U.S. patent application number 14/982467 was filed with the patent office on 2016-07-21 for vertebral body spacer.
The applicant listed for this patent is MITSUBISHI MATERIALS CORPORATION. Invention is credited to Yuzo Daigo, Komei Kato, Toshio Matsumoto, Shinichi Ohmori.
Application Number | 20160206441 14/982467 |
Document ID | / |
Family ID | 46051008 |
Filed Date | 2016-07-21 |
United States Patent
Application |
20160206441 |
Kind Code |
A1 |
Matsumoto; Toshio ; et
al. |
July 21, 2016 |
VERTEBRAL BODY SPACER
Abstract
A vertebral body spacer of the present invention is used by
being inserted between a vertebral body and a vertebral body
(intervertebral space). The vertebral body spacer has a block body
constituted of titanium or a titanium alloy as a main component
thereof, and provided with a pair of contact surfaces to be made
contact with the vertebral body and the vertebral body. The block
body includes needle parts formed into a needle shape having both
end portions and a porous part having through holes passing through
the porous part in a thickness direction thereof, and a porosity of
at least a surface of the porous part is larger than a porosity of
each of the needle parts. The needle parts are inserted into the
through holes so that the both end portions are projected from the
contact surfaces.
Inventors: |
Matsumoto; Toshio; (Tokyo,
JP) ; Daigo; Yuzo; (Saitama, JP) ; Ohmori;
Shinichi; (Saitama, JP) ; Kato; Komei;
(Saitama, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI MATERIALS CORPORATION |
Tokyo |
|
JP |
|
|
Family ID: |
46051008 |
Appl. No.: |
14/982467 |
Filed: |
December 29, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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13884357 |
Jul 3, 2013 |
|
|
|
PCT/JP2011/075841 |
Nov 9, 2011 |
|
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14982467 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2/4455 20130101;
A61F 2002/3097 20130101; A61F 2002/30971 20130101; A61F 2310/00431
20130101; A61F 2/30771 20130101; A61F 2002/30841 20130101; A61F
2002/30892 20130101; A61F 2002/448 20130101; A61F 2002/30011
20130101; A61F 2310/00976 20130101; A61F 2002/30451 20130101; A61F
2/4465 20130101; A61F 2002/30967 20130101; A61F 2002/3092 20130101;
A61F 2002/30593 20130101; A61F 2310/00497 20130101; A61F 2310/00514
20130101; A61F 2/442 20130101; A61F 2310/00023 20130101; A61F
2002/30492 20130101; A61F 2310/00485 20130101; A61F 2310/00532
20130101; A61F 2310/00491 20130101; A61F 2002/30433 20130101; A61F
2002/30616 20130101; A61F 2310/00443 20130101; A61F 2002/30224
20130101; A61F 2310/00544 20130101; A61F 2310/00562 20130101; A61F
2002/30471 20130101; A61F 2/44 20130101 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61F 2/30 20060101 A61F002/30 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2010 |
JP |
2010-252230 |
Claims
1-9. (canceled)
10. A vertebral body spacer configured for insertion between two
vertebral bodies, the vertebral body spacer comprising: at least
one block body including a porous part and a pair of contact
surfaces on opposite sides thereof configured to contact the
vertebral bodies, the block body defining a hole from one of the
pair of contact surfaces to the other of the pair of contact
surfaces; and a needle part having a first end and a second end
configured for fixing the block body between the vertebral bodies,
the needle part extending between the contact surfaces through the
hole with the first end projecting outward from one of the pair of
contact surfaces and the second end projecting outward from the
other of the pair of contact surfaces.
11. The vertebral body spacer as claimed in claim 10, wherein each
of the contact surfaces is substantially planar.
12. The vertebral body spacer as claimed in claim 10, wherein the
needle part extending through the hole is substantially
perpendicular to the contact surfaces.
13. The vertebral body spacer as claimed in claim 10, wherein the
first and second ends of the needle part extend substantially
perpendicular to the contact surfaces in opposite directions.
14. A vertebral body spacer configured for insertion between two
vertebral bodies, the vertebral body spacer comprising: at least
one block body including a porous part and a pair of contact
surfaces configured to contact the vertebral bodies, the block body
defining a plurality of holes from one of the pair of contact
surfaces to the other of the pair of contact surfaces; and a
plurality of needle parts extending through the plurality of holes,
each needle part having a first end and a second end configured for
fixing the block body between the vertebral bodies, the first end
projecting outward from one of the pair of contact surfaces and the
second end projecting outward from the other of the pair of contact
surfaces, wherein the plurality of needle parts extend in
substantially the same direction.
15. The vertebral body spacer as claimed in claim 14, wherein the
porous part has a thickness, and the plurality of needle parts
extend in a thickness direction of the porous part.
16. The vertebral body spacer as claimed in claim 14, wherein the
pair of contact surfaces are planar and configured to face the
vertebral bodies.
17. The vertebral body spacer as claimed in claim 14, wherein the
contact surfaces are substantially perpendicular to the plurality
of needle parts.
Description
[0001] This application is a continuation application of U.S.
application Ser. No. 13/884,357, filed May 9, 2013 which claims the
right of priority under 35 U.S.C. .sctn.119 based on Japanese
Patent Application No. 2010-252230 filed Nov. 10, 2010.
TECHNICAL FIELD
[0002] The present invention relates to a vertebral body
spacer.
RELATED ART
[0003] Spinal canal stenosis is caused by degeneration of an
intervertebral disk interposed between adjacent vertebral bodies
(intervertebral space), degenerative facet joint disease, secondary
deformation of a vertebral body, spinal deformation, or the like,
and results in cauda equina/nerve root disorders.
[0004] One approach for treating such spinal canal stenosis
includes interbody fusion in which a degenerated intervertebral
disk is removed from between the adjacent vertebral bodies, and
then used is an vertebral body fusion surgery of fusing the
vertebral bodies by implanting an autologous bone into an
intervertebral space in which the intervertebral disk has been
removed.
