U.S. patent application number 12/856426 was filed with the patent office on 2010-12-02 for interspinous process apparatus and method with a selectably expandable spacer.
This patent application is currently assigned to KYPHON SARL. Invention is credited to Ken Y. Hsu, Charles J. Winslow, James F. Zucherman.
Application Number | 20100305611 12/856426 |
Document ID | / |
Family ID | 32233462 |
Filed Date | 2010-12-02 |
United States Patent
Application |
20100305611 |
Kind Code |
A1 |
Zucherman; James F. ; et
al. |
December 2, 2010 |
INTERSPINOUS PROCESS APPARATUS AND METHOD WITH A SELECTABLY
EXPANDABLE SPACER
Abstract
The present invention is an interspinous process implant with a
selectably expandable spacer that can be placed between adjacent
spinous processes.
Inventors: |
Zucherman; James F.; (San
Francisco, CA) ; Hsu; Ken Y.; (San Francisco, CA)
; Winslow; Charles J.; (Walnut Creek, CA) |
Correspondence
Address: |
MEDTRONIC;Attn: Noreen Johnson - IP Legal Department
2600 Sofamor Danek Drive
MEMPHIS
TN
38132
US
|
Assignee: |
KYPHON SARL
Neuchatel
CH
|
Family ID: |
32233462 |
Appl. No.: |
12/856426 |
Filed: |
August 13, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11558352 |
Nov 9, 2006 |
7803190 |
|
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12856426 |
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|
10684847 |
Oct 14, 2003 |
7306628 |
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11558352 |
|
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60421921 |
Oct 29, 2002 |
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Current U.S.
Class: |
606/249 |
Current CPC
Class: |
A61B 17/7065
20130101 |
Class at
Publication: |
606/249 |
International
Class: |
A61B 17/70 20060101
A61B017/70 |
Claims
1-25. (canceled)
26. An implant adapted to be placed between spinous processes
comprising: a body having a shaft extending therefrom; a spacer
mounted on the shaft that is adapted to fit between spinous
processes, the spacer including a first portion and a second
portion; and a threaded screw mounted on the shaft between the
first portion and second portion; and an actuatable spreading
device mounted on the threaded screw to adjust the height of the
spacer in order to adjust the spacing between the spinous
processes.
27. The implant of claim 26 wherein the actuatable spreading device
is a slotted sphere that engages the first and second portion of
the spacer to maintain the profile height.
28. The implant of claim 27 wherein the slotted sphere engages a
screw extending from between the first and second portion of the
spacer to maintain the profile height.
29. An implant adapted to be placed between spinous processes
comprising: a body having a shaft extending therefrom; a spacer
mounted on the shaft, the spacer including a first portion and a
second portion; and a mechanism positioned between the first
portion and the second portion that can adjust a space between the
first and second portion, wherein the mechanism of the implant
further comprises a threaded screw mounted on the shaft, and an
actuatable spreading device engaging threads of the threaded screw,
wherein the actuatable spreading device further comprises a slotted
sphere.
30. The implant of claim 29 wherein the slotted sphere engages the
first and second portion of the spacer to maintain a profile
height.
31. The implant of claim 29 wherein the slotted sphere is mounted
on the threaded screw to maintain a profile height.
32. An implant adapted to be placed between spinous processes
comprising: a body having a shaft extending therefrom; a wing
extending from the shaft and adapted to be placed adjacent a first
and a second spinous process; a tissue expander extending from the
distal end of the shaft; said body including a spacer that is
mounted to the shaft, the spacer having a first portion and a
second portion; and a mechanism that is mounted to the spacer and
that can adjust the spacing between the first and second portions
of the spacer.
33. The implant of claim 32 wherein the spacer is elliptical in
shape with the first portion and the second portion divided about a
major axis of the elliptical shaped spacer.
34. The implant of claim 32 wherein the first portion and the
second portion of the spacer are connected by a hinge.
35. The implant of claim 32 wherein the mechanism of the implant
further comprises a slotted sphere.
36. The implant of claim 35 wherein the slotted sphere engages the
first and second portion of the spacer to maintain the profile
height.
