488.
In one embodiment, insert member 522 may be made from a
polyethylene material to provide altered or enhanced wear
characteristics as compared to metal on metal contact. In yet
another embodiment, insert member 522 may be made from a
polyurethane or other like flexible material to provide a
cushioning or a dampening characteristic to the articulating joint.
In one variation of prosthesis 530, shown in FIGS. 34A-34C, insert
member 522 may be screwed into the interior portion of receiver
488. In another embodiment of a prosthesis 520, the interior of
receiver 488 may have an insert member 522 slidably or snapped into
the interior portion of receiver 488. Insert member 522 generally
encapsulates the distal tip of hook 485 having an interior shape to
accommodate and/or mate the distal tip and to facilitate
constrained movement between the inferior and superior segments
484, 486. In operation, hook 485 may contact or engage insert 522
and the distal tip may articulate or rotate with respect
thereto.
[0080] While the invention herein disclosed has been described by
means of specific embodiments and applications thereof, numerous
modifications and variations can be made thereto by those skilled
in the art without departing from the scope of the invention.
* * * * *