U.S. patent application number 11/370537 was filed with the patent office on 2006-07-13 for intervertebral disk prosthesis.
This patent application is currently assigned to Concept Matrix, LLC. Invention is credited to Walter W. Eckman.
Application Number | 20060155378 11/370537 |
Document ID | / |
Family ID | 27616749 |
Filed Date | 2006-07-13 |
United States Patent
Application |
20060155378 |
Kind Code |
A1 |
Eckman; Walter W. |
July 13, 2006 |
Intervertebral disk prosthesis
Abstract
An intervertebral disk prosthesis includes a first part, and the
first part has a top, a bottom having an opening, an outer surface,
an inner surface and a socket extending into an interior of the
first part from the opening and defined by the inner surface. The
disk prosthesis further includes a second part including a top, a
bottom, and an outer surface. The outer surface of the second part
proximate the top of the second part cooperatively engages the
inner surface of the first part thereby allowing at least
two-degrees of freedom of movement. At least one of the upper part
and the lower part further comprises at least one arch spanning the
outer surface proximate the top and the outer surface proximate the
bottom, respectively.
Inventors: |
Eckman; Walter W.; (Tupelo,
MI) |
Correspondence
Address: |
AKIN GUMP STRAUSS HAUER & FELD L.L.P.
ONE COMMERCE SQUARE
2005 MARKET STREET, SUITE 2200
PHILADELPHIA
PA
19103
US
|
Assignee: |
Concept Matrix, LLC
|
Family ID: |
27616749 |
Appl. No.: |
11/370537 |
Filed: |
March 8, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10345634 |
Jan 16, 2003 |
7011684 |
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11370537 |
Mar 8, 2006 |
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60349743 |
Jan 17, 2002 |
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60369667 |
Apr 2, 2002 |
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Current U.S.
Class: |
623/17.15 |
Current CPC
Class: |
A61F 2310/00017
20130101; A61F 2220/0025 20130101; A61F 2310/00023 20130101; A61F
2230/0071 20130101; A61F 2/4611 20130101; A61F 2002/30784 20130101;
A61F 2220/0033 20130101; A61F 2310/00179 20130101; A61F 2/30907
20130101; A61F 2002/30797 20130101; A61F 2310/00029 20130101; A61F
2230/0076 20130101; A61F 2002/30807 20130101; A61F 2/4425 20130101;
A61F 2002/4629 20130101; A61F 2002/30253 20130101; A61F 2310/00796
20130101; A61F 2002/4627 20130101; A61F 2002/30242 20130101; A61F
2002/30685 20130101; A61F 2/4603 20130101; A61F 2002/30331
20130101; A61F 2220/0075 20130101; A61F 2002/30112 20130101; A61F
2002/30649 20130101; A61F 2002/3049 20130101; A61F 2002/30462
20130101; A61F 2230/0004 20130101 |
Class at
Publication: |
623/017.15 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61F 2/46 20060101 A61F002/46 |
Claims
1. An intervertebral disk prosthesis having a convexly tapered
distal end, a convexly tapered proximal end, an anterior side and a
posterior side, the intervertebral disk prosthesis comprising: an
upper part including a convexly-shaped and rounded top, a bottom
having an opening, an outer surface, an inner surface and a socket
extending into an interior of the upper part from the opening, the
outer surface proximate the top being configured to contact a
concave portion of a first vertebra; and a lower part including a
top, a convexly-shaped and rounded bottom, and an outer surface,
the outer surface proximate the bottom being configured to contact
a concave portion of a second vertebra that is adjacent to the
first vertebra, and the outer surface of the lower part proximate
the top of the lower part being cooperatively and movably
overlapped by the inner surface of the upper part thereby allowing
at least two-degrees of freedom of movement, at least one of the
upper part and the lower part further comprising at least one arch
spanning the outer surface proximate the top and the outer surface
proximate the bottom, respectively.
2. The intervertebral disk prosthesis of claim 1, wherein the top
of the upper part has an ingrowth opening to encourage vertebral
ingrowth and is configured to align the intervertebral disk
prosthesis within an intervertebral space.
3. The intervertebral disk prosthesis of claim 2, further
comprising a generally continuous sheet of biocompatible porous
material at least partially spanning the ingrowth opening.
4 The intervertebral disk prosthesis of claim 3, wherein the porous
material is hydroxyapatite-coated metal.
5. The intervertebral disk prosthesis of claim 2, further
comprising a mesh structure at least partially spanning the
ingrowth surface.
6. The intervertebral disk prosthesis of claim 2, wherein the upper
part further comprises at least one arch spanning the ingrowth
opening.
7. The intervertebral disk prosthesis of claim 1, wherein the
bottom of the lower part has an ingrowth opening to encourage
vertebral ingrowth and is configured to align the intervertebral
disk prosthesis within an intervertebral space.
8. The intervertebral disk prosthesis of claim 7, further
comprising a generally continuous sheet of biocompatible porous
material at least partially spanning the ingrowth surface.
9. The intervertebral disk prosthesis of claim 8, wherein the
porous material is hydroxyapatite-coated metal.
10. The intervertebral disk prosthesis of claim 7, further
comprising a mesh structure at least partially spanning the
ingrowth surface.
11. The intervertebral disk prosthesis of claim 7, wherein the
lower part further comprises at least one arch spanning the
ingrowth opening.
12. The intervertebral disk prosthesis of claim 1 in combination
with an insertion tool, the insertion tool have a first finger
configured to engage an ingrowth opening in the top of the upper
part, a second finger configured to engage an ingrowth opening in
the bottom of the lower part and a driving member disposed between
the first and second fingers.
13. The combination according to claim 12, wherein the driving
member is configured to engage the intervertebral prosthesis.
14. The combination according to claim 12, wherein the first and
second fingers are retractable relative to the driving member.
15. The combination according to claim 12, wherein when the first
and second fingers are engaged with the ingrowth openings, all
exposed surfaces of the combination are generally round.
16. The combination according to claim 12 further comprising third
and fourth fingers configured to retractably move between the space
between the upper part and the lower part of the intervertebral
prosthesis.
17. The intervertebral disk prosthesis of claim 1, further
comprising a connector configured to temporarily and removably
couple with an insertion tool.
18. The intervertebral disk prosthesis of claim 17, wherein the
connector is one of a threaded shaft, a socket, a detent, a hole
and a slot.
19. The intervertebral disk prosthesis of claim 1, wherein a distal
end of the intervertebral prosthesis is generally bluntly
rounded.
20. The intervertebral disk prosthesis of claim 1, wherein a
proximal end of the intervertebral prosthesis is generally bluntly
rounded.
21. The intervertebral disk prosthesis of claim 1, wherein an
exterior surface of the intervertebral prosthesis is generally
rounded.
22. The intervertebral disk prosthesis of claim 1, wherein the
intervertebral prosthesis is formed at least partially of a
biocompatible material selected from the group consisting of
stainless steel, titanium, cobalt-chrome alloy, nickel plated
metal, a biocompatible alloy, a biocompatible ceramic, and a
biocompatible polymeric material.