37. The implant of claim 35 wherein the slotted sphere engages a
screw extending from between the first and second portion of the
spacer to maintain the profile height.
38. The implant of claim 32 wherein the mechanism of the implant
further comprises a jack.
39. The implant of claim 38 wherein the jack engages the first and
second portion of the spacer to maintain the profile height.
40. The implant of claim 38 where the said jack is adjustable to a
greater profile and a lesser profile by turning a screw in one of a
first direction and a second direction.
41. An implant adapted to be placed between spinous processes
comprising: a body having a shaft extending therefrom; a tissue
expander extending from the distal end of the shaft; a spacer
mounted on the shaft, the spacer having a first portion and a
second portion, wherein the spacer has an adjustable profile; a
threaded screw mounted on the shaft between the first portion and
second portion; and a slotted sphere mounted on the threaded
screw.
42. The implant of claim 41 wherein the slotted sphere engages the
first and second portion of the spacer to maintain a profile
height.
43. The implant of claim 42 wherein the slotted sphere engages the
threaded screw to maintain a profile height.
44. An implant to be placed between spinous processes comprising: a
body having a shaft extending therefrom; and a spacer that is
mounted on the shaft, wherein the spacer has a first portion and a
second portion; a threaded screw mounted on the shaft between the
first portion and second portion; and a device mounted on the
threaded screw to adjust a space between the first portion and the
second portion; wherein the device of the implant further comprises
a slotted sphere.
45. The implant of claim 44 wherein the slotted sphere engages the
first and second portion of the spacer to maintain the profile
height.
46. An implant adapted to be placed between spinous processes
comprising: a spacer adapted to fit between spinous processes, the
spacer including a first portion and a second portion; and an
actuatable spreading device mounted to the first and second
portion, wherein the spreading device is actuatable to adjust the
height of the spacer in order to adjust the spacing between the
spinous processes.
47. The implant of claim 46, wherein the actuatable spreading
device further includes a threaded element.
48. An implant adapted to be placed between spinous processes
comprising: a body having a shaft extending therefrom; a spacer
mounted on the shaft that is adapted to tit between spinous
processes, the spacer including a first portion and a second
portion; and an actuatable spreading device mounted on the shaft
between the first and second portion, the spreading device
including a threaded screw mounted on the shaft between the first
portion and second portion and a slotted sphere mounted on the
threaded screw; wherein the spreading device is actuatable to
adjust the height of the spacer in order to adjust the spacing
between the spinous processes.
Description
CLAIM OF PRIORITY
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/684,847, entitled "Interspinous Process
Apparatus and Method with Selectably Expandable Spacer," by
Zucherman et al., filed Oct. 14, 2003, (Attorney Docket No.
SFMT-01056USD) which claims benefit to U.S. Provisional Application
No. 60/421,921, entitled "Interspinous Process Apparatus and Method
with Selectably Expandable Spacer," by Zucherman et al., filed Oct.
29, 2002, (Attorney Docket. No. SFMT-01056USC) both of which are
incorporated herein by reference in their entireties.
CROSS REFERENCES TO RELATED APPLICATION
[0002] This application is related to U.S. patent application Ser.
No. 10/037,236, filed Nov. 9, 2001, which is related to U.S. patent
application Ser. No. 09/799,215, filed Mar. 5, 2001, now U.S. Pat.
No. 7,101,375, issued Sep. 5, 2006, which is a related to U.S.
patent application Ser. No. 09/179,570, filed Oct. 27, 1998, now
U.S. Pat. No. 6,048,342, issued Apr. 11, 2000, which is related to
U.S. patent application Ser. No. 09/175,645, filed Oct. 20, 1998,
now U.S. Pat. No. 6,068,630, issued May 30, 2000. This application
is also related to U.S. Pat. No. 5,836,948, issued Nov. 17, 1998
and U.S. Pat. No. 5,860,977, issued Jan. 19, 1999. All of the above
are incorporated herein by reference.
FIELD OF THE INVENTION
[0003] This invention relates to an apparatus and method for
adjustably distracting the spinous process of adjacent
vertebrae.
