U.S. patent application number 12/380840 was filed with the patent office on 2010-06-10 for lockable spinal implant.
This patent application is currently assigned to Innvotec Surgical, Inc.. Invention is credited to John E. Ashley, Walter Dean Gillespie, George A. Mansfield, III, David G. Matsuura, Philip J. Simpson.
Application Number | 20100145455 12/380840 |
Document ID | / |
Family ID | 42231957 |
Filed Date | 2010-06-10 |
United States Patent
Application |
20100145455 |
Kind Code |
A1 |
Simpson; Philip J. ; et
al. |
June 10, 2010 |
Lockable spinal implant
Abstract
A spinal implant which is configured to be deployed between
adjacent vertebral bodies. The implant has at least one extendable
support element with a retracted configuration to facilitate
deployment of the implant and an extended configuration so as to
expand the implant and effectively distract the disc space,
stabilize the motion segments and eliminate pathologic spine
motion. Angular deformities can also be corrected, and natural
curvatures restored. Preferably, the implant has a minimal
dimension in its unexpanded state that is smaller than the
dimensions of the neuroforamen through which it typically passes to
be deployed within the intervertebral space. The implant is
provided with a locking system preferably having a plurality of
locking elements to lock the implant in an extended
configuration.
Inventors: |
Simpson; Philip J.;
(Escondido, CA) ; Matsuura; David G.; (Encinitas,
CA) ; Gillespie; Walter Dean; (Carlsbad, CA) ;
Mansfield, III; George A.; (San Diego, CA) ; Ashley;
John E.; (Danville, CA) |
Correspondence
Address: |
DOWNS RACHLIN MARTIN PLLC
199 MAIN STREET, P O BOX 190
BURLINGTON
VT
05402-0190
US
|
Assignee: |
Innvotec Surgical, Inc.
|
Family ID: |
42231957 |
Appl. No.: |
12/380840 |
Filed: |
March 4, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61201518 |
Dec 10, 2008 |
|
|
|
Current U.S.
Class: |
623/17.16 ;
623/17.12 |
Current CPC
Class: |
A61F 2230/0015 20130101;
A61F 2002/30365 20130101; A61F 2220/0025 20130101; A61F 2002/482
20130101; A61F 2220/0033 20130101; A61F 2310/00023 20130101; A61F
2/30742 20130101; A61F 2002/30405 20130101; A61F 2002/3008
20130101; A61F 2002/30514 20130101; A61F 2002/30841 20130101; A61F
2310/00017 20130101; A61F 2002/30476 20130101; A61F 2002/30579
20130101; A61F 2002/30581 20130101; A61F 2002/30601 20130101; A61F
2210/009 20130101; A61F 2002/485 20130101; A61F 2002/30525
20130101; A61F 2002/30079 20130101; A61F 2002/30522 20130101; A61F
2002/30133 20130101; A61F 2002/30505 20130101; A61F 2002/30484
20130101; A61F 2002/30589 20130101; A61F 2250/0007 20130101; A61F
2/4455 20130101; A61F 2002/3055 20130101; A61F 2/44 20130101; A61F
2250/0069 20130101; A61F 2/442 20130101; A61F 2250/0098 20130101;
A61F 2002/30495 20130101 |
Class at
Publication: |
623/17.16 ;
623/17.12 |
International
Class: |
A61F 2/44 20060101
A61F002/44 |
Claims
1. A spinal implant for placement between superior and inferior
vertebral bodies, comprising: a. a first member having a surface
for engaging an end of the superior vertebral body; b. a second
member having a surface for engaging an end of the inferior
vertebral body; c. at least one extendable support element having a
contracted configuration to facilitate deployment of the implant
between the superior and inferior vertebral bodies and at least one
extended configuration to extend the first member so that the
surface thereof engages the end of the superior vertebral body; and
d. a locking system which has a locking element that mechanically
engages or interlocks with the extendable support element or the
first member to lock the implant between the superior and inferior
vertebral bodies in an expanded configuration.
2. The spinal implant of claim 1 wherein the first surface for
engaging an end of the superior vertebral body includes a top end
plate and the second surface for engaging an end of the inferior
vertebral body includes a base plate.
3. The spinal implant of claim 2 wherein at least one top end plate
cooperates with and is coupled to the extendable support
element.
4. The spinal implant of claim 3 wherein the extendable support
element is adapted to be extended by fluid.
5. The spinal implant of claim 4 wherein the fluid is an
incompressible fluid.
6. The spinal implant of claim 1 wherein the locking system
comprises a plurality of inter-engaging locking elements.
7. The spinal implant of claim 6 wherein one of the inter-engaging
locking elements is a locking actuator configured to move the
locking element into mechanical engagement or interlock with the
extendable support element or first member after expansion of the
expandable support member so as to lock the implant in an expanded
configuration.
8. The spinal implant of claim 1 wherein the locking element which
mechanically engages or interlocks with the expandable member or
the first member directly applies a vertical force to the
expandable member or the first member so as to lock the implant in
the expanded configuration.
9. The spinal implant of claim 6 wherein one of the inter-engaging
locking elements is an upper lock support member and another of the
inter-engaging locking elements is a lower lock support member.
10. The spinal implant of claim 9 wherein the upper lock support
member has a multi-stepped support surface and the lower lock
support member has a multi-stepped support surface configured to
engage the multi-stepped support surface of the upper lock support
member.
11. The spinal implant of claim 10 including a locking actuator
that is configured to effect relative motion between the upper and
lower lock support members when the at least one extendable member
is extended so as to lock the implant in an extended configuration
by engaging the multi-stepped support surfaces of the upper lock
support members and the lower lock support members.
12. The spinal implant of claim 10 wherein the lower and upper lock
support members have arcuate shapes.
13. The spinal implant of claim 12 wherein the lower and upper lock
support members have matching arcuate shapes.
14. The spinal implant of claim 11 wherein the locking actuator is
a biased member configured to move one of the lock support members
relative to the other.
15. The spinal implant of claim 14 wherein the biased member is a
spring located in a groove in a base of the implant.
16. The spinal implant of claim 15 wherein the spring has a forward
end configured to engage and rotate the lower lock support member
when the implant is extended.
17. The spinal implant of claim 16 wherein the groove has an
arcuate shape.
18. The spinal implant of claim 2 wherein the at least one
extendable member is a piston that engages the top plate.
19. The spinal implant of claim 18 including an internal cylinder
configured to receive the piston.
20. The spinal implant of claim 19 including a source for fluid to
extend the piston within the cylinder and raise the top plate.
21. The spinal implant of claim 1 including a housing which
contains at least in part the at least one extendable support
element and the locking system.
22. The spinal implant of claim 13 wherein the arcuate shaped lower
lock support member is disposed about a cylinder configured to
receive a piston.
23. The spinal implant of claim 22 wherein the arcuate shaped upper
lock support member is disposed about the piston and is secured to
the top plate.
24. The spinal implant of claim 11 wherein the multi-stepped
support surface of the lower lock support member has an upper
surface with a lock support stop which prevents over rotation of
the arcuate lower lock support member.
25. The spinal implant of claim 16 wherein the lower lock support
member has a lower surface with a locking actuator transfer element
configured to engage the forward end of the spring which effects
rotation of the lower lock support member.
26. The spinal implant of claim 13 wherein the lower lock support
member is disposed within the cylinder and the upper lock support
member is within the piston.
27. The spinal implant of claim 18 including a pair of
independently acuatable pistons which are rotatably interconnected
to an articulating top plate.
