U.S. patent application number 13/964836 was filed with the patent office on 2013-12-12 for vertebral body replacement.
This patent application is currently assigned to NuVasive, Inc.. The applicant listed for this patent is NuVasive, Inc.. Invention is credited to Benjamin Arnold, Sharath Bellary, Ryan Donahoe, Michael Mindoro, Rich Mueller, William Smith.
Application Number | 20130331943 13/964836 |
Document ID | / |
Family ID | 46637502 |
Filed Date | 2013-12-12 |
United States Patent
Application |
20130331943 |
Kind Code |
A1 |
Arnold; Benjamin ; et
al. |
December 12, 2013 |
VERTEBRAL BODY REPLACEMENT
Abstract
The present invention involves a system and methods for
assembling and implanting a vertebral body implant. The vertebral
body implant includes, but is not necessarily limited to, an
expandable core body and endplates that can be attached at both
ends. Endplates of various shapes, sizes and angles are attachable
to the expandable core so that a suitable vertebral body implant
can be implanted between vertebrae.
Inventors: |
Arnold; Benjamin; (San
Diego, CA) ; Mindoro; Michael; (Chula Vista, CA)
; Mueller; Rich; (Carlsbad, CA) ; Smith;
William; (Las Vegas, NV) ; Donahoe; Ryan; (San
Diego, CA) ; Bellary; Sharath; (Cumberland,
MD) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NuVasive, Inc. |
San Diego |
CA |
US |
|
|
Assignee: |
NuVasive, Inc.
San Diego
CA
|
Family ID: |
46637502 |
Appl. No.: |
13/964836 |
Filed: |
August 12, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12661206 |
Mar 12, 2010 |
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13964836 |
|
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61159792 |
Mar 12, 2009 |
|
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61260375 |
Nov 11, 2009 |
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Current U.S.
Class: |
623/17.15 |
Current CPC
Class: |
A61F 2002/30556
20130101; A61F 2002/30393 20130101; A61F 2002/4622 20130101; A61F
2/4465 20130101; A61F 2002/30789 20130101; A61F 2/4611 20130101;
A61F 2002/4627 20130101; A61F 2002/30395 20130101; A61F 2002/30904
20130101; A61F 2/447 20130101; A61F 2002/30772 20130101; A61F
2002/30507 20130101; A61F 2002/30433 20130101; A61F 2310/00017
20130101; A61F 2002/3055 20130101; A61F 2002/30785 20130101; A61F
2/44 20130101; A61F 2002/30593 20130101; A61F 2/28 20130101; A61F
2002/30777 20130101; A61F 2002/30601 20130101; A61F 2002/30779
20130101; A61F 2002/30579 20130101; A61F 2/4455 20130101; A61F
2310/00023 20130101; A61F 2002/2835 20130101; A61F 2002/30405
20130101; A61F 2002/30235 20130101; A61F 2002/305 20130101; A61F
2002/4628 20130101 |
Class at
Publication: |
623/17.15 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. (canceled)
2. A method for implanting a vertebral body implant from a lateral
direction into a space remaining between a first vertebra and a
second vertebra after the removal of at least part of one vertebra,
the method comprising: selecting first and second endplates from a
plurality of differently sized endplates for attachment to an
intermediate expansion member, the first and second plates being
configured to engage the first and second vertebrae through a
lateral approach to the spine after the removal of said at least
part of one vertebra; after selecting the first and second
endplates, assembling the first endplate to the intermediate
expansion member via a first mechanical structure of the first
endplate that mates with a first complementary mechanical structure
at a first end of the intermediate expansion member, the
intermediate expansion member having an axis and an axial length
extending between the first end and a second end, wherein the
intermediate expansion member includes a ring member rotatable
about the axis of the intermediate expansion member to adjust the
axial length between the first end and the second end from a
collapsed state to an expanded state, wherein the first endplate
includes: a central aperture generally aligned with the axis of the
intermediate expansion member and spaced inwardly from an anterior
side, a posterior side, and opposing lateral sides of the first
endplate, a plate width of 18 mm to 22 mm extending between
opposing flat regions of the anterior side and the posterior side
which extend generally parallel to one another, a plate length of
30 mm to 60 mm extending generally between the opposing lateral
sides and being perpendicular to the plate width; after selecting
the first and second endplates, assembling the second endplate to
the intermediate expansion member via a second mechanical structure
of the second endplate that mates with a second complementary
mechanical structure at the second end of the intermediate
expansion member, wherein the second endplate includes: a central
aperture generally aligned with the axis of the intermediate
expansion member and spaced inwardly from an anterior side, a
posterior side, and opposing lateral sides of the first endplate, a
plate width of 18 mm to 22 mm extending between opposing flat
regions of the anterior side and the posterior side which extend
generally parallel to one another, a plate length of 30 mm to 60 mm
extending generally between the opposing lateral sides and being
perpendicular to the plate width; releasably mounting an inserter
tool to a pair of indented slots of the intermediate expansion
member, the indented slots being symmetrically offset on opposing
sides of a central longitudinal plane of the intermediate expansion
member, the central longitudinal plane passing through the axis of
the intermediate expansion member and being generally parallel to
the plate length of each of the first and second endplates, the
inserter tool including a gear that engages the ring member of the
intermediate expansion member; while the inserter tool is
releasably mounted to the intermediate expansion member and the
first and second endplates assembled to the intermediate expansion
member, laterally inserting the intermediate expansion member in
the collapsed state from a lateral direction into the space
remaining between the first and second vertebrae; and after
laterally inserting the intermediate expansion member into the
space, rotating the gear of the inserter tool about an axis that is
generally parallel to the axis of the intermediate expansion member
so as to rotate the ring member about the axis of the intermediate
expansion member, wherein the rotation of the ring member of the
intermediate expansion member causes the intermediate expansion
member to adjust from the collapsed state to the expanded state so
that anti-migration features of the first endplate secure to the
first vertebra and anti-migration features of the second endplate
secure to the second vertebra.
3. An implant The method of claim 2, further comprising inserting
bone growth promoting material to an interior space of the
intermediate expansion member after laterally inserting the
intermediate expansion member into the space and after causing the
intermediate expansion member to adjust from the collapsed state to
the expanded state.
4. The method of claim 3, wherein said inserting bone growth
promoting material to the interior space of the intermediate
expansion member comprises inserting the bone growth promoting
material through an elongate opening formed in a sidewall of the
intermediate expansion member, wherein the central longitudinal
plane extending between the pair of indented slots bisects the
elongate opening, the elongate opening having an aperture height
extending generally parallel to the axis of the intermediate
expansion member and an aperture width extending generally
perpendicularly to the aperture height, the aperture height being
greater than the aperture width
5. The method of claim 3, wherein the interior space of the
intermediate expansion member is in communication with the central
aperture of first endplate and the central aperture of second
endplate.
6. The method of claim 2, further comprising engaging a set screw
into the intermediate expansion member so as to lock the
intermediate expansion member in the expanded state.
7. The method of claim 2, wherein the intermediate expansion member
includes said rotatable ring member, an outer core member, an inner
core member configured to linearly translate in an axial direction
relative to the outer core member in response to rotation of said
rotatable ring member relative to said outer core member.
8. The method of claim 7, wherein said rotatable ring member is
rotatable relative to the outer core member while being generally
fixed in said axial direction relative to the outer core member,
said inner core member being non-rotatable relative to the outer
core member while being configured to linearly translate in the
axial direction relative to the outer core member, wherein said
rotatable ring member comprises an internal thread configured to
mate with an exterior thread of the inner core member, and external
engagement structures extending radially outwardly for mating with
a tool, and wherein at least a portion of the inner core member
that engages with the outer core member is positioned radially
inward of the outer core member, and at least a portion of the
outer core member that engages with the rotatable ring member is
positioned radially inward of the rotatable ring member.