BACKGROUND OF INVENTION
[0004] The spinal column is a bio-mechanical structure composed
primarily of ligaments, muscles, vertebrae and intervertebral
disks. The bio-mechanical functions of the spine include: (1)
support of the body, which involves the transfer of the weight and
the bending movements of the head, trunk, and arms to the pelvis
and legs, (2) complex physiological motion between these parts, and
(3) protection of the spinal cord and the nerve roots.
[0005] As the population ages, it is anticipated that there will be
an increase in adverse spinal conditions characteristic in older
persons. For example, with aging comes an increase in spinal
stenosis (including, but not limited to, central canal and lateral
stenosis), the thickening of the bones that make up the spinal
column, and facet antropathy. Spinal stenosis is characterized by a
reduction in the available space for the passage of blood vessels
and nerves. Pain associated with such stenosis can be relieved by
medication and/or surgery. Of course, it is desirable to eliminate
the need for major surgery for all individuals, and, in particular,
for the elderly.
[0006] In addition, there are a variety of other ailments that can
cause back pain in patients of all ages. For these ailments it is
also desirable to eliminate such pain without major surgery.
[0007] Accordingly, there is a need for a method for alleviating
such conditions that is minimally invasive, can be tolerated by
patients of all ages (in particular, the elderly), can be performed
on an out-patient basis, and allows adjustments both during and
after surgery to minimize patient discomfort. There is a further
need for an apparatus with which to apply the method.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIGS. 1A-1F. FIG. 1A is a front plan view of one embodiment
of an apparatus with a selectably expandable spacer; FIG. 1B is a
left side view of the apparatus of FIG. 1A; FIG. 1C is a front plan
view of the apparatus of FIG. 1A including a selectably expandable
spacer, a main body and a first wing; FIG. 1D is a left side view
of the second wing of the apparatus of FIG. 1A; FIG. 1E is a front
plan view of the second wing of the apparatus of FIG. 1A; FIG. 1F
is an end view of the selectably expandable spacer of the apparatus
of FIG. 1A.
[0009] FIGS. 2A and 2B. FIG. 2A is a right side view of an
embodiment of the selectably adjustable spacer in an unexpanded
position. FIG. 2B is a right side view of an embodiment of the
selectably adjustable spacer in a fully expanded position.
[0010] FIGS. 3A and 3B. FIG. 3A is a right side cross-sectional
view of an embodiment of the selectably adjustable spacer in an
unexpanded position. FIG. 3B is a left side cross-sectional view of
an embodiment of the selectably adjustable spacer in a fully
expanded position.
[0011] FIG. 4 is a front side view of an embodiment of the
selectably adjustable spacer.
[0012] FIG. 5A is a perspective view of an embodiment of the
selectably adjustable spacer.
[0013] FIG. 5B is a back view of another embodiment of the spacer
similar to that shown in FIG. 5A with a mechanism for allowing the
spacer to expand.
[0014] FIGS. 6A and 6B. FIG. 6A is a right side view of an
alternative embodiment of the selectably expandable spacer with a
jack expansion mechanism in an unexpanded position. FIG. 6B is a
right side view of an alternative embodiment of the selectably
expandable spacer with a jack expansion mechanism in a fully
expanded position.
[0015] FIG. 7 is a block diagram demonstrating the steps for
performing the method.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] The following description is presented to enable any person
skilled in the art to make and use the invention. Various
modifications to the embodiments described will be readily apparent
to those skilled in the art, and the principles defined herein can
be applied to other embodiments and applications without departing
from the spirit and scope of the present invention as defined by
the appended claims. Thus, the present invention is not intended to
be limited to the embodiments shown, but is to be accorded the
widest scope consistent with the principles and features disclosed
herein. To the extent necessary to achieve a complete understanding
of the invention disclosed, the specification and drawings of all
patents and patent applications cited in this application are
incorporated herein by reference.
[0017] FIGS. 1A-1F illustrate an embodiment of an apparatus, or
implant 100, suitable for use with the method of this invention.
