U.S. patent application number 11/786595 was filed with the patent office on 2007-08-23 for surgical instrumentation and method for treatment of the spine.
Invention is credited to Kevin T. Foley, Jeff R. Justis.
Application Number | 20070198013 11/786595 |
Document ID | / |
Family ID | 26918772 |
Filed Date | 2007-08-23 |
United States Patent
Application |
20070198013 |
Kind Code |
A1 |
Foley; Kevin T. ; et
al. |
August 23, 2007 |
Surgical instrumentation and method for treatment of the spine
Abstract
Instrumentation for treatment of the spine, including an
elongate member having a deformable distal end portion at least
partially formed of a flexible and preferably elastic material. The
distal end portion has an initial configuration for placement
adjacent a vertebral body and a deformed configuration defining at
least one outwardly extending projection for displacement of at
least a portion of the vertebral body. The elongate member
preferably comprises a rod member, a sleeve member and an actuator
mechanism for imparting relative linear displacement between the
rod and sleeve members to effect outward deformation of the distal
end portion of the sleeve member. In one embodiment, the
instrumentation is used to compact cancellous bone to form a cavity
within a vertebral body. In another embodiment, the instrumentation
is used to reduce a compression fracture. In yet another
embodiment, the instrumentation is used to distract a disc space
between adjacent vertebral bodies.
Inventors: |
Foley; Kevin T.;
(Germantown, TN) ; Justis; Jeff R.; (Gulf Breeze,
FL) |
Correspondence
Address: |
KRIEG DEVAULT LLP
ONE INDIANA SQUARE, SUITE 2800
INDIANAPOLIS
IN
46204-2709
US
|
Family ID: |
26918772 |
Appl. No.: |
11/786595 |
Filed: |
April 12, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10756970 |
Jan 13, 2004 |
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11786595 |
Apr 12, 2007 |
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09928949 |
Aug 13, 2001 |
6676665 |
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10756970 |
Jan 13, 2004 |
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60224491 |
Aug 11, 2000 |
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Current U.S.
Class: |
606/57 ; 606/62;
606/86R |
Current CPC
Class: |
A61B 17/025 20130101;
A61B 2017/00867 20130101; A61B 17/8858 20130101; A61F 2/44
20130101; A61F 2/4601 20130101; A61B 2017/0256 20130101 |
Class at
Publication: |
606/057 ;
606/062; 606/086 |
International
Class: |
A61B 17/00 20060101
A61B017/00; A61B 17/56 20060101 A61B017/56; A61F 5/00 20060101
A61F005/00 |
Claims
1.-79. (canceled)
80. A method for treatment of the spine, comprising: providing an
instrument including a deformable distal portion having an
insertion configuration and a deformed configuration, the deformed
configuration defining at least one transverse projection arranged
along a single transverse axis; positioning the deformable distal
portion adjacent a spinal structure while in the insertion
configuration; and deforming the distal portion toward the deformed
configuration to uniaxially displace at least a portion of the
spinal structure along the transverse axis.
81. The method of claim 80, wherein the deforming is directionally
controlled.
82. The method of claim 80, further comprising: deforming the
distal end portion back toward the insertion configuration; and
removing the distal end portion from the spinal structure.
83. The method of claim 80, wherein the positioning comprises
inserting the deformable distal portion through an outer wall of a
vertebral body; and wherein displacement of the at least a portion
of the spinal structure comprises compacting cancellous bone to
form a cavity within the vertebral body.
84. The method of claim 80, wherein the positioning comprises
inserting the deformable distal portion through an outer wall of a
vertebral body; and wherein displacement of the at least a portion
of the spinal structure comprises at least partially reducing a
compression fracture in the vertebral body.
85. The method of claim 80, wherein the positioning comprises
inserting the deformable distal portion into an intervertebral disc
space between adjacent vertebral bodies; and wherein displacement
of the at least a portion of the spinal structure comprises
exerting a force onto the adjacent vertebral bodies and distracting
the intervertebral disc space.
86. The method of claim 80, wherein the deforming of the distal
portion toward the deformed configuration comprises selectively
controlling the deforming to generate a controlled magnitude of
force against the at least a portion of the spinal structure.
87. The method of claim 80, wherein the instrument includes a first
member and a second member engaged with the first member, the
second member comprising the deformable distal portion, the
deforming of the distal portion occurring in response to relative
displacement between the first and second members, the relative
displacement between the first and second members being regulated
to generate a controlled magnitude of force against the at least a
portion of the spinal structure.
88. A method for treatment of the spine, comprising: providing an
instrument including a first member and a second member engaged
with the first member, the second member including a deformable
distal portion having an insertion configuration and a deformed
configuration; positioning the deformable distal portion adjacent a
spinal structure while in the insertion configuration; and
deforming the distal portion toward the deformed configuration in
response to relative displacement between the first and second
members, the deformed configuration displacing at least a portion
of the spinal structure.
89. The method of claim 88, wherein the relative displacement
between the first and second members is regulated to control the
deforming and to generate a controlled magnitude of force against
the at least a portion of the spinal structure.
90. The method of claim 88, wherein the deforming is directionally
controlled.
91. The method of claim 88, wherein the deformed configuration of
the distal portion defines at least one transverse projection
arranged along a single transverse axis; and wherein the deforming
of the distal portion toward the deformed configuration uniaxially
displaces at least a portion of the spinal structure along the
transverse axis.
92. The method of claim 88, further comprising: inserting a cannula
having a working channel through the skin and tissue of a patient;
positioning a distal end of the cannula adjacent a vertebral body;
and inserting the distal end portion of the instrument through the
working channel to access the vertebral body.
93. The method of claim 92, further comprising inserting a viewing
element into a working channel of the cannula to provide
visualization of the vertebral body.
94. A method for treatment of the spine, comprising: providing an
instrument including a deformable distal end portion having an
insertion configuration and a deformed configuration; inserting a
cannula having a working channel through the skin and tissue of a
patient; positioning a distal end of the cannula adjacent a spinal
structure; inserting the deformable distal end portion of the
instrument through the working channel of the cannula; positioning
the deformable distal end portion proximately adjacent the spinal
structure while in the insertion configuration; and deforming the
deformable distal end portion toward the deformed configuration to
displace at least a portion of the spinal structure.
95. The method of claim 94, wherein the deformed configuration of
the deformable distal end portion defines at least one transverse
projection arranged along a single transverse axis; and wherein the
deforming results in uniaxially displacing the at least a portion
of the spinal structure along the single transverse axis.
96. The method of claim 94, wherein the deforming is directionally
controlled.
97. The method of claim 94, wherein the positioning comprises
inserting the deformable distal end portion through an outer wall
of a vertebral body; and wherein displacement of the at least a
portion of the spinal structure comprises compacting cancellous
bone to form a cavity within the vertebral body.
98. The method of claim 97, wherein the compacting results in at
least partially reducing a compression fracture in the vertebral
body.
99. The method of claim 94, wherein the deforming of the deformable
distal end portion toward the deformed configuration comprises
selectively controlling the deforming to generate a controlled
magnitude of force against the at least a portion of the spinal
structure.
100. The method of claim 94, wherein the instrument includes a
first member and a second member engaged with the first member, the
second member comprising the deformable distal end portion, the
deforming of the distal end portion occurring in response to
relative displacement between the first and second members.
101. The method of claim 100, wherein the relative displacement
comprises linearly displacing the first member relative to the
second member.