[0005] However, in a case where only bone grafting into the
intervertebral space is carried out, there is a possibility that
unstable fusing between the vertebral bodies are caused by
resorption of a grafted bone until bone fusion is achieved.
Further, an amount capable of harvesting an autologous bone is
limited, so that there is a possibility that a bone to be grafted
is not acquired in a sufficient amount.
[0006] Therefore, used is a method of fusing the vertebral bodies
stably by inserting a vertebral body spacer by itself as a
substitute material of an autologous bone or the vertebral body
spacer together with the autologous bone into the intervertebral
space.
[0007] In this case, it is required that this vertebral body spacer
supports the vertebral bodies stably and fuses with the vertebral
bodies easily. From a point of such a view, a constituent material
and a shape of the vertebral body spacer have been studied, so that
various kinds of vertebral body spacers have been developed (for
example, Patent Document 1).
[0008] Such a vertebral body spacer, generally, is constituted from
a block body having a uniform porosity. Such a porosity is set to
fall within the range of about 30 to 60% for a purpose of achieving
bone fusion between the vertebral body spacer and vertebral bodies
making contact with the vertebral body spacer promptly.
[0009] However, it is impossible for the vertebral body spacer
having the porosity falling within such a range to withstand stress
on the vertebral body spacer depending on a body type of a patient
to which the spacer is to be applied and a position of an
intervertebral space such as lumbar vertebra and cervical vertebra.
As a result, there is a fear that the vertebral body spacer is
broken by the stress. [0010] Patent Document: JP 2002-95685 A
SUMMARY OF THE INVENTION
[0011] It is an object of the present invention to provide a
vertebral body spacer that is capable of maintaining an appropriate
size between vertebral bodies (intervertebral space) and reliably
preventing the vertebral body spacer from being broken irrespective
of cases and a position of the intervertebral space, and thereby
capable of achieving bone fusion between the vertebral body spacer
and the vertebral bodies promptly.
[0012] The object is achieved by the present inventions (1) to (9)
described below.
[0013] (1) A vertebral body spacer to be used by being inserted
between vertebral bodies, comprising:
[0014] at least one block body constituted of titanium or a
titanium alloy as a main component thereof, and the block body
having a pair of contact surfaces to be made contact with the
vertebral bodies, respectively, and
[0015] wherein the block body includes needle parts each formed
into a needle shape having both end portions and a porous part
having through holes passing through the porous part in a thickness
direction thereof, and a porosity of at least a surface of the
porous part is larger than a porosity of each of the needle parts,
and
[0016] wherein the needle parts are inserted into the through holes
so that the both end portions are projected from the contact
surfaces, so that the both end portions exhibit a function of
fixing the block body between the vertebral bodies.
[0017] This makes it possible to maintain an appropriate size
between the vertebral bodies (intervertebral space). Further, it is
possible to reliably prevent the block body from being broken
irrespective of cases (patients) and a position of the
intervertebral space, and thereby capable of achieving bone fusion
between the block body and the vertebral bodies promptly. Further,
it is possible to reliably prevent the block body from dropping off
from the intervertebral space.
[0018] (2) In the vertebral body spacer in above-mentioned item
(1), the both end portions of the needle parts are formed into a
pointed shape.
[0019] According to the vertebral body spacer mentioned above, by
wedging the both end portions of the needle parts formed into the
pointed shape into the vertebral bodies, the both end portions
exhibit a function as wedges, so that the block body is prevented
from being dropped off from the intervertebral space reliably.
[0020] (3) In the vertebral body spacer in above-mentioned item
(1), the needle parts are constituted from a dense body.
[0021] According to the vertebral body spacer mentioned above,
since the needle parts exhibit more excellent strength, it is
possible to reliably prevent cracks and the like from occurring in
the needle parts (in particular, the both end portions) when stress
is applied to the block body in a state of inserting the block body
into the intervertebral space.
[0022] (4) In the vertebral body spacer in above-mentioned item
(1), the needle parts and the porous part are integrally
formed.
[0023] According to the vertebral body spacer mentioned above, it
is possible to reliably prevent the stress from being applied to
the needle parts or the porous part unevenly when the stress is
applied to the block body in the state of inserting the block body
into the intervertebral space.
[0024] (5) In the vertebral body spacer in above-mentioned item
(1), the block body further includes a frame-shaped dense part
provided at a circumference side of the porous part,
[0025] wherein the porosity of at least a surface of the porous
part is larger than a porosity of the dense part.
[0026] This makes it possible to reliably prevent the block body
from being broken irrespective of the cases and the position of the
intervertebral space while enabling the appropriate size between
the vertebral bodies (intervertebral space) to maintain.
[0027] (6) In the vertebral body spacer in above-mentioned item
(5), the porous part has a plurality of corner portions, and the
dense part is provided along the plurality of corner portions of
the porous part.
[0028] According to the vertebral body spacer mentioned above, the
dense part is formed so as to define the whole shape of the block
body.
[0029] (7) In the vertebral body spacer in above-mentioned item
(1), at least one block body is constituted from a pair of block
bodies.
[0030] This makes it possible to change relative positions of the
pair of block bodies, namely to position the pair of block bodies
in a state of spacing front ends and back ends of the pair of block
bodies from each other and/or approaching them to each other.
Therefore, it is possible to provide an appropriate cure depending
on the cases by using such a vertebral body spacer.
[0031] (8) In the vertebral body spacer in above-mentioned item
(1), a whole of the porous part is constituted from a porous
body.
[0032] This makes it possible to achieve the bone fusion between
the porous part and the vertebral bodies promptly. Therefore, it is
possible to reliably fuse the block body in the intervertebral
space.
[0033] (9) In the vertebral body spacer in above-mentioned item
(1), an osteoinductive factor is carried on the porous part.