The implant 100 includes a first wing 104, a selectably expandable
spacer 150 and a lead-in tissue expander or distraction guide 110.
The implant further includes, as required, a second wing 132. As
can be seen in FIG. 1A, a shaft 102 extends from the first wing 104
and is the body that connects the first wing to the distraction
guide 110. Also, as can be seen in FIGS. 1A and 1B, the guide 110
in this particular embodiment is pointed in order to allow the
implant to be inserted between, and, if necessary, to distract
adjacent spinous processes. In this particular embodiment, the
guide 110 has a wedge-shaped cross-section, expanding from the
distal end 111 to the area where the second wing 132 can be
optionally secured to the guide. FIGS. 1B and 1C illustrate an
embodiment of the implant 100 with only a first wing 104.
[0018] As required, implant 100 can include a second wing 132 which
fits over the guide 110 and is secured by a bolt 130 placed through
aperture 134 of the second wing 132 to the threaded bore 112
located in the guide 110. As implanted, the first wing 104 is
located adjacent to first sides of the spinous processes and the
second wing 132 is located adjacent to second sides of the same
spinous processes.
[0019] The spacer 150 is rotatably mounted about a shaft 102. The
spacer 150 is positioned between the first wing 104 and the guide
110. The tissue expander 110 guides the spacer 150 into position
between the spinous process of adjacent vertebrae. The spacer 150
includes a slotted sphere 151 that when rotated is positioned along
a lead-screw, expanding or collapsing the spacer.
[0020] FIGS. 1F, 2A-B, 3A-B, and 5A-B illustrate a preferred
embodiment of the spacer 150 wherein the shape of the spacer 150 is
oval or elliptical in cross-section, although it can alternatively
be circular or ovoid or race-track shaped in cross-section. It is
to be understood that the spacer 150 can have other shapes as
described throughout the specification and be within the spirit and
scope of the invention. In a preferred embodiment, the spacer 150
includes a bore 152 extending the length of the spacer 150. The
bore 152 of the spacer 150 is received over the shaft. 102 of the
implant 100 so that, as described above, the spacer can be rotated
about the shaft 102. In these embodiments, the spacer 150 can have
minor and major dimensions as follows:
TABLE-US-00001 Minor Dimension (116a) Major Dimension (116b) 6 mm
10 mm 8 mm 10.75 mm 12 mm 14 mm 6 mm 12.5 mm 8 mm 12.5 mm 10 mm
12.5 mm
[0021] One advantage of the use of the spacer 150, as depicted in
the embodiment of FIG. 1A, is that the spacer 150 can be partially
rotated and repositioned with respect to the first wing 104 in
order to optimize positioning of the implant 100 between spinous
processes. It is to be understood that the cortical bone or the
outer bone of the spinous processes is stronger at an anterior
position adjacent to the vertebral bodies of the vertebra than at a
posterior position distally located from the vertebral bodies.
Also, biomechanically for load bearing, it is advantageous for the
spacer 150 to be close to the vertebral bodies. In order to
facilitate this and to accommodate the anatomical form of the bone
structures, as the implant is inserted between the spinous
processes and/or urged toward the vertebral bodies, the spacer 150
rotates relative to the wings, such as wing 104, so that the spacer
150 is optimally positioned between the spinous processes, and the
wing 104 is optimally positioned relative to the spinous
processes.
[0022] In another embodiment, the spacer 150 has a cross-section
with a major dimension and a minor dimension, wherein the major
dimension is greater than the minor dimension, and, for example,
less than about two times the minor dimension. It is to be
understood that the spacer 150 can be fabricated from somewhat
flexible and/or deflectable material.
[0023] In this embodiment the spacer is made out of a polymer, more
specifically, the polymer is a thermoplastic. Still more
specifically, the polymer is a polyketone known as
polyetheretherketone (PEEK.TM.). Still more specifically, the
material is PEEK 450G, which is an unfilled PEEK approved for
medical implantation available from Victrex of Lancashire, Great
Britain. (Victrex is located at www.matweb.com or see Boedeker
www.boedeker.com). Other sources of this material include Gharda,
located in Panoli, India (www.ghardapolymers.com).