9. The method of claim 2, wherein the first endplate comprises at
least two offset apertures that are spaced apart from the central
aperture of the first endplate and that extend fully through the
first endplate, and wherein the second endplate comprises at least
two offset apertures that are spaced apart from the central
aperture of the second endplate and that extend fully through the
first endplate
10. The method of claim 2, wherein the first endplate is defined by
a perimeter that includes anterior and posterior aspects that
extend longitudinally straight and generally parallel to the plate
length of the first plate and opposing lateral aspects including
convexly curved portions.
11. The method of claim 2, wherein said selecting the first and
second endplates from the plurality of differently sized endplates
comprises: selecting the first endplate of a size to extend across
the space from an apophyseal ring at a first lateral aspect of the
first vertebra to the apophyseal ring at a second opposing lateral
aspect of the first vertebra, and selecting the first endplate of a
size to extend across the space from an apophyseal ring at a first
lateral aspect of the second vertebra to the apophyseal ring at a
second opposing lateral aspect of the second vertebra.
12. The method of claim 2, wherein after laterally inserting the
intermediate expansion member into the space, the plate length the
first endplate extends across the space from an apophyseal ring at
a first lateral aspect of the first vertebra to the apophyseal ring
at a second opposing lateral aspect of the first vertebra, and the
plate length the second endplate extends across the space from an
apophyseal ring at a first lateral aspect of the second vertebra to
the apophyseal ring at a second opposing lateral aspect of the
second vertebra.
13. The method of claim 2, wherein the plate width of the first and
second endplates is 22 mm, and the plate length of the first and
second endplates is 30 mm to 60 mm.
14. A method for implanting a vertebral body implant from a lateral
direction into a space remaining between a first vertebra and a
second vertebra after the removal of at least part of one vertebra,
the method comprising: selecting first and second lateral insertion
endplates from a plurality of differently sized endplates and
attaching the selected first and second lateral insertion endplates
to opposing ends of an intermediate expansion member, wherein each
of the first and second lateral insertion endplates includes: a
central aperture generally aligned with the axis of the
intermediate expansion member and spaced inwardly from an anterior
side, a posterior side, and opposing lateral sides of the
respective endplate, a plate width of 18 mm to 22 mm extending
between opposing flat regions of the anterior side and the
posterior side which extend generally parallel to one another, a
plate length of 30 mm to 60 mm extending generally between the
opposing lateral sides and being perpendicular to the plate width;
releasably mounting an inserter tool to the intermediate expansion
member so that a longitudinal axis of the inserter tool extends
generally parallel to the plate length of each of the first and
second endplates, the inserter tool including a gear that engages
the intermediate expansion member and that is rotatable about a
gear axis generally perpendicular to the longitudinal axis of the
inserter tool; while the inserter tool is releasably mounted to the
intermediate expansion member and the first and second endplates
assembled to the intermediate expansion member, laterally inserting
the intermediate expansion member in the collapsed state from a
lateral direction into the space remaining between the first and
second vertebrae; and after laterally inserting the intermediate
expansion member into the space, rotating the gear of the inserter
tool to cause the intermediate expansion member to adjust from a
collapsed state to an expanded state.
15. An implant The method of claim 14, further comprising inserting
bone growth promoting material to an interior space of the
intermediate expansion member after laterally inserting the
intermediate expansion member into the space and after causing the
intermediate expansion member to adjust from the collapsed state to
the expanded state.
16. The method of claim 15, wherein said inserting bone growth
promoting material to the interior space of the intermediate
expansion member comprises inserting the bone growth promoting
material through an elongate opening formed in a sidewall of the
intermediate expansion member, wherein the central longitudinal
plane extending between the pair of indented slots bisects the
elongate opening, the elongate opening having an aperture height
extending generally parallel to the axis of the intermediate
expansion member and an aperture width extending generally
perpendicularly to the aperture height, the aperture height being
greater than the aperture width
17. The method of claim 15, wherein the interior space of the
intermediate expansion member is in communication with the central
aperture of first endplate and the central aperture of second
endplate.
18. The method of claim 14, further comprising engaging a set screw
into the intermediate expansion member so as to lock the
intermediate expansion member in the expanded state.
19. The method of claim 14, wherein the intermediate expansion
member has an axis and an axial length extending between the
opposing ends, wherein the intermediate expansion member includes:
a ring member rotatable about the axis of the intermediate
expansion member to adjust the axial length between the opposing
ends from the collapsed state to the expanded state, an outer core
member, an inner core member configured to linearly translate in an
axial direction relative to the outer core member in response to
rotation of said rotatable ring member relative to said outer core
member.
20. The method of claim 19, wherein said rotatable ring member is
rotatable relative to the outer core member while being generally
fixed in said axial direction relative to the outer core member,
said inner core member being non-rotatable relative to the outer
core member while being configured to linearly translate in the
axial direction relative to the outer core member, wherein said
rotatable ring member comprises an internal thread configured to
mate with an exterior thread of the inner core member, and external
engagement structures extending radially outwardly for mating with
a tool, and wherein at least a portion of the inner core member
that engages with the outer core member is positioned radially
inward of the outer core member, and at least a portion of the
outer core member that engages with the rotatable ring member is
positioned radially inward of the rotatable ring member.
21. The method of claim 14, wherein the first endplate comprises at
least two offset apertures that are spaced apart from the central
aperture of the first endplate and that extend fully through the
first endplate, and wherein the second endplate comprises at least
two offset apertures that are spaced apart from the central
aperture of the second endplate and that extend fully through the
first endplate
22. The method of claim 14, wherein the first endplate is defined
by a perimeter that includes anterior and posterior aspects that
extend longitudinally straight and generally parallel to the plate
length of the first plate and opposing lateral aspects including
convexly curved portions.
23. The method of claim 14, wherein said selecting the first and
second endplates from the plurality of differently sized endplates
comprises: selecting the first endplate of a size to extend across
the space from an apophyseal ring at a first lateral aspect of the
first vertebra to the apophyseal ring at a second opposing lateral
aspect of the first vertebra, and selecting the first endplate of a
size to extend across the space from an apophyseal ring at a first
lateral aspect of the second vertebra to the apophyseal ring at a
second opposing lateral aspect of the second vertebra.
24. The method of claim 14, wherein after laterally inserting the
intermediate expansion member into the space, the plate length the
first endplate extends across the space from an apophyseal ring at
a first lateral aspect of the first vertebra to the apophyseal ring
at a second opposing lateral aspect of the first vertebra, and the
plate length the second endplate extends across the space from an
apophyseal ring at a first lateral aspect of the second vertebra to
the apophyseal ring at a second opposing lateral aspect of the
second vertebra.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/661,206 filed on Mar. 12, 2010, which is a
non-provisional patent application and claims the benefit of
priority from commonly owned and co-pending U.S. Provisional Patent
Application Ser. Nos. 61/159,792 filed on Mar. 12, 2009, and
61/260,375 filed on Nov. 11, 2009. The entire contents of these
previous related applications are each hereby expressly
incorporated by reference into this disclosure.
FIELD
[0002] The present application relates generally to spinal implants
and methods for replacing at least a portion of one or more
vertebral bodies of a spine.