[0034] This makes it possible to achieve the bone fusion between
the porous part and the vertebral bodies promptly.
[0035] According to the vertebral body spacer of the present
invention, it is capable of maintaining the appropriate size
between the vertebral bodies (intervertebral space). Further, it is
possible to reliably prevent the vertebral body spacer from being
broken irrespective of the cases and the position of the
intervertebral space, and thereby capable of achieving the bone
fusion between the vertebral body spacer and the vertebral bodies
promptly.
[0036] Further, by inserting the vertebral body spacer into the
intervertebral space, it is ensured to obtain a space for filling a
filler into the intervertebral space. Therefore, by filling, for
example, a grafted bone into such a space, it is possible to
achieve the bone fusion between the vertebral bodies through the
vertebral body spacer and the grafted bone more reliably and
promptly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0037] FIG. 1A is a plan view of a first embodiment of a block body
constituting a vertebral body spacer of the present invention;
[0038] FIG. 1B is a front view of the first embodiment of the block
body constituting a vertebral body spacer of the present
invention;
[0039] FIG. 1C is a side view of the first embodiment of the block
body constituting a vertebral body spacer of the present
invention;
[0040] FIG. 2A is a first schematic view showing a used state of
the first embodiment of the vertebral body spacer of the present
invention.
[0041] FIG. 2B is a second schematic view showing the used state of
the first embodiment of the vertebral body spacer of the present
invention.
[0042] FIG. 3 is a cutaway view showing a used state of the first
embodiment of the vertebral body spacer of the present
invention.
[0043] FIG. 4A is a plan view of a second embodiment of a block
body constituting a vertebral body spacer of the present
invention;
[0044] FIG. 4B is a front view of a second embodiment of a block
body constituting a vertebral body spacer of the present
invention;
[0045] FIG. 4C is a side view of a second embodiment of a block
body constituting a vertebral body spacer of the present
invention;
[0046] FIG. 5A is a plan view of a third embodiment of a block body
constituting a vertebral body spacer of the present invention;
[0047] FIG. 5B is a front view of a third embodiment of a block
body constituting a vertebral body spacer of the present
invention;
[0048] FIG. 5C is a side view of a third embodiment of a block body
constituting a vertebral body spacer of the present invention;
and
[0049] FIG. 6 is a view showing a used state of the third
embodiment of the vertebral body spacer of the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0050] Hereinbelow, description will be made on a vertebral body
space according to the present invention in detail with reference
to preferred embodiments shown accompanied drawings.
First Embodiment
[0051] First, description will be made on a first embodiment of the
vertebral body space according to the present invention.
[0052] FIG. 1 is a plan view (1A), a front view (1B) and a side
view (1C) which show the first embodiment of a block body
constituting the vertebral body spacer of the present invention.
FIGS. 2A, 2B, and FIG. 3 are a views showing a used state of the
vertebral body spacer of the present invention, respectively.
[0053] In the following description, it is to be noted that a state
of inserting the vertebral body spacer between vertebral bodies of
a case (patient) is defined as a basic state, thereby defining a
position thereof, unless it is explicitly stated otherwise.
[0054] Specifically, a ventral side of the patient (namely, a right
side in each of FIG. 1A, FIG. 1B, and FIG. 2B, a near side in each
sheet of FIG. 1C and FIG. 2A, and a lower side in FIG. 3 will be
referred to as "front", and a dorsal side of the patient (namely, a
left side in each of FIG. 1A, FIG. 1B, and FIG. 2B, a back side in
each sheet of FIG. 1C and FIG. 2A, and an upper side in FIG. 3 will
be referred to as "back". Further, a head side of the patient
(namely, an upper side in each of FIG. 1B and FIGS. 2A, 2B, a near
side in each sheet of FIG. 1A and FIG. 3, and a left side in FIG.
1C) will be referred to as "upper", and a leg side of the patient
(namely, a lower side in each of FIG. 1B and FIGS. 2A, 2B, a back
side in each sheet of FIG. 1A and FIG. 3, and a right side in FIG.
1C will be referred to as "lower". It is to be noted that a
position of the vertebral body spacer in each of FIGS. 4 to 6 is
also defined as the same as those in FIGS. 1 to 3.
[0055] As shown in FIGS. 2A, 2B, a vertebral body spacer 1 is
inserted between a vertebral body 101 and a vertebral body 102
(hereinafter, referred to as "intervertebral space") at the time of
fusing the upper vertebral body 101 and the lower vertebral body
102 after an intervertebral disk has been removed. It is ensured to
maintain (hold) an appropriate space (distance) between the
vertebral body 101 and the vertebral body 102 in a state of
inserting the vertebral body spacer 1 into the intervertebral space
(hereinafter, referred to as "inserted state").
[0056] In the present embodiment, as shown in FIG. 2A and FIG. 3,
the vertebral body spacer 1 (hereinafter, simply referred to as
"spacer 1") is constituted from a pair of elongated block bodies 2,
2. Each of the block bodies 2, 2 is substantially identical to each
other in a shape (constitution).
[0057] As described above, each of the block bodies 2, 2 is
substantially identical to each other in the shape. Therefore,
hereinafter, the description will be made on one of the pair of
elongated block bodies 2, 2 as a representative.
[0058] As shown in FIGS. 1A-1C, the block body 2 is constituted
from a polyhedral body which is formed from a plurality of surfaces
having a first surface 31, a second surface 32, a third surface 33,
a fourth surface 34, a fifth surface 35 and a sixth surface 36.
[0059] As shown in FIG. 3, the first surface 31 constitutes a
contact surface to be made contact with the vertebral body 101 and
the second surface 32 constitutes a contact surface to be made
contact with the vertebral body 102 in the state of inserting the
block body 2 into the intervertebral space (inserted state).
Further, in the inserted state, the third surface 33 defines an
inside space 103 in the intervertebral space and the fourth surface
34 defines an outside space 103 in the intervertebral space.