[0024] The spacer 150 can be formed by extrusion, injection,
compression molding and/or machining techniques. This material has
appropriate physical and mechanical properties and is suitable for
carrying and spreading the physical load between the spinous
process. For example, in this embodiment, the PEEK has the
following approximate properties:
TABLE-US-00002 Density 1.3 g/cc Rockwell M 99 Rockwell R 126
Tensile Strength 97 MPa Modulus of Elasticity 3.5 GPa Flexural
Modulus 4.1 GPa
[0025] It should be noted that the material selected may also be
filled. For example, other grades of PEEK are also available and
contemplated, such as 30% glass-filled or 30% carbon-filled,
provided such materials are cleared for use in implantable devices
by the FDA, or other regulatory body. Glass-filled PEEK reduces the
expansion rate and increases the flexural modulus of PEEK relative
to that which is unfilled. The resulting product is known to be
ideal for improved strength, stiffness, or stability. Carbon-filled
PEEK is known to enhance the compressive strength and stiffness of
PEEK and lower its expansion rate. Carbon-filled PEEK offers wear
resistance and load carrying capability.
[0026] In this embodiment, as described above, the spacer 150 is
manufactured from polyetheretherketone (PEEK.TM.), available from
Victrex. As will be appreciated, other suitable similarly
biocompatible thermoplastic or thermoplastic polycondensate
materials that resist fatigue, have good memory, are flexible,
and/or deflectable, have very low moisture absorption, and good
wear and/or abrasion resistance, can be used without departing from
the scope of the invention. The spacer can also be comprised of
polyetherketoneketone (PEKK).
[0027] Other materials that can be used include polyetherketone
(PEK), polyetherketoneetherketoneketone (PEKEKK), and
polyetheretherketoneketone (PEEKK), and generally a
polyaryletheretherketone. Further other polyketones can be used as
well as other thermoplastics. The spacer can also be made of
titanium.
[0028] Reference to appropriate polymers that can be used in the
spacer can be made to the following documents, all of which are
incorporated herein by reference. These documents include: PCT
Publication WO 02/02158 A1, dated Jan. 10, 2002, entitled
"Bio-Compatible Polymeric Materials;" PCT Publication WO 02/00275
A1, dated Jan. 3, 2002, entitled "Bio-Compatible Polymeric
Materials;" and, PCT Publication WO 02/00270 A1, dated Jan. 3,
2002, entitled "Bio-Compatible Polymeric Materials."
[0029] Other materials such as Bionate.RTM., polycarbonate
urethane, available from the Polymer Technology Group, Berkeley,
Calif., may also be appropriate because of the good oxidative
stability, biocompatibility, mechanical strength and abrasion
resistance. Other thermoplastic materials and other high molecular
weight polymers can be used.
[0030] A preferred embodiment of the spacer is illustrated in FIGS.
2A-5. In FIGS. 2A and 2B the spacer 150 includes a first portion
260 pivotably or rotatably coupled with a second portion 261 by a
hinge (shown in FIG. 4). Both the first portion 260 and the second
portion 261 have tapered distal ends that form an acute angle
between the two portions. FIG. 2A illustrates the acute angle 265a
formed when the spacer 150 is in the unexpanded position. The first
portion 260 has a bore 252 through which the shaft 102, shown in
FIG. 1A, is received, connecting the first wing 104 with the guide
110 and connecting the spacer 150 with the implant 100. The bore
252 allows the spacer 150 to partially rotate about the shaft 102.
The second portion 261 of the spacer 150 also has a bore that is
located behind and aligned with the bore 252, shown in FIG. 2A.
This bore is also received on the shaft 102 so that both the first
and second portions of the spacer 150 can rotate about the shaft
102. A threaded screw 253 protrudes through the angle 265 a formed
by the tapered distal ends of the portions. The end of the threaded
screw 253 also has a bore that aligns with the bores of the first
and second portions of the spacer 150 and is received on the shaft
102 and can rotate about the shaft 102. A slotted sphere 151 is
connected with the distal end of screw 253. In the least expanded
position, the slotted sphere 151 is at the farthest point of travel
away from the proximal end of the screw 253 FIG. 2A.