23. The intervertebral disk prosthesis of claim 1, further
comprising a pliable, biocompatible slip-cover that covers at least
a portion of the upper part and a portion of the lower part, the
slip-cover being configured to flexibly retain the movably coupled
upper and lower parts.
24. The intervertebral disk prosthesis of claim 1, wherein the
length of the intervertebral prosthesis as measured from the distal
end to the proximal end is between about 10 mm and about 30 mm.
25. The intervertebral disk prosthesis of claim 1, wherein the
width of the intervertebral prosthesis as measured between the
anterior side and the posterior side is between about 10 mm and
about 25 mm.
26. The intervertebral disk prosthesis of claim 1, wherein the
height of the intervertebral prosthesis as measured between the top
of the upper part and the bottom of the lower part is between about
5 mm and about 25 mm.
27. The intervertebral disk prosthesis of claim 1, wherein the
freedom of movement is limited to between about 2-15 degrees tilt
in any direction.
28. The intervertebral disk prosthesis of claim 1, wherein the disk
prosthesis minimizes translational movement.
29. An intervertebral disk prosthesis having a convexly tapered
distal end, a convexly tapered proximal end, an anterior side and a
posterior side, the intervertebral disk prosthesis comprising: an
upper part including a convexly-shaped and rounded top, a bottom
having an opening, an outer surface, an inner surface and a socket
extending into an interior of the upper part from the opening, the
outer surface proximate the top being configured to contact a
concave portion of a first vertebra; and a lower part including a
top, a convexly-shaped and rounded bottom, and an outer surface,
the outer surface proximate the bottom being configured to contact
a concave portion of a second vertebra that is adjacent to the
first vertebra, and the outer surface of the lower part proximate
the top of the lower part being cooperatively and movably
overlapped by the inner surface of the upper part thereby allowing
at least two-degrees of freedom of movement, at least one of the
upper part and the lower part further comprising at least one
sharpened cone disposed thereon being configured to subside into
vertebral bone.
30. An intervertebral disk prosthesis having a convexly tapered
distal end, a convexly tapered proximal end, an anterior side and a
posterior side, the intervertebral disk prosthesis comprising: an
upper part including a convexly-shaped and rounded top, a bottom
having an opening, an outer surface, an inner surface and a socket
extending into an interior of the upper part from the opening, the
outer surface proximate the top being configured to contact a
concave portion of a first vertebra; and a lower part including a
top, a convexly-shaped and rounded bottom, and an outer surface,
the outer surface proximate the bottom being configured to contact
a concave portion of a second vertebra that is adjacent to the
first vertebra, and the outer surface of the lower part proximate
the top of the lower part being cooperatively and movably
overlapped by the inner surface of the upper part thereby allowing
at least two-degrees of freedom of movement, at least one of the
upper part and the lower part further comprising at least one arch
having a partially sharpened edge spanning the outer surface
proximate the top and the outer surface proximate the bottom,
respectively.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional of co-pending U.S. patent
application Ser. No. 10/345,634 filed Jan. 16, 2003 entitled
"INTERVERTEBRAL DISK PROSTHESIS." This application is related to
U.S. patent application Ser. No. 10/951,317, filed Sep. 27, 2004.
This application claims the benefit of U.S. Provisional patent
application Ser. No. 60/349,743, filed Jan. 17, 2002 and U.S.
Provisional patent application No. 60/369,667, filed Apr. 2,
2002.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an apparatus for
intervertebral disk replacement and more particularly to an
intervertebral disk prosthesis capable of being implanted in a
patient utilizing minimally invasive surgical techniques.
[0003] Referring to prior art FIGS. 9 and 10, the spine 120, also
known as the vertebral column or the spinal column, is a flexible
column of vertebrae 100 (special types of bones) held together by
muscles, ligaments and tendons. The spine 120 extends from the
cranium (not shown) to the coccyx 126, encasing a spinal cord 128
and forming the supporting axis of the body (not shown). The spinal
cord 128 is a thick bundle of nerve tissue (nerves) that branch off
to various areas of the body for the purposes of motor control,
sensation, and the like. The spine 120 includes seven cervical
vertebrae (not shown), twelve thoracic vertebrae (not shown), five
lumbar vertebrae, L.sup.I-L.sup.V, five sacral vertebrae,
S.sup.I-S.sup.V, and three coccyx vertebrae 126. The sacral and
coccyx vertebrae are each fused, thereby functioning as a single
unit. FIG. 10 shows the lumbar region 122, the sacral region 124
and the coccyx 126 of the spine 120 and that the vertebrae 100 are
stacked one upon another. The top portion 100a and bottom portion
100b of each vertebrae 100 is slightly concave. The opposing
concave vertebral surfaces form the intervertebral space 121 in
which an intervertebral disk (not shown) resides. Each of the
intervertebral disks has a soft core referred to as a nucleus
pulposus or nucleus (not shown).
[0004] In FIG. 9, directional arrow 101a is pointing in the
posterior direction and directional arrow 101b is pointing in the
anterior direction. FIG. 9 shows that each vertebrae 100 includes a
body 106 in the innermost portion, a spinal canal 108 and a spinous
process 102 at the posterior-most end of the vertebra 100. The
vertebrae 100 are substantially similar in composition, but vary in
size from the larger lumbar vertebrae to the smallest coccyx
vertebrae 126. Each vertebrae 100 further includes two transverse
processes 104 located on either side and a protective plate-like
structure referred to as a lamina 110. Nerves from the spinal cord
128 pass through the spinal canal 108 and foramina 111 to reach
their respective destinations within the body.
[0005] The natural aging process can cause a deterioration of the
intervertebral disks, and therefore, their intrinsic support
strength and stability is diminished. Sudden movements may cause a
disk to rupture or herniate. A herniation of the disk is primarily
a problem when the nucleus pulposus protrudes, bulges or ruptures
into the spinal canal 108 placing pressure on nerves which in turn
causes spasms, tingling, numbness, and/or pain in one or more parts
of the body, depending on the nerves involved. Further
deterioration of the disk can cause the damaged disk to lose height
and as bone spurs develop on the vertebrae 100, result in a
narrowing of the spinal canal 108 and foramen 111 (not shown
clearly), and thereby causes pressure on the nerves emanating from
the spinal cord 128.
[0006] Presently, there are several techniques, in addition to
non-surgical treatments, for relieving the symptoms related to
intervertebral disk deterioration. Surgical options include
chemonucleolysis, laminectomy, diskectomy, microdiskectomy, and
spinal fusion.