28. The spinal implant of claim 13 wherein the lock support members
are circular.
29. The spinal implant of claim 28 wherein the circular lock
support members have a plurality of multi-stepped support
surfaces.
30. The spinal implant of claim 9 wherein the upper and lower lock
support members are disposed between a pair of pistons and a pair
of cylinders.
31. The spinal implant of claim 9 wherein a pair of upper and lower
lock support members are disposed on opposite sides of a piston and
cylinder.
32. The spinal implant of claim 6 wherein lock support members
comprise at least one rack and pinion.
33. The spinal implant of claim 32 wherein the pinion has a
plurality of teeth configured to engage the rack with different
teeth when the pinion moves as the implant is expanded.
34. The spinal implant of claim 32 wherein lock support members
comprise a pair of rack and pinions on opposing sides of the
implant.
35. The spinal implant of claim 9 wherein the lower and upper lock
support members are straight.
36. The spinal implant of claim 9 wherein the upper lock support
member has at least one cantilever extension.
37. The spinal implant of claim 36 wherein the lower lock support
member has a recessed support surface which is configured to
receive the at least one cantilever extension of the upper lock
support member.
38. The spinal implant of claim 9 wherein the upper lock support
member is secured to the extendable member.
39. The spinal implant of claim 9 wherein the upper support member
has at least one groove.
40. The spinal implant of claim 39 wherein the lower support member
is a U-shaped tong configured to be slidably received within the at
least one groove in the upper support member.
41. The spinal implant of claim 39 wherein the upper lock support
member has at least one flat vertical surface.
42. The spinal implant of claim 41 wherein the lower support member
is a circular washer having an inwardly projecting edge which is
configured to be slidably received by at least one groove in the
upper support member when the lower support member is rotated with
respect to the upper support member.
43. The spinal implant of claim 42 wherein the circular washer is
configured to move vertically with respect to the upper support
member when the inwardly projecting ridge is aligned with the flat
surface of the upper support member.
44. The spinal implant of claim 39 wherein the lower support member
is a pawl with a surface configured to be received by the at least
one groove in the upper support member.
45. The spinal implant of claim 44 wherein the pawl is biased so as
to urge the surface thereof into the groove of the upper support
member.
46. The spinal implant of claim 9 wherein the upper support member
has a passageway therein with an inner support surface.
47. The spinal implant of claim 46 wherein the lower support member
is a pin which is configured to be slidably received by the
passageway in the upper support member and which has an exterior
support surface configured to engage the inner support surface of
the upper support member.
48. The spinal implant of claim 9 wherein the upper support member
has at least one notch on the exterior thereof.
49. The spinal implant of claim 48 wherein the lower support member
has at least one pivoting jaw having an upper support surface
configured to engage the notch in the exterior of the spinal
implant.
50. The spinal implant of claim 6 wherein the upper support member
has a vertically oriented flat surface.
51. The spinal implant of claim 46 which includes at least one
rotating lower support member having a surface configured to engage
the flat surface of the upper support member.
52. The spinal implant of claim 9 wherein the upper support member
is a cylindrical member.
53. The spinal implant of claim 9 wherein the upper support member
has a plurality of recesses in an exterior surface thereof.
54. The spinal implant of claim 53 wherein the lower support member
has a rotating member with a plurality of teeth configured to fit
within the recesses in the exterior surface of the upper support
member.
55. The spinal implant of claim 54 wherein the rotating member of
the upper support member has a circular rack with recesses and the
lower support member is a pawl having an end surface configured to
engage a recess of the circular rack.
56. The spinal implant of claim 9 wherein the locking system
comprises at least two upper lock support members having grooves in
the surface thereof, at least one lower lock support member
comprising a continuous wire-form which is configured to be
received by the grooves of the upper lock support members and which
is configured to change shape in order to remove the continuous
wire form from a groove from an upper lock support member so as to
reposition the continuous wire-form into another groove in the
upper support member.
57. The spinal implant of claim 1 wherein the locking element
directly applies a vertical force to the extendable support element
or the first member.
58. A spinal implant for placement between adjacent vertebral
bodies, comprising: a. a top end plate for engaging an end of a
first adjacent vertebral body; b. a bottom end plate for engaging
an end of a second adjacent vertebral body; c. at least one
extendable piston member having a contracted configuration within
the implant to facilitate deployment of the implant between the
first and second vertebral bodies and an extended configuration to
extend the top end plate into engagement with the end of the first
adjacent vertebral body; d. an upper lock support member having a
multi-stepped support surface; e. a lower lock support member
having a multi-stepped support surface configured to engage the
multi-stepped support surface of the upper lock support member; and
f. a locking actuator which causes relative motion between the
upper and lower lock support members when the at least one
extendable member is extended so as to lock the implant in an
expanded configuration by engaging the multi-stepped support
surfaces of the upper lock support members and the lower lock
support members.
59. The spinal implant of claim 58 wherein the upper and lower lock
support members have matching shapes which facilitate engagement of
stepped support surfaces thereof.
60. The spinal implant of claim 59 wherein the upper and lower lock
support members have matching arcuate shapes.
61. The spinal implant of claim 58 wherein a spring locking
actuator is provided to move the lower lock support member toward
the upper lock support when the at least one extendable member is
extended.
62. A method of treating a patient's vertebral structure,
comprising: a. providing a spinal implant having i. a first member
having a pressure applying surface for engaging an end of a first
adjacent vertebral body; ii. a second member having a pressure
applying surface for engaging an end of a second adjacent vertebral
body; iii. at least one extendable support element having a
contracted configuration within the implant to facilitate
deployment of the implant between the first and second vertebral
bodies and an extended configuration to extend the first pressure
applying member to engage the end plate of the first adjacent
vertebral body, and iv. a locking system with a locking element for
locking the implant in an extended configuration by engaging the
extendable support element or the first member with the locking
element; b. inserting the spinal implant into a space between two
vertebral bodies in the contracted configuration; c. extending the
extendable support member so as to expand the implant until the
first pressure applying surface engages an end of the first
adjacent vertebral body and urges the vertebral body into a desired
position; and d. locking the implant in the extended configuration
by moving the locking member into engagement with the extendable
support element or the first member so as to fix the implant
between the first and second vertebral bodies in an expanded
configuration.
63. A spinal implant for placement between superior and inferior
vertebral bodies, comprising: a. a first member having a surface
for engaging an end of the superior vertebral body; b. a second
member having a surface for engaging an end of the inferior
vertebral body; c. at least one extendable support element having a
contracted configuration to facilitate deployment of the implant
between the superior and inferior vertebral bodies and an extended
configuration to extend the first member so that the surface
thereof engages the end of the superior vertebral body; and d. a
locking system which has an upper lock support member that engages
or is coupled to the extendable support element or the first member
and a lower lock support member which frictionally engages the
upper lock support member to lock the implant between the superior
and inferior vertebral bodies in an expanded configuration.
Description
FIELD OF THE INVENTION
[0001] The invention relates to devices and methods for stabilizing
the vertebral motion segment. More specifically, the field of the
invention relates to an expandable spinal implant with locking
elements configured to lock the implant in an expanded
configuration within an intervertebral space to provide controlled
spinal correction in three dimensions for improved spinal
intervertebral body distraction and fusion.