BACKGROUND
[0003] The spine is formed of a column of vertebra that extends
between the cranium and pelvis. The three major sections of the
spine are known as the cervical, thoracic and lumbar regions. There
are 7 cervical vertebrae, 12 thoracic vertebrae, and 5 lumbar
vertebrae, with each of the 24 vertebrae being separated from each
other by an intervertebral disc. A series of about 9 fused
vertebrae extend from the lumbar region of the spine and make up
the pelvic region of the vertebral column. These fused vertebrae
consist of the sacral and coccygeal region of the vertebral
column.
[0004] The main functions of the spine are to provide skeletal
support and protect the spinal cord. Even slight disruptions to
either the intervertebral discs or vertebrae can result in serious
discomfort due to compression of nerve fibers either within the
spinal cord or extending from the spinal cord. If a disruption to
the spine becomes severe enough, damage to a nerve or part of the
spinal cord may occur and can result in partial to total loss of
bodily functions (e.g. walking, talking, and breathing). Therefore,
it is of great interest and concern to be able to both correct and
prevent any ailments of the spine.
[0005] Trauma to the spine (e.g. car accident, sports injury) can
cause fracturing of one or more vertebrae. Certain diseases
affecting the spine (e.g. tumors, osteoporosis) can cause
degeneration of the spine. Both trauma and degeneration may result
in severe disruption to the spine. In these circumstances, the
complete removal of one or more vertebrae may be required. If one
or more vertebrae are removed, a replacement support system must be
implanted in order to protect the spinal cord and maintain, or
improve, the structure and integrity of the spine.
[0006] The present invention is directed at overcoming, or at least
improving upon, disadvantages of the prior art.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a perspective view of one example of a vertebral
body implant assembly, according to one embodiment of the present
invention;
[0008] FIG. 2 is a perspective view of an outer tubular core
forming part of the implant assembly of FIG. 1;
[0009] FIG. 3 is an exploded view of the core expanding body
forming part of the implant assembly of FIG. 1;
[0010] FIG. 4 is a partially exploded view directed at illustrating
the guide pin and guide track interaction of the implant assembly
of FIG. 1;
[0011] FIG. 5 is a perspective view of the adjustment ring forming
part of the implant assembly of FIG. 1;
[0012] FIG. 6 is a cross section view of the adjustment ring of
FIG. 5 taken along line 6-6 of FIG. 5;
[0013] FIG. 7 is a perspective view of the core expanding body
forming part of the implant assembly of FIG. 1;
[0014] FIG. 8A is a cross section view of the core expanding body
of FIG. 7 taken along line 8-8 of FIG. 7;
[0015] FIG. 8B is a cross section view of the adjustment ring and
outer tubular core of the core expanding body of FIG. 7 taken along
line 8-8 of FIG. 7;
[0016] FIG. 9 is a perspective view of the inner tubular core
forming part of the implant assembly of FIG. 1;
[0017] FIG. 10 is a top perspective view of one example of an
endplate forming part of the implant assembly of FIG. 1;
[0018] FIG. 11 is a top view of the endplate of FIG. 11;
[0019] FIG. 12A is a cross section view of the endplate of FIG. 11
taken along line 12-12 of FIG. 11;
[0020] FIG. 12B is a cross section view of the endplate and inner
tubular core of the implant assembly of FIG. 1;
[0021] FIG. 12C is a cross section view of the endplate and outer
tubular core of the implant assembly of FIG. 1;
[0022] FIG. 13 is a bottom perspective view of the endplate of FIG.
10;
[0023] FIG. 14 is a bottom view of a second example of an endplate
forming part of the implant assembly of FIG. 1;
[0024] FIG. 15 is a bottom view of a third example of an endplate
forming part of the implant assembly of FIG. 1;
[0025] FIG. 16 is a bottom view of a fourth example of an endplate
forming part of the implant assembly of FIG. 1;
[0026] FIG. 17 is a bottom view of a fifth example of an endplate
forming part of the implant assembly of FIG. 1;
[0027] FIG. 18 is a side view of the endplate of FIG. 16;
[0028] FIG. 19 is a perspective view of a vertebral body implant
assembly according to a another embodiment of the present
invention;
[0029] FIG. 20 is a perspective view of an extension piece forming
part of the implant assembly of FIG. 22;
[0030] FIG. 21 is a cross section view of the extension piece of
FIG. 20 taken along line 21-21 of FIG. 23;
[0031] FIG. 22 is a top view of one example of a combined insertion
and expansion tool, according to one embodiment of the present
invention;
[0032] FIG. 23 is a side view of the expanding tool of FIG. 22;
[0033] FIGS. 24A-B are a cross section view of the expanding tool
of FIG. 23 taken along line 24-24 of FIG. 23;
[0034] FIG. 25 is a cross section view of the expanding tool of
FIG. 23 taken along line 25-25 of FIG. 23;
[0035] FIG. 26 is a partial view of the expanding tool taken from
partial view area 26 of FIG. 25;
[0036] FIG. 27 is a partial view of the expanding tool taken from
partial view area 27 of FIG. 24;
[0037] FIG. 28 is a partial view of the expanding tool taken from
partial view area 28 of FIG. 27;
[0038] FIG. 29 is a partial view of the expanding tool taken from
partial view area 29 of FIG. 24;
[0039] FIG. 30 is a side perspective view of the core expanding
body of FIG. 7 coupled with the expanding tool of FIG. 25,
according to one embodiment of the present invention;
[0040] FIG. 31 is a perspective cross section view of the expanding
body coupled with the expanding tool of FIG. 30 taken along line
31-31 of FIG. 30;
[0041] FIG. 32 is a top view of the loading block, according to one
embodiment of the present invention;
[0042] FIG. 33 is a side view of the loading block of FIG. 32;
[0043] FIG. 34 is a perspective view of a vertebral body implant
assembly according to a another embodiment of the present
invention;
[0044] FIG. 35 is a perspective view of a first side of an endplate
according to the embodiment of FIG. 34;
[0045] FIG. 36 is a perspective view of a second side of an
endplate according to the embodiment of FIG. 34;
[0046] FIG. 37 is a perspective view of a lock screw for releasably
fixing the endplate of FIGS. 35 and 36 to the core of the implant
of FIG. 34;
[0047] FIG. 38 is an exploded perspective view of the implant of
the implant of FIG. 34;
[0048] FIG. 39 is a perspective cross section of the implant of
FIG. 34;
[0049] FIG. 40 is a side view of one example of an expansion tool
for inserting and expanding the implant of FIG. 34;
[0050] FIG. 41 is a cross section view of the distal end of the
expansion tool of FIG. 40;
[0051] FIG. 42 is a side view of the distal end of the expansion
tool of FIG. 41 with the outer housing and outer tube removed for
the purposes of illustration; and
[0052] FIG. 43A-43E is a series of side views of the implant
assembly of FIG. 1 engaged with the expanding tool of FIG. 23 and
the process of implanting the expandable vertebral body between a
first vertebra and second vertebra.
DETAILED DESCRIPTION OF AN EXAMPLE EMBODIMENT
[0053] Illustrative embodiments of the invention are described
below. In the interest of clarity, not all features of an actual
implementation are described in this specification. It will of
course be appreciated that in the development of any such actual
embodiment, numerous implementation-specific decisions must be made
to achieve the developers' specific goals, such as a compliance
with system-related and business-related constraints, which will
vary from one implementation to another. Moreover, it will be
appreciated that such a development effort might be complex and
time-consuming, but would nevertheless be a routine undertaking for
those of ordinary skill in the art having the benefit of this
disclosure. The expandable vertebral body replacement disclosed
herein boasts a variety of inventive features and components that
warrant patent protection, both individually and in
combination.