[0007] Chemonucleolysis is the injection of an enzyme, such as
chymopapain, into the disk to dissolve the protruding nucleus
pulposus. The enzyme is a protein-digesting enzyme and is used to
dissolve the disk material. Since the enzyme is essentially a
tissue-dissolving agent, it is indiscriminate in the protein-based
matter it dissolves. Should the enzyme be injected into the wrong
place, or if there is a breach in the disk capsule that would allow
the solution to enter the spinal canal or to contact nerve tissue
or the like, the resultant damage to nerve tissue could not be
reversed. Even worse, about half of the patients who receive
chemonucleolysis treatments experience increased back pain and
muscle spasms immediately after the injection and more than half
have incapacitating back pain for durations up to three months
after such treatments.
[0008] A laminectomy is performed to decompress the spinal canal
108 by open surgical techniques under general anesthesia. In this
procedure, the lamina 110, (the bone that curves around and covers
the spinal canal 108 as shown in FIG. 9), and any disk tissue
causing pressure on a nerve or the spinal canal 108, are partially
removed. This technique is highly invasive and traumatic to the
body, and therefore requires an extended recovery time of about
five weeks and a hospital stay of a few days. In addition to the
trauma inflicted on the body from even a successful surgery, there
are increased risks of future problems due to the removed portion
of the lamina 110 which is no longer in place to support and
protect the spinal canal 108 at the area where the surgery took
place. Further, the vertebrae 100 may shift due to the lack of
support in the structure. Thus, simply removing the disk and parts
of the vertebral bone is a short-term, pain-relieving corrective
action but not a long-term solution.
[0009] Diskectomy is a form of spinal surgery wherein part of an
intervertebral disk is excised typically through open surgical
techniques. Recently, less invasive techniques referred to as
percutaneous diskectomy or microdiskectomy have been developed to
reduce the surgical trauma to the patient. In microdiskectomy, a
much smaller incision is made than in normal open surgeries. A
small retractor, working channel or tube is inserted through the
posterior muscles (not shown) to allow access to the intervertebral
space of a damaged or herniated disk. Surgeons utilize special
surgical instruments modified to work in such small openings such
as curettes, osteotomes, reamers, probes, retractors, forceps, and
the like to cut and remove part of the disk while monitoring their
technique using a microscope, a fluoroscope (real-time X-ray
monitoring), and/or an endoscope (a miniature TV camera with
associated viewing monitor). While this technique is much less
invasive than conventional open surgeries, due to their design the
instruments presently available tend to extend the length of time
of the surgery and may cause possible damage to areas other than
the herniated disk.
[0010] The removal of a significant amount of disk material or
numerous surgeries often increases the instability of the spine 120
thereby necessitating spinal fusion surgery. In a fusion procedure,
a damaged disk may be completely removed. Parts of a bone from
another part of the body, such as the pelvis, are harvested, and
the bone parts or grafts are subsequently placed between the
adjacent vertebrae 100 so that the adjacent vertebrae 100 grow
together in a solid mass. In the fusion surgery, which is presently
performed as an open surgical technique, the posterior lamina 110
and the centers of the vertebral bodies 106 may both be cut. The
surgery often involves consequential damage to the associated
posterior ligaments, muscles and joints in addition to the removal
of part or all of the lamina 110. The recovery time for a normal
spinal fusion surgery is significant due not only to the fact that
normal movement cannot be allowed until detectable bone growth has
occurred between the bone grafts and the adjacent vertebrae 100,
but the associated ligaments, muscles and the location where the
bone grafts were harvested must also recover. Oftentimes portions
of the spine 120 must be immobilized during the recovery period
causing added discomfort and inconvenience to the patient.
[0011] A relatively new concept (within the past two decades) is
intervertebral total disk replacement or nucleus pulposus (nuclear)
replacement. Nuclear replacements are generally designed with
either a water retaining chemical in a compartment (bag-like
container) or with various woven fiber or pad configurations using
synthetic materials as a support cushion. In concept, nuclear
replacements have significant potential because the annulus and the
endplates are substantially preserved, so long as they were not
damaged by previous trauma. However, to date, the available nuclear
replacements lack the strength of a human disk nucleus pulposus
matter and/or the damage to the annulus during implantation may
allow extrusion of the nuclear replacement not unlike a disk
herniation.
[0012] The prior art devices for total disk replacements are
generally made with opposing metal bodies and an interstitial
polyethylene plastic body or the like. The greatest difficulty to
date has been designing a mechanical structure that closely matches
that of the human intervertebral disk with regard to such
properties as compression, flexion, extension, torsion and the
like, not to mention in endurance/durability. Further, prior art
intervertebral disk implants are typically as large as a human
intervertebral disk so as to match the vertebrae 100 thereby
distributing the compressive loads over a greater area, but
necessitating extensive open surgery. Even worse, critical support
materials, such as the ligaments and endplate 110, are usually cut
away during the surgical procedure leaving the newly implanted disk
replacement with less stability.
[0013] What is required, but not presently provided by the prior
art devices and methods, is a device for replacing damaged, failed,
and/or removed intervertebral disks that is able to be implanted in
a minimally invasive procedure, is easy to use, safe to insert into
the body during surgery, and which allows a range of motion in
adjacent vertebrae similar to that of the human intervertebral
disk. What is further required is an artificial disk or disk
prosthesis that allows for rapid patient recovery times and that
can be used on an outpatient basis.
BRIEF SUMMARY OF THE INVENTION
[0014] Briefly stated, the present invention comprises an
intervertebral disk prosthesis. The disk prosthesis includes a
first part having a top, a bottom having an opening, an outer
surface, an inner surface and a socket extending into an interior
of the first part from the opening and defined by the inner
surface. The outer surface proximate the top contacts a concave
portion of a first vertebra. The disk prosthesis further includes a
second part including a top, a bottom, and an outer surface. The
outer surface proximate the bottom contacts a concave portion of a
second vertebra, and the outer surface of the second part proximate
the top of the second part cooperatively engages the inner surface
of the first part thereby allowing at least two-degrees of freedom
of movement.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0015] The foregoing summary, as well as the following detailed
description of preferred embodiments of the invention, will be
better understood when read in conjunction with the appended
drawings. For the purpose of illustrating the invention, there are
shown in the drawings embodiments which are presently preferred. It
should be understood, however, that the invention is not limited to
the precise arrangements and instrumentalities shown.
[0016] In the drawings:
[0017] FIG. 1 is a perspective view of a disk prosthesis in
accordance with a first preferred embodiment of the present
invention;
[0018] FIG. 2 is a side elevational view of the disk prosthesis of
FIG. 1;
[0019] FIG. 3 is a front elevational view of the disk prosthesis of
FIG. 1;
[0020] FIG. 4 is a top plan view of the disk prosthesis of FIG.