BACKGROUND OF THE INVENTION
[0002] A conventional spine cage or implant is characterized by a
kidney bean shaped body which is typically inserted posteriorly
through the neuroforamen of the distracted spine after a trial
implant creates a pathway. Existing devices for interbody
stabilization have important and significant limitations, including
inability to expand and distract the endplates or to fix the device
in place to prevent relative movement between the device and an
adjacent vertebral body. Current devices for interbody
stabilization include static spacers composed of titanium, PEEK,
and high performance thermoplastic polymer produced by VICTREX,
(Victrex USA Inc, 3A Caledon Court; Greenville, S.C. 29615), carbon
fiber, or resorbable polymers. Moreover, current interbody spacers
do not maintain interbody lordosis and can contribute to the
formation of a straight or even kyphotic segment and the clinical
problem of "flatback syndrome." Separation of vertebral endplates
increases space available for the neural elements, specifically the
neural foramen. Existing static cages do not reliably improve space
for the neural elements. Therefore, what is needed is a spinal
implant that will provide space for the neural elements posteriorly
between the vertebral bodies, or at least maintain the natural bone
contours to avoid neuropraxia (nerve stretch) or encroachment.
[0003] Conventional devices for intervertebral body stabilization
includes poor interface between bone and the biomaterial of the
device. Conventional static interbody spacers form a weak interface
between bone and biomaterial. Although the surface of such implants
is typically provided with a series of ridges or coated with
hydroxyapetite, the ridges may be in parallel with applied
horizontal vectors or side-to-side motion. That is, the ridges or
coatings on the implant offer little resistance to movement applied
to either side of the endplates. Thus, nonunion is common in
allograft, titanium and polymer spacers, due to motion between the
implant and host bone.
SUMMARY OF THE INVENTION
[0004] This invention is generally directed to a spinal implant for
insertion between superior and inferior vertebral end plates after
partial or total removal of a spinal disc. The spinal implant
embodying features of the invention has a contracted configuration
for easy installation between adjacent vertebral bodies and an
expanded configuration to support the vertebrae in a desirable
position. More specifically, the implant has a plurality of
inter-engagable elements which locks the implant in an expanded
configuration to hold the vertebral or joint sections in the
desired positions.
[0005] The invention is particularly directed to a spinal implant
suitable for placement between superior and interior vertebral
bodies. The spinal implant has a first member or top plate for
engaging an end of the superior vertebral body and a second member
or base for engaging an end of the inferior vertebral body and has
one or more extendable support elements preferably with one or more
top end plates that engage vertebral bodies in the expanded
configuration. The one or more extendable support elements have a
first contracted configuration to facilitate deployment of the
implant between the superior and inferior vertebral bodies and
safely past sensitive neural elements and a second or an extended
configuration to engage the end plates of the vertebral bodies. The
implant has a locking system which has a locking element that
mechanically engages or interlocks with the extendable support
element or the first member to lock the implant between the
superior and inferior vertebral bodies in an expanded
configuration.
[0006] The extendable support element(s) may be extended in a
variety of ways such as with fluid pressure, e.g. hydraulic fluid
or gas, by mechanical force, such as a threaded connection with a
rotating driving member or other suitable means. Fluidic
displacement is preferred. The extendable support element(s) are
disposed in cylinders which support and guide the extendable
support elements when they are extended. However, the locking
system is separate from the extendable support member and cylinder
receiving the supporter member, although the extending support
member may initiate the locking system and the support member and
cylinder may have lock support members attached thereto.
[0007] In one presently preferred system, the spinal implant having
features of the invention comprises an inferior pressure applying
member or base with a first bone engaging surface, one or more
extendable support members cooperating with the base and a superior
pressure applying member such as a top end plate with a second bone
engaging surface that is coupled to the at least one extendable
member. The spinal implant preferably has a plurality of engaging
locking elements that are configured to independently lock one or
more of the extendable support members or pressure applying members
in an extended configuration to thereby provide desired disc height
between adjacent vertebrae and in some instances to provide a
desired corrective spinal alignment in a plurality of
dimensions.
[0008] The spinal implant or selectively expanding spine cage (SEC)
embodying features of the invention is particularly suitable for
posterior or transforaminal insertion between superior and inferior
vertebral end plates as described in copending application Ser. No.
11/535,432, filed Sep. 26, 2006, and Ser. No. 11/692,800, filed
Mar. 28, 2007. The implant has a contracted or unexpanded
configuration which allows easy deployment and is typically about
0.5 to about 1 cm in maximum short transverse dimension so as to
enable minimally invasive insertion posteriorly between vertebral
pedicles through a working space of approximately 1 cm in
diameter.
[0009] In one preferred embodiment, the spinal implant for
placement between adjacent vertebral bodies as described above has
an upper locking member with stepped supporting surfaces on the
underside thereof and a lower locking member with stepped
supporting surfaces on the top side thereof which are configured to
engage the stepped supporting surface of the upper locking member
to lock the implant in an extended configuration. Extension of the
expandable members or pistons to raise the superior pressure
applying member increases longitudinal spacing between the upper
and lower locking members. Relative motion, rotational or linear,
between the upper and lower locking members causes the stepped
supporting surfaces of the lower locking members and the stepped
supporting surfaces of the upper locking members to re-engage to
fix the locking members in an increased spaced apart relationship
and thereby lock the implant in the extended configuration.
[0010] Since the vertebral end plates are held together at one end
by a ligament much like a clamshell, as the implant expands against
the vertebral end plates, the amount of vertical expansion can be
adjusted to create the desired anterior/posterior correction
angle.
[0011] Left and right lateral correction of the spine is achieved
by differential vertical expansion of the two or more extendable
members of the implant. Each extendable member may be independently
controlled by a master cylinder or syringe located ex vivo (away
from the patient) for moving the pistons and attached top plate
vertical for correcting spinal deformities anteriorly or
posteriorly, medial or lateral, thus available to provide spinal
correction in three dimensions. See for example U.S. applications
copending application Ser. No. 11/535,432, filed Sep. 26, 2006, and
Ser. No. 11/692,800, filed Mar. 28, 2007.
[0012] A minimally invasive downsized insertion tool, such as
described in the above referenced applications, both inserts the
unexpanded implant posteriorly and provides the hydraulic or
mechanical lines communicating with the interior of the implant.
The insertion tool may also provide a line for communicating the
liquid or slurry bone graft material into the intervertebral space
for subsequent fusion. Advantageously, hydraulic lines are small
size tubing to allow for high hydraulic pressure without danger of
the lines bursting.
[0013] Due to the mechanical advantage provided by a hydraulic
system or a proximally operated mechanical system, the implant has
minimized size and diameter in its unexpanded state that is smaller
than the diameter of a prepared neuroforamen. The implant thus can
be inserted transforaminally and engaged between the endplates of
the adjacent vertebra to effectively distract the intervertebral
area, restore space for neural elements, stabilize the motion
segment and eliminate pathologic segmental motion. The implant
enhances spine arthrodesis by creating a rigid spine segment.
[0014] The implant is preferably provided with a hollow interior to
enable a comparatively large quantity of bone growth conductive or
inductive agents to be contained therein that through openings
communicate directly to adjacent bone. Importantly, this results in
fixation forces greater than adjacent bone and soft tissue failure
forces. The implant can be used to promote fusion, and/or to
correct deformities such as scoliosis, kyphosis, and
spondylolisthesis.
[0015] The clinical goals of the implant and the method for its
insertion provide a minimally invasive risk of trauma to nerve
roots, reduce pain, improve function, and permit early mobilization
of the patient after fusion surgery. The fixation elements maintain
the implant in a desired position until healing (fusion or
arthrodesis) occurs. At this point, the implant is incorporated
inside bone and its role becomes quiescent.