[0054] FIG. 1 illustrates an example of a vertebral body implant
assembly 10 according to a first embodiment of the present
invention. The vertebral body implant assembly 10 includes
endplates 11 fixed at the superior and inferior ends of a tubular
core expanding body 12 wherein the expandable implant can be
customized to accommodate various needs by attaching from a
selection of different endplates. The customization of the
expandable tubular core can be done moments before implant of the
expandable vertebral body replacement, which gives the benefit of
customizing the implant based on expected and unexpected
circumstances and conditions of the surrounding vertebral
bodies.
[0055] The core expanding body 12 includes an adjustment ring 13,
an outer tubular core 14, an inner tubular core 15, one or more
guide pins 20, and one or more set screws 16. As will be explained
in greater detail below, the vertebral body implant assembly 10 of
the present invention may be inserted into a space left by the
removal of at least part of one or more vertebra in order to
maintain a desired spacing between the remaining vertebrae and to
stabilize the affected spinal segments. To do so, the vertebral
body implant assembly 10 is placed, preferably in a collapsed
state, in the space between the remaining superior and inferior
vertebral bodies. Rotation of the adjustment ring 13, which is
fixed at one end of the outer tubular core 14 of the core expanding
body 12, results in the expansion of the core expanding body 12 due
to the outer tubular core 14 and inner tubular core 15 moving in
opposite directions along their central axis. Expansion of the core
expanding body 12 may be continued until the desired spacing
between the vertebral bodies is achieved. Once the desired spacing
is reached, a set screw 16 in the wall of the outer tubular core 14
is engaged into the exterior threads 31 of the inner tubular core
15 to secure the expanded position of the vertebral body implant
assembly 10 and prevent further height alterations of the vertebral
body implant assembly 10.
[0056] Referring to FIGS. 2-9, the outer tubular core 14 includes
indented slots 23, a plurality of holes 38, an opening 24, a first
end 39, a second end 41, a plurality of flanges 25 with a distal
step 26 forming a groove 44, and an endplate attachment feature 22.
Indented slots 23 on the exterior wall of the outer tubular core 14
allow for the anti-rotational attachment of the expanding tool,
described below. The plurality of holes 38 in the wall of the outer
tubular core 14 allow the transport of blood and nutrients through
the core expanding body 12 once implanted, which assists in new
bone growth between the remaining vertebra. The relatively large
opening 24 in the side of the outer tubular core 14 allows the
placement of additional bone growth promoting material to be added
once the vertebral body implant assembly 10 has been positioned in
the body and expanded to a desired height. A plurality of flanges
25 with a distal step 26 extend from the first end 39 of the outer
tubular core 14 and function to secure the attachment of the
adjustment ring 13 to the first end 39.
[0057] The adjustment ring 13, shown by way of example in FIGS. 5
and 6, includes external features 21, internal threads 17, and an
annular under-step 18 forming a groove 19. When assembled, the
annular under-step 18 of adjustment ring 13 engages in the groove
41 of the core expanding body 12 and the distal step 26 engages in
the groove 19 of the adjustment ring 13, longitudinally fixing the
adjustment ring 13 and core expanding body 12 together while
permitting rotational movement therebetween. External features 21
on the adjustment ring 13 are configured to engage a combination
inserter/expansion tool which may be operated to rotate adjustment
ring 13 to expand core expanding body 12. The internal threads 17
of the adjustment ring 13 engage with the external threads 31 of
the inner tubular core 15 so that as the adjustment ring 13
rotates, it acts as a nut and forces the linear translation of the
inner tubular core 15 along its central axis. The longitudinal
fixation of the outer tubular core 14 to the adjustment ring 13
ensures the relative displacement of the inner tubular core 15 to
the outer tubular core 14 as the adjustment ring 13 rotates.
[0058] The inner tubular core 15, illustrated in FIG. 9, is
composed of a first end 40 and a generally elongated tubular body
51 extending centrally from the first end 40, and with at least one
generally helical exterior thread 31. The first end 40 of the inner
tubular core 15 includes endplate attachment feature 42, as will be
discussed in greater detail below. One or more guide tracks 19
ingrained into the exterior wall of the tubular body 51 run
parallel to the central axis of the tubular body 51. The guide
track 19 receives guide pins 20 which extend through the outer
tubular core 14. A guide pin 20 travels along a guide track 19,
rotationally fixing inner tubular core 15 to outer tubular core 14,
while permitting longitudinal movement therebetween. A guide pin 20
may have threaded features that allow it to screw into threaded
holes in the wall of the outer tubular core. The threads of the
guide pins 20 may be surface treated (e.g. bead blasted) to cause
the surface of the threads to be roughened, which can assist in
preventing slippage or backout of the guide pins 20. The rotational
fixation between the inner tubular core 15 to outer tubular core 14
ensure that the inner tubular core 14 and outer tubular core 14
(and the vertebrae engaging endplates 11) remain in the desired
orientation as the vertebral body implant assembly 10 is adjusted,
and for the duration that it is implanted in a patient. A central
lumen 27 through the inner tubular core 15 enables additional bone
growth promoting material to be placed within the core expanding
body 12, and ultimately to allow new bone to form uninterrupted
through the entire central axis of the vertebral body implant
assembly 10. The central lumen 27 may be generally cylindrical in
shape (having a generally circular cross-section) or in the
alternative may have a cross section having any geometric shape
without departing from the scope of the present invention.
[0059] According to one example embodiment, the vertebral body
implant 10 the core can be made to the following dimensions. The
inner and outer diameter of the tubular body 51 may be generally in
the range of 6.1 to 13.1 mm and 12.2 to 16.7 mm, respectively. The
height of the inner tubular core 15 may be generally in the range
of 19.4 to 38.9 mm. The inner and outer diameter of the adjustment
ring 13 may be generally in the range of 10.4 to 15.7 mm and 18.0
to 22.0 mm, respectively. The height of the adjustment ring 13 may
be generally 7.6 mm. The inner and outer diameter of the outer
tubular core 14 may be generally in the range of 11.9 to 16.5 mm
and 18.0 to 22.0 mm, respectively. The height of the outer tubular
core 14 may be generally in the range of 14.8 to 34.3 mm.
[0060] FIGS. 10-12C illustrate in greater detail the features that
allow the attachment of the endplates 11 to the expanding tubular
core 12. The endplate 11 includes a first surface 33, a second
surface 34, a recessed tubular core attachment feature 35, and at
least one window 30 through the endplate 11. The windows 30 allow
bone growth to form through the endplate 11. The first surface 33
is generally flat, except for the recessed tubular core attachment
feature 35. Moreover, although the perimeter of the recessed
tubular core attachment feature 35 is shown as rectangular in shape
with rounded corners, it will be appreciated that the perimeter
shape may be provided in any number of suitable shapes or
dimensions without departing from the scope of the invention,
provided that the perimeter shape allows the endplate attachment
features 42, 22 to be received therein. The tubular core attachment
feature 35 includes at least one center hole 62 and at least one
toothed flange 36 with a distal step feature 37. The toothed
flanges 36 are generally the height of the recess of the tubular
core attachment feature 35 and their distal step feature 37 extends
out from the toothed flange 36 in the lateral direction.
[0061] The endplate attachment feature 42 of the inner tubular core
15 is partially responsible for the secure attachment of an
endplate 11 to the first end 40 of the inner tubular core 15. The
endplate attachment feature 42 includes tapered transitions 28 into
the central opening 43, and an attachment under-step 29. The
central opening 43 allows the continuous formation of new bone
growth throughout the entire length of the inner tubular core 15.
The tapered transitions 28 act as guides for toothed flanges 36 of
the endplate 11. As the toothed flanges 36 engage the tapered
transitions 28, the toothed flanges 36 are deflected inward. After
the toothed flanges 36 travel the length of a tapered transition
28, the toothed flanges 36 return back to their natural positions
and engage the attachment under-step 29 (and best viewed in FIG.