102. The method of claim 100, further comprising mechanically
regulating the relative displacement between the first and second
members to generate a controlled magnitude of force against the at
least a portion of the spinal structure.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims the benefit of Provisional
Application Ser. No. 60/224,491, filed Aug.11, 2000 and entitled
Vertebral Plasty Reduction Device, the contents of which are hereby
incorporated by reference in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of
surgical instrumentation and methods for treatment of the spine,
and more particularly relates to instrumentation and methods for
transversely displacing structures associated with the spine.
BACKGROUND OF THE INVENTION
[0003] Various instruments and methods for the treatment of
compression-type bone fractures and other osteoporotic and/or
non-osteoporotic conditions have been developed. Such methods
generally include a series of steps performed by a surgeon to
correct and stabilize the compression fracture. A cavity is
typically formed in the bone to be treated, followed by the
insertion of an inflatable balloon-like device into the bone
cavity. Inflation of the balloon-like device causes a compaction of
the cancellous bone and/or bone marrow against the inner cortical
wall of the bone, thereby resulting in enlargement of the bone
cavity and/or reduction of the compression fracture. The
balloon-like device is then deflated and removed from the bone
cavity. A biocompatible filling material, such as
methylmethacrylate cement or a synthetic bone substitute, is
sometimes delivered into the bone cavity and allowed to set to a
hardened condition to provide internal structural support to the
bone.
[0004] While the above-described instruments and methods provide an
adequate protocol for the treatment and fixation of
compression-type bone fractures, it has been found that expansion
of the balloon-like device is not controllable. Instead, when such
balloon-like device is inflated, expansion occurs along a path of
least resistance. As a result, the direction of compaction of the
cancellous bone and/or reduction of the compression fracture is not
controllable, and expansion occurs in multiple directions and along
multiple axes.
[0005] Thus, there is a general need in the industry to provide
surgical instrumentation and methods for use in treatment of the
spine that provide a greater degree of control over transverse
displacement of structures associated with the spine than is
currently available within the industry. The present invention
meets this need and provides other benefits and advantages in a
novel and unobvious manner.
SUMMARY OF THE INVENTION
[0006] The present invention relates generally surgical
instrumentation and methods for displacement of at least a portion
of a vertebral body. While the actual nature of the invention
covered herein can only be determined with reference to the claims
appended hereto, certain forms of the invention that are
characteristic of the preferred embodiments disclosed herein are
described briefly as follows.
[0007] In one form of the present invention, instrumentation is
provided for treatment of the spine, comprising an elongate member
extending along a longitudinal axis and including a deformable
distal end portion having an initial configuration for placement
adjacent a spinal structure and a deformed configuration defining
at least one transverse projection for transverse displacement of
at least a portion of the spinal structure.
[0008] In another form of the present invention, instrumentation is
provided for treatment of the spine, comprising a first member, a
second member having a distal end portion engaged with the first
member, with the distal end portion having an initial configuration
for placement adjacent a spinal structure and an expanded
configuration for displacement of at least a portion of the spinal
structure, and wherein relative displacement between the first and
second members causes the distal end portion to reform from the
initial configuration toward the expanded configuration.
[0009] In yet another form of the present invention,
instrumentation is provided for treatment of the spine, comprising
a member including a deformable distal end portion having an
initial configuration for positioning adjacent a spinal structure
and a deformed configuration for displacing at least a portion of
the spinal structure, and means for mechanically deforming the
distal end portion from the initial configuration toward the
deformed configuration to displace the spinal structure in at least
one predetermined direction.
[0010] In still another form of the present invention, a method is
provided for treatment of the spine, comprising providing an
instrument including a distal end portion having an insertion
configuration and a deformed configuration. The method further
comprises positioning the distal end portion adjacent a spinal
structure while in the insertion configuration and deforming the
distal end portion toward the deformed configuration to displace at
least a portion of the spinal structure.
[0011] It is one object of the present invention to provide
improved surgical instrumentation and methods for treatment of the
spine.
[0012] Further objects, features, advantages, benefits, and aspects
of the present invention will become apparent from the drawings and
description contained herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a perspective view of a surgical instrument
according to one form of the present invention.
[0014] FIG. 2 is an exploded side view of a distal end portion of
the surgical instrument depicted in FIG. 1.
[0015] FIG. 3 is an exploded side view of a proximal end portion of
the surgical instrument depicted in FIG. 1.
[0016] FIG. 4 is a broken cross-sectional side view of the surgical
instrument depicted in FIG. 1.
[0017] FIG. 5 is a perspective view of the distal end portion of
the surgical instrument depicted in FIG. 1, as shown in an initial
configuration.
[0018] FIG. 6 is a perspective view of the distal end portion
depicted in FIG. 5, as shown in a deformed configuration.
[0019] FIG. 7 is a perspective view of the distal end portion of a
surgical instrument according to another form of the present
invention, as shown in an initial configuration.
[0020] FIG. 8 is a perspective view of the distal end portion
depicted in FIG. 7, as shown in a deformed configuration.
[0021] FIG. 9 is a perspective view of the distal end portion of a
surgical instrument according to another form of the present
invention, as shown in an initial collapsed configuration.
[0022] FIG. 10 is a perspective view of the distal end portion
depicted in FIG. 9, as shown in a partially expanded
configuration.
[0023] FIG. 11 is a perspective view of the distal end portion
depicted in FIG. 9, as shown in a fully expanded configuration.
[0024] FIG. 12 is a partial cross-sectional side view of a spinal
column illustrating treatment of a vertebral body using the
surgical instrument illustrated in FIG. 1.
DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
[0025] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
embodiments illustrated in the drawings and specific language will
be used to describe the same. It will nevertheless be understood
that no limitation of the scope of the invention is hereby
intended, such alterations and further modifications in the
illustrated devices, and such further applications of the
principles of the invention as illustrated herein being
contemplated as would normally occur to one skilled in the art to
which the invention relates.
[0026] Referring to FIG. 1, shown therein is an instrument 20 for
treatment of the spine according to one form of the present
invention. Instrument 20 is particularly useful for placement
adjacent a spinal structure and selective displacement of at least
a portion of the spinal structure. In one embodiment of the
invention, the spinal structure is a vertebral body. It should be
understood that instrument 20 may be used in intrabody applications
such as, for example, a vertebral plasty procedure to compact
cancellous bone within the vertebral body and/or to reduce a
compression fracture of the vertebral body. Additionally, it should
be understood that instrument 20 may be used in interbody
applications such as, for example, to distract a space between
adjacent vertebral bodies, such as the vertebral disc space. It
should further be understood that in other embodiments of the
invention, the spinal structure may be comprised of a spinal
implant such as, for example, a cage device, or any other structure
used in association with treatment of the spine. Additionally,
although instrument 20 is illustrated and described in the context
of treatment of a human spine, it should be understood that
instrument 20 may be used to treat other animals. It should further
be understood that instrument 20 may be used in association with
applications outside of the spinal field such as, for example, to
treat other types of bony structures.
[0027] Instrument 20 is generally comprised of an elongate member
22 extending generally along a longitudinal axis L and having a
distal end portion 22a and a proximal end portion 22b. Although the
illustrated embodiment depicts elongate member 22 as having a
generally linear, unitary configuration, it should be understood
that elongate member 22 may take on other configurations as well,
such as, for example, a curvilinear configuration or a hinged
configuration. Instrument 20 also includes an actuator mechanism 24
coupled to the proximal end portion 22b of elongate member 22. As
will be discussed in greater detail below, the distal end portion
22a is deformable and is configured to outwardly expand in response
to a mechanically induced force. Such force may be effected, for
example, by the selective actuation of actuator mechanism 24.