[0016] Thus, a key feature of the invention is that an implant can
be inserted posteriorly between vertebral pedicles in only a
working space of about 1/2 cm and then be expanded to about 100% to
about 200%, typically about 160%, of its original insertion size
and locked in that position to provide a closely controlled full
range of permanent spinal correction in three dimensions. These and
other advantages of the invention will become more apparent from
the following detailed description and the accompanying exemplary
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a perspective view of an intervertebral implant in
a contracted configuration embodying features of the invention.
[0018] FIG. 2 a perspective view of the implant shown in FIG. 1 in
an expanded configuration.
[0019] FIG. 3 is an exploded perspective view of the implant shown
in FIG. 1.
[0020] FIG. 4A is a top view of the implant shown in FIG. 1.
[0021] FIG. 4B is a side cross-sectional view through line 4B-4B of
the implant shown in FIG. 4A.
[0022] FIG. 5A is a perspective view of a lower part of the implant
shown in FIG. 1 with upper portions and bottom face removed.
[0023] FIG. 5B is a bottom view of the lower portion shown in FIG.
5A.
[0024] FIG. 6A is a perspective view of the upper portion of the
implant shown in FIG. 1 with the lower portion removed.
[0025] FIG. 6B is an enlarged perspective view of the
staircase-like lower lock support shown in FIG. 3.
[0026] FIG. 7 is a partial side view of one of the locking
mechanisms of the implant shown in FIG. 2.
[0027] FIGS. 8A-9B are partial side views of the locking mechanism
in FIG. 7 shown in different expanded and locked
configurations.
[0028] FIGS. 10A and 10B of the locking mechanism illustrate the
expanded but unlocked configuration in FIG. 10A and the expanded
and locked configuration in FIG. 10B.
[0029] FIGS. 11A and 11B are perspective views of the lower lock
support and spring locking actuator illustrating the operation
thereof.
[0030] FIG. 11C is a perspective view of an alternate locking
mechanism and locking actuator embodying features of the
invention.
[0031] FIGS. 12A-12C are perspective views of alternate lower lock
support designs embodying features of the invention.
[0032] FIGS. 13A-13B are perspective and side views respectively of
an alternative implant embodying features of the invention which
has an articulating top end plate.
[0033] FIG. 14A is an exploded perspective view of yet another
alternative implant embodying features of the invention which has
the lower lock supports within the extendable pistons.
[0034] FIG. 14B is a top view of the implant shown in FIG. 14A.
[0035] FIG. 14C is a side cross-sectional view through line 13C-13C
of the implant shown in FIG. 14B.
[0036] FIG. 15 is a perspective view of an alternate implant design
having features of the invention wherein the locking mechanism
surrounds a central opening in the top end plate.
[0037] FIG. 16 is a perspective view of an alternate implant design
having features of the invention wherein the expanding piston is
centrally located and locking mechanisms are provided on both sides
of the expanding piston.
[0038] FIG. 17 is a simplified schematic illustration of an
alternate implant design having ratchet and pawl locking members
between the top and bottom plates of the implant.
[0039] FIG. 18 is a perspective view of an alternative implant
design with ratchet and pawl locking members between the top and
bottom plates of the implant.
[0040] FIG. 19 is a cross sectional perspective view of an implant
design with ratchet and cantilevered spring members between the top
and bottom plates of the implant.
[0041] FIGS. 20-29 schematically illustrate various means for
locking an expanding member of implants in extended configurations
embodying features of the invention.
[0042] FIG. 30 is a perspective view of yet another alternate
implant design having features of the invention wherein the locking
mechanism has straight upper and lower interfitting lock
supports.
[0043] FIG. 31A-31G illustrate an alternative implant locking
mechanism in which a wire-form surrounds a pair of upper support
members with grooves configured to receive the wire-form.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0044] FIGS. 1-10B Illustrate an example of an intervertebral
implant 10, a Selectively Expandable Cage (SEC), having features of
the invention. The implant 10 generally includes a housing 11, a
housing base 12, an interlocking top endplate 13, a bottom endplate
14, an interior cavity 15 within the housing 11 and a pair of
cylinders 16. Upper lock supports 17 are attached to the underside
of the top endplate 13 and have multi-stepped lower support
surfaces 18 much like an inverted staircase. Lower lock supports
20, having multi-stepped upper support surfaces 21 surround
cylinders 16 much like an upright staircase. Pistons 22 are secured
to the under surface of top endplate 13. Seal members 23 are
slidably disposed within the cylinders 16 and are mounted on
pistons 22. The upper surface 24 of bottom end plate 14 is provided
with locking actuator channels 25 which partially receive spring
locking actuators 26. The base 12 of the housing 11 has arcuate
slots 27 which are configured to slidably receive the depending
elements 28 or locking actuator transfer element of the lower lock
supports 20 and partially receive the spring locking actuators 26.
Depending elements 28 engage the forward end 30 of spring locking
actuators 26. The spring locking actuators 26 are initially in a
compressed configuration so that upon the extension of the top
endplate 13 and the attached upper lock supports 17, the lower lock
supports 20 rotate about the cylinders 16 due to the force applied
by the biased spring locking actuator 26. This causes the lock
support surfaces 21 of the lower lock supports 20 to engage support
surfaces 18 of the upper lock supports so as to lock the top end
plate 13 in an extended configuration. The support surfaces 18 of
the upper lock supports 17 and the support surfaces 21 of the lower
lock supports 20 are tiered with multiple steps so that the implant
10 can be locked at several different expanded heights. The
underside stepped support surfaces 18 of the upper lock support 17
may be provided with increasing riser height (alignment faces 46)
in the upward direction to provide smaller incremental expansion
near the end of the piston expansion. In addition or alternatively,
the stepped support surfaces 21 of the lower lock support 20 may be
provided with decreasing riser height in the upward direction for
the same reason. A variety of riser heights of the upper lock
support 17 or lower lock support 20 can be provided. The lowermost
stepped support surface 18 of the upper lock support 17 and the
uppermost stepped support surface 21 of the lower lock support 20
may be provided with various lengths and widths to ensure better
support.
[0045] As can be seen in FIG. 2 there are two sets of upper lock
supports 17 attached to the top endplate 13 and there are two sets
of lower lock supports 20 in this embodiment, but a single set or
more than two sets of upper and lower lock supports can also be
used to lock the implant 10 in the expanded state.
[0046] The implant 10 is configured to be implanted between
opposing vertebral bodies in the spine to facilitate bony fusion
between those vertebral bodies. The implant 10 is shown in its
collapsed or contracted configuration in FIG. 1 and in one example
of its expanded configuration in FIG. 2. In the collapsed state,
the implant 10 can be inserted easily into the intervertebral body
space through a minimal incision and with minimal tissue removal.
Once in that space, the implant 10 can be expanded against the two
opposing vertebral bodies to distract them and thereby restore
height to the intervertebral space. This provides stable opposition
of the implant 10 to both vertebral bodies and optimizes the bony
fusion process. The fusion process can also be enhanced by filling
the interior cavity 15 with autologous bone graft, a bone growth
enabling matrix, and/or bone growth stimulating substances prior to
and/or after insertion into the body.