12B), locking the endplate 11 to the core expanding body 12.
[0062] The perimeter shape of the endplate attachment feature 42 of
the inner tubular core 15 may be provided in any number of suitable
shapes or dimensions without departing from the scope of the
invention, provided that the perimeter shape corresponds to the
perimeter shape of the tubular core attachment feature 35 and
allows the tubular core attachment feature 35 to be received
therein.
[0063] FIG. 12C illustrates the attachment of an endplate 11 to the
endplate attachment feature 22 of the outer tubular core 14. The
endplate attachment feature 22 is partially responsible for the
secure attachment of an endplate 11. The endplate attachment
feature 22 includes tapered transitions 58 into the central opening
53, and an attachment under-step 59. The corresponding features and
functions are substantially identical to those of the endplate
attachment feature 42 described previously, such that a repeat
discussion is not necessary.
[0064] The endplate attachment features 42, 22 allow for the unique
ability to customize the tubular core expanding body 12 with
various endplate 11 configurations. The ability to customize the
core expanding body 12 may provide numerous advantages. By way of
example, the customizable core expanding body 12 can be used in a
variety of surgical approaches (e.g. anterior, anterior-lateral,
lateral, etc.). By way of further example, the customizable core
expanding body 12 can be placed in a variety of positions along the
spine, and the customizable core expanding body 12 can be made
compatible with a variety of conditions of the surrounding
vertebral bodies (e.g. partial removal of vertebral body).
[0065] The vertebral body implant assembly 10 is preferably
composed of either metal (e.g. titanium, stainless steel, etc.) or
polymer (e.g. poly-ether-ether-ketone (PEEK)). When the implant
assembly is made out of a polymer, one or more marker rods 46 are
preferably composed of a radiopaque material (e.g. titanium) and
are positioned within the vertebral body implant assembly 10 so
that the positioning of the vertebral body implant assembly 10 can
be visible upon X-ray imaging. This visual indication may be
obtained either post-operatively or intra-operatively to confirm
placement of the vertebral body implant assembly 10. Additionally,
in patients where one or more vertebral bodies have been removed
due to diseases, such as tumors, and an vertebral body implant
assembly 10 has been implanted between the remaining vertebral
bodies, it is beneficial during post-operative x-ray imaging to be
able to see through the implant in order to detect any reoccurrence
of the disease.
[0066] FIG. 13 illustrates the second surface 34 of the endplate 11
which includes one or more liner ridges 60, a taper 61 around the
center hole 62, an anterior side 64, a posterior side 66, lateral
sides 65, and one or more marker rods 46. When implanted, the
second surface 34 is configured to be positioned against the
adjacent vertebral body with the anterior side 64 positioned
generally towards the anterior side of the adjacent vertebral body.
The generally larger radii corners at the ends of the anterior side
64 are configured to generally conform to the natural shape of the
anterior portion of a vertebral body. Endplate 11 is configured for
a preferred use through a lateral approach to the spine, and
preferably when endplate coverage is desired to span across the
ring apophysis of the vertebra. The distance between the two
lateral sides 65 has a length dimensioned to extend generally
across the space from the apophyseal ring at one lateral aspect of
the spine to the apophyseal ring at the other lateral aspect of the
spine. This allows the endplate 11 to provide more support and
distribute the weight more evenly throughout the adjacent vertebral
body, which lessens stress and potential damage to the adjacent
vertebral body. The ridges 60 provide additional placement
stabilization and are shown in this embodiment to be generally
parallel to the lateral sides 65. The ridges 60 may also travel
parallel to or in angled directions from the anterior or posterior
side 64, 66, without departing from the scope of the invention.
While the ridges 60 are shown as linear, it will be appreciated
that the ridges 60 may be non-linear without departing from the
scope of the present invention. The travel of the ridge 60 is
generally along the entire length of the lateral side 65, but it
may only travel a portion of the lateral side 65, or any side,
without departing from the scope of the invention, and therefore is
not limited to the length of travel that the ridge 60 makes along
the second surface 34 of the endplate 11.
[0067] The tapered entry 61 from the second surface 34 into the
center hole 62, works like a funnel and provides additional room to
impact graft material into the center hole 62 of the endplate 11.
At least one marker rod 46 is press fit into the second side 34 of
the endplate 11. The formation of the marker rods 46 are shown by
example to be positioned in a rectangular formation, but can be
positioned in other configurations without departing from the scope
of the present invention.
[0068] FIG. 14 illustrates another example of an endplate 74
according to an alternative embodiment of the present invention.
Endplate 74 differs from endplate 11 in the perimeter shape. The
endplate 74 is generally circular in shape, and has an outer
diameter dimension that is generally in the range of 22-33 mm. By
way of example only, the generally circular endplate 74 is
preferred for placement of a vertebral body implant assembly 10
through an anterior approach. Additionally, the generally circular
shape can be beneficial in circumstances where the adjacent
vertebral body is more circular in shape.
[0069] FIG. 15 illustrates another example of an endplate 84
according to an alternative embodiment of the present invention.
Endplate 84 differs from endplate 74 in the direction of their
grooves relative to the generally rectangular marker rod 46
formation. The different relative directions of the grooves cater
to different spinal procedures, particularly pertaining to the
direction of implant insertion. By way of example only, endplate 84
is configured for a preferred use through a lateral approach to the
spine.
[0070] FIG. 16 illustrates another example of an endplate 94
according to an alternative embodiment of the present invention.
Endplate 94 is configured for a preferred use through a lateral
surgical approach to the spine. Endplate 94 has generally the same
outer perimeter shape as endplate 11, but in this example the
anterior side 95, posterior side 98, and lateral sides 96 of
endplate 94 are shown to have generally different lengths than the
anterior side 64, posterior side 66, and lateral sides 65 of
endplate 11. The width of an endplate is defined as the distance
between the anterior side and posterior side of an endplate.
Therefore, the width of endplate 11 and endplate 94 is preferably
dimensioned generally in the range of 18-22 mm. The length of an
endplate is defined as the distance between the opposing lateral
sides of an endplate. Therefore, the length of endplate 11 and
endplate 94 is preferably dimensioned generally in the range of
30-60 mm. The variable lengths of the sides of endplate 94 and
endplate 11 make the core expanding body 12 even more customizable
and enable the vertebral body implant assembly 10 to maximize the
surface area contact between the endplates 11, 94 and the adjacent
vertebral body, resulting in the ability to provide the most stable
support.
[0071] FIG. 17 illustrates another example of an endplate 104
according to an alternative embodiment of the present invention.
The asymmetrical shape of endplate 104 is configured for a
preferred use through a lateral approach, and generally under the
circumstance where a partial removal of the adjacent vertebral body
has been performed and endplate coverage is to be biased in one
direction relative to the core expanding body 12. Endplate 104
includes an anterior side 105, a posterior side 106, a rounded
lateral side 107, and a second lateral side 108. The width of
endplate 104 is preferably dimensioned generally in the range of
18-22 mm. The length of endplate 104 is preferably dimensioned
generally in the range of 27-40 mm.
[0072] FIG. 18 illustrates an example of the angle 97 formed
between the first surface 33 and second surface 34 of endplate 94.
