U.S. patent application number 11/923814 was filed with the patent office on 2008-02-21 for interspinous process implant including a binder and method of implantation.
Invention is credited to John J. Flynn, Ken Y. Hsu, Henry A. Klyce, John A. Markwart, Steven T. Mitchell, Charles J. Winslow, Scott A. Yerby, James F. Zucherman.
Application Number | 20080046087 11/923814 |
Document ID | / |
Family ID | 36075090 |
Filed Date | 2008-02-21 |
United States Patent
Application |
20080046087 |
Kind Code |
A1 |
Zucherman; James F. ; et
al. |
February 21, 2008 |
INTERSPINOUS PROCESS IMPLANT INCLUDING A BINDER AND METHOD OF
IMPLANTATION
Abstract
Systems in accordance with embodiments of the present invention
can include an implant comprising a spacer for defining a minimum
space between adjacent spinous processes, a distraction guide for
piercing and distracting an interspinous ligament during
implantation, and a binder for limiting or preventing flexion
motion of the targeted motion segment. The binder can be secured to
a brace associated with the implant during implantation by a
capture device. In one embodiment, the capture device includes a
fixed piece extending from the brace and a slidable piece
associated with the fixed piece. A fastener can be rotated to pinch
the binder between the slidable piece and a wall of the brace,
securing the binder. A physician need not know the length of the
binder prior to implantation, reducing the time required to perform
a procedure.
Inventors: |
Zucherman; James F.; (San
Francisco, CA) ; Hsu; Ken Y.; (San Francisco, CA)
; Klyce; Henry A.; (Piedmont, CA) ; Winslow;
Charles J.; (Walnut Creek, CA) ; Yerby; Scott A.;
(Montara, CA) ; Flynn; John J.; (Concord, CA)
; Mitchell; Steven T.; (Pleasant Hill, CA) ;
Markwart; John A.; (Castro Valley, CA) |
Correspondence
Address: |
COOLEY GODWARD KRONISH LLP;ATTN: Patent Group
Suite 1100
777 - 6th Street, NW
WASHINGTON
DC
20001
US
|
Family ID: |
36075090 |
Appl. No.: |
11/923814 |
Filed: |
October 25, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11095680 |
Mar 31, 2005 |
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11923814 |
Oct 25, 2007 |
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60612465 |
Sep 23, 2004 |
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Current U.S.
Class: |
623/17.16 ;
606/99 |
Current CPC
Class: |
A61B 17/7065 20130101;
A61B 17/7068 20130101 |
Class at
Publication: |
623/017.16 ;
606/099 |
International
Class: |
A61F 2/44 20060101
A61F002/44; A61B 17/58 20060101 A61B017/58 |
Claims
1. A method, comprising: disposing an elongated member
substantially around a pair of adjacent spinous processes; and
rotating a distal end portion of a tool to couple a first end
portion of the elongated member to a second end portion of the
elongated member after the disposing.
2. The method of claim 1, further comprising: adjusting, before the
rotating, a length of the elongated member substantially around the
pair of adjacent spinous processes such that an amount of flexion
associated with the pair of adjacent spinous processes is
limited.
3. The method of claim 1, further comprising: adjusting, before the
rotating, a tension of the elongated member substantially around
the pair of adjacent spinous processes such that an amount of
flexion associated with the pair of adjacent spinous processes is
limited.
4. The method of claim 1, wherein the tool is a first tool, the
method further comprising: inserting, before the disposing, the
elongated member into a patient's body via a second tool.
5. The method of claim 1, wherein the disposing include threading
the elongated member between interspinous ligaments of the pair of
adjacent spinous processes so that the pair of adjacent spinous
processes are disposed within a loop defined by the elongated
member.
6. The method of claim 1, wherein the rotating includes rotating a
capture device such that the second end portion of the elongated
member is coupled to a brace, the first end portion of the
elongated member is fixedly coupled to the brace.
7. The method of claim 1, further comprising: forming, before the
inserting, an incision in the patient's body; and inserting, before
the disposing, the elongated member into the patient's body through
the incision.
8. The method of claim 1, further comprising: forming, before the
inserting, an incision in the patient's body; inserting, before the
disposing, the elongated member into the patient's body through the
incision; and inserting, before the rotating, a distal end portion
of the tool into the patient's body through the incision such that
a proximal end portion of the tool is disposed outside of the
patient's body.
9. The method of claim 1, wherein the tool is a first tool, further
comprising: forming, before the inserting, the incision in the
patient's body; inserting, before the disposing, the elongated
member into the patient's body through the incision via a second
tool; and inserting, before the actuating, a distal end portion of
the first tool into the patient's body through the incision such
that a proximal end portion of the first tool is disposed outside
of the patient's body.