[0047] Further details of individual parts of the implant 10 are
depicted in FIGS. 3, 4A and 4B. Pistons 22 are attached to the
underside of the top endplate 13 which are configured to support
seal members 23 which run inside of cylinders 16 located in the
housing 11. When the cylinders 16 are pressurized as will be
described in more detail below, the seals 23 running inside the
cylinders 16 and pistons 22 slidably disposed within the seals are
vertically displaced, translating the top endplate 13 vertically
above the housing 11. Lower lock supports 20 are located around the
outer wall of the cylinders 16. When the top endplate 13 is
vertically displaced, which in turn displaces the attached upper
lock supports 17, the lower lock supports are rotated by the biased
locking actuators 26 to a locking position. Arcuate locking
actuator channels 25 in the top surface of bottom plate 14 and the
arcuate slots 27 in the housing base 12 confines the locking
actuators 26 to the housing 11.
[0048] Additional details of the housing 11 are depicted in FIGS.
5A and 5B. The housing 11 comprises an outer wall 31 and cylinders
16 which are secured to housing base 12. The outer wall 31 supports
a leading nose 32 on the distal end and a delivery boss 33 on the
proximal end. The leading nose 32 has inwardly directed side
tapered faces 34 and top tapered face 35 and bottom tapered face
36. These tapered faces 34, 35 and 36 enable non-traumatic
insertion of the implant 10 passed neural elements and between the
vertebral bodies. The delivery boss 33 contains a delivery tool
anchor 37 which allows secure attachment of the implant 10 to a
delivery tool (not shown), which is illustrated in copending
application Ser. No. 11/535,432, filed Sep. 26, 2006, and Ser. No.
11/692,800, filed Mar. 28, 2007 for insertion into a vertebral
space. The delivery boss 33 also contains pressure input ports 38
which are used to deliver a pressurized fluid to the interiors of
cylinders 16. The outer wall 31 of the housing 11 also provides
side openings 40 which provide space for bony in-growth into
central cavity 15 in the housing 11 and provide radiolucent
openings for the radiographic imaging of the process of bony
in-growth. The housing base 12 also contains pressure channels 41
which deliver pressurized fluid from the pressure input ports 38 to
the interior of cylinders 16. Although the housing base 12 of
implant 10 is depicted with independent pressure channel 41 for
each cylinder 16, other embodiments can contain one or more
branching pressure channels for delivering pressurized fluid to two
or more cylinders 16. As previously mentioned, the housing base 12
also has locking actuator slots 27 which hold and guide the locking
actuators 26. The locking actuator slots 27 contain a wider
portion, locking actuator opening 42, to enable insertion of the
locking actuator 26 into the channels defined by the locking
actuator slots 27 in housing base 12 and the locking actuator
channels 25 in the bottom end plate 14. The housing base 12 also
has optional alignment bosses 19 which align the bottom endplate 14
to the housing 11 via optional alignment holes 9.
[0049] FIGS. 6A and 6B illustrate further details of the top
endplate 13 and the lower lock support 20. The two sets of pistons
22 and upper lock supports 17 are joined by connecting members or
struts 44. The pistons 22 have seal bosses 45 on which the seals 23
are mounted. The upper lock supports 17 have tiered lower support
surfaces 18 and risers or alignment faces 46. The tiered or stepped
support surfaces 18 of the upper lock supports 17 engage the
stepped or tiered support surfaces 21 of the lower lock supports
20. The alignment faces 46 of the upper lock support are configured
to engage the alignment faces 47 of the lower lock supports 20. The
uppermost support surface of the lower lock support 20 has a lock
support stop 50 which engages with the lower most alignment faces
46 of the upper lock support to prevent the lower lock support 20
from over rotating as it engages the upper lock support 17. The
bottom of the lower lock support 20 also has the locking actuator
transfer element 28 which engages the forward end 30 of the spring
locking actuator 26 to transfer the actuation force from the
locking actuator 26 to the lower lock support 20.
[0050] FIGS. 7 through 10B show details of the selectively
expanding locking sequence of implant 10 with the housing 11
removed. The collapsed configuration is shown in FIG. 7 with the
support surfaces 18 of the upper lock support 17 resting on the
support surfaces 21 of the lower lock support 20. The locking
actuator 26 which is a spring, is engaging the depending element or
locking actuator transfer element 28 which forces the alignment
faces 47 of the lower lock support 17 against the alignment faces
46 of the upper lock support 17. The lock support stops 50 fit
within the lower lock stop relief 52 (shown best in FIG. 6A) on the
top endplate 13. When the cylinders 16 are pressurized, the pistons
22 raise the top endplate 13 and attached upper lock supports 17
(straight arrow) moving the support surfaces 18 of the upper lock
support 17 off of the support surfaces 21 and moving the lower
alignment faces 46 passed the upper alignment faces 47. When the
alignment faces 46 of the upper lock support 17 have cleared the
alignment faces 47 of the lower lock support 20, the locking
actuators 26 (in this embodiment a compressed coiled spring)
engaging the locking actuator transfer element 28 force the lower
lock supports 20 to rotate (curved arrow in FIGS. 8B and 9B). The
support surfaces 21 of the rotating lower lock supports 20 move to
the next lower level of the support surfaces 18 of the raised upper
lock supports 17 until the alignment faces 47 of the lower lock
supports 20 engage the next level of the alignment faces 46 of the
upper lock supports 17. The lower lock support 20 and upper lock
support 17 then lock the top endplate 13 at this expanded level.
This process repeats itself at each locking level (FIGS. 8A, 8B,
9A, 9B and 10A) until the top level (or somewhere between) is
reached as shown in FIG. 10B. At this top level, the locking
actuators 26 engage the locking actuator transfer elements 28 and
the lower lock supports 20 are rotated so the lowermost alignment
surface 46 of the upper lock support 17 engages lock support stop
50 of the uppermost support surface 21 of the lower lock support
20. At this highest locked level only the lowest support surfaces
18 of the upper lock supports 17 and the highest support surfaces
21 are engaged providing all of the locking support. As can be seen
from FIGS. 10A and 10B the lowest support surfaces 18 of the upper
lock supports 17 and the highest support surfaces 21 of the lower
lock supports 20 can be wider than the other support faces to
provide sufficient support material when only these two faces are
engaged.
[0051] FIGS. 11A and 11B illustrate the operation of locking
actuator 26. In this embodiment the spring locking actuator 26 is
compressed into an arc beneath the lower lock support 20. One end
of the spring locking actuator 26 is constrained by the housing 11
(not shown) and the other is engaged with the locking actuator
transfer element 28. When the lower alignment faces 46 of the upper
lock support 17 are raised above the upper alignment faces 47 of
the lower lock support 20 by the extension of piston 22, the
locking actuator 26 pushes against the locking actuator transfer
element 28 and rotates the lower lock support 20 in a clockwise
direction (arrow) as viewed from above. It should be noted that in
the embodiment of the current implant as describe thus far, the
angular orientation of the tiered upper and lower support surfaces
18 and 21 can vary when there is more than one set of supports. As
shown in FIG. 3 the proximal lower support surfaces 21 are oriented
clockwise as viewed from above and the distal lower support
surfaces 21 are oriented counter-clockwise. This opposite
orientation provides enhanced locking support for rotational forces
applied to the implant.
[0052] An alternate locking actuator 26a is shown in FIG. 11C as a
torsion spring. This locking actuator 26a has constraining tab 53
secured to the lower lock support 20 and constraining tab 54
secured to the housing 11a. Just as the compression spring shown in
FIGS. 11A and 11B applies a force to the lower lock support 20a to
rotate it, the torsion spring in FIG. 11C does the same. An
extension spring would work equally as well as a locking actuator
26a. Spring actuators can be made of an appropriate biocompatible
material such as stainless steel, NITINOL, titanium or a suitable
polymer. Locking actuators are not limited to springs. A wide
variety of mechanisms can be used to actuate the lower lock
supports 20, including but not limited to, a linear drive, an
externally actuated tensile member, a worm gear, an inflated member
such as a balloon or bellows, a magnet, a rotational drive such as
a micro motor, a super elastic shape memory element, and the
like.