[0031] FIG. 2B illustrates the acute angle 265b formed when the
spacer 150 is in the fully expanded position. The slotted sphere
151 is rotated such that the sphere travels toward the proximal end
of the threaded screw 253. As the slotted sphere 151 travels toward
the proximal end of the screw 253, the sphere 151 forces the
tapered distal ends of the portions 260, 261 apart. As the distal
ends of the portions are forced apart, the first portion 260 and
the second portion 261 rotate in opposite directions about a common
hinge 463 (shown in FIG. 4), sliding along the contact surface 262.
As the acute angle formed by the distal ends of the portions
increases, the height of the spacer 150 expands.
[0032] FIGS. 3A and 3B illustrate in cross-section the preferred
embodiment of the selectably expandable spacer described in
reference to FIGS. 2A and 2B. The slotted sphere 151 has a threaded
cavity for receiving the threaded screw 253 when the sphere 151 is
rotated. The slotted sphere 151 travels the distance 351c such that
the distal end of the screw 253 moves from position 351a to
position 351b along the threaded cavity of the sphere when adjusted
from an unexpanded to a fully expanded position. When rotated in
the opposite direction, the slotted sphere 151 moves away from the
proximal end of the screw 253, collapsing the spacer 150. FIG. 3B
illustrates the spacer 150 in a fully expanded position with the
distal end of the screw 253 at the maximum position 351b in the
threaded cavity of the slotted sphere 151. It is to be understood
that portions the 260, 261 of the spacer 150 can be biased to the
closed position shown in FIG. 3A. The biasing can be accomplished
by a spring that is coiled in or about the bore of the spacer that
receives the shaft 102. Such a spring would be connected to both of
the portions 260, 261 of the spacer 150.
[0033] The first and second portions of the spacer 150 in
combination, can have a cross-section that is elliptical, oval,
ovoid, football-shaped, circular-shaped, rectangular with rounded
ends (where the cross-section has two somewhat flattened surfaces
and two rounded surfaces similar to the effect of a flattened
ellipse) or race-track shaped. Further, the first and second
portions can have different cross-sectional shapes relative to each
other. At least the minor dimension (the height) of the spacer is
between 6 mm and 14 mm. Typically, the minor outer dimension is one
of 6 mm, 8 mm, 10 mm, 12 mm, and 14 mm. The different sizes and
selectable expandability enable the spacer to accommodate different
sized patients.
[0034] As discussed above, the spacer 150 and its components,
including either the first or second portions, or both, can be made
of a number of materials. Suitable materials can include polymers,
such as, for example, polyetheretherketone (PEEK.TM.), as well as
other materials described above, including titanium. Such materials
can be deflectable and flexible depending on the configuration of
the spacer 150.
[0035] Further, the deflectable or flexible material can have a
graduated stiffness to help gradually distribute the load when the
spinous processes place a force upon the exterior surface of the
spacer. This can be accomplished by forming multiple layers of the
deflectable or flexible material with decreasing stiffness or
hardness from the center of the spacer outwardly. Alternatively,
the material can have a higher stiffness or hardness in the center
of the inner spacer.
[0036] Referring to FIG. 4, the slotted sphere 151 is positioned
approximately equidistant from a first and second ends of the
spacer 150, distributing the parting force of the sphere 151 so as
not to create disproportionate stress on either side of the spacer
150.
[0037] A hinge 463 couples a first portion 260 with a second
portion 261, such that the two portions pivot about the hinge 463,
expanding or collapsing the gap 465.
[0038] A perspective view is provided in FIG. 5A, showing the
clam-shape of the preferred embodiment of the spacer 150. The
implant 100 is positioned between the adjacent vertebrae so as to
permit access to the slot 554 from a posterior direction both
during and after surgery. Post-surgery adjustment is made using a
cannula inserted through the patient's back. Convenient access to
the slot 554 is important for reducing patient discomfort and
procedure complication.