1;
[0021] FIG. 5 is a side sectional view of the disk prosthesis of
FIG. 1;
[0022] FIG. 6A is a side sectional view of a second preferred
embodiment of a disk prosthesis in accordance with the present
invention;
[0023] FIG. 6B is a side sectional view of a third preferred
embodiment of a disk prosthesis in accordance with the present
invention;
[0024] FIG. 6C is a side sectional view of a fourth preferred
embodiment of a disk prosthesis in accordance with the present
invention;
[0025] FIG. 7A is a side elevational view of the disk prosthesis of
FIG. 6A connected to a first insertion tool;
[0026] FIG. 7B is a side elevational view of the disk prosthesis of
FIG. 6A connected to a second insertion tool;
[0027] FIG. 7C is a side elevational view of the disk prosthesis of
FIG. 6A connected to a third insertion tool;
[0028] FIG. 8 is a side view of the lumbar section of a human spine
with a disk prosthesis shown not to scale installed between
vertebra L.sup.III and vertebra L.sup.IV;
[0029] FIG. 9 is a top sectional view of a human vertebra as is
known in the art;
[0030] FIG. 10 is a side sectional view of a portion of a human
spine as is known in the art;
[0031] FIG. 11A is a side elevational view of a fifth preferred
embodiment of a disk prosthesis in accordance with the present
invention;
[0032] FIG. 11B is a front elevational view of the disk prosthesis
of FIG. 11A;
[0033] FIG. 12A is a side elevational view of a sixth preferred
embodiment of a disk prosthesis in accordance with the present
invention;
[0034] FIG. 12B is a front elevational view of the disk prosthesis
of FIG. 12A;
[0035] FIG. 13A is a side elevational view of a seventh preferred
embodiment of a disk prosthesis in accordance with the present
invention;
[0036] FIG. 13B is a front elevational view of the disk prosthesis
of FIG. 13A;
[0037] FIG. 14A is a side elevational view of an eighth preferred
embodiment of a disk prosthesis in accordance with the present
invention;
[0038] FIG. 14B is a front elevational view of the disk prosthesis
of FIG. 14A;
[0039] FIG. 15A is a side elevational view of a fourth insertion
tool for a disk prosthesis in accordance with the present
invention;
[0040] FIG. 15B is a top plan view of the insertion tool of FIG.
15A;
[0041] FIG. 16A is a side elevational view of a fifth insertion
tool for a disk prosthesis in accordance with the present
invention; and
[0042] FIG. 16B is a top plan view of the insertion tool of FIG.
16A.
DETAILED DESCRIPTION OF THE INVENTION
[0043] Certain terminology is used in the following description for
convenience only and is not limiting. The words "right", "left",
"lower", and "upper" designate directions in the drawing to which
reference is made. The words "inwardly" and "outwardly" refer
direction toward and away from, respectively, the geometric center
of the disk prosthesis and designated parts thereof. The
terminology includes the words above specifically mentioned,
derivatives thereof and words of similar import. Additionally, the
word "a", as used in the claims and in the corresponding portions
of the specification, means "at least one."
[0044] Referring to the drawings in detail, wherein like reference
numerals indicate like elements throughout, there is shown in FIG.
1 an artificial disk or disk prosthesis 10 having a distal end 10a,
a proximal end 10b, a lower wall 10c, an upper wall 10d, a first
sidewall 10e and a second sidewall 10f (FIGS. 3, 4). The disk
prosthesis 10 includes a first part or a cap 13. The cap 13
includes a top 13d, a bottom 13c having an opening 13f, an outer
surface 13a, and with reference to FIG. 5, an inner surface 13b and
a socket 13e extending into an interior of the cap 13 from the
opening 13f and defined by the inner surface 13b. The outer surface
13a proximate the top 13d contacts a concave portion 100b of a
first vertebra 100. The disk prosthesis 10 further includes a
second part or a base 11 including a top 11d, a bottom 11c, and an
outer surface 11a. The outer surface 11a proximate the bottom 11c
contacts a concave portion 100a of a a second vertebra 100, and the
outer surface of the base 11 proximate the top 11d of the base 11
cooperatively engages the inner surface 13b of the cap 13 thereby
preferably allowing at least two-degrees of freedom of
movement.
[0045] As shown in FIG. 8, when inserted into an intervertebral
space 121 the cap 13 and the base 11 function together as one
overall device, i.e., the disk prosthesis 10. However, it should be
noted that the cap 13 and the base 11 are preferably not
mechanically connected. In alternate embodiments the cap 13 and the
base 11 are connected by a flexible structure or element (not
shown) or are totally encased in a pliable, bio-compatible
slip-cover or pouch (not shown). The inner surface 13b and a
portion 11e of the outer surface 11a that contacts the inner
surface 13b are preferably formed of or coated with a
bio-compatible, smooth, low-friction material with high durability,
such as ceramic, an alloy or the like.
[0046] Together, the outer surface 13a of the cap 13 and a portion
11b of the outer surface 11a of the base 11 that is not covered by
the cap 13 comprise an outer prosthesis surface 12 that is
substantially smooth over the entire surface. The structure of the
prosthesis 10 is preferably a bio-compatible metal, a
bio-compatible alloy or a bio-compatible ceramic. However, the
structure may be titanium, stainless steel, alloys such as a
cobalt-chrome molybdenum alloy, polymeric materials, composites,
and the like without departing from the broad inventive scope of
the present invention.
[0047] The disk prosthesis 10 preferably is generally ovoid or
egg-shaped and symmetrical along the longer axis with rounded or
contoured edges on all sides. The lower wall 10c and upper wall 10d
preferably are generally convex in order to cooperatively mate with
the natural concavity of adjacent vertebrae 100. Similarly, the
first sidewall 10e and second sidewall 10f of the disk prosthesis
10 preferably are similarly convex for similar reasons and to
facilitate installation of the disk prosthesis 10 into an
intervertebral space 121. The overall shape of the disk prosthesis
is such that it can be inserted into an intervertebral space 121
using minimally invasive techniques through a special portal or
channel allowing disk arthroplasty on an outpatient basis. In an
alternate embodiment of the first preferred embodiment, the
proximal end 10b is rounded but more bluntly-shaped than the distal
end 10a which is sloped into a bullet-shaped tip.
[0048] The lower wall 10c preferably includes a lower mesh
structure 16a and the upper wall 10d of the disk prosthesis 10
preferably includes an upper mesh structure 16b at the point of
vertebral contact to encourage successful vertebral bone ingrowth
thereby affixing the cap 13 to a first or upper vertebra 100 and
the base 11 to a second or lower vertebra 100 in an adjacent pair
of vertebrae 100. The lower mesh structure 16a and the upper mesh
structure 16b may be a grid, a lattice, a plurality of perforations
or apertures that extend partially through or completely through
the outer surface 12, or any other configuration capable of
allowing vertebral bone ingrowth. The mesh structures 16a, 16b may
or may not be symmetrically-shaped. The mesh structures 16a, 16b
are preferably identically-shaped with respect to one another and
are preferably symmetrically-shaped, but need not be. It is
contemplated that the mesh structures 16a, 16b are each a larger
aperture, or alternatively, are each a generally continuous section
of a bio-compatible porous material such as hydroxyapatite coated
metals or an irregular metal surface coated with hydroxyapatite
coating. It is further contemplated that the mesh structures 16a,
16b are not flush with the edges of the outer surface 12, but are
instead slightly below the edges of the outer surface 12 to allow
for subsidence of the vertebrae and greater bone ingrowth.