10. A method, comprising: inserting an elongated member into a
patient's body through an incision in the body; disposing, after
the inserting, the elongated member substantially around a pair of
adjacent spinous processes; and actuating, after the disposing, a
tool through the incision to couple a first end portion of the
elongated member to a second end portion of the elongated
member.
11. The method of claim 10, further comprising: adjusting, before
the actuating, a length of the elongated member substantially
around the pair of adjacent spinous processes such that an amount
of flexion associated with the pair of adjacent spinous processes
is limited.
12. The method of claim 10, further comprising: adjusting, before
the actuating, a tension of the elongated member substantially
around the pair of adjacent spinous processes such that an amount
of flexion associated with the pair of adjacent spinous processes
is limited.
13. The method of claim 10, wherein the disposing include threading
the elongated member between interspinous ligaments of the pair of
adjacent spinous processes so that the pair of adjacent spinous
processes are disposed within a loop defined by the elongated
member.
14. The method of claim 10, wherein the actuating includes rotating
a distal end portion of the tool such that a capture device couples
the second end portion of the elongated member to a brace, the
first end portion of the elongated member is fixedly coupled to the
brace.
15. The method of claim 10, further comprising: forming, before the
inserting, the incision in the patient's body; and inserting,
before the disposing, the elongated member into the patient's body
through the incision.
16. The method of claim 10, further comprising: forming, before the
inserting, the incision in the patient's body; inserting, before
the disposing, the elongated member into the patient's body through
the incision; and inserting, before the actuating, a distal end
portion of the tool into the patient's body through the incision
such that a proximal end portion of the tool is disposed outside of
the patient's body.
17. A kit, comprising: a coupler; an elongated member, a first end
portion of the elongated member being fixedly coupled to the
coupler; and a tool configured to couple a second end portion of
the elongated member to the coupler while the elongated member is
disposed substantially around a pair of adjacent spinous
processes.
18. The kit of claim 17, wherein: the coupler includes a brace and
a capture device; the first end portion of the elongated member
fixedly coupled to the brace, the second end portion of the
elongated member removably coupleable to the brace via the capture
device; and the tool configured to rotate the capture device while
the elongated member is disposed around the pair of adjacent
spinous processes.
19. The kit of claim 17, wherein the tool is a first tool, the kit
further comprising: a second tool configured to insert the coupler
and the elongated member into a patient's body through an
incision.
20. The kit of claim 17, wherein the tool is a first tool, the kit
further comprising: a second tool configured to insert the coupler
and the elongated member into a patient's body through an incision,
a distal end portion of the first tool is configured to be inserted
into the patient's body through the incision and couple the second
end portion of the elongated member to the coupler.
21. A method, comprising: placing an elongated member around a pair
of adjacent spinous processes in a patient's body, the elongated
member having a distal end and a proximal end; and coupling a
distal portion of the elongated member to a proximal portion of the
elongated member, via a tool, such that a displacement of the two
adjacent spinous processes away from each other is limited.
22. The method of claim 21, further comprising: adjusting a
coupling member, the coupling member engaging the distal portion
and the proximal portion of the elongated member, such that the
displacement of the two adjacent spinous processes away from each
other is further limited.
23. The method of claim 21, further comprising: adjusting a
coupling member via tool, the coupling member moveably engaged with
the distal portion and the proximal portion of the elongated
member, such that a displacement of the two adjacent spinous
processes away from each other after the adjusting is greater than
the displacement of the two adjacent spinous processes before the
adjusting.
24. The method of claim 21, further comprising: positioning a
spacer between the pair of adjacent spinous processes.
25. The method of claim 21, further comprising: positioning, before
the coupling, a spacer between the pair of adjacent spinous
processes, the spacer being coupled to the elongated member.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/095,680, entitled "Interspinous Process
Implant Including a Binder and Method of Implantation," filed Mar.
31, 2005, which claims priority to U.S. Provisional Patent
Application No. 60/612,465, entitled "Interspinous Process Implant
Including a Binder and Method of Implantation," filed Sep. 23,
2004; each of which is incorporated herein by reference in its
entirety.