[0028] As shown in FIGS. 5 and 6, the distal end portion 22a is
reformable between an initial configuration (FIG. 5) and a deformed
configuration (FIG. 6). As used herein, the term "initial
configuration" is broadly defined to encompass a structural
configuration of elongate member 22 that is suitable for placement
adjacent a spinal structure, and the term "deformed configuration"
is broadly defined to encompass a structural configuration of
elongate member 22 that is suitable for displacement of at least a
portion of the spinal structure. As discussed above, in one
embodiment of the invention, the spinal structure is a vertebral
body, and displacement of the vertebral body could be associated
with either intrabody or interbody applications.
[0029] Referring to FIG. 2, shown therein are further details
regarding the elongate member 22, and more specifically the
deformable distal end portion 22a of elongate member 22. In one
embodiment of the invention, the elongate member 22 is comprised of
an inner rod member 30 and an outer sleeve member 32. The inner rod
30 is preferably formed of a substantially rigid medical grade
material such as, for example, titanium or stainless steel. The
distal end portion 30a of rod 30 includes a tapered portion 34, a
reduced cross-section intermediate portion 36, and a rounded distal
end portion 38. In one embodiment, the intermediate portion 36 has
a diameter somewhat smaller than the diameter of the tapered
portion 34 and the rounded distal end portion 38 so as to define a
pair of opposing shoulders 40, 42. Although rod 30 has been
illustrated and described as having a substantially circular cross
section, it should be understood that other shapes and
configurations are also contemplated as being within the scope of
the invention including, for example, elliptical, square,
rectangular or other polygonal configurations.
[0030] The outer sleeve 32 preferably has a tubular configuration
defining an inner passage extending therethrough generally along
longitudinal axis L and sized to slidably receive rod 30. Sleeve 32
is preferably formed of a flexible material that is capable of
facilitating deformation from an initial configuration toward a
deformed configuration. Additionally, sleeve 32 is preferably
formed of an elastic material that is capable of facilitating
elastic deformation from the initial configuration toward the
deformed configuration and reformation back toward the initial
configuration. Sleeve 32 may be formed of materials including, but
not limited to, titanium, stainless steel, an elastomer, a polymer,
a rubber, a composite material or a shape-memory material. Although
the entire length of sleeve 32 may be formed of a flexible, elastic
material, it should be understood that only the distal end portion
32a of sleeve 32 need be formed of such material, with the
remainder of sleeve 32 being formed of any suitable medical grade
material. Moreover, although outer sleeve 32 is illustrated as
having a substantially tubular configuration, it should be
understood that other shapes and configurations of sleeve 32 are
also contemplated as being within the scope of the present
invention. Additionally, although sleeve 32 has been illustrated
and described as being formed as a single-piece, unitary structure,
it should be understood that the distal end portion 32a could be
formed separately from the remainder of sleeve 32, and coupled
together by any known method, such as, for example, by fastening,
welding or adhesion.
[0031] The distal end portion 32a of sleeve 32 includes at least
one slot 50 extending generally along longitudinal axis L, and
preferably includes at least a pair of slots 50 and 52 (not shown)
disposed generally opposite one another so as to define a pair of
longitudinally extending flexible strips of material 54, 56. It
should be understood, however, that the distal end portion 32a of
sleeve 32 could be configured to define any number of
longitudinally extending slots, including three or more slots,
which would in turn define a corresponding number of longitudinally
extending flexible strips of material. It should further be
understood that distal end portion 32a may include a number of
slots disposed at various axial locations along longitudinal axis
L. As will be described below, the slots 50, 52 are provided to
facilitate outward buckling of the distal end portion 32a of sleeve
32 in at least one predetermined direction upon the selective
actuation of the actuator mechanism 24.
[0032] In the illustrated embodiment, the slots 50, 52 are
substantially identical in shape and configuration, and thus only
slot 50 will be described in detail. However, it should be
understood that slots 50, 52 may take on different shapes and
configurations. Slots 50, 52 and strips of material 54, 56 are
illustrated as having a predetermined shape to provide a degree of
control over the outward buckling of the strips of material 54, 56.
In one embodiment of the invention, the slots 50, 52 and strips of
material 54, 56 have an irregular shape. Slot 50 includes a
relatively narrow and straight slot portion 60, a first
hourglass-shaped slot portion 62 formed by a first series of
arcuate portions, and a second hourglass-shaped slot portion 64
formed by a second series of arcuate portions. As will become
apparent below, the widened areas of the hourglass-shaped portions
62 and 64 serve as bending or flexion points to control the outward
deformation of the flexible strips of material 54, 56.
[0033] The straight slot portion 60 extends longitudinally from the
distal end of sleeve 32. The first hourglass-shaped portion 62
extends longitudinally from slot portion 60 and includes a first
widened area 62a, a narrowed area 62b, and a second widened area
62c. The second hourglass-shaped portion 64 extends longitudinally
from the first hourglass-shaped portion 62 and includes a first
widened area 64a, a narrow area 64b, and a second widened area 64c.
Although a specific configuration of slots 50, 52 have been
illustrated and described, it should be understood that other
shapes and configuration of slots 50, 52 are also contemplated as
falling within the scope of the invention.
[0034] In one embodiment of the invention, the distal end portion
32a of sleeve 32 is secured to the inner rod 30 by way of a
compression ring 70. Specifically, the distal-most portion of
sleeve 32 is disposed about portion 36 of rod 30, with the distal
end of sleeve 32 abutting the shoulder 42 formed by the rounded
distal end portion 38. The compression ring 70 is positioned about
the distal-most portion of sleeve 32 and is compressed thereabout,
such as, for example, by mechanical crimping to secure sleeve 32 to
inner rod 30. As should be appreciated, slot portion 60 aids in
tightly compressing sleeve 32 about inner rod 30 to provide secure
engagement therebetween. It should be understood that compression
ring 70 could alternatively be compressed about distal-most portion
of sleeve 32 by other means, such as, for example, by forming
compression ring 70 out of a shape-memory material that is
reformable to a memorized configuration having an internal diameter
that is less than the outer diameter of sleeve 32. It should
further be understood that the distal-most end portion of sleeve 32
could be secured to rod 30 by other means, such as, for example, by
fastening, welding, adhesion or other methods of attachment known
to those of skill in the art.
[0035] Referring to FIGS. 3 and 4, shown therein are further
details regarding the actuator mechanism 24. Actuator mechanism 24
is generally comprised of a rotary handle 100, a stationary handle
102, a connector assembly 104, and an actuator member 106. As will
be discussed in further detail below, the connector assembly 104 is
configured to secure the elongate member 22, and more specifically
the outer sleeve 32, to the remainder of the actuator mechanism 24.
As will also be discussed below, the threaded actuator member 106
is coupled to the inner.rod 30 and is engaged with the rotary
handle 100 such that rotational displacement of handle 100 about
longitudinal axis L linearly displaces the actuator member 106
along longitudinal axis L. As described above, the linear
displacement of rod 30 relative to sleeve 32 causes the distal end
portion 32a of sleeve 32 to reform from its initial configuration
toward its deformed configuration.
[0036] The rotary handle 100 includes a pair of lateral extensions
110, 112 extending outwardly from a main body portion 114 to define
a T-handle arrangement which aids the surgeon in rotating the
handle 100 relative to the stationary handle 102. The main body
portion 114 includes an opening extending along longitudinal axis L
and having a threaded portion 116 and an unthreaded portion 118. A
hub portion 120 extends from the main body portion 114 and defines
an annular groove 122.