[0049] The length of the disk prosthesis as measured from the
distal end 10a to the proximal end 10b is approximately 10-30 mm,
depending on the particular intervertebral space 121 in which the
disk prosthesis 10 is to be inserted. For example, the
intervertebral space between lumbar vertebra L.sup.III and lumbar
vertebra L.sup.IV for an average male would accommodate a disk
prosthesis 10 of a length between approximately 25-30 mm. But, the
length of the disk prosthesis 10 could vary from the aforementioned
range without departing from the spirit of the invention.
[0050] The width of the disk prosthesis 10 as measured between the
first sidewall 10e and the second sidewall 10f of the disk
prosthesis 10 will vary from approximately 10 mm to 25 mm depending
upon the particular intervertebral space 121 in which the disk
prosthesis 10 is to be inserted. For example, the intervertebral
space between vertebra L.sup.III and vertebra L.sup.IV in an
average male would accommodate a disk prosthesis 10 having a width
of approximately 15-20 mm. But, the width of the disk prosthesis 10
could vary from the aforementioned range without departing from the
spirit of the invention.
[0051] The height of the disk prosthesis 10 as measured between the
upper wall 10d and the lower wall 10c of the disk prosthesis 10
will vary from approximately 5 mm to 25 mm depending upon the
particular intervertebral space 121 in which the disk prosthesis 10
is to be inserted. For example, the intervertebral space between
vertebra L.sup.III and vertebra L.sup.IV in an average male would
accommodate a disk prosthesis 10 having a height of approximately
8-16 mm. But, the height of the disk prosthesis 10 could vary from
the aforementioned range without departing from the spirit of the
invention.
[0052] FIG. 5 shows a side sectional view of the disk prosthesis 10
as viewed from lines 5-5 of FIG. 4. FIG. 5 more clearly shows the
cooperative interaction between the cap 13 and the base 11. As
mentioned above, a portion 11e of the outer surface 11a of the base
11 proximate the top 11d of the base 11 cooperatively engages the
inner surface 13b of the cap 13 thereby allowing at least
two-degrees of freedom of movement. Motion allowed includes
rotation (roll) and tilting or angulation (pitch) in any direction,
but not motion in the plane from front to back or side to side
(i.e., parallel to the disk space). The inner surface 13b and the
portion 11e of the outer surface 11a that contacts the inner
surface 13b are generally concealed.
[0053] The overall shape of the disk prosthesis 10 is designed for
insertion using minimally invasive techniques through a special
portal or channel allowing a replacement procedure to be
implemented on an outpatient basis. The convex and contoured shape
of the disk prosthesis 10 will allow the disk prosthesis 10 to be
driven into an intervertebral disk space 121 by merely temporarily
distracting the vertebrae with minimal removal of the vertebral rim
or annulus (not shown clearly) at the point of entry, thereby
reducing the chance of dislodging the device post-surgery. The
smooth contour and edges of the disk prosthesis 10 provide for a
safe and easy entrance into the intervertebral space 121.
[0054] The disk prosthesis 10 is a self centering device. Due
largely to the shape of the disk prosthesis 10, the disk prosthesis
10 will tend to find the natural concavity of adjacent vertebrae
100. As such, placement of the disk prosthesis 10 is much faster
than that of prior art intervertebral disk replacement devices,
thereby effectively reducing the duration of an intervertebral disk
replacement procedure and the associated risks therewith. Further,
the self-centering feature of the disk prosthesis 10 will allow
rapid settling of the disk prosthesis 10 into adjacent vertebral
bone to promote rapid bone ingrowth while retention of most of the
annulus and peripheral rim of the vertebrae 100 would provide good
load sharing support to prevent excessive subsidence, where
subsidence is the natural settling of intervertebral matter into a
softer central portion of the vertebral bodies 106.
[0055] FIG. 8 shows a side view of the lumbar region 122 of a
portion of a human spine 120. In particular, the disk prosthesis 10
in accordance with the first preferred embodiment of the present
invention is shown installed between lumbar vertebra L.sup.III and
lumbar vertebra L.sup.IV. In this particular installation, the
second sidewall 10f of the disk prosthesis 10 is placed on the
anterior side of the L.sup.III- L.sup.IV intervertebral space, the
first sidewall 10e of the disk prosthesis 10 is placed closest to
the posterior side of the L.sup.III-L.sup.IV intervertebral space,
the upper wall 10d of the disk prosthesis 10 is adjacent to
vertebra L.sup.III, and the lower wall 10c of the disk prosthesis
10 is adjacent to vertebra L.sup.IV. In this example, the surgeon
would have inserted the distal end 10a of the disk prosthesis 10
into the gap between the L.sup.III-L.sup.IV vertebrae as depicted
in FIG. 9 by a directional arrow D. It is just as likely and
possible for the surgeon to place the distal end 10a of the disk
prosthesis 10 through the space between the L.sup.III-L.sup.IV
vertebrae in the direction of a directional arrow C (FIG. 9) or
from any other direction.
[0056] FIG. 6A shows a side sectional view of a second preferred
embodiment of a disk prosthesis 60 in accordance with the present
invention. The disk prosthesis 60 has a distal end 60a, a proximal
end 60b, a lower wall 60c, an upper wall 60d, a first sidewall 60e
(FIGS. 7A-7C), and a second sidewall (not shown). The disk
prosthesis includes a first part or a cap 63. The cap 63 includes a
top 63d, a bottom 63c having an opening 63f, an outer surface 63a,
an inner surface 63b and a socket 63e extending into an interior of
the cap 63 from the opening and defined by the inner surface 63b.
The outer surface 63a proximate the top 63d contacts a concave
portion 100b of a first vertebra 100. The disk prosthesis 60
further includes a second part or a base 61 including a top 61d, a
bottom 61c, and an outer surface 61a. The outer surface 61a
proximate the bottom 61c contacts a concave portion 100a of a
second vertebra 100, and the outer surface 61a of the base 61
proximate the top 61d of the base 61 cooperatively engages the
inner surface 63b of the cap 63 thereby allowing at least
two-degrees of freedom of movement.
[0057] When inserted into an intervertebral space 121 the cap 63
and the base 61 function together as one overall device, i.e., the
disk prosthesis 60. The cap 63 and the base 61 are preferably not
mechanically connected. The base 61 is preferably not retained in
the cap 63, but could be. In alternate embodiments the cap 63 and
the base 61 are connected by a flexible structure or element (not
shown) or are totally encased in a pliable, bio-compatible
slip-cover or pouch (not shown). The inner surface 63b and a
portion 61e of the outer surface 61a that contacts the inner
surface 63b are preferably formed of or coated with a
bio-compatible, smooth, low-friction material with high durability,
such as a ceramic, an alloy or the like. The top 61d of the base 61
includes a spherically or hemispherically-shaped portion or a ball
61f. The ball 61f of the base 61 cooperatively engages the socket
63e of the cap 63 thereby mimicking a ball and socket joint such as
a hip-joint. Obviously, other iterations and combinations of
mutually cooperating engagement designs providing relative movement
could be implemented without departing from the broad general scope
of the present invention.