[0039] The bore 252 provides a sleeve for the shaft 102, and also
limits the rotation of the spacer 150 about the shaft 102. Limiting
the rotation of the spacer 150 can be accomplished, for example, by
providing a slot 255 in the bore 252 and a key on the shaft 102, or
vice-versa. One of skill in the art can appreciate that different
mechanisms and geometries can be used to limit spacer rotation.
Reference is also made to a copending U.S. patent application
entitled "Spinal Implants, Insertion Instruments, and Methods of
Use," filed on Mar. 5, 2001, as U.S. patent application Ser. No.
09/799,470 (KLYC-1027 US1), which is incorporated herein by
reference and which discloses an implant which has a spacer with a
slot and an implantation tool that includes a probe that engages
the slot in order to position the spacer relative to the
implantation tool for desirable initial positioning of the space
relative to the spinous processes. Such a mechanism can be used by
itself or in addition to the above discussed keyway and key for
purposes of positioning the sphere 151 so that the height of the
spacer 150 can be selectively adjusted during the initial surgical
procedure or, thereafter, should such adjustment be desirable due,
for example, to the need for more distraction between the spinous
processes.
[0040] FIG. 5B depicts the back of another embodiment of the spacer
ISO of the implant 100 of the invention. FIG. 5B is similar to a
back view of the embodiment depicted in FIG. 4. In FIG. 5B, the
spacer 150 includes the first and second portions 260, 261,
respectively. The first portion includes a bore 252 that receives
the shaft 102 and the second portion includes bore 254 that also
receives the shaft 102. In addition, the screw 253 is shown with a
portion of the sphere 151 that is used to adjust the height of the
spacer 150. The screw 253 includes a bore 257 that also receives
the shaft 102. Thus, the first and second portions of the spacer
and the screw are rotatable about the shaft.
[0041] One of skill in the art can also appreciate the different
expansion mechanisms that can be employed to expand the spacer 150.
For example, an expansion mechanism could include: pistons,
ratchets, cams, jacks, or other machines. FIGS. 6A and 613
illustrate one alternative embodiment in which a jack 651 is used
to expand the spacer 150. The jack 651 is expanded or collapsed by
rotating a slotted screw 653, thereby increasing or decreasing the
gap 665. FIG. 6A shows the spacer 150 in an unexpanded position
with a narrow gap 665a.
[0042] FIG. 6B illustrates another alternative embodiment utilizing
a jack, whereby the hinge 462 can allow for translation of the
first and second portions in the y-direction as well as for
rotation about the hinge 462, thereby reducing the stresses on the
side of the jack closest to the hinge caused by uneven compression
when the gap 665b expands. For the embodiment in FIGS. 6A and 6B
any of the above devices for allowing the first portion of the
spacer to move relative to the second portion of the spacer can be
employed, as well as other known methods, and be within the spirit
and scope of the invention.
[0043] The preferred method for inserting the implant between
adjacent vertebrae is block-diagramed in FIG. 7. The method
requires that the spine be surgically exposed. The implant is then
inserted between the spinous processes, with the wedge shape of the
guide forcing tissue apart to create room for the implant. Once the
implant is in place, with the spacer between adjacent vertebrae,
the profile of the implant is adjusted by expanding or collapsing
the spacer using a tool for operating the expansion mechanism. The
wound is then closed.
[0044] The implant can subsequently be readjusted with the
insertion of a cannula through which a tool is inserted for
operating the expansion mechanism.
[0045] The embodiment of this apparatus as well as the several
other apparatuses described herein, act to limit extension
(backward bending) of the spine. These apparatuses, however, do not
inhibit the flexion (forward bending) of the spinal column.
[0046] The foregoing description of embodiments of the present
invention has been provided for the purposes of illustration and
description. It is not intended to be exhaustive or to limit the
invention to the precise forms disclosed. Many modifications and
variations will be apparent to the practitioner skilled in the art.
The embodiments were chosen and described in order to best explain
the principles of the invention and its practical application,
thereby enabling others skilled in the art to understand the
invention and the various embodiments and with various
modifications that are suited to the particular use contemplated.
It is intended that the scope of the invention be defined by the
following claims and their equivalence.
* * * * *
References