[0037] The stationary handle 102 includes a pair lateral extensions
130, 132 extending outwardly from a main body portion 134 to define
a second T-handle arrangement which aids the surgeon in securely
gripping instrument 20 and in maintaining the handle 102 in a
stationary rotational position during rotation of handle 100. The
main body portion 134 includes an opening extending therethrough
along longitudinal axis L and defining a first cavity 136 and a
second cavity 138. A pair of openings 140, 142 extend through the
main body portion 134 and are disposed in communication with the
first cavity 136. The hub portion 120 of handle 100 is inserted
within the first cavity 136 and a pin or fastener 148 is inserted
through opening 140 and positioned within the annular groove 122 to
axially couple rotary handle 100 to stationary handle 102 while
permitting relative rotational displacement therebetween.
[0038] The actuator member 106 includes a threaded shank portion
150 and an unthreaded shank portion 152. The threaded shank portion
150 is configured to threadingly engage the threaded opening 116 in
rotary handle 100. In one embodiment of the invention, the threaded
shank portion 150 and the threaded opening 116 each define right
hand threads. The unthreaded shank portion 152 includes a slotted
opening 154 extending therethrough that is aligned with the opening
142 in the stationary handle 102. A pin or fastener 155 is inserted
through the opening 142 and the slotted opening 154 to couple the
actuator member 106 to the stationary handle 102. As should be
apparent, pin 155 substantially prevents relative rotational
displacement between actuator member 106 and handle 102 while
allowing a limited amount of relative linear displacement along
longitudinal axis L. The distal end portion of the actuator member
106 includes a socket 156 configured to accept a corresponding ball
portion 158 extending from the proximal end portion 30b of rod 30.
The socket opening 156 includes a spherical portion 160 sized to
receive the ball portion 158 therein, and a cylindrical portion 162
sized to receive the distal end portion 30b of rod 30 therethrough
to connect rod 30 to actuator member 106. It should be understood,
however, that other methods of interconnecting rod 30 and actuator
member 106 are also contemplated as would occur to one of skill in
the art.
[0039] As discussed above, the connector assembly 104 is configured
to connect the elongate member 22, and more specifically the outer
sleeve 32, to the remainder of the actuator mechanism 24. The
connector assembly 104 is generally comprised of a gripper member
170, a lock collar member 172 and a biasing member 174. The gripper
member 170 includes a connecting segment 176, a gripping segment
178 and a longitudinal passage having a first portion 180 extending
through connecting segment 176 and a second portion 181 extending
through the gripping segment 178. The first portion 180 of the
passage is sized to receive the shank portion 152 of actuator
member 150 therein, and the second portion 181 of the passage is
sized to receive the proximal end portion 32b of sleeve 32
therein.
[0040] The gripping segment 178 of gripper member 170 has a
generally conical shape and includes a tapered outer surface 182.
The gripping segment 178 also includes a longitudinally extending
slit 183 and a pair of transverse slots 184 that intersect slit
183, with both the slit 183 and the slots 184 intersecting the
longitudinal passage 181. One purpose of the slit 183 and the slots
184 is to facilitate compression of the gripping segment 178 about
the proximal end portion 32b of sleeve 32. The proximal end portion
32b of sleeve 32 defines an opening or window 185 extending
therethrough to further facilitate gripping of sleeve 32 by
gripping segment 178. Another purpose of slit 183 is to provide a
passageway for the lateral insertion of the proximal end portion
30b of rod 30 therethrough to permit assembly with the actuator
member 106. The gripping segment 178 also includes an outer tapered
surface 186, the purpose of which will become evident below.
[0041] The connecting segment 176 of gripper member 170 defines an
elongate opening 187 extending transversely therethrough and being
positioned in communication with the longitudinal slit 183. One
purpose of the elongate opening 187 is to facilitate compression of
the gripping segment 178 about the proximal end portion 32b of
sleeve 32. Another purpose of the transverse slot 187 is to provide
a passageway for the lateral insertion of the ball portion 158 of
rod 30 therethrough and into engagement with the socket 156 defined
in actuator member 106. The connecting segment 176 also includes an
opening 188 extending transversely therethrough and aligned with
the opening 142 in the stationary handle 102. Pin 155 is inserted
through the opening 188 to axially couple the gripper member 170,
and in turn the elongate member 22, to the stationary handle 102 in
a manner that substantially prevents relative linear and rotational
displacement therebetween.
[0042] The lock collar member 172 includes a cylindrically-shaped
body portion 190, a tapered end portion 192, and a longitudinal
passage 194 extending therethrough and being sized to receive the
connecting segment 176 of gripper member 170 therein. The
cylindrical body portion 190 is sized to be received within cavity
138 of stationary handle 102. The longitudinal passage 194 includes
an inner tapered surface 196 that corresponds to the outer tapered
surface 186 of gripping segment 178. In one embodiment of the
invention, the biasing member 174 is a coil spring. However, it
should be understood that other types of biasing devices may
alternatively be used as would occur to one of skill in the
art.
[0043] Referring to FIG. 4, spring 174 is disposed within the
cavity 138 of stationary handle 102 and is engaged against the
proximal end of the lock collar 172 to bias the lock collar 172
toward the gripping segment 178. The biasing of lock collar 172
engages the tapered inner surface 196 tightly against the tapered
outer surface 186 of gripping segment 178. Such engagement creates
an inward compression force onto the gripping segment 178 which
causes the gripping segment 178 to collapse tightly about the
proximal end portion 32b of sleeve 32 to securely grip sleeve 32
within the longitudinal passage 181. The tapered outer surface 192
of lock collar 172 is oriented at about the same angle as the
tapered outer surface 182 of gripping segment 178 to provide a
relatively smooth transition between lock collar 172 and gripping
segment 178.
[0044] Based on the above description and corresponding
illustrations, it should be apparent that rotation of handle 100
relative to stationary handle 102 in a clockwise direction
(assuming right hand threading) will cause the actuator member 106
to be linearly displaced in the direction of arrow A, which will
correspondingly cause rod 30 to be linearly displaced in the
direction of arrow A. Furthermore, since the distal end portion of
sleeve 32 is engaged with the distal end portion of rod 30, linear
displacement of rod 30 in the direction of arrow A will cause the
deformable distal end portion 32a of sleeve 32 to buckle outwardly
toward the deformed configuration illustrated in FIG. 6. It should
also be apparent that rotation of handle 100 relative to stationary
handle 102 in a counter-clockwise direction will cause the actuator
member 106 to be linearly displaced in the direction of arrow B,
which will correspondingly cause rod 30 to be linearly displaced in
the direction of arrow B. Linear displacement of rod 30 in the
direction of arrow B will cause the deformable distal end portion
32a of sleeve 32 to reform back toward the insertion configuration
illustrated in FIG. 5. As should be apparent, instead of rotating
handle 100 relative to handle 102 to impart relative linear
displacement between rod 30 and sleeve 32, it is also possible to
hold handle 100 in a stationary position and to rotate handle 102
relative to handle 100 to impart relative linear displacement
between rod 30 and sleeve 32.
[0045] Although one specific embodiment of the actuator mechanism
24 has been illustrated and described herein, it should be
understood that the use of other types and configurations of
actuator mechanisms are also contemplated as would occur to one of
skill in the art. As should be apparent, any type of actuator
mechanism that is capable of imparting relative displacement
between rod 30 and sleeve 32 to reform the distal end portion 32a
of sleeve 32 between the initial and deformed configurations may be
used. It should further be understood that in an alternative form
of the invention, rod 30 may be manually displaced by the surgeon
relative to sleeve 32, thereby eliminating the need for a separate
actuator mechanism 24.