[0053] FIG. 12A through 12C show variations of the lower lock
support 20 described above. In FIG. 12A a tri-set lock support 20a
is shown whereby there is are three sets of upper support surfaces
21a, upper alignment surfaces 47a and lock support stops 50 rather
than the 2 sets described above. This tri-set lower lock support
20a has two advantages over the 2 sets design, 1) there are three
support columns rather than two locking the implant 10 in an
expanded state thereby creating a more stable lock and 2) the
tri-set lower lock support-20a has to move or rotate much less for
each locking level. This last advantage is significant when the
locking actuator is a spring such as spring locking actuator 26 as
this places less strain on the spring to achieve the required
locking force at each step. Each lower lock support column will
have a corresponding upper lock support column (not shown). The
upper support surfaces 21 and lower support surfaces 18 are not
limited to 2 or 3 sets of surfaces. Any number of sets of support
surfaces including a single set may be employed.
[0054] FIG. 12B shows an inter-digitating lower lock support 20b.
Each of the inter-digitating upper support surfaces 21b on the
inter-digitating lock support 20b is paired with an
inter-digitating stop 50b which when paired with matching
inter-digitating support surfaces and stops of an upper lock
support (not shown) prevents the inter-digitating support surfaces
21b from moving relative to the inter-digitating support surfaces
of an upper lock support to unlock the implant 10b without the
inter-digitating lower support faces first lifting above the
inter-digitating stop 50b. This design provides an enhanced locking
feature.
[0055] Generally the lower support surfaces 18 and the upper
support surfaces 21 are horizontal to maximize vertical support in
the locked implant. However, the locking support 20c shown in FIG.
12C provides an enhanced locking feature by providing inclined
support surfaces 21c which have a slope relative to the horizontal
which requires matching inclined lower support surfaces on the
upper lock supports (not shown) to be lifted above the inclined
upper support surfaces 21c before the upper lock support can be
rotated to unlock the implant 10c.
[0056] FIGS. 12A and 12C show various lengths of locking actuator
transfer elements or depending elements 28. The locking actuator
transfer element 28 can vary in length depending on how much
engagement is desired between the locking actuator transfer element
28 and the locking actuator slots 27. The locking actuator transfer
element 28 includes one or more transfer element tabs 29a and 29c
which vertically constrain the lower lock support 20 to the locking
actuator slots 27 in the housing 11. The wider locking actuator
opening 42 described above enables insertion of the locking
actuator transfer element 28 with transfer element tabs 29a and 29c
into the locking actuator slots 27 in housing base 12 at the
rotational position where the locking actuator transfer element 28
is aligned with the locking actuator opening 42. In other
rotational positions the transfer element tabs are constrained by
lateral extensions 49 (shown in FIG. 4B) on the sides of the
narrower locking actuator slots 27. In this manner the locking
actuator transfer element 28 provides both the function of
transferring force from the locking actuator 26 to the lower lock
support 20 as well as constraining the lower lock support 20 to the
housing 11. This later function prevents the frictional forces
between the lower alignment faces 46 and the upper alignment faces
47 created by the biased spring locking actuator 26 from lifting
the lower lock support 20 along with the upper lock support 17 when
the upper lock support 17 is lifted by the piston 22.
[0057] As an alternative to the locking actuator transfer element
28, the embodiment shown in FIG. 12B depicts a locking actuator
guide channel 80. This locking actuator guide channel 80 engages a
tensile member (not shown) which transfers actuation force from the
locking actuator 26 to the lower lock support 20. Tensile members
can be an of a number of known elements such as sutures made of
polymers or natural materials, metal cable, plastic or metal rod
and the like.
[0058] FIGS. 13A and 13B illustrate an alternate design of an
implant 110 embodying features of the invention. The implant 110
has independent actuation of the distal piston 122a and proximal
piston 122b. The two pistons 122a and 122b are interconnected by an
articulating top endplate 113 which allows independent lift and
locking of each side of the implant 110. This independent lift and
locking of both ends of the implant 110 enables the implant to
conform to intervertebral endplates that have uneven lateral
heights between them. Further, this independent lift and locking
allows the implant 110 to be used to create varying lateral heights
between vertebral endplates which can be useful to compensate for a
scoliosis in the spine.
[0059] Implant 110 has a housing 111 which has an alternate
delivery tool anchor 160 located in it as well as alternate
pressure input ports 137. A variety of anchor design or pressure
ports can be used with any of the embodiments of the current device
without departing from the scope of this invention. Lock and unlock
access ports 138 are also located on this housing 111. These ports
are used to guide lock and unlock mechanisms (not shown) which can
be manipulated externally to the implant 110 to actuate the lower
lock support 120 to not only move it under the upper lock support
117 to hold the piston 122b and articulating endplate 113 in an
expanded position, but also to move the lower lock support 120 away
from the upper lock support 117 to allow the piston 122b and
articulating endplate 113 to collapse back into the housing 110.
This later action maybe desirable to remove the implant 110 from or
reposition the implant within the intervertebral space. A variety
of lock/unlock mechanism can be used with the current invention
such as but not limited by, a tensile member including suture
thread and metallic cable, a compressive member such as a metallic
or polymer rod, pressurized fluid, a rotating drive, a super
elastic shape memory element, and the like.
[0060] FIGS. 14A-14C depict yet another alternate implant 210 that
embodies features of the invention. Implant 210 has an interfacing
top plate 213 which connects to separate and freely rotating
pistons 222 via the piston capture plate 270 on the interfacing top
plate 213 and the piston heads 318 on the rotating pistons 222ab.
The rotating pistons 222ab also interiorly contain upper lock
supports 217 with support faces 218 and alignment faces 246. Seals
223 are mounted on the rotating pistons 222ab and the seals 223 and
rotating pistons 222ab fit into internal cylinders 216 that are
located on the housing 211. The internal cylinders 216 have lower
lock supports 220 with support surfaces 221 and alignment faces 247
as well as lower retaining features 273. The housing 211 also
contains one or more pressure input ports 238.
[0061] In use, the implant 210 is inserted into the intervertebral
body space in a collapsed state and fluid pressure is delivered
through the pressure input port(s) 238 to the internal cylinder(s)
216 to raise the seal(s) 223 and rotating piston(s) 222ab out of
the internal cylinder(s) thereby raising the interfacing top plate
213 and expanding the implant 210. Once the rotating pistons 222ab
have been raised such that the lower alignment faces 246 of the
upper lock supports 217 have cleared the upper alignment surfaces
247 of lower lock supports 220, an actuator (not shown) rotates the
rotating pistons 222ab such that the lower support surfaces 218 of
the upper lock supports 217 are moved above the upper support
surfaces 221 of the lower lock supports 220, to thereby lock the
implant 210 in the expanded configuration. The actuator can be one
or more tensile members such as suture threads or cables that
extend from the user into the implant 210 through the lock and
unlock access ports 238 on the interfacing top plate 213 to the
piston head 271. Applying tension to one or more tensile members
when the piston is in an extended configuration will rotate the
piston heads 271 such that the support surfaces 218 of upper lock
supports 217 are moved above the support surfaces 221 of the lower
lock supports 220 thereby locking the implant 210. Alternately or
in addition to applying tension to lock the implant 210 in an
expanded configuration, apply tension to one or more tensile
members will rotate the piston heads 271 such that the lower
support surfaces 218 are moved away from the upper support surfaces
221 thereby unlocking the implant 210 and allowing the rotating
pistons 22ab2 to seat back into the internal cylinders 216 such
that the implant 210 is once again in a collapsed
configuration.