[0060] In the present embodiment, the third surface 33 constitutes
a curved concave surface and the fourth surface constitutes a
curved convex surface. This makes it possible to easily insert the
block body 2 into the intervertebral space so as to correspond to
shapes of the vertebral bodies (vertebral bone).
[0061] Further, the fifth surface 35 and the sixth surface 36
constitute substantially a plane surface (flat surface),
respectively. The first surface 31 and the second surface 32
constitute substantially a plane surface (flat surface),
respectively, except an area in which projection portions 41
described later are provided.
[0062] Further, the first surface 31 and the second surface 32 have
substantially an equal length. The third surface 33 and the fourth
surface 34 also have substantially an equal length. The fifth
surface 35 and the sixth surface 36 also have substantially an
equal length.
[0063] In other words, the block body 2 is formed so that a cuboid
is curved along a longitudinal direction thereof so as to concave
the third surface 33 and convex the fourth surface 34.
[0064] In this regard, the vicinities of corner portions formed by
making contact with each surface are chamfered, respectively. This
makes it possible to prevent breakages such as a crack of the block
body 2. In addition to that, it is possible to easily insert the
block body 2 into the intervertebral space with making no contact
with the vertebral bodies 101 and 102.
[0065] Dimension such as the length of such a block body 2 in a
front-back direction (L.sub.1 in FIG. 1), the length thereof in a
horizontal direction (L.sub.2 in FIG. 1) and the length thereof in
an upper-lower direction (L.sub.3 in FIG. 1) is arbitrarily
dependent from a kind of vertebral body such as cervical vertebra
and lumbar vertebra or cases. The dimension, however, is set to
fall within ranges as follows.
[0066] The length of such a block body 2 in the front-back
direction (L.sub.1 in FIG. 1) is preferably set to the range of
about 6 to 25 mm and more preferably the range of about 8 to 22
mm.
[0067] The length of the block body 2 in the horizontal direction
(L.sub.2 in FIG. 1) is preferably set to the range of about 4 to 25
mm, more preferably the range of about 10 to 25 mm and even more
preferably the range of about 16 to 21 mm.
[0068] The length of the block body 2 in the upper-lower direction
(L.sub.3 in FIG. 1) is preferably set to the range of about 6 to 15
mm and more preferably the range of about 9 to 12 mm.
[0069] Meanwhile, the block body 2 having such a configuration of
the present invention includes needle parts 40 of which both end
portions are formed into a needle shape, and a porous part 21
having through holes 22 passing through the porous part 21 in a
thickness direction thereof. A porosity of at least a surface of
the porous part 21 is larger than a porosity of each of the needle
parts 40. In the block body 20, the needle parts 40 are inserted to
the through holes 22 so that the both end portions thereof project
from the first surface 31 and the second surface 32 which are the
contact surfaces (porous part 21). This means that the both end
portions constitute projection portions 41. Each of the projection
portions 41 exhibits a function of fixing the block body 2 into the
intervertebral space in the inserted state. Even if the stress is
applied to the block body 2 having such a configuration in the
inserted state, it is possible to restrict to approach the
vertebral bodies 101, 102 to each other due to the existence of the
projection portions 41 (needle parts 40) projecting from both the
surfaces 31 and 32. Therefore, it is possible to reliably prevent
or suppress the porous part 21 from being broken while keeping the
appropriate size of the intervertebral space. Further, since the
projection portions 41 wedged in the vertebral bodies 101, 102
exhibit a function as wedges, it is possible to reliably prevent
the block body 2 from dropping off from the intervertebral space.
Moreover, it is ensured to achieve the bone fusion between the
vertebral bodies 101, 102 and the porous part 21 promptly.
[0070] Such a block body 2 is constituted from the needle parts 40,
the porous part 21 and a dense part 25 in the present embodiment.
Hereinafter, description will be made on these parts.
[0071] The both end portions of the needle parts 40 are formed into
a conical shape as shown in FIG. 1. Further, middle portions of the
needle parts 40 are formed into a cylindrical shape.
[0072] It is preferred that the needle parts 40 are constituted
from a dense body in a substantial whole thereof. The porosity of
each of the needle parts 40 is not limited particularly as long as
the porosity is smaller than the porosity of the porous part 21.
Specially, the porosity of each of the needle parts 40 is
preferably in the range of about 3 to 50%, more preferably in the
range of about 10 to 40% and even more preferably in the range of
about 15 to 35%. The porosity of each of the needle parts 40 may be
substantially 0%. The porosity makes it possible for the needle
parts 40 to exhibit more excellent strength. Therefore, it is
possible to reliably prevent cracks and the like from occurring in
the needle parts 40 (in particular, the projection portions 41)
when the stress is applied to the block body 2 in the inserted
state.
[0073] In the present embodiment, the porous part 21 is constituted
so as to be filled into a frame-shaped dense part 25 described
later and exposed to the surfaces 31 to 36 of the block body 2 from
the inside of the dense part 25.
[0074] Further, a plurality of through holes 22 (21 in the present
embodiment) is provided with the porous part 21. The through holes
22 pass through the porous part 21 in the thickness direction of
the porous part 21. Openings are formed on the surfaces 31 and 32
to be made contact with the vertebral bodies 101, 102.
[0075] In each of the through holes 22, the needle parts 40 are
inserted so that the both end portions thereof project from the
surfaces 31 and 32, and the middle portions thereof are located
inside the through holes 222. Therefore, the projection portions 41
in the conical shape, which project from the porous part 21, are
formed at the end portions of the needle parts 40.