[0046] Referring now to FIGS. 5 and 6, shown therein is the distal
end portion 22a of elongate member 22, as shown in an initial
insertion configuration and a mechanically deformed expanded
configuration, respectively. When in the initial configuration
(FIG. 5), the distal end portion 32a of sleeve 32 has a relatively
low profile to facilitate positioning adjacent a vertebral body. As
should be appreciated, the rounded distal end portion 38 reduces
the likelihood of damage to adjacent tissue during such
positioning. As used herein, positioning of the distal end portion
32a adjacent a vertebral body is meant to include positioning of
the distal end portion 32a in proximity to a vertebral body, within
a vertebral body or within a space between adjacent vertebral
bodies. As discussed above, instrument 20 may also be used in
association with spinal structures other than a vertebral body,
such as, for example, a spinal implant, with the distal end portion
32a of sleeve 32 being positioned adjacent or within the spinal
implant when in the insertion configuration.
[0047] Once properly positioned adjacent the vertebral body, the
distal end portion 32a of sleeve 32 is mechanically deformed by
displacing the rod 30 relative to the sleeve 32. In the illustrated
embodiment of the invention, such relative displacement is
accomplished by linearly displacing rod 30 relative to sleeve 32 in
the direction of arrow A, and is initiated by the selective
actuation of actuator mechanism 24. In an alternative embodiment of
the invention, the distal end portion 32a of sleeve 32 may be
mechanically deformed toward the expanded configuration by way of
relative rotational displacement between rod 30 and sleeve 32.
[0048] When reformed toward the expanded configuration (FIG. 6),
the distal end portion 32a of sleeve 32 is outwardly deformed
relative to longitudinal axis L so as to form a number of laterally
extending projections or protrusions 198a, 198b. As discussed
above, the deformed configuration of instrument 20 may define any
number of laterally extending projections, including a single
projection or three or more projections, and may define a number of
laterally extending projections at various axial locations along
longitudinal axis L. It should be apparent that the number,
position, and direction of the laterally extending projections is
at least partially controlled by the configuration and placement of
the slots 50 in sleeve 32. In this manner, formation of the
laterally extending projections and the resulting displacement of
the vertebral body is said to be directionally controlled.
Moreover, if the deformed configuration of instrument 20 defines a
single projection 198a, or a single pair of opposing projections
198a, 198b aligned along a common transverse axis T, then formation
of the laterally extending projection and the resulting
displacement of the vertebral body is said to be uniaxial. Further,
if the deformed configuration of instrument 20 defines a single
projection 198a extending in a single direction, then formation of
the laterally extending projection and the resulting displacement
of the vertebral body is said to be unidirectional.
[0049] Following displacement of the vertebral body, the distal end
portion 32a of sleeve 32 may be reformed from its deformed/expanded
configuration back toward its initial insertion configuration by
linearly displacing rod 30 relative to sleeve 32 in the direction
of arrow B. As discussed above, the distal end portion 32a of
sleeve 32 may be formed of a shape-memory material, such as, for
example, a shape-memory alloy ("SMA") to aid in reforming the
distal end portion 32a from the deformed configuration back toward
its initial configuration. More specifically, SMAs are known to
exhibit a characteristic or behavior in which a particular
component formed of an SMA is capable of being deformed from an
initial "memorized" shape or configuration to a different shape or
configuration, and then reformed back toward its initial shape or
configuration.
[0050] The ability to possess a shape-memory characteristic or
behavior is a result of the fact that the SMA undergoes a
reversible transformation from an austenitic state to a martensitic
state. If the martensitic transformation occurs due to the
imposition of stress, the shape-memory phenomena is referred to as
stress-induced martensitic transformation. As a result, SMAs are
known to display a superelastic or rubber-like behavior in which a
strain attained beyond the elastic limit of the SMA material during
loading is recovered during unloading. This superelastic phenomena
occurs when stress is applied to an SMA article at a temperature
slightly higher than the temperature at which the SMA begins to
transform into austenite (sometimes referred to as the
transformation temperature or A.sub.s). When stressed, the article
first deforms elastically up to the yield point of the SMA material
(sometimes referred to as the critical stress). However, upon the
further imposition of stress, the SMA material begins to transform
into stress-induced martensite. This transformation takes place at
an essentially constant stress, up to the point where the SMA
material is completely transformed into martensite. When the stress
is removed, the SMA material will revert back into austenite and
the article will automatically return toward its original,
pre-programmed or memorized shape without a corresponding change in
temperature.
[0051] Further details regarding the superelastic phenomena of a
SMA and additional characteristics of stress-induced martensite are
more fully described by Yuichi Suzuki in an article entitled Shape
Memory Effect and Super-Elasticity in Ni--Ti Alloys, Titanium and
Zirconium, Vol. 30, No. 4, Oct. 1982, the contents of which are
hereby incorporated by reference. Additionally, while there are
many alloys that exhibit shape-memory or superelastic
characteristics, one of the more common SMAs is an alloy of nickel
and titanium. One such well-known SMA is Nitinol.RTM., which has
proven to be highly effective for devices to be placed within the
human body because its transformation temperature range generally
falls between room temperature and normal human body temperature
(i.e., at about 35-40 degrees Celsius). Moreover, Nitinol.RTM. has
a very low corrosion rate and excellent wear resistance, thereby
providing an advantage when used as a support structure within the
human body. Additionally, implant studies in animals have shown
minimal elevations of nickel in the tissues in contact with the
Nitinol.RTM. material. It should be understood, however, that other
SMA materials that exhibit superelastic characteristics are
contemplated as being within the scope of the invention.
[0052] If the distal end portion 32b of outer sleeve 32 is formed
of an SMA material and is reshaped or deformed while at a
temperature above the transformation temperature A.sub.s of the
SMA, the distal end portion 32b will automatically recover or
reform toward its initial shape or configuration when the stress is
removed from distal end portion 32b. As illustrated in FIG. 5, when
distal end portion 32b is in its unstressed initial configuration,
virtually all of the SMA material will be in an austenitic state.
However, upon the imposition of stress onto distal end portion 32b
(e.g., by turning actuator handle 100 in a clockwise direction
relative to stationary handle 102), at least a portion of the SMA
material will transform into reversible stress-induced martensite
as the distal end portion 32b is deformed toward the expanded
configuration. Upon the reduction or removal of the stress (e.g.,
by turning actuator handle 100 in a counter clockwise direction),
at least a portion of the SMA material will be transformed back
into austenite and the distal end portion 32b will automatically
reform back toward the initial configuration.
[0053] Referring now to FIGS. 7 and 8, shown therein is the distal
end portion of an instrument 200 according to another form of the
present invention, as shown in an initial insertion configuration
and a mechanically deformed configuration, respectively. It should
be understood that instrument 200 may be used in association with
applications similar to those discussed above with regard to
instrument 20, including both intrabody and interbody applications
involving displacement of at least a portion of a vertebral
body.
[0054] Instrument 200 is generally comprised of an elongate member
222 extending along a longitudinal axis L and having a distal end
portion (as shown) and a proximal end portion (not shown) coupled
to an actuator mechanism which may be configured similar to
actuator mechanism 24. The distal end portion of elongate member
222 is deformable and is configured to outwardly expand in response
to a mechanically induced force. Specifically, the distal end
portion is reformable between an initial configuration (FIG. 7) for
positioning adjacent a vertebral body, and a deformed configuration
(FIG. 8) for displacement of at least a portion of the vertebral
body. Although the illustrated embodiment depicts elongate member
222 as having a generally linear, unitary configuration, it should
be understood that elongate member 222 may take on other
configurations as well, such as, for example, a curvilinear
configuration or a hinged configuration.