The angle 97 that will be described for endplate 94 is available in
any of the previously described endplates and is therefore not
limited to only endplate 94. By way of example only, the angle 97
of the endplate 94 is preferably dimensioned generally in the range
of 0-15 degrees and functions to improve the natural curvature of
the spine when implanted. The preferred direction of the angle 97
formed between the first surface 33 and second surface 34 lies
generally in a plane that is either along or parallel to a ridge
60, which in this example also happens to be parallel to the
lateral sides 96. This configuration is intended to accompany
specific procedures and directions that the endplate 94 will be
implanted relative to adjacent vertebral bodies. Additionally, the
angle 97 that is formed between the first surface 33 and second
surface 34 may benefit the maintenance or correction of, for
example, either the lordotic or kyphotic curvature of the spine,
depending on the direction of angulation. By way of example only,
if the distance between the first surface 33 and second surface 34
is greater at the anterior side 95 than the posterior side 98 of
the endplate 94, then it can be assumed that the endplate 94 is
configured to have the preferred use to correct or maintain
lordosis. By way of example only, the distance between the first
surface 33 and second surface 34 of endplate 94 is preferably
dimensioned to be generally within the range of 4.06-11.81 mm, with
the 11.81 mm dimension being generally the maximum height between
the first surface 33 and second surface 34 of an endplate
configured with a 15 degree angle 97. In the condition where the
first surface 34 and second surface 34 is in a parallel
configuration (an angle 97 of zero degrees), the height between the
two surfaces is preferably dimensioned to be generally 4.06 mm.
[0073] Although described with respect to specific examples of the
different embodiments, any feature of the endplates disclosed
herein by way of example only may be applied to any of the
embodiments without departing from the scope of the present
invention. Furthermore, procedures described, for example only,
involving specific regions of the spine (e.g. thoracic and lumbar)
may be applied to another region of the spine without departing
from the scope of the present invention and dimensioning of the
implant may be adjusted to accommodate any region.
[0074] FIG. 19 illustrates an example embodiment of a vertebral
body implant assembly 300 including an additional extension piece
150. For simplicity, elements of vertebral body implant assembly
300 that are substantially identical to elements of vertebral body
implant assembly 10 have been assigned the same callout numbers and
repeat discussion of those elements is excluded. Vertebral body
implant assembly 300 may be used, for example, when greater height
is required to bridge the space between remaining adjacent
vertebral bodies.
[0075] FIGS. 20-21 illustrate, by way of example, an extension
piece 150. The features of the extension piece 150 are
substantially similar to the features of the outer tubular core 14
described above, including a first end 39, a second end 41, an
endplate attachment feature 22, and a plurality of holes 38. These
features are substantially similar (if not identical) to the
corresponding features of the outer tubular core 14, and
consequently the details will not be repeated here. Centrally
positioned at the first end 39 of the extension piece 150 is a
tubular core attachment feature 35 which is substantially similar
to the tubular core attachment feature 35 of endplate 11 described
above. These features are substantially similar (if not identical)
to the corresponding features of the tubular core attachment
feature 35 of endplate 11, and consequently the details will not be
repeated here. The inner and outer diameter of the extension piece
150 is preferably dimensioned to be generally in the range of 11.9
to 16.5 mm and 18.0 to 22.0 mm, respectively. The height of the
extension piece 150 is preferably dimensioned to be generally 22.9
mm.
[0076] The extension piece 150 can be attached at either end, or
both ends, of the core expanding body 12. The attachment of the
extension piece 150 to either end of the core expanding body 12 is
accomplished using the same feature orientations described above.
For example, the tubular core attachment feature 35 of the
extension piece 150 can become attached to the endplate attachment
feature 22 of the outer tubular core 14 or the endplate attachment
feature 42 of the inner tubular core 15. By way of example only,
the extension piece 150 can be attached to the outer tubular core
14 of the core expanding body 12 by aligning them along their
center axis and allowing the endplate attachment feature 22 of the
outer tubular core 14 to receive the tubular core attachment
feature 35 of the extension piece 150. This attachment permanently
secures the anti-rotational and longitudinal fixation of the
extension piece 150 to the core expanding body 12. When the
extension piece 150 is attached to either end of the core expanding
body 12, an endplate 11 (or any variation of endplate 11) can be
attached to the extension piece 150 by aligning the endplate
attachment feature 22 of the extension piece 150 with the tubular
core attachment feature 35 of endplate 11 and allowing them to
receive each other. This attachment permanently secures the
anti-rotational and longitudinal fixation of the endplate 11 to the
extension piece 150. Additionally, at least one extension piece 150
can be attached to at least one extension piece 150 in order to
accomplish additional height of the vertebral body implant assembly
10. An extension piece 150 can be attached to another extension
piece 150 by aligning a tubular core attachment feature 35 of one
extension piece 150 with an endplate attachment feature 22 of a
second extension piece 150 and allowing the attachment features 35,
22 to receive each other. The attachment between a tubular core
attachment feature 35 and an endplate attachment feature 22 has
been previously described above, and therefore the details will not
be repeated here.
[0077] FIGS. 22-31 illustrates an example of an expanding tool 110
for use with the vertebral body implant assembly 10 described
above. By way of example only, expanding tool 110 includes a
proximal handle 111, a medial handle 112, a distal handle 113, a
distal engagement region 114, and an elongated first shaft 115.
Distal engagement region 114 includes a plurality of engagement
arms 116, a first gear 117, a second gear 118, a third gear 119,
and a housing 120 (and best viewed in FIG. 29). By way of example
only, an engagement arm 116 is composed of a base member 121 and an
extension member 122 connected by a hinge. The engagement arms 116,
and particularly the extension member 122, are sized and
dimensioned to securely grasp the indented slots 23 of the outer
tubular core 14 and secure the position and anti-rotation of the
vertebral body implant assembly 10.
[0078] The opening (lateral direction) and closing (medial
direction) of the engagement arms 116 can be performed by rotating
the medial handle 112. The medial handle 112 is fixed to a threaded
coupler 170 which has threaded features (not shown) in its inside
diameter. The threaded features of the coupler 170 are engaged with
the threaded features (not shown) on the outside diameter and
proximal end 181 of the elongated second shaft 180. At the distal
end 182 of the elongated second shaft 180, the base member 121 is
attached. Therefore, when the medial handle 112 is rotated, it
causes the threads of the coupler 170 to rotate (and best viewed in
FIG. 28) which forces the second shaft 180 to travel linearly along
its central axis and force the proximal hinge members 121 to move.
By way of example only, movement of a base member 121 forces the
movement of an extension member 122 in either direction (open or
closed). The direction of travel of the second shaft 180 depends on
the direction of rotation of the medial handle 112 and the
direction of the threaded features. Therefore, by way of example
only, a clockwise turn of the medial handle 112 can result in the
movement of the engagement arms 116 to an open position due to the
advancement of the second shaft 180 in the direction of its distal
end 182. A set screw 130 (shown in FIG. 22) through the medial
handle 112 engages an annular groove 131 (best viewed in FIG. 28)
at the proximal end 132 of the distal handle 113 which allows the
medial handle 112 to rotate freely while fixing its longitudinal
position at the proximal end 132 of the distal handle 113. The
distal handle 113 is permanently fixed at its distal end 133 to the
proximal end 134 of the first shaft 115 which is permanently fixed
at its distal end 135 to the housing 120, with both of these
connections preventing longitudinal and rotational movement
relative to each other. The partial function of the distal handle
113 is to provide a grasping area for the user.
[0079] The proximal handle 111 can rotate about its center axis and
can do so independently from the medial handle 112, and vice versa.
The end cap 165 is secured into the proximal end 140 of the medial
handle 112 and one of its functions is to secure the proximal
handle 111 to the proximal end 140 of the medial handle 112.
Extending rigidly from approximately the center of the distal end
142 of the proximal handle 111 is the third shaft 144. At the
distal end 146 of the third shaft 144 is the first gear 117 which
can be caused to rotate by rotating the proximal handle 111. An
adapter feature 128 at the proximal end 143 of the proximal handle
111 enables tools (e.g. t-handles, etc--not shown) to couple to the
adapter feature 128.