[0076] As described above, each of the projection portions 41 is
constituted from parts (tip portions) of the needle parts 40
projecting from the surfaces 31 and 32. By taking such a
configuration, even if the stress is applied to the block body 2 in
the inserted state, it is possible to restrict to approach the
vertebral bodies 101, 102 to each other with the whole of the
needle parts 40. Therefore, the appropriate size of the
intervertebral space is maintained, thereby reliably suppressing
the stress from being applied to the porous part 21. As a result,
it is possible to reliably prevent or suppress the porous part 21
from being broken. Further, by wedging the projection portions 41
formed into the conical shape into the vertebral bodies 101, 102,
the projection portions 41 exhibit the function as the wedge.
Therefore, it is possible to reliably prevent the block body 2 from
dropping off from the intervertebral space, so that the block body
2 is fixed into the intervertebral space reliably.
[0077] The porosity of at least the surface of the porous part 21
may be larger than the porosity of each of the needle parts 40.
Therefore, the porous part 21 may have a dense part inside it, but
is preferably constituted from a porous body in the whole thereof.
This constitution ensures to achieve the bone fusion between the
vertebral bodies 101, 102 and the porous part 21 promptly.
Therefore, the block body 2 is fused into the intervertebral space
reliably.
[0078] The porosity of the porous part 21 is not limited
particularly as long as the porosity of the porous part 21 is
larger than a porosity of the dense part 25. Specifically, the
porosity of the porous part 21 is in the range of about 20 to 95%,
more preferably in the range of about 50 to 85% and even more
preferably in the range of about 55 to 85%. This makes it possible
to achieve the bone fusion between the vertebral bodies 101, 102
and the porous part 21 promptly. In the case where the porosity of
the porous part 21 falls within such ranges, it is possible to
reliably prevent or suppress the block body 2 from being broken
when the stress is applied to the block body 2 in the inserted
state. This is because the block body 2 has the dense part 25 in
the present embodiment as well as the projection portions 40 in
addition to the porous part 21. In this regard, it is to be noted
that it is easy to form communicating holes, in which holes are
connected with each other, in the porous part 21 if the porosity of
the porous part 21 is equal to or larger than 55%.
[0079] Further, it is preferred that an osteoinductive factor is
carried on inner surfaces of the communicating holes (holes) of the
porous part 21. This makes it possible to achieve the bone fusion
between the vertebral bodies 101, 102 and the porous part 21
promptly.
[0080] The osteoinductive factor is not limited particularly as
long as it has an activity of promoting bone formation by deriving
differentiated osteoblast from an undifferentiated mesenchymal
cell. Specifically, bone morphogenic protein (BMP) is used
preferably as the osteoinductive factor.
[0081] Examples of BMP include BMP-1, BMP-2, BMP-3, BMP-4, BMP-5,
BMP-6, BMP-7, BMP-8, BMP-9, BMP-12 (these are a homodimer), a
heterodimer of their BMPs or a modified body thereof, and the
like.
[0082] The dense part 25 has a lower frame portion (first frame
portion) 251 and an upper frame portion (second frame portion) 252
which have a shape corresponding to the shape of the block body 2
in the plane view as shown in FIG. 1(a). The dense part 25 also has
a plurality of connecting portions 253 which connect the lower
frame portion 251 and the upper frame portion 252.
[0083] The configuration forms the dense part 25 defining the whole
shape of the block body 2. In other words, the block part 2 has the
porous part 21 having a plurality of corner portions and the dense
part 25 formed along (at a circumference side) the corner portions
of the porous part 21. In the inserted state, the lower frame
portion 251 is in contact with the vertebral body (one of the
vertebral bodies) 102 and the upper frame portion 252 is in contact
with the vertebral body (the other of the vertebral bodies)
101.
[0084] In the present embodiment, the plurality of connecting
portions 253 includes four connecting portions provided at corner
portions of each of the frame portion 251 and the frame portion
252, and two connecting portions provided at middle portions of the
frame portion 251 and the frame portion 252, respectively. Such
connecting portions 253 exhibit a function of supporting the lower
frame portion 251 and the upper frame portion 252 as a supporting
post. Therefore, when the stress is applied to the block body 2 in
the inserted state, it is possible to reliably prevent or suppress
the lower frame portion 251 and the upper frame portion 252 from
approaching to each other. In this regard, it is to be noted that
the porosity of the dense part 25 may be substantially 0%.
[0085] As described above, the connecting portions 253 exhibit the
function as the supporting post and support the lower frame portion
251 and the upper frame portion 252. In this specification, such a
structure is referred to as "supporting post structure".
[0086] By providing the dense part 25 having such a configuration,
even if the stress is applied to the block body in the inserted
state, it is possible to reliably keep the shape of the block body
2 due to the existence of the dense part 25. Therefore, it is
possible to reliably prevent or suppress the porous part 21 from
being broken while maintaining the appropriate size of the
intervertebral space.
[0087] It is preferred that the dense part 25 is constituted from a
dense body in a substantial whole thereof like the needle parts 40.
This makes it possible for the dense part 25 to exhibit more
excellent strength. Therefore, it is possible to reliably prevent
cracks and the like from occurring in the dense part 25 when the
stress is applied to the block body in the inserted state.
[0088] Further, in the present invention, the block body 2 can be
produced by using a producing method as described later. According
to such a producing method, it is possible to form the needle parts
40 and the dense part 25, and the porous part 21 integrally. Such a
block body 2 is capable of reliably preventing the stress from
unevenly being applied to the needle parts 40, the dense part 25 or
the porous part 21 when the stress is applied in the inserted
state. Moreover, it is possible to reliably prevent the needle
parts 40 from dropping off from the through holes 22 of the porous
part 21.
[0089] In the present invention, a titanium based material such as
titanium or a titanium alloy is mainly used as a constituent
material of such a block body 2, namely constituent materials of
the needle parts 40, the dense part 25 and the porous part 21.
[0090] The titanium based material has high biocompatibility and
excellent strength, and therefore is used as the constituent
material of the block body 2 reliably. In the titanium based
material, the titanium alloy is preferably used as the constituent
materials of the needle parts 40 and the dense part 25 requiring
the excellent strength in a constituent member of the block body 2.