[0055] In the illustrated embodiment of instrument 200, the
elongate member 222 is generally comprised of an inner rod member
230 and an outer sleeve member 232. The inner rod 230 is preferably
formed of a substantially rigid medical grade material such as, for
example, titanium or stainless steel. The rod 230 includes a distal
end portion 230a that is disposed within and coupled to a distal
end portion 232a of sleeve 232. Although rod 230 has been
illustrated and described as having a substantially circular cross,
it should be understood that other shapes and configurations are
also contemplated as being within the scope of the present
invention, such as, for example, elliptical, square, rectangular or
other polygonal configurations.
[0056] The outer sleeve 232 preferably has a tubular configuration
defining an inner passage extending therethrough generally along
longitudinal axis L and sized to slidably receive rod 230 therein.
Sleeve 232 is formed of a relatively flexible material that is
capable of being reformed from an initial configuration to an
expanded configuration. Preferably, sleeve 232 is formed of a
relatively elastic material that is capable of being elastically
deformed to the expanded configuration and reformed back toward the
initial configuration. Sleeve 232 may be formed of materials
including, but not limited to, titanium, stainless steel, an
elastomer, a polymer, a rubber, a composite material or a
shape-memory material. Although the entire length of sleeve 232 may
be formed of a flexible, elastic material, it should be understood
that only the distal end portion 232a need be formed of such
material, with the remainder of sleeve 232 being formed of any
suitable medical grade material. Additionally, although sleeve 232
is illustrated as having a substantially cylindrical or tubular
configuration, it should be understood that other shapes and
configurations of sleeve 232 are also contemplated as being within
the scope of the present invention. Furthermore, although sleeve
232 has been illustrated and described as being formed as a
single-piece, unitary structure, it should be understood that the
distal end portion 232a could be formed separately from the
remainder of sleeve 232, and coupled together by any known method,
such as, for example, by fastening, welding or adhesion.
[0057] In one embodiment of instrument 200, the distal-most end
portion 270 of sleeve 232 is secured to the distal end portion 230a
of rod 230 by way of crimping. In other embodiments, sleeve portion
270 may be connected to rod portion 230a by a compression ring
similar to compression ring 70, or by other connection techniques
such as, for example, fastening, welding, adhesion, or other
methods of attachment known to those of skill in the art.
[0058] The distal end portion 232a of sleeve 232 includes at least
one rectangular-shaped window or slot 250 extending generally along
longitudinal axis L, and preferably includes at least a pair of
slots 250 and 252 (not shown) disposed generally opposite one
another so as to define a pair of longitudinally extending flexible
strips of material 254, 256. However, it should be understood that
the distal end portion 232a of sleeve 232 could define any number
of longitudinally extending slots, including three or more slots,
which would in turn define a corresponding number of flexible
strips of material disposed between the slots. The slots 250, 252
are provided to facilitate outward buckling of the distal end
portion 232a of sleeve 232 upon the imposition of relative linear
displacement between rod 230 and sleeve 232. As illustrated in FIG.
8, when reformed toward the expanded configuration, the flexible
strips of material 254, 256 will outwardly buckle along transverse
axis T at a location adjacent the midpoint of slots 250, 252. In
the illustrated embodiment of instrument 200, the slots 250, 252
are substantially identical in shape and configuration. However, it
should be understood that slots 250, 252 may take on different
predetermined shapes and configurations. Additionally, although
slots 250, 252 and strips of material 254, 256 are illustrated as
having a generally rectangular shape, other predetermined shapes
and configurations are also contemplated.
[0059] When in the initial configuration (FIG. 7), the distal end
portion 232a of sleeve 232 has a relatively low profile to
facilitate positioning adjacent a vertebral body. However, once
properly positioned adjacent the vertebral body, the distal end
portion 232a is mechanically deformed by displacing rod 230
relative to sleeve 232. In the illustrated embodiment, such
relative displacement is accomplished by linearly displacing rod
230 relative to sleeve 232 in the direction of arrow A. In an
alternative form of the present invention, the distal end portion
232a of sleeve 232 may be mechanically deformed toward the expanded
configuration by way of relative rotational displacement between
rod 230 and sleeve 232.
[0060] When reformed toward the expanded configuration (FIG. 8),
the distal end portion 232a of sleeve 232 is outwardly deformed
relative to longitudinal axis L so as to form a number of laterally
extending projections or protrusions 298a, 298b. As discussed
above, the deformed/expanded configuration of instrument 200 may
alternatively define any number of laterally extending projections,
including a single projection or three or more projections. Similar
to instrument 20, formation of the laterally extending projections
and the resulting displacement of the vertebral body by instrument
200 is directionally-controlled, and can be uniaxial,
unidirectional or both uniaxial and unidirectional. Following
displacement of the vertebral body, the distal end portion 232a of
sleeve 232 may be reformed back toward its initial insertion
configuration by linearly displacing rod 230 relative to sleeve 232
in the direction of arrow B. As discussed above with regard to
instrument 20, the distal end portion 232a of sleeve 232 may be
formed of a shape-memory material, such as, for example, a
shape-memory alloy to aid in reforming distal end portion 232a back
toward its initial configuration.
[0061] In one embodiment of the invention, at least the distal end
portion of the elongate member 222 is covered by a flexible
membrane 280. The flexible membrane 280 is preferably formed of a
resilient material that is capable of conforming to the shape of
the distal end portion 232a of sleeve 232 during reformation
between the initial and deformed configurations. Such flexible
materials include, but are not limited to, silicone, latex, rubber,
a polymer or other suitable elastomeric materials. One purpose of
the flexible membrane 280 is to prevent tissue or other foreign
material from passing through the slots 250, 252 and being
deposited within the space between the strips of material 254, 256
and the rod 230 and/or between the rod 230 and the remainder of the
sleeve 232. As should be appreciated, such a build-up of tissue or
foreign material may block or otherwise inhibit reformation of the
distal end portion 232a of sleeve 232 from the deformed
configuration (FIG. 8) back toward the initial configuration (FIG.
7). Although the flexible membrane 280 is illustrated as covering
the distal end portion of elongate member 222, it should be
understood that the flexible membrane 280 could be sized to cover
the entire length of the elongate member 222. It should also be
understood that a flexible membrane similar to flexible membrane
280 may be used in association with the surgical instrument 20
discussed above and/or the surgical instrument 300 discussed
below.
[0062] Referring now to FIGS. 9-11, shown therein is the distal end
portion of an instrument 300 according to another form of the
present invention, as shown in an initial insertion configuration,
a partially deformed intermediate configuration, and a fully
deformed configuration, respectively. It should be understood that
instrument 300 may be used in association with applications similar
to those discussed above with regard to instrument 20, including
both intrabody and interbody applications involving displacement of
at least a portion of a vertebral body.
[0063] Instrument 300 is comprised of an elongate member 322
extending generally along a longitudinal axis L and having a distal
end portion (as shown) and a proximal end portion (not shown) which
may be coupled to an actuator mechanism similar to actuator
mechanism. The distal end portion is deformable and is configured
to outwardly expand upon the imposition of a mechanically induced
force. Specifically, the distal end portion is reformable between
an initial configuration (FIG. 9) for positioning adjacent a
vertebral body, and a deformed configuration (FIG. 11) for
displacement of at least a portion of the vertebral body. Although
the illustrated embodiment depicts elongate member 322 as having a
generally linear, unitary configuration, it should be understood
that elongate member 322 may take on other configurations as well,
such as, for example, a curvilinear configuration or a hinged
configuration.