[0058] The lower wall 60c includes a lower mesh structure 66a and
the upper wall 60d of the disk prosthesis 60 includes an upper mesh
structure 66b at the point of vertebral contact to encourage
successful vertebral bone ingrowth thereby affixing the cap 63 to a
first or upper vertebra 100 and the base 61 to a second or lower
vertebra 100 in an adjacent pair of vertebrae 100. The lower mesh
66a and the upper mesh 66b may have the attributes of the lower
mesh 16a and the upper mesh 16b discussed above with reference to
the first preferred embodiment.
[0059] FIG. 6B shows a side sectional view of a third preferred
embodiment of a disk prosthesis 70 in accordance with the present
invention. The disk prosthesis 70 has a distal end 70a, a proximal
end 70b, a lower wall 70c, an upper wall 70d, a first sidewall (not
shown), and a second sidewall (not shown). The disk prosthesis
includes a first part or a cap 73. The cap 73 includes a top 73d, a
bottom 73c having an opening 73f, an outer surface 73a, an inner
surface 73b and a socket 73e extending into an interior of the cap
73 from the opening and defined by the inner surface 73b. The outer
surface 73a proximate the top 73d contacts a concave portion 100b
of a first vertebra 100. The disk prosthesis 70 further includes a
second part or a base 71 including a top 71d, a bottom 71c, and an
outer surface 71a. The outer surface 71a proximate the bottom 71c
contacts a concave portion 100a of a second vertebra 100, and the
outer surface 71a of the base 71 proximate the top 71d of the base
71 cooperatively engages the inner surface 73b of the cap 73
thereby allowing at least two-degrees of freedom of movement.
[0060] When inserted into an intervertebral space 121 the cap 73
and the base 71 function together as one overall device, i.e., the
disk prosthesis 70. The cap 73 and the base 71 are preferably not
mechanically connected. The base 71 is preferably not retained in
the cap 73, but could be. In alternate embodiments the cap 73 and
the base 71 are connected by a flexible structure or element (not
shown) or are totally encased in a pliable, bio-compatible
slip-cover or pouch (not shown). The inner surface 73b and a
portion 71e of the outer surface 71a that contacts the inner
surface 73b are preferably formed of or coated with a
bio-compatible, smooth, low-friction material with high durability,
such as a ceramic, an alloy or the like. The top 71d of the base 71
includes a spherically or hemispherically-shaped portion or a ball
71f. The ball 71f of the base 71 cooperatively engages the socket
73e of the cap 73 thereby mimicking a ball and shallow socket joint
such as a shoulder-joint. Obviously, other iterations and
combinations of mutually cooperating engagement designs providing
relative movement could be implemented without departing from the
broad general scope of the present invention.
[0061] The lower wall 70c includes a lower mesh structure 76a and
the upper wall 70d of the disk prosthesis 70 includes an upper mesh
structure 76b at the point of vertebral contact to encourage
successful vertebral bone ingrowth thereby affixing the cap 73 to a
first or upper vertebra 100 and the base 71 to a second or lower
vertebra 100 in an adjacent pair of vertebrae 100. The lower mesh
76a and the upper mesh 76b may have the attributes of the lower
mesh 16a and the upper mesh 16b discussed above with reference to
the first preferred embodiment.
[0062] FIG. 6C shows a side sectional view of a fourth preferred
embodiment of a disk prosthesis 80 in accordance with the present
invention. The disk prosthesis 80 has a distal end 80a, a proximal
end 80b, a lower wall 80c, an upper wall 80d, a first sidewall (not
shown), and a second sidewall (not shown). The disk prosthesis
includes a first part or a cap 83. The cap 83 includes a top 83d, a
bottom 83c having an opening 83f, an outer surface 83a, an inner
surface 83b and a socket 83e extending into an interior of the cap
83 from the opening and defined by the inner surface 83b. The outer
surface 83a proximate the top 83d contacts a concave portion 100b
of a first vertebra 100. The disk prosthesis 80 further includes a
second part or a base 81 including a top 81d, a bottom 81c, and an
outer surface 81a. The outer surface 81a proximate the bottom 81c
contacts a concave portion 100a of a second vertebra 100, and the
outer surface 81a of the base 81 proximate the top 81d of the base
81 cooperatively engages the inner surface 83b of the cap 83
thereby allowing at least two-degrees of freedom of movement.
[0063] When inserted into an intervertebral space 121 the cap 83
and the base 81 function together as one overall device, i.e., the
disk prosthesis 80. The cap 83 and the base 81 are preferably not
mechanically connected. The base 81 is preferably not retained in
the cap 83, but could be. In alternate embodiments the cap 83 and
the base 81 are connected by a flexible structure or element (not
shown) or are totally encased in a pliable, bio-compatible
slip-cover or pouch (not shown). The inner surface 83b and a
portion 81e of the outer surface 81a that contacts the inner
surface 83b are preferably formed of or coated with a
bio-compatible, smooth, low-friction material with high durability,
such as a ceramic, an alloy or the like. The top 81d of the base 81
includes a spherically or hemispherically-shaped portion or a ball
81f. The ball 81f of the base 81 cooperatively engages the socket
83e of the cap 83 thereby mimicking a ball and shallow socket joint
such as a shoulder-joint. Obviously, other iterations and
combinations of mutually cooperating engagement designs providing
relative movement could be implemented without departing from the
broad general scope of the present invention.
[0064] The lower wall 80c includes a lower mesh structure 86a and
the upper wall 80d of the disk prosthesis 80 includes an upper mesh
structure 86b at the point of vertebral contact to encourage
successful vertebral bone ingrowth thereby affixing the cap 83 to a
first or upper vertebra 100 and the base 81 to a second or lower
vertebra 100 in an adjacent pair of vertebrae 100. The lower mesh
86a and the upper mesh 86b may have the attributes of the lower
mesh 16a and the upper mesh 16b discussed above with reference to
the first preferred embodiment.
[0065] FIG. 7A shows the disk prosthesis 60 of the second preferred
embodiment with a specially designed first insertion tool 18 having
a handle 18a and a plurality of resilient grasping fingers 19. The
grasping fingers 19 are actuated to grasp and hold the disk
prosthesis 60 by moving a tool actuation stem 17 proximally and to
open and release the disk prosthesis 60 by moving the tool
actuation stem 17 distally. The handle 18a of the first insertion
tool 18 may be formed of any substantially rigid material, but
preferably is formed of a material that is bio-compatible such as
titanium, stainless steel, or of a bio-compatible alloy, composite,
polymeric material or the like. It should be noted that the
material of construction of the handle 18a of the first insertion
tool 18 could be any material without diverging from the broad
scope of the present invention. The grasping fingers 19 are
preferably formed of a resilient, bio-compatible synthetic or
polymeric material. It is contemplated that the grasping fingers 19
are biased by either their own resiliency or by other resilient
means (not shown) such as coil springs in order to allow the
grasping fingers 19 to grasp the disk prosthesis 60 without
actuation but to be capable of releasing the disk prosthesis by
merely twisting or moving the first insertion tool 18 proximally at
a slight angle.