[0080] A third gear 119 is housed in the superior portion 123 of
the housing 120 and has third gear features 124 that are compatible
with the external features 21 of the adjustment ring 13 (and best
viewed in FIGS. 30-31). This is so that when the expanding tool 110
is fully engaged with the vertebral body implant assembly 10, the
third gear 119 is able to engage the external features 21 of the
adjustment ring 13 and can cause it to rotate. The rotation of the
third gear 119 is controlled by the rotation of the second gear 118
which has second gear features 125 that are compatible and engage
with the third gear features 124 of the third gear 119 and cause it
to rotate (and best viewed in FIG. 29). Rotation of the second gear
118 is controlled by the rotation of the first gear 117, which has
first gear features 126 that are compatible and engage with the
second gear features 125 of the second gear 118 and can cause it to
rotate. Rotation of the first gear 117 is accomplished by rotating
the proximal handle 111, as described above.
[0081] FIGS. 32 and 33 illustrate one example of a loading block
200, which can be used for assisting in the attachment of a tubular
core attachment feature 35 of an endplate to the endplate
attachment feature 22, 42 of a core expanding body 12 or extension
piece 150. By way of example only, loading block 200 includes a
first side 201, a second side 202, a top face 207, and a bottom
face 203. Additionally, loading block 200 includes endplate profile
trenches 205 which consist of a center post 204, a base 210, and
gutters 206. The endplate profile trenches 205, along with the
center posts 204, serve as positioning guides for when the endplate
is loaded, and for once the endplate is positioned in the loading
block 200. By way of example, the center post, which passes through
the large center hole 62 of the endplate, and the walls of the
endplate profile trench 205 both provide a generally sliding fit to
the center hole 62 and outer profile of the endplate being loaded
into the loading block 200. Different dimensions are available for
the profiles of the endplate profile trenches 205 and center posts
204 such that each available endplate previously mentioned has a
center post 204 and encompassing endplate profile trench 205 that
corresponds to its size and shape, and, thus, can facilitate in
providing secure positioning during assembly of the endplate.
Additionally, the profile shapes of the endplate profile trenches
205 are shaped to accommodate all endplate shapes, both previously
mentioned (e.g. rectangular, circular) and a range of
variations.
[0082] Gutters 206 in the base 210 provide, for example, additional
space for any features that may extend from the base of the
endplate (e.g. marker rods), allowing the second surface 34 to rest
generally flush against the base 210. The base 210 of the endplate
profile trenches 205 may be flat (parallel to the bottom surface
203 of the loading block 200), or may be angled so that they can
accommodate endplates that have first and second surfaces 33, 34
that are angled 97 in relation to each other (for assisting in the
correction or maintaining of lordosis). The angles of the bases 210
of the loading block 200 are provided in dimensions that correspond
to the angles 97 of the first and second surfaces 33, 34 of the
endplates (as previously discussed) for which the loading block 200
is to be used for assembly. A loading block 200 may be provided
with more than one size and shape endplate profile trench 205 and
center post 204 so that one loading block 200 may be used for the
assembly of a variety of endplates. Additionally, more than one
base 210 may have a different angle within a loading block 200.
[0083] Once an endplate is placed completely in the loading block
such that the second surface 34 of the endplate is generally
resting on the base 210 with its tubular core attachment feature 35
facing in the direction of the top face 207, the endplate is then
ready to be assembled to an endplate attachment feature 22, 42. An
endplate attachment feature 35 of either an inner or outer tubular
core 14, 15, or an extension piece 150, is then inserted in the
loading block 200 such that its endplate attachment feature 22, 42
is aligned with the tubular core attachment feature 35 of the
endplate. Once the endplate attachment feature 22, 42 is aligned
and generally resting on the tubular core attachment feature 35, a
force can then be applied (for example, by using a mallet of other
instrument to strike the top of the core expanding body, extension
piece, or second surface 34 of the endplate that was first attached
to the assembly) to cause the secure attachment of the endplate
attachment feature 22, 42 to the tubular core attachment feature
35.
[0084] In an alternate embodiment, the center post 204 may include
an internal thread that travels from the top surface of the center
post 204 to at least a portion of its length. This internal thread
could be used to allow a threaded shaft to be secured at one end to
the center post 204 and still allow the endplate and mating parts
to be loaded into the loading block. The opposite end of threaded
shaft includes an element to attach and assist in applying the
force necessary to cause the attachment of the endplate attachment
feature 22, 42 to the tubular core attachment feature 35. By way of
example only, this element could consist of a handle and a modified
washer such that when the endplate attachment feature 22, 42 was
positioned and ready to attach to a tubular core attachment feature
35, the modified washer could be placed over the opposite end of
the threaded shaft and the handle could be threaded onto the
opposite end of the threaded shaft. The modified washer could act
as a protective barrier between the handle and the attachment piece
(e.g. inner or outer tubular core) as the handle is screwed onto
the threaded shaft and travels downward (toward the loading block).
The handle could be screwed onto the end of the threaded shaft and
continue to travel downward until it forced the modified washer
against the attachment piece with enough force to cause the
attachment of the endplate attachment feature 22, 42 to the tubular
core attachment feature 35.
[0085] FIG. 34 illustrates a vertebral body implant assembly 400
according to an additional example embodiment employing alternate
mechanisms for coupling endplates 11 (or any variation described
above, e.g. 74, 84, 94, 104) with the expanding core body 12, as
well as for coupling the expanding core body 12 and adjustment ring
13 with an insertion/expansion tool.
[0086] FIGS. 35-36 illustrate, by way of example, the end plate 11.
The endplate 11 includes a first surface 33, a second surface 34.
The first surface 33 is generally flat, and includes recessed
tubular core attachment feature 35. Although the perimeter of the
recessed tubular core attachment feature 35 is shown as rectangular
in shape with rounded corners, it will be appreciated that the
perimeter shape may be provided in any number of suitable shapes
provided that the perimeter shape allows the endplate attachment
features 42, 22 to be received therein. The tubular core attachment
feature 35 includes a center hole 62. The second surface 34
includes a recess 401 including a shoulder 402 concentrically
adjacent the center hole 62. With endplate attachment features 22,
42 positioned within the recessed tubular core attachment feature
35, an endplate lock screw 404, illustrated by way of example in
FIG. 37, cooperates with recessed shoulder 402 to fix the endplates
11 to the outer tubular core 14 and the inner tubular core 15.
[0087] The endplate lock screw 404 includes a threaded body 406 and
a head 410. The threaded body 406 is dimensioned such that it
passes through the center hole 62 and engages a complementary
threaded region 414, 416 (FIG. 39) within the endplate attachment
features 22, 42 of the outer tubular core 14 and inner tubular core
15, respectively. The head 410 is dimensioned such that it fits
within the recess 401 and engages shoulder 402 when the threaded
body 406 is threaded into the endplate attachment features 42, 22.
The lock screw 406 includes a through hole 412 extending all the
way through the lock screw. Through hole 412 communicates with the
interior of tubular core 12 to permit bone growth between the
remaining vertebrae. The sides of through hole 412 are configured
with an engagement feature 410 to engage a driver tool (not shown)
which is utilized to couple the endplate lock screw 404 to the
tubular body 12. By way of example, the engagement feature 410 may
be configured to receive a standard hex wrench. According to one
example, the engagement feature 410 (and/or the driver tool) may be
tapered to create a friction fit between the driver tool and the
lock screw 404. The endplate lock screw arrangement of this example
embodiment may be advantageous in that it provides for fast and
efficient assembly, disassembly, and reassembly. That is, the
implant 10 may be assembled intra-operatively according to a first
customized selection (e.g. various endplate sizes and/or shape
configurations) and then, as needed, easily disassembled and
reassembled according to a second customized customization
selection.