[0062] FIG. 15 illustrates an alternate implant design 310
embodying features of the invention which has a housing 311, top
end plate 313 and pistons 322 similar to the prior embodiments.
This implant 310 has upper lock supports 317 and lower lock
supports 320 within a central portion of the implant. The upper
lock supports 317 are secured to the top end plate 313 and the
lower lock supports 320 are secured to the base 314 with depending
elements (not shown) as was described above and are moved as in the
prior embodiments.
[0063] FIG. 16 illustrates an alternate implant design 410
embodying features of the invention which has a housing 411, top
end plate 413 and a centrally located piston 422 similar to the
prior embodiments. This implant 410 has upper lock supports 417 and
lower lock supports 420 distal and proximal to the centrally
located cylinder 416 and piston 422. The upper lock supports 417
are secured to the top end plate 413 and the lower lock supports
420 are secured to the base 412 and are moved as in the prior
embodiments via depending elements (not shown) as was described
above.
[0064] FIG. 17 shows another alternate implant 510 which has a pair
of pistons 522 and which has a locking support system which
includes ratchets 520 on the base 512 and pawls 517 pivotally
mounted to and depending from the top end plate 513. Expansion of
the pistons 522 causes the free ends 518 of pawls 517 to engage
recesses 520 in the ratchets 521 so as to lock the top end plate
513 in an extended configuration.
[0065] FIG. 18 illustrates another alternative implant design 610
which is similar to that shown in FIG. 17. In this embodiment the
free end of the pawl 617 has a plurality of teeth 618 to provide
greater effective contact between the pawl 617 and the ratchet 621
for locking of the implant 610.
[0066] FIG. 19 is the cross section of another embodiment of
implant 710 embodying features of the invention. In this embodiment
the pistons 722 are surrounded by upper lock support 717 which has
at least one cantilever extension ending at the support surface
718. The support surfaces 718 are captured by the recessed support
surfaces 721 which are located on the inner wall of the housing
711. Once the pistons 722 are expanded in an upward direction, the
support surfaces 718 of the upper lock support 717 engages the
recessed support faces 721 locking the implant 710 in place. The
upper lock support 717 can be rotated relative to the piston 722
and housing 711 to disengage the support surfaces 718 from the
support faces 721 to unlock the implant 710 and lower the pistons
722 as needed. Alternately the implant 710 can be unlocked by
rotating the upper lock support constraints 775 relative to the
upper lock support 717 to press on the cantilever extensions and
disengage the support surfaces 718 from the support surfaces
721.
[0067] FIGS. 20A-31 illustrate a variety of suitable means for
locking extendable members such as pistons in extended
configurations. FIGS. 20A, 20B, 21A, 21B, and 22-31 show variations
of lower lock supports and upper lock supports. In each of these
variations there are support surfaces on the lower lock supports
which engage support surfaces on the upper lock supports.
[0068] In FIGS. 20A and 20B support surfaces 818 comprise grooves
set into the upper lock support 817. The lower lock support 820 is
a U-shaped tong which is configured to advance (as indicated by the
arrow in FIG. 20A) towards the upper lock support 817 and to engage
one of the grooves with its upper support surface 821 for locking
an implant not shown in these drawings. Lower lock support 820 is
withdrawn (as indicated by the arrow in FIG. 20B) from the groove
to disengage the lower lock support and unlock the implant.
[0069] In the variation shown in FIG. 21A, the lower lock support
920 is a plate with an upper lock clearance opening 970 that is
shaped to allow passage of the cylindrical flat sided upper lock
support 917 through the lower lock support 920 (arrow). As shown in
FIG. 21B, once the lower lock support 920 is positioned at the
desired location it can be rotated approximately 90.degree. (arrow)
to engage the support faces of the lower lock support 920 with the
support surfaces 918 of the upper lock support 917. The shape of
the upper lock support 917 and mating upper lock clearance opening
970 on the lower lock support 920 are not restricted to the profile
shown in FIGS. 21A and 21B nor is the locking actuation restricted
to 90.degree. rotation of one of the elements but can vary to any
number of shapes that allow passage in one configuration but
constraint when one of the elements is moved to another
configuration.
[0070] In FIG. 22, the upper lock support 1017 is a cylinder with
notches cut to create support surfaces 1018. The lower lock support
1020 is a pivoting pin 1070 with a pawl 1071 for the lower support
surface 1021. In the configuration shown, the support surface is
biased as indicated by the arrow 1072 to allow the upper lock
support 1017 to rise with an expandable member of an implant and to
prevent the upper lock support from dropping. This allows the
device to lock at each level when the subsequent support surface
1018 of the upper lock support 1017 engages the support surface
1021 of the lower lock support 1020. In this variation having
features of the present invention, the upper lock support 1017 can
also be lowered by moving the pivoting pin 1070 of the lower lock
support 1020 away from the upper lock support 1017 to disengage the
support surface 1021 from the support surface 1018.
[0071] FIG. 23 shows yet another embodiment having features of the
invention where the lower lock support 1120 is a pin configured to
engage (arrow) support surfaces 1118 located in the upper lock
support 1117. The lower lock support 1120 does not have to engage
the full thickness of the upper lock support 1117 as shown in this
figure, nor does the support surface 1118 have to extend through
the entire thickness of the upper lock support 1117 but rather can
engage any portion of the upper lock support 1117 that is
sufficient to lock an implant in position. This embodiment also
allows a variety of shapes of pins 1120 and matching support
surfaces 1118.
[0072] In FIG. 24 the lower lock support 1220 is a grip with two
pivoting jaws 1270, the ends of which have support surfaces 1221.
The upper lock support 1217 has a series of notches 1271 which have
the support surfaces 1218. A lock actuator such as a compressive
spring (not shown) can apply force (as shown by the arrows 1272) to
the grip base extensions 1273 to lock the device. This variation
having features of the invention allows the upper lock support 1217
to move upwards but prevents downward motion thereof. Downward
motion of the upper lock support 1217 can be allowed by reversing
the force on grip base extensions 1273.
[0073] Not all locking systems embodying features of the invention
require the engagement of support surfaces of the upper lock
supports directly on top of the support surfaces of the lower lock
supports. A frictional support can be created to lock the device as
shown in FIGS. 25 through 32.
[0074] In FIG. 25 the upper lock support 1317 has one or more flat
faces as the support surfaces 1318. The lower lock support 1320 has
one or more pivoting pawls that have a support surface 1321 that
engage the support surface 1318 and supports a load (arrow).
[0075] In FIG. 26 the upper lock support 1417 has an exterior
support face 1418 which is gripped by the support face 1421 on the
inner diameter of the wrapped lower lock support 1420. This lower
lock support 1420 can be a torsion spring that in its free state
grips the upper lock support 1417 and releases the upper lock
support when a force (arrows) is applied to one or more of its ends
1470 as shown to increase the spring's inner diameter. The reverse
is possible where in its free state the lower lock support 1420
allows movement of the upper lock support 1417 inside the inner
diameter. When a tensile force is applied to the ends 1470 to
reduce the inner diameter, the lower lock support grips the support
surface 1418 of the upper lock support 1417 to lock the
implant.