[0066] FIG. 7B shows the disk prosthesis 60 of the second preferred
embodiment with a specially designed second insertion tool 22
having a handle 22a and a suction cup 23. The handle 22a of the
second insertion tool 22 may be formed of any substantially rigid
material, but preferably is formed of a material that is
bio-compatible such as titanium, stainless steel, or of a
bio-compatible alloy, composite, polymeric material or the like. It
should be noted that the material of construction of the handle 22a
of the second insertion tool 22 could be any material without
diverging from the broad scope of the present invention. The
suction cup 23 is preferably formed of a resilient, bio-compatible
synthetic or polymeric material. Preferably, the suction cup 23 is
biased inwardly by its own resiliency in order to allow the suction
cup 23 to grasp the disk prosthesis 60 without actuation but to be
capable of releasing the disk prosthesis by merely twisting or
moving the second insertion tool 22 proximally at a slight
angle.
[0067] FIG. 7C shows the disk prosthesis 60 of the second preferred
embodiment with a specially designed third insertion tool 20 having
a handle 20a and being threaded into a socket 64 with female
threads 64a by male threads 20b of the third insertion tool 20. The
handle 20a of the third insertion tool 20 may be formed of any
substantially rigid material, but preferably is formed of a
material that is bio-compatible such as titanium, stainless steel,
or of a bio-compatible alloy, composite, polymeric material or the
like. It should be noted that the material of construction of the
third insertion tool 20 could be any material without diverging
from the broad scope of the present invention. Design of insertion
tools are not critical to the present invention, and a variety of
tool designs are contemplated for use with various disk
prostheses.
[0068] FIGS. 11A-11B show a fifth preferred embodiment of a disk
prosthesis in accordance with the present invention. The disk
prosthesis 90 has a distal end 90a, a proximal end 90b, a lower
wall 90c, an upper wall 90d, a first sidewall (not shown), and a
second sidewall (not shown). The disk prosthesis includes a first
part or a cap 93. The cap 93 includes a top 93d, a bottom 93c
having an opening 93f, an outer surface 93a, an inner surface 93b
and a socket 93e extending into an interior of the cap 93 from the
opening and defined by the inner surface 93b. The outer surface 93a
proximate the top 93d contacts a concave portion 100b of a first
vertebra 100. The disk prosthesis 90 further includes a second part
or a base 91 including a top 91d, a bottom 91c, and an outer
surface 91a. The outer surface 91a proximate the bottom 91c
contacts a concave portion 100a of a second vertebra 100, and the
outer surface 91a of the base 91 proximate the top 91d of the base
91 cooperatively engages the inner surface 93b of the cap 93
thereby allowing at least two-degrees of freedom of movement. The
cap 93 is preferably slightly smaller than the base 91 in both
length and width in order to allow freedom movement even when bone
growth reaches near the edges of the cap 93 and/or base 91.
Alternatively, the base 91 may be slightly smaller than the cap 93
for similar reasons without departing from the present
invention.
[0069] Further, the disk prosthesis 90 includes at least one upper
arch 150 and at least one lower arch 152, but preferably the disk
prosthesis 90 includes three upper arches 150 and three lower
arches 152. The arches 150, 152 are generally disposed
symmetrically along and about a centerline of the longer axis of
the disk prosthesis 90 and are secured to the body of the disk
prosthesis 90. Of course the arches 150, 152 may be secured to the
disk prosthesis 90 by other means and may be disposed in other
orientations without departing from the spirit of the present
invention. Preferably, the arches 150, 152 protrude above the top
and bottom 190d, 190c of the disk prosthesis 90, respectively. The
arches 150, 152 are configured to settle into bone matter, and
therefore, the arches 150, 152 have sharpened edges 150a, 152a. The
sharpened edges 150a, 152a may include serrations, pins, sharpened
cones or a simple knife-like edge, but need not be. Preferably, the
sharpened edges 150a, 152a are partially knife like proximate the
ends of the arches and partially covered with sharpened cones 153.
The arches 150, 152 are preferably about 0.5 mm to about 2.0 mm
wide. The arches 150, 152 also serve to center the disk prosthesis
90 during placement and prevent the disk prosthesis 90 from rolling
or canting thereafter.
[0070] FIGS. 12A-12B show a sixth preferred embodiment of a disk
prosthesis 190 in accordance with the present invention. The disk
prosthesis 190 has a distal end 190a, a proximal end 190b, a lower
wall 190c, an upper wall 190d, a first sidewall 190e, and a second
sidewall 190f. The disk prosthesis includes a first part or a cap
193. The cap 193 includes a top 193d, a bottom 193c having an
opening 193f, an outer surface 193a, an inner surface (not shown)
and a socket (not shown) extending into an interior of the cap 193
from the opening and defined by the inner surface. The outer
surface 193a proximate the top 193d contacts a concave portion 100b
of a first vertebra 100. The disk prosthesis 190 further includes a
second part or a base 191 including a top 191d, a bottom 191c, and
an outer surface 191a. The outer surface 191a proximate the bottom
191c contacts a concave portion 100a of a second vertebra 100, and
the outer surface 191a of the base 191 proximate the top 191d of
the base 191 cooperatively engages the inner surface (not shown) of
the cap 193 thereby allowing at least two-degrees of freedom of
movement. Further, the disk prosthesis 190 includes at least one
upper arch 150 and at least one lower arch 152, but preferably the
disk prosthesis 190 includes three upper arches 150 and three lower
arches 152 similar to the disk prosthesis 90. The arches 150, 152
are generally disposed symmetrically along and about a centerline
of the longer axis of the disk prosthesis 190 and are secured to
the body of the disk prosthesis 190. The top of the cap 193 has a
recess and the bottom of the base 191 has a recess, the recesses
include a platform 193h and 191h, respectively. The platforms 191h,
193h are preferably are texturized and/or coated with a material to
promote bone growth.