This is because the titanium alloy has more excellent strength.
Further, examples of the titanium alloy are not limited
particularly, but include an alloy, such as Ti-6Al-4V and
Ti-29Nb-13Ta-4.6Zr, in which one or more of Al, Sn, Cr, Zr, Mo, Ni,
Pd, Ta, Nb, V, Pt and the like are added to Ti of a main component.
Examples of such an alloy include Ti-6Al-4V, Ti-29Nb-13Ta-4.6Zr and
the like.
[0091] The pair of block bodies 2 as described above is inserted
between the vertebral body 101 and the vertebral body 102
(intervertebral space) side by side with each other.
[0092] By inserting the block body 2 into the intervertebral space,
a space 103 is formed in an area of the intervertebral space in
which no block body 2 exists. A grafted bone (in particular,
autologous bone) as a filler is filled into the space 103, so that
it is ensured to achieve the bone fusion between the vertebral body
101 and the vertebral body 102 through the block body 2 and the
grafted bone more reliably and promptly.
[0093] Further, the spacer 1 is constituted from the pair of block
bodies 2, 2. Therefore, if the arrangement of the block bodies 2, 2
is changed, that is, they are arranged in a state of spacing the
front ends or the back ends of the block bodies 2 from each other
and/or approaching them to each other, it becomes possible to treat
an appropriate cure depending upon the cases.
[0094] The spacer 1 as described above, for example, can be
produced as follows.
[0095] <1> First, prepared are road-shaped dense bodies to
become the needle parts 40 and a frame-shaped dense body to become
the dense part 25 by performing a debinding process and sintering
process.
[0096] Such road-shaped dense bodies and a frame-shaped dense body
can be obtained easily by preparing a sheet-shaped dense body
constituted of the titanium based material and cutting the
sheet-shaped dense body in a predetermined shape and size by using
a slice cut method such as a laser cut method, a water jet method,
a discharge wire method and an ultrasound ablation method.
Alternatively, the road-shaped dense bodies and the frame-shaped
dense body are prepared by using a slurry of which concentration is
adjusted so that the porosity thereof is more smaller, which is the
same process as that of a green body to become the porous part 21
as described later. Moreover, the frame-shaped dense body is also
prepared by using a slurry of which composition and an additive
amount of a foaming agent (0% to) are adjusted, which is the same
process as that of the green body to become the porous part 21 as
described later.
[0097] <2> Next, prepared is a green body to become the
porous part 21 having the through holes 22 by performing a
debinding process and a sintering process.
[0098] <2-1> First, prepared is a slurry containing metal
powder and a foam agent.
[0099] Powder constituted of the titanium based material described
above or an oxidant thereof is used as the metal powder.
[0100] Further, an average particle size of particles of the metal
powder is not limited particularly, but preferably in the range of
about 0.5 to 50 .mu.m and more preferably in the range of about 3
to 30 .mu.m. By using the metal powder including the particles
having such a size, it becomes possible to set the porosity of the
obtained porous part 21 and an average pore size of pores thereof
to a predetermined value. In this regard, it is to be noted that
the average particle size of the particles of the metal powder can
be obtained by a laser diffractometry and the like.
[0101] An amount of the metal powder in the slurry is preferably in
the range of about 30 to 80 mass % and more preferably in the range
of about 40 to 70 mass %. By setting the amount of the metal powder
to such ranges, it becomes possible to reliably set the porosity of
the obtained porous part 21 and the average pore size of the pores
thereof to the predetermined value.
[0102] Examples of the foam agent is not limited particularly, but
include a surfactant, a volatile organic solvent and the like. A
water-insoluble hydrocarbon-based organic solvent having a carbon
number of 5 to 8 is preferably used as the volatile organic
solvent. Further, neopentane, hexane, heptanes and cyclohexane are
more preferably used. The use of such a foam agent makes it
possible to obtain the porous part 21 having a high porosity with
ease.
[0103] Such a slurry preferably contains a water-soluble resin
binder and water. In addition to that, the slurry contains other
components such as a plasticizer, an organic solvent and the like,
if needed.
[0104] Examples of the water-soluble resin binder include
methylcellulose, hydroxyl propyl methylcellulose, polyvinyl
butyral, polyvinyl alcohol and the like. These materials may be
used singly or in combination of two or more of them. A skeleton of
the porous part 21 is formed well by using the slurry containing
the water-soluble resin binder.
[0105] Examples of the plasticizer include glycerin, ethylene
glycol, polyethylene glycol, and the like.
[0106] Examples of the organic solvent include methanol, ethanol,
isopropanol, and the like.
[0107] <2-2> Next, the prepared slurry is applied onto a base
in a sheet shape, then the applied slurry is heated and foamed and
thereafter is dried to obtain a green body (green sheet).
[0108] A method of molding the slurry in the sheet shape is not
limited particularly, but is preferably a doctor blade method.
[0109] The heating process is not limited particularly, but is
preferably performed under a high humidity atmosphere having
humidity of 80% or more. By controlling a temperature condition at
this time, it is possible to uniformly control pore sizes of a huge
number of foam pores formed by acts of the foam agent in the whole
of the slurry. As a result, it is possible to form a three
dimensional skeleton constituted of the slurry containing the metal
powder.
[0110] At this time, the foam pores are formed into a flat shape on
a contact surface (back surface) between the slurry and the base.
On the other hand, on a surface (front surface) of the slurry
opposite to the base, foam pores inflated three-dimensionally due
to free foam are formed. Therefore, according to the producing
method as the present embodiment, a green body having an asymmetric
foam structure on the back surface and the front surface each other
is formed.
[0111] Further, the drying process of the slurry in which the foam
pores have been formed is performed by heating at a temperature of
100.degree. C. or less under the atmosphere or an inert gas
atmosphere. This makes it possible to reliably remove moisture
contained in the slurry while maintaining the foam pores included
in the slurry.