[0064] In the illustrated embodiment of instrument 300, the
elongate member 322 is generally comprised of an inner rod member
330 and an outer sleeve member 332. The inner rod 330 is preferably
formed of a substantially rigid medical grade material such as, for
example, titanium or stainless steel. Rod 330 includes a distal end
portion 330a extending from a main body portion 330b. In the
illustrated embodiment, the distal end portion 330a has a
rectangular shape and the main body portion 330b has a square
shape. However, it should be understood that other shapes and
configurations of rod 330 are also contemplated as being within the
scope of the present invention such as, for example, circular,
elliptical or polygonal configurations.
[0065] The outer sleeve 332 has a deformable distal end portion
332a coupled to a main body portion 332b. The main body portion
332b has a square configuration defining an inner passage extending
therethrough generally along longitudinal axis L and sized to
slidably receive portion 330b of rod 330 therein. How-ever, it
should be understood that other shapes and configurations of sleeve
portion 332b are also contemplated as being within the scope of the
present invention. Preferably, the main body portion 332b is formed
of a substantially rigid material, such as, for example, titanium,
stainless steel or other substantially rigid medical grade
materials.
[0066] The deformable distal end portion 332a of sleeve 332 is at
least partially formed of a relatively flexible material that is
capable of being reformed from the initial configuration
illustrated in FIG. 9 toward the deformed configuration illustrated
in FIG. 1. Preferably, distal end portion 332b is formed of a
relatively elastic material that is capable of being elastically
deformed toward the deformed configuration and reformed back toward
the initial configuration. The deformable distal end portion 332b
may be formed of materials including, but not limited to, titanium,
stainless steel, an elastomer, a polymer, a rubber, a composite
material or a shape-memory material. Distal end portion 332b is
preferably formed separately from main body portion 332a and
connected thereto by any method know to one of skill in the art,
such as, for example, by fastening, welding or adhesion. However,
is should be understood that distal end portion 332b could
alternatively be formed integral with main body portion 332a to
define a single-piece, unitary structure.
[0067] The deformable distal end portion 332a of sleeve 332
includes a plurality of wall elements 354-357 that are flexibly
interconnected by a number or interconnection portions 360. In one
embodiment of the invention, the interconnection portions 360 are
defined by forming an opening or channel 362 at locations where
adjacent wall elements adjoin to one another. In one embodiment of
the invention the wall elements 354-357 are integrally formed to
define a unitary, single-piece reformable structure that is
collapsible to define a relatively low-profile insertion
configuration and expandable to define an outwardly deformed
configuration.
[0068] To aid in reformation of the distal end portion 332a between
the insertion and deformed configurations, the distal end portion
332a of sleeve 332 is preferably flexibly coupled to the main body
portion 332b. In one embodiment. the outer wall elements 354, 355
each include a flexible interconnection portion 366 defined by
forming an opening or channel 367 adjacent their respective distal
end portions 354a, 355a. The distal end portions 354a, 355a of the
outer wall elements 354, 355 are in turn coupled to inner surfaces
of the main body portion 332b of sleeve 332, such as, for example,
by fastening, welding or adhesion. The outer wall elements 354, 355
are separated by a distance sufficient to receive the distal end
portion 330a of rod 330 therebetween.
[0069] As shown in FIG. 9, the insertion configuration has a
substantially rectangular-shaped profile, with each of the wall
elements 354-357 being disposed in a substantially uniform
orientation (i.e., parallel to one another), and with the two inner
wall elements 356, 357 being disposed between the two outer wall
elements 354, 355. As shown in FIG. 11, the deformed/expanded
configuration has a substantially triangular-shaped profile, with
the two inner wall elements 356, 357 being disposed in a
substantially parallel and co-linear orientation, and the two outer
wall elements 354, 355 being disposed at an angle .theta. relative
to inner wall elements 356, 357. In one embodiment, the angle
.theta. is about 30.degree.-45.degree.. It should be understood
that other insertion and expanded configurations are also
contemplated as falling within the scope of the present invention.
Additionally, although the reformable distal end portion 332b of
sleeve 332 has been illustrated and described as including four
wall elements 354-357, it should be understood that any number of
wall elements may be flexibly interconnected to form the reformable
distal end portion 332b.
[0070] When in the initial folded configuration illustrated in FIG.
9, the deformable distal end portion 332a of sleeve 332 has a
relatively low profile to facilitate positioning adjacent a
vertebral body. However, once properly positioned adjacent the
vertebral body, the distal end portion 332a is mechanically
deformed by displacing rod 330 relative to sleeve 332. In the
illustrated embodiment, such relative displacement is accomplished
by linearly displacing rod 330 relative to sleeve 332 in the
direction of arrow B, and is initiated by the selective actuation
of an actuator mechanism (not shown).
[0071] As shown in FIG. 10, relative displacement of rod 330 in the
direction of arrow B causes the distal end portion 330a of rod 330
to engage the interconnection portion 360 extending between the
inner wall elements 356, 357, thereby initiating the outward
expansion or unfolding of the wall elements 354-357. In one
embodiment of the invention, the distal end portion 330a of rod 330
is secured to the interconnection portion 360, such as, for
example, by fastening, welding or adhesion. However, it should be
understood that the distal end portion 330a of rod 330 need not
necessarily be rigidly secured to interconnection portion 360, but
could alternatively form an abutting relationship therewith to
initiate the outward expansion of wall elements 354-357.
[0072] As shown in FIG. 11, when reformed to the deformed
configuration, the wall elements 354-357 are unfolded and expanded
outwardly relative to longitudinal axis L so as to form laterally
extending projections or protrusions 398a, 398b disposed along a
transverse axis T. Although instrument 300 has been illustrated and
described as including a pair of oppositely disposed projections
398a, 398b when in the expanded configuration, it should be
understood that the distal end portion 332a of sleeve 332 may be
configured to define any number of projections, including a single
projection or three or more projections. Further, similar to
instrument 20, the expansion of the distal end portion 332a of
sleeve 332 and the resulting displacement of the spinal structure
accomplished by instrument 300 is directionally-controlled, and can
be uniaxial, unidirectional or both uniaxial and
unidirectional.
[0073] Following displacement of the vertebral body, the distal end
portion 332a of sleeve 332 may be reformed toward its initial
insertion configuration by linearly displacing rod 330 relative to
sleeve 332 in the direction of arrow A (FIG. 11). As discussed
above with regard to instrument 20, the distal end portion 332a of
sleeve 332 may be formed of a shape-memory material, such as, for
example, a shape-memory alloy ("SMA") to aid in reforming distal
end portion 332a back toward its initial configuration.