[0088] With reference again to FIG. 34, the adjustment ring 13 of
vertebral body implant assembly 400 includes engagement features
418 formed along a beveled side surface 420. By way of example, the
side surface may have a 30 degree bevel. The beveled side surface
420 and engagement features 418 cooperate with complementary
beveled surfaces of a drive wheel 442 on expansion instrument 430,
described below. Also pictured in FIG. 34, are side receptacles 422
positioned within the indented slots 23 of outer tubular core 14
and a center receptacles 424 that enhance the connection between
expansion tool 430 and the outer tubular core 14. According to the
example shown, center receptacle 424 includes an aperture for
receiving set screw 16 to lock the tubular core 12 in the desired
position. While a single set screw 16 is shown, it should be
appreciated that multiple set screws 16 may be utilized and the
outer tubular core 12 may be configured to receive any number of
set screws in various arrangements. For example, the outer tubular
body 14 could include apertures on either side of the center
receptacle 424 in addition to, or in place of, the aperture within
the center receptacle in order to receive three or two set screws,
respectively.
[0089] Turning to FIGS. 40-42, there is shown an example embodiment
of an alternate expansion tool 430 for use with the vertebral
replacement implant 400. Expanding tool 430 includes a grip 431
having a distal grip 434 and proximal grip 432, a distal engagement
region 438, a drive shaft 452, an elongated inner tube 454, and an
elongated outer tube 456. Distal engagement region 438 includes a
plurality of engagement arms 440, a beveled drive wheel 442, and a
housing 444. By way of example only, an engagement arm 440 is
composed of a base member 446 and an extension member 448 connected
by an angled slot 466 and pin 468. Extension arm 448 is also
connected to housing 444 by hinge 464. The engagement arms 440, and
particularly the extension member 448, are sized and dimensioned to
securely grasp the indented slots 23 of the outer tubular core 14
and secure the position and anti-rotation of the vertebral body
implant assembly 400. Ridges 450 on the engagement arms 440
complement and engage with the receptacles 422 located in the
indented slots to provide additional stabilization.
[0090] The opening (lateral direction) and closing (medial
direction) of the engagement arms 440 can be performed by squeezing
the grip 431. The proximal grip 432 is fixed to the inner tube 454
by a joint 458 through an opening 460 in the outer tube 456. The
distal end of the inner tube 454 meanwhile is fixed to the base
members 446 of the engagement arms. The outer tube 456 is fixed at
one end to the distal handle 434. At the opposite end the outer
tube 456 is fixed to the housing 444. Thus, squeezing the grip 431
causes the proximal handle 432 to translate the inner tube 454
toward the distal end moving the base member 446 distally, which in
turn causes the extension arms 448 to rotate around the hinge 464
as the pin 468 moves through angled slot 466. With the engagement
arms 440 coupled to the implant 400, a locking mechanism may be
engaged to prevent decoupling of the implant. By way of example,
the locking mechanism may include a ratchet arm 470 attached to one
of the proximal and distal grips. Additionally, or in place of the
ratchet arm 470, the locking mechanism may include a threaded nut
472 attached to an arm 474 attached to one of the proximal and
distal grips and extending through an opening in the opposite
grip.
[0091] The drive shaft 452 traverses through the inner tube 454 and
is fixed to the beveled drive wheel 442 within housing 44. Rotating
the drive shaft 452 causes the beveled drive wheel to rotate in the
same direction. Thus, when the expansion tool 430 is fixedly
coupled to the implant 400 and the drive shaft 452 is rotated, the
drive wheel will impart rotation to the adjustment ring 13, causing
expansion of the tubular body 12.
[0092] FIG. 43A-43E illustrates one example of a preferred use of a
vertebral body implant assembly 10 coupled with an expanding tool
110. While FIGS. 43A-43E picture implant 10 and expanding tool 110,
it should be appreciated that the implant 400 and expanding tool
430 may be used according to the same principals while substituting
the differences described above. FIG. 43A shows an anterior view of
a portion of a spine, which includes a superior vertebra, a medial
vertebra and an inferior vertebra which are shown labeled as V1,
V2, and V3 respectively. In FIG. 43B, the medial vertebra has been
removed so that there is now a large space between the superior and
inferior vertebral bodies. In the following figure, FIG. 43C,
endplates 11 have been chosen that are preferred for being
positioned against the surfaces of the superior and inferior
vertebral bodies. These selected endplates 11 are shown being
attached (without the use of a loading block 200) at the endplate
attachment features 22, 42 of the inner tubular core 15 and outer
tubular core 14 of the core expanding body 12. As previously
mentioned, a loading block 200 may be used to assist in attaching
the endplates to the endplate attachment features 22, 42. The
expanding tool 110 can then grasp the indented slots 23 of the
outer tubular core 14 by turning the proximal handle 111. This is
accomplished by turning the proximal handle 111 one way so that the
engagement arms 116 can open and receive the vertebral body implant
assembly 10 between the engagement arms 116. Once the core
expanding body 12 is positioned between the engagement arms 116,
the proximal handle 111 is turned in the opposite direction so that
the engagement arms 116 securely grasp the vertebral body implant
assembly 10, and preferably so that the engagement arms 116 grasp
the vertebral body implant assembly 10 at the general location of
the indented slots 23 on the outer tubular core 14.
[0093] By way of example only, FIG. 43D illustrates the vertebral
body implant assembly 10 being inserted in its collapsed state from
a lateral direction into the space remaining between the superior
and inferior vertebral bodies using the expanding tool 110. The
height of the vertebral body implant assembly 10 is then increased
by rotating the medial handle 112 which causes the third gear 119
to rotate, as described above. Since the vertebral body implant
assembly 10 is secured between the engagement arms 116, the third
gear 119 of the expanding tool 110 can engage the external features
21 of the adjustment ring 13 so that when the third gear 119
rotates, it causes the adjustment ring 13 to rotate in concert. As
detailed above, rotation of the adjustment ring 13 causes expansion
of the vertebral body implant assembly 10, as shown in FIG. 43E.
The vertebral body implant assembly 10 is expanded until its
desired height has been achieved. It is also possible to rotate the
proximal handle 111 in the opposite direction in order to cause the
vertebral body implant assembly 10 to decrease in height. Once the
desired height has been achieved, the medial handle 112 is rotated
in the direction to cause the engagement arms 116 to open and
release the vertebral body implant assembly 10. The expanding tool
110 is then separated from the vertebral body implant assembly 10
so that at least one set screw 16 from the outer tubular core 14
can be engaged into the outer wall of the inner tubular core 15 in
order to secure the expanded height of the vertebral body implant
assembly 10. Additional bone growth promoting material can then be
added to the vertebral body implant assembly 10 before it is left
to remain implanted between the first and second vertebrae.
[0094] While not specifically described above, it will be
understood that various other steps may be performed in using and
implanting the devices disclosed herein, including but not limited
to creating an incision in a patient's skin, distracting and
retracting tissue to establish an operative corridor to the
surgical target site, advancing the implant through the operative
corridor to the surgical target site, removing instrumentation from
the operative corridor upon insertion of the implant, and closing
the surgical wound.
[0095] While this invention has been described in terms of a best
mode for achieving this invention's objectives, it will be
appreciated by those skilled in the art that variations may be
accomplished in view of these teachings without deviating from the
spirit or scope of the invention.
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