[0112] <2-3> Next, the obtained green body is peeled off from
the base. Thereafter, the green body is cut in a predetermined
shape and size by using the slice cut method described above. The
cut green body to become the porous part 21 by performing the
debinding process and sintering process is obtained. In this
regard, during this cutting, through holes to become the through
holes 22 are also formed in the cut green body.
[0113] <3> Next, the cut green body (porous part 21 before
performing the debinding process and sintering process) is placed
into the flame-shaped dense body (dense part 25 before performing
the debinding process and sintering process), and then the
road-shaped dense bodies (needle parts 40 before performing the
debinding process and sintering process) are inserted into the
through holes to become the through holes 22. Thereafter, they are
heated in this state. By performing the debinding process and
sintering process of the cut green body, the flame-shaped dense
body and the road-shaped dense bodies, a block body 2 is obtained
as the porous part 21, the dense part 25 and the needle parts 40.
In this regard, it is to be noted that the porosities of the dense
part 25 and the needle parts 40 after performing the debinding
process and sintering process are preferably set to the range of 3
to 50%.
[0114] The cut green body, the flame-shaped dense body and the
road-shaped dense bodies are debinded at a temperature within the
range of about 350 to 600.degree. C. for about 1 to 10 hours. The
debinding under such conditions makes it possible to decompose and
remove components other than the metal powder included in the cut
green body, the flame-shaped dense body and the road-shaped dense
bodies while maintaining a foam pore structure. Consequently, it is
possible to change the cut green body, the flame-shaped dense body
and the road-shaped dense bodies to a metal brown body having a
skeleton structure in which the metal powder is aggregated.
[0115] Further, the cut green body, the flame-shaped dense body and
the road-shaped dense bodies (metal brown body) after performing
the debinding process are sintered at a temperature within the
range of about 1100 to 1350.degree. C. for about 1 to 10 hours
under a non-oxidizing atmosphere. The sintering process under such
conditions makes it possible to sinter the metal powder while
maintaining the foam pore structure. In addition to that, the metal
powder is diffused in the cut green body, the flame-shaped dense
body and the road-shaped dense bodies after performing the
debinding process. As a result, the needle parts 40 and the dense
part 25, and the porous part 21 are diffusion-bonded together.
Further, it is possible to sinter the metal powder while
maintaining the foam pore structure, so that it is possible to
obtain the block body 2 in which the needle parts 40 and the dense
part 25, and the porous part 21 are bonded together firmly.
[0116] In this regard, a degree of vacuum in the non-oxidizing
atmosphere is preferably 5.0.times.10.sup.-2 Pa or less. The
non-oxidizing atmosphere is preferably an argon atmosphere.
[0117] As described above, by performing the debinding process and
the sintering process, the cut green body, the flame-shaped dense
body and the road-shaped dense bodies change to the porous part 21,
the dense part 25 and the needle parts 40, respectively, thereby
enabling a block body 2 in which the porous part 21, the dense part
25 and the needle parts 40 are bonded together firmly (integrally)
to obtain.
[0118] Although the block body 2 has the dense part 25 in the
present embodiment, the dense part 25 may be omitted in the case
where the needle parts 40 give sufficient strength to the block
body 2.
[0119] In the case where the road-shaped dense bodies and the
flame-shaped dense body are constituted of the titanium based alloy
(material), frame-shaped dense bodies are formed separately in
advance, and then the separately formed frame-shaped dense bodies
and the porous part 21 (sintered cut green body) are assembled.
Next, the road-shaped dense bodies are inserted into the through
holes 22, and then end portions of the separately formed
frame-shaped dense bodies and the road-shaped dense bodies are
welded to the porous part 21 by laser and the like to obtain an
assembled body. Thereafter, the assembled body is subjected to a
heating treatment at a temperature in the range of 800 to
1050.degree. C. for 1 to 10 hours under the non-oxidizing
atmosphere (argon atmosphere or vacuum). This makes it possible to
change the frame-shaped dense bodies and the road-shaped dense
bodies to the dense part 25 and the needle parts 40 to obtain a
block body 2 by diffusion-bonding between the dense part 25 and the
needle parts 40, and the porous part 21. In this regard, when the
separately formed frame-shaped dense bodies and the porous part 21
are assembled, used is the porous part 21 formed so that each
surface constitutes a flat surface in the assembled body except the
road-shaped dense bodies. That is, used is the porous part 21 in
which grooves capable of containing the frame-shaped dense bodies
are formed.
Second Embodiment
[0120] Next, description will be made on a second embodiment of a
vertebral body space according to the present invention.
[0121] FIG. 4 is a plan view (a), a front view (b) and a side view
(c) which show the second embodiment of a block body constituting
the vertebral body spacer of the present invention.
[0122] In the following description, the description will be made
on a block body 2 shown in FIG. 4. The description will be made by
focusing on different points from the block body 2 shown in FIG. 1
to FIG. 3 and the description on the common points is omitted.
[0123] The block body 2 shown in FIG. 4 is the same as the block
body 2 shown in FIG. 1 to FIG. 3, except that a shape of the whole
thereof is different.
[0124] In the present embodiment, both a first surface 31 and a
second surface 32 constitute a curved convex surface, except an
area in which projection portions 41 are provided. The first
surface 31 and the second surface 32 are connected to each other at
an end portion on a front side thereof. Thus, a sixth surface 36 is
omitted. Further, each of a third surface 33, a fourth surface 34
and a fifth surface 35 constitutes substantially a flat
surface.
[0125] Further, in the present embodiment, a hole portion 255 is
provided at a substantial center of a dense part which forms a
bonding part between the first surface 31 and the second surface
32. In the case where the block body 2 is inserted into the
intervertebral space by using a jig, this hole portion 255 is used
to fix the block body 2 to the jig by inserting a convex portion of
the jig thereinto. This makes it possible to insert the block body
2 into the intervertebral space with ease by using the jig.