[0076] FIGS. 27A and 27B show another variation which can be
described as a canted washer type device. The lower lock support
1520 is a plate with an upper lock clearance opening 1570 which
allows relative movement of the upper lock support 1517 as shown in
FIG. 27A. When the lower lock support 1520 is canted as shown in
FIG. 28B the edge of the upper lock clearance opening 1570
comprises a lower support surface 1521 which engages the upper
support surface 1518 which is the outer surface of the upper lock
support 1517 locking it relative to the lower lock support
1520.
[0077] Yet another variation of the gripping lock of the current
invention is shown in FIG. 28. In this variation the lower lock
support 1620 comprises of one or more jaws which have support
surfaces 1621 that are configure to be forced against the support
surface 1618 of the upper lock support 1617 to produce friction to
lock the device in place.
[0078] FIG. 29 illustrates a lower lock support 1720 which
comprises a pivot and pawl as has been detailed above. The end of
the pawl comprises a lower support surface 1721 which engages an
upper support surface 1718 on the upper lock support 1717. In this
embodiment the upper lock support 1717 is rotated counter clockwise
by an expanding element (not shown). This rotation in turn raises
the piston 1722 which expands the implant. In this manner the upper
lock support 1817 is integrated into the lifting mechanism to
engage the lower lock support 1720 and lock the implant as it
expands.
[0079] FIG. 30 illustrates yet another alternative implant 1810,
similar to that shown in FIG. 1 except that the upper locking
member 1817 and lower locking member 1818 have a linear shape
rather than the arcuate shape of the prior embodiments. The implant
1810 generally has a housing 1811, a top plate 1813, a bottom plate
1814, pistons 1822 and cylinders 1816. The upper locking member
1817 has support surfaces 1818 and the lower locking member 1820
has support surfaces 1821. The implant 1810 has a locking actuator
(not shown).
[0080] FIGS. 31A-31G illustrates another implant 1910 embodying
features of the invention which has upper locking members 1917 with
grooves 1970 having support surfaces 1918 and lower locking member
1920 with locking surfaces 1921. The lower locking member 1920 is a
wire-form which encircles the exterior of both upper locking
members 1917 and is configured to seat within the grooves 1970.
Expansion of the lower locking member 1920 (arrows in FIG. 31B) by
the locking actuator (not shown) causes the lower locking member
1920 to be pulled out of the groove 1970 and allows the upper
locking member 1917 to rise with the expansion of the implant.
Release of this expansion of the lower locking member 1920 (arrows
in FIG. 31A) allows the lower locking member 1920 to seat back into
the groove 1970 locking the implant 1910.
[0081] FIGS. 31G illustrates a detail of an alternate implant 1910a
embodying features of the invention which has upper locking members
1917a with grooves 1970a having support surfaces 1918a and lower
locking member 1920a with locking surfaces 1921a. The lower locking
member 1920a is a wire-form which encircles the exterior of both
upper locking members 1917a and is configured to seat within the
grooves 1970a. The support surface 1918a locks on the supports
surface 1921a when there is a compressive or downward force (hollow
arrow) on the upper locking member 1917a locking the implant 1910a.
Upward force or extension (solid arrow) of the upper locking member
1917a causes the lower locking member 1920a to ride on the
disengaging surface 1919a and out of the groove 1970a allowing the
upper locking member 1917a to rise with the expansion of the
implant 1910a.
[0082] The description herein focused on the manner in which the
locking elements are configured to lock the implant in extended
configurations. Although this locking action resists the forces
placed on the implant that would tend to force it back into a
collapsed configuration that is not the only force the locking
elements address. Once inserted between vertebral bodies the
implant is subject to lateral forces and torsion moments as well as
compressive forces. The locking features along with the other
elements of the invention are designed to resist all of these
forces to provide an implant that provides stable fixation and
distraction.
[0083] A partial or complete discectomy is usually performed prior
to the insertion of the spinal implant having features of the
invention between vertebral bodies. The implant is introduced in
its unexpanded state to enable it to be inserted posteriorly with
minimal trauma to the patient and risk of injury to nerve roots.
Once in place the implant can be expanded to provide both medial
and lateral spinal correction. The implant has an unexpanded height
of about 5 to about 15 mm, typically about 7 mm and is expandable
to at least 130% to about 180% of the unexpanded height. Typically
the implant is about 9 to about 15 mm wide, typically about 12 mm
wide and about 25 to about 55 mm long, typically about 35 mm long
to facilitate minimally invasive insertion and thereby minimize
trauma to the patient and risk of injury to nerve roots.
[0084] Additional details of the implant such as the attachment of
hydraulic lines and lines for transmission of a slurry or liquid
bone graft material, device and hydraulic fluid delivery
accessories and the like can be found in co-pending applications
Ser. No. 11/535,432 filed on Sep. 26, 2006 and Ser. No. 11,692,800,
filed on Mar. 28, 2007, which are incorporated herein by
reference.
[0085] It will be appreciated that the implant, including its
various components should be formed of biocompatible, substantially
incompressible material such as PEEK or titanium, and preferably
type 6-4 titanium alloy or other suitable materials which will
allow for long term deployment within a patient.
[0086] The extension of extendable members or pistons may be
individually controlled so that the physician is able to provide a
controlled angle of the corrective implant surface. While only two
extendable members or pistons are described herein, the implant may
be provided with three or more individually extendable members so
that the physician can exercise three-dimensional control of the
implant extension.
[0087] While the invention has been described in connection with
what are presently considered to be the most practical and certain
preferred embodiments, it is to be understood that the invention is
not limited to the disclosed embodiments and alternatives as set
forth above, but on the contrary is intended to cover various
modifications and equivalent arrangements included within the scope
of the following claims.
[0088] For example, the implants described herein are expanded by
hydraulic fluid. Other expansion means may be employed. For
example, a screw mechanism may be employed to expand the implant
into engagement with adjacent vertebral surfaces. Further, the
implant can be provided with load or pressure sensors that register
differential pressure and pressure intensity exerted on the
engaging surfaces of the SEC by the patient's vertebrae end plates
to generate corrective signals, for example by computer control,
that are used, e.g. by the surgeon or by a computer controlled
mechanism to realign the patient's spine. The invention may further
include a system that makes these adjustments, responsive to sensor
signals, in real time and on a continual basis, such that the
shapes of the implant changes to realign the patient's spine or
mechanism. Preferably, such system is contemplated for use in
setting the positions of the pistons during installation of the
implant.
[0089] While particular forms of the invention have been
illustrated and described herein, it will be apparent that various
modifications and improvements can be made to the invention.
Additional details of the spinal implant devices may be found in
the patents and applications referenced herein. To the extent not
otherwise disclosed herein, materials and structure may be of
conventional design.
[0090] Moreover, individual features of embodiments of the
invention may be shown in some drawings and not in others, but
those skilled in the art will recognize that individual features of
one embodiment of the invention can be combined with any or all the
features of another embodiment. Accordingly, it is not intended
that the invention be limited to the specific embodiments
illustrated. It is therefore intended that this invention be
defined by the scope of the appended claims as broadly as the prior
art will permit.
[0091] Terms such as "element", "member", "component", "device",
"means", "portion", "section", "steps" and words of similar import
when used herein shall not be construed as invoking the provisions
of 35 U.S.C .sctn.112(6) unless the following claims expressly use
the terms "means for" or "step for" followed by a particular
function without reference to a specific structure or a specific
action. All patents and all patent applications referred to above
are hereby incorporated by reference in their entirety.
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