[0074] Referring to FIG. 12, shown therein is a lateral view of a
spinal column, illustrating the introduction and expansion of
instrument 20 within a vertebral body V.sub.1 to perform intrabody
distraction. The distal end portion 32a of sleeve 30 is initially
passed through an access opening (not shown) extending through an
outer wall of the vertebral body V.sub.1 while in the undeformed
initial configuration illustrated in FIG. 5. Subsequent to
insertion within the vertebral body V.sub.1, the distal end portion
32a of sleeve 32 is reformed by a mechanically-induced force
created by linearly displacing rod 30 relative to sleeve 32 in the
direction of arrow A. As a result, the distal end portion 32a is
outwardly deformed to form opposing projections 198a, 198b
extending along transverse axis T. Such outward deformation is
particularly useful, for example, to compact or compress cancellous
bone against the inner cortical wall of the vertebral body V.sub.1
to form a cavity C therein. Compaction of the cancellous bone may
have the effect of exerting an outward force on the inner surface
of the cortical wall, making it possible to elevate or push broken
and/or compressed bone back to or near its original pre-fracture
condition or another desired condition. Alternatively, the opposing
projections 198a, 198b may bear directly against the inner surface
of the cortical bone to reduce a compression fracture in the
vertebral body V.sub.1.
[0075] In one form of the present invention, access into the inner
cancellous region of the vertebral body V.sub.1 is be accomplished
by drilling a relatively small access opening through an outer wall
of the vertebral body, such as, for example, through the pedicular
region of the vertebral body V.sub.1. The undeformed initial
configuration of the distal end portion 32a of sleeve 30 is sized
to pass through the small access opening to gain access to the
inner cancellous region of the vertebral body V.sub.1. In this
manner, insertion of the distal end portion 32a of sleeve 32 is
accomplished in a minimally invasive manner. Additionally, unlike
certain prior art devices that require a relatively larger access
opening to accommodate spreading of the proximal end portions of
opposing members attached to one another in a scissors-like manner,
only the distal end portion 32a of sleeve 32 is outwardly expanded
when reformed toward the deformed configuration.
[0076] In one embodiment of the invention, the initial
configuration of the distal end portion 32a of sleeve 32 is sized
to pass through an access opening having a diameter between about 1
millimeter and about 5 millimeters. In a specific embodiment, the
initial configuration of the distal end portion 32a is sized to
pass through an access opening having a diameter of about 3
millimeters. In another embodiment of the invention, the deformed
configuration of the distal end portion 32a of sleeve 30 is sized
to displace the vertebral body V.sub.1 within a range of about 3
millimeters to about 15 millimeters. In a specific embodiment, the
deformed configuration of the distal end portion 32a is sized to
displace the vertebral body V.sub.1 about 10 millimeters. In
another specific embodiment of the invention, the instrument 20 is
capable of assuming a deformed configuration that is over three
times greater than its initial configuration. Although ranges and
specific sizes of the initial and deformed configurations of distal
end potion 32b of sleeve 32 have been set forth above, it should be
understood that such ranges and specific sizes are exemplary and
are not intended to limit the scope of the present invention in any
manner whatsoever.
[0077] Following displacement of the vertebral body V.sub.1, the
distal end portion 32a of sleeve 32 is reformed toward its initial
insertion configuration by displacing rod 30 relative to sleeve 32
in the direction of arrow B. As a result, the opposing projections
198a, 198b are inwardly deformed to the extent necessary to provide
uninhibited removal of the distal end portion 32a of sleeve 32 from
the vertebral body V.sub.1. As discussed above, reformation of the
instrument 20 back toward its initial insertion configuration may
be facilitated by forming the distal end portion 32a of sleeve 32
from a shape-memory material. Following the removal of instrument
20 from the vertebral body V.sub.1, the cavity C may be filled with
a biocompatible filling material, such as, for example,
methylmethacrylate cement (e.g., bone cement), a structural
implant, and/or a therapeutic substance to promote healing. Once
set to a hardened condition, the filling material provides internal
structural support to the vertebral body V.sub.1, and more
particularly provides structural support to the cortical bone of
the vertebral body V.sub.1.
[0078] In another form of the present invention, a cannula assembly
400 may be used to provide minimally invasive access to the
vertebral bodies V.sub.1, V.sub.2 and/or the disc space D. As shown
in FIG. 12, use of the cannula assembly 400 permits displacement of
the vertebral body V.sub.1 via insertion and manipulation of
instrument 20 through a single working channel. Further details
regarding a cannula assembly suitable for use in association with
the present invention are disclosed in U.S. patent application Ser.
No. 09/692,932 to Foley et al., filed on Oct. 20, 2000, the
contents of which are incorporated herein by reference.
[0079] The cannula assembly 400 includes a cannula 402 having a
distal end 402a and defining an inner working channel 404 extending
between the distal end 402a and a proximal end (not shown). The
length of the cannula 402 is sized such that the proximal end (not
shown) of the cannula 402 is positioned beyond the skin of the
patient when the distal end 402a is positioned adjacent the
vertebral body V.sub.1. One advantageous feature of the cannula
assembly 400 is the relatively large cross section of the working
channel 404 extending through cannula 402. Such a large cross
section permits the surgeon to introduce a wide variety of
instruments or tools into the working channel 404, as well as the
simultaneous introduction of two or more instruments or tools.
Furthermore, the relatively large cross section of working channel
404 permits a wide range of motion of the instruments and
tools.
[0080] The cannula assembly 400 may also include an endoscope
assembly (not shown) mounted to the proximal end portion of the
cannula 402 to provide remote visualization of the surgical site.
The endoscope assembly may include, for example, a viewing element
406 disposed within the working channel 404 of cannula 402 and
having a distal end 406a positioned adjacent the surgical site. The
viewing element 406 is preferably linearly and rotatably
displaceable within the working channel 404 to provide a wide
degree of visualization of the surgical site. The endoscope
assembly may also include an illumination element (not shown), a
remote viewing apparatus such as an eyepiece (not shown), and/or
irrigation and aspiration components (not shown) extending along
viewing element 406. One embodiment of an endoscope assembly
suitable for use in association with the present invention is
described in U.S. Pat. No. 6,152,871 to Foley et al., issued on
Nov. 28, 2000, the contents of which are incorporated herein by
reference. The cannula assembly 400 may also include a microscopic
viewing system (not shown) mounted to the proximal end portion of
the cannula 402 to provide microscopic visualization of the
surgical site. One embodiment of a microscopic viewing system
suitable for use in association with the present invention is
described in U.S. patent application Ser. No. 09/815,693 to Foley
et al., filed on Mar. 23, 2001, the contents of which are
incorporated herein by reference.
[0081] Although FIG. 12 illustrates the use of instrument 20 to at
least partially displace the vertebral body V.sub.1, it should be
understood that instruments 200 and 300 could alternatively be used
to perform the technique. It should also be understood that in
addition to performing intrabody distraction, instruments 20, 200
and 300 may be used to perform interbody distraction of one or both
of the adjacent vertebral bodies V.sub.1, V.sub.2, such as, for
example, to increase the height of the disc space D. Interbody
distraction of adjacent vertebral bodies V.sub.1, V.sub.2 may also
be effective to increase the distance between corresponding
portions of the vertebral bodies V.sub.1, V.sub.2. In cases
involving brittle portions of the vertebral bodies V.sub.1,
V.sub.2, shims may be positioned between the deformable distal end
portion 32a of sleeve 32 and the vertebral bodies V.sub.1, V.sub.2
to distribute the compressive force over a larger area to avoid
puncturing or crushing of the brittle portions. It should
additionally be understood that although the distraction technique
illustrated in FIG. 12 uses a posterior surgical approach, other
surgical approaches are also contemplated, such as, for example,
anterior, lateral, and postero-lateral approaches.
[0082] While the invention has been illustrated and described in
detail in the drawings and foregoing description, the same is to be
considered as illustrative and not restrictive in character, it
being understood that only the preferred embodiments have been
shown and described and that all changes and modifications that
come within the spirit of the invention are desired to be
protected.
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