[0126] The block body 2 having such a whole shape has a lower frame
portion 251 and an upper frame portion 252 which have a shape
corresponding to the shape of the block body 2 in the plane view as
shown in FIG. 4(a). The block body 2 also has a connecting portion
253 which connects the lower frame portion 251 and the upper frame
portion 252. In the present embodiment, the connecting portion 253
is constituted from one wide connecting portion provided at an end
portion on a back side of the frame portion 251 and the frame
portion 252. Further, each of the frame portion 251 and the frame
portion 252 is curved and directly connected at the end portion on
the front side to each other. Thus, a connecting portion is omitted
at the end portion on the front side of the frame portion 251 and
the frame portion 252.
[0127] The block body 2 of the present embodiment configured as
described above can be also used as the block body 2 of the first
embodiment and obtain the same effects as those of the block body 2
(spacer 1) of the first embodiment.
Third Embodiment
[0128] Next, description will be made on a third embodiment of a
vertebral body space according to the present invention.
[0129] FIG. 5 is a plan view (a), a front view (b) and a side view
(c) which show the third embodiment of a block body constituting
the vertebral body spacer of the present invention. FIG. 6 is a
view showing a used state of the third embodiment of the vertebral
body spacer of the present invention.
[0130] In the following description, the description will be made
on a block body 2 shown in FIGS. 5 and 6. The description will be
made by focusing on different points from the block body 2 shown in
FIG. 1 to FIG. 3 and the description on the common points is
omitted.
[0131] The block body 2 shown in FIG. 5 is the same as the block
body 2 shown in FIG. 1 to FIG. 3, except that a connecting portion
50 of rotatably connecting a pair of block bodies 2 to each other
is provided with the pair of block bodies 2.
[0132] In the present embodiment, the connecting portion 50 has a
plate-shaped connection finger 51 provided at an end portion on a
front side of a third surface 33 of one of the block bodies 2 and a
plate-shaped connection finger 52 provided at an end portion on a
front side of a third surface 33 of the other of the block bodies
2. A road-shaped body 53 is formed at an end portion on a side of
the connection finger 51 opposite to the block body 2 so as to
project toward an upper direction. A through hole 54 is formed at
an end portion on a side of the connection finger 52 opposite to
the block body 2. The two block bodies 2 are connected to each
other through the connecting portion 50 by inserting the rod-shaped
body 53 into the through hole 54. Further, a hinge portion is
formed by inserting the rod-shaped body 53 into the through hole
54, so that it is possible for the block bodies to approach to and
space from each other at the hinge portion as a center of rotation.
In other words, the block bodies 2 are capable of rotating in a
horizontal direction with respect to a first surface 31.
[0133] According to the spacer 1 having such an configuration, it
is possible to change a position of each block body 2, namely to
perform operations easily and rapidly of spacing front ends and
back ends of the block bodies 2 from each other and/or approaching
them to each other, which depend on the cases. Therefore, it
becomes possible to perform an appropriate cure by using such a
spacer 1 promptly. Further, since the block bodies 2 are connected
to each other through the connecting portion 50, it is easy to
accurately position them in the intervertebral space in the
inserted state.
[0134] The block body 2 of the present embodiment configured as
described above can be also used as the block body 2 of the first
embodiment and obtain the same effects as those of the block body 2
(spacer 1) of the first embodiment.
[0135] The description has been made on the embodiments of the
vertebral body space according to the present invention as shown in
the drawings. However, the present invention is not limited to
them.
[0136] For example, any configuration of the first to third
embodiments may be combined arbitrarily in the vertebral body space
according to the present invention.
[0137] Further, in each of the embodiments, the porous part 21 is
constituted from one member, however, may be constituted by
laminating (attaching) a plurality of sheet-shaped bodies each
having a different porosity. In this case, it is possible to give
anisotropy to the strength of the porous part 21, thereby improving
flexibility in a design of the block body 2 (spacer 1).
[0138] Further, in each of the embodiments, the description has
been made on the case of inserting the pair of block bodies 2 into
the intervertebral space. However, the case is not limited thereto,
and may be a case of inserting one block body 2 into the
intervertebral space. In this case, the block body 2 is inserted in
the front side of the intervertebral space so that the fourth
surface 34 faces to the front side and the third surface 33 faces
to the back side.
[0139] Moreover, the both end portions of the needle parts are
formed into the conical shape and the middle portions thereof are
formed into the cylindrical shape, but are not limited to them. The
both end portions of the needle parts may be formed into a pointed
shape. Therefore, the both end portions of the needle parts may be,
for example, that they are formed into a triangular pointed shape
and the middle portions thereof are formed into a triangular prism
shape or they are formed into a quadrangular pointed shape and the
middle portions thereof are formed into a quadrangular prism shape.
In other words, the shape of the projection portions is not limited
to the conical shape, may be the pointed shape, for example, may be
the quadrangular pointed shape or the triangular pointed shape.
[0140] Further, the filler is not limited to the grafted bone
(autologous bone), for example, may be powder or granule of a
calcium phosphate based compound, a calcium phosphate based cement
and the like.
INDUSTRIAL APPLICABILITY
[0141] The vertebral body spacer of the present invention is
capable of maintaining the appropriate size between vertebral
bodies (intervertebral space). Further, the vertebral body spacer
of the present invention is capable of reliably preventing the
vertebral body spacer from being broken irrespecitve of the cases
and the position of the intervertebral space, and thereby capable
of achieving the bone fusion between the vertebral body spacer and
the vertebral bodies promptly. Moreover, a space of filling the
filler into the intervertebral space is ensured by inserting the
vertebral body spacer thereinto. For these reasons, by filling the
grafted bone to such a space, it is possible to reliably and
promptly achieve the bone fusion between the vertebral bodies
through the vertebral body spacer and the grafted bone.
Accordingly, the present invention has industrial
applicability.
* * * * *