[0002] This U.S. Patent Application incorporates by reference all
of the following co-pending applications and issued patents:
[0003] U.S. patent application Ser. No. 10/850,267 (now Publication
No. 2005-0010293), entitled "Distractible Interspinous Process
Implant and Method of Implantation," filed May 20, 2004;
[0004] U.S. Pat. No. 6,419,676, entitled "Spine Distraction Implant
and Method," issued Jul. 16, 2002 to Zucherman, et al.;
[0005] U.S. Pat. No. 6,451,019, entitled "Supplemental Spine
Fixation Device and Method," issued Sep. 17, 2002 to Zucherman, et
al.;
[0006] U.S. Pat. No. 6,582,433, entitled "Spine Fixation Device and
Method," issued Jun. 24, 2003 to Yun;
[0007] U.S. Pat. No. 6,652,527, entitled "Supplemental Spine
Fixation Device and Method, issued Nov. 25, 2003 to Zucherman, et
al.;
[0008] U.S. Pat. No. 6,695,842, entitled "Interspinous Process
Distraction System and Method with Positionable Wing and Method,"
issued Feb. 24, 2004 to Zucherman, et al.;
[0009] U.S. Pat. No. 6,699,246, entitled "Spine Distraction
Implant," issued Mar. 2, 2004 to Zucherman, et al.; and
[0010] U.S. Pat. No. 6,712,819, entitled "Mating Insertion
Instruments for Spinal Implants and Methods of Use," issued Mar.
30, 2004 to Zuchennan, et al.
BACKGROUND
[0011] This invention relates to interspinous process implants. As
the present society ages, it is anticipated that there will be an
increase in adverse spinal conditions which are characteristic of
older people. Certain biochemical changes can occur with aging,
affecting tissue found throughout the body. In the spine, the
structure of the intervertebral disks can be compromised, in part
as the structure of the annulus fibrosus of the intervertebral disk
weakens due to degenerative effects. Spondylosis (also referred to
as spinal osteoarthritis) is one example of a degenerative disorder
that can cause loss of normal spinal structure and function. The
degenerative process can impact the cervical, thoracic, and/or
lumbar regions of the spine, affecting the intervertebral disks and
the facet joints. Pain associated with degenerative disorders is
often triggered by one or both of forward flexion and
hyperextension. Spondylosis in the thoracic region of the spine can
cause disk pain during flexion and facet pain during
hyperextension. Spondylosis can affect the lumbar region of the
spine, which carries most of the body's weight, and movement can
stimulate pain fibers in the annulus fibrosus and facet joints.
[0012] Over time, loss of disk height can result in a degenerative
cascade with deterioration of all components of the motion segment
resulting in segment instability and ultimately in spinal stenosis
(including, but not limited to, central canal and lateral
stenosis). Spinal stenosis results in a reduction in foraminal area
(i.e., the available space for the passage of nerves and blood
vessels) which compresses the nerve roots and causes radicular
pain. Another symptom of spinal stenosis is myelopathy. Extension
and ipsilateral rotation further reduces the foraminal area and
contributes to pain, nerve root compression and neural injury.
During the process of deterioration, disks can become herniated
and/or become internally torn and chronically painful. When
symptoms seem to emanate from both anterior (disk) and posterior
(facets and foramen) structures, patients cannot tolerate positions
of extension or flexion.
[0013] A common procedure for handling pain associated with
degenerative spinal disk disease is the use of devices for fusing
together two or more adjacent vertebral bodies. The procedure is
known by a number of terms, one of which is interbody fusion.
Interbody fusion can be accomplished through the use of a number of
devices and methods known in the art. These include screw
arrangements, solid bone implant methodologies, and fusion devices
which include a cage or other mechanism which is packed with bone
and/or bone growth inducing substances. All of the above are
implanted between adjacent vertebral bodies in order to fuse the
vertebral bodies together, alleviating associated pain.
[0014] Depending on the degree of slip and other factors, a
physician may fuse the vertebra "as is," or fuse the vertebrae and
also use a supplemental device. Supplemental devices are often
associated with primary fusion devices and methods, and assist in
the fusion process. Supplemental devices assist during the several
month period when bone from the adjacent vertebral bodies is
growing together through the primary fusion device in order to fuse
the adjacent vertebral bodies. During this period it is
advantageous to have the vertebral bodies held immobile with
respect to each other so that sufficient bone growth can be
established. Supplemental devices can include hook and rod
arrangements, screw arrangements, and a number of other devices
which include straps, wires, and bands, all of which are used to
immobilize one portion of the spine relative to another.
Supplemental devices have the disadvantage that they generally
require extensive surgical procedures in addition to the extensive
procedure surrounding the primary fusion implant. Such extensive
surgical procedures include additional risks, including risk of
causing damage to the spinal nerves during implantation. Spinal
fusion can include highly invasive surgery requiring use of a
general anesthetic, which itself includes additional risks. Risks
further include the possibility of infection, and extensive trauma
and damage to the bone of the vertebrae caused either by