[0071] FIGS. 13A-13B show a seventh preferred embodiment of a disk
prosthesis 290 in accordance with the present invention. The disk
prosthesis 290 has a distal end 290a, a proximal end 290b, a lower
wall 290c, an upper wall 290d, a first sidewall 290e, and a second
sidewall 290f. The disk prosthesis includes a first part or a cap
293. The cap 293 includes a top 293d, a bottom 293c having an
opening 293f, an outer surface 293a, an inner surface (not shown)
and a socket (not shown) extending into an interior of the cap 293
from the opening and defined by the inner surface. The outer
surface 293a proximate the top 293d contacts a concave portion 100b
of a first vertebra 100. The disk prosthesis 290 further includes a
second part or a base 291 including a top 291d, a bottom 291c, and
an outer surface 291a. The outer surface 291a proximate the bottom
291c contacts a concave portion 100a of a second vertebra 100, and
the outer surface 291a of the base 291 proximate the top 291d of
the base 291 cooperatively engages the inner surface (not shown) of
the cap 293 thereby allowing at least two-degrees of freedom of
movement. Further, the disk prosthesis 290 includes at least one
upper arch 150 and at least one lower arch 152, but preferably the
disk prosthesis 290 includes three upper arches 150 and three lower
arches 152 similar to the disk prosthesis 90. The arches 150, 152
are generally disposed symmetrically along and about a centerline
of the longer axis of the disk prosthesis 290 and are secured to
the body of the disk prosthesis 290. The top of the cap 293 and the
bottom of the base 291 are preferably flatly shaped. The flat
surfaces preferably are texturized and/or coated with a material to
promote bone growth.
[0072] FIGS. 14A-14B show an eighth preferred embodiment of a disk
prosthesis 390 in accordance with the present invention. The disk
prosthesis 390 has a distal end 390a, a proximal end 390b, a lower
wall 390c, an upper wall 390d, a first sidewall 390e, and a second
sidewall 390f. The disk prosthesis includes a first part or a cap
393. The cap 393 includes a top 393d, a bottom 393c, an outer
surface 393a, an inner surface (not shown) and a socket (not shown)
extending into an interior of the cap 393 from the opening and
defined by the inner surface 393b. The outer surface 393a proximate
the top 393d contacts a concave portion 100b of a first vertebra
100. The disk prosthesis 390 further includes a second part or a
base 391 including a top 391d, a bottom 391c, and an outer surface
391a. The outer surface 391a proximate the bottom 391c contacts a
concave portion 100a of a second vertebra 100, and the outer
surface 391a of the base 391 proximate the top 391d of the base 391
cooperatively engages the inner surface (not shown) of the cap 393
thereby allowing at least two-degrees of freedom of movement.
Further, the disk prosthesis 390 includes at least one row of
sharpened cones 153 on the top of the cap 393 and at least one row
of sharpened cones 153 on the bottom of the base 391, but
preferably the disk prosthesis 390 includes three rows of sharpened
cones 153 on the top of the cap 393 and three rows of sharpened
cones 153 on the bottom of the base 391. The rows of sharpened
cones 153 are generally disposed symmetrically along and about a
centerline of the longer axis of the disk prosthesis 390 and are
secured to the body of the disk prosthesis 390. The top of the cap
393 and the bottom of the base 391 are preferably convexly shaped
to more readily find the contours of the concave portions 100a,
100b of adjacent vertebrae 100. Preferably, the surface of the disk
prosthesis 390 proximate the rows of sharpened cones 153 is
texturized and/or coated with a material to promote bone growth
such as hydroxyapatite.
[0073] FIGS. 15A-15B show a fourth insertion tool 220 for a disk
prosthesis 10 (60, 70, or 80) having lower and upper openings 16a,
16b (66a, 66b, 76a, 76b, 86a, 86b), respectively. The insertion
tool 220 has a first finger 224 configured to cooperatively engage
the lower opening 16a and a second finger 222 configured to
cooperatively engage the upper opening 16b. The fingers 222, 224
have outer surfaces which are shaped to match the contoured shape
of the disk prosthesis 10 to allow a smooth insertion of the disk
prosthesis 10. The combination of the insertion tool 220 and the
disk prosthesis 10 when the first and second fingers 222, 224 are
engaged with the ingrowth openings 16a, 16b, forms a combined
structure having generally rounded exposed surfaces. The fingers
222, 224 also prevent foreign matter and debris from getting caught
in the openings 16a, 16b during insertion. Because the fingers 222,
224 grasp the disk prosthesis 10 in a specific orientation defined
by the upper and lower openings 16a, 16b, the insertion tool 220
provides the surgeon with means to orient the disk prosthesis 10
correctly during insertion.
[0074] The insertion tool 220 further includes a driving member 226
that is configured to engage the body of the disk prosthesis 10.
The driving member 226 is configured to be impacted such that
during insertion a surgeon may tap or hammer the driving member 226
to push the disk prosthesis 10 through a small opening. Preferably,
the first and second fingers 222, 224 are retractable relative to
the driving member 226. Thus, after the disk prosthesis 10 is
inserted to a desired position, the first and second fingers 222,
224 are retracted while the driving member 226 holds the disk
prosthesis 10 in place. Optionally, the disk prosthesis 10 may have
grooves 166 (shown in phantom in FIG. 15B) extending from the upper
and lower openings 16a, 16b to facilitate the removal of the
retractable fingers 222, 224. Optionally, the insertion tool 220
includes third and fourth fingers 228 (shown in phantom in FIG.
15A-15B) configured to retractably move along the space between the
upper part 13 and the lower part 11 of the body of the disk
prosthesis 10.
[0075] FIGS. 16A-16B is a side elevational view of a fifth
insertion tool 230 for a disk prosthesis 90 (190, 290 or 390)
having upper and lower openings 96a, 96b and upper and lower arches
150, 152. For example, the upper finger 232 has first and second
prongs 232a, 232b for straddling the upper arches 150 as best seen
in FIG. 16B. The insertion tool 230 is similar to the insertion
tool 220, but each of the retractable fingers 232, 234 is forked to
accommodate the arches 150, 152. Preferably, the arches 150, 152
and the rows of cones 153 are just below the outer surface of the
fingers 232, 234, so that the arches 150, 152 do not injure
adjacent tissue during insertion. Optionally, the insertion tool
230 includes third and fourth fingers 238 (shown in phantom in FIG.
16A-16B) configured to retractably move between the space between
the upper part 93 and the lower part 91 of the body of the disk
prosthesis 90. Furthermore, it would be obvious to one skilled in
the art to utilize multiple prongs in each of the retractable
fingers 232, 234 in order to accommodate multiple arches 150, 152
(such as on disk prostheses 190 and 290) and multiple rows of
sharpened cones 153 (such as on disk prosthesis 390).
[0076] Preferably, the intervertebral disk prostheses 10, 60, 70,
90, 190, 290 and 390 have a freedom of movement that is limited to
between about 2-15 degrees tilt in any direction. The annular
ligament of a human being is built for physiologic limiting thereby
stopping over rotation. The facets in the lumbar region also limit
rotation and tilt.
[0077] It will be appreciated by those skilled in the art that
changes could be made to the embodiments described above without
departing from the broad inventive concept thereof. It is
understood, therefore, that this invention is not limited to the
particular embodiments disclosed, but it is intended to cover
modifications within the spirit and scope of the present invention
as defined by the appended claims.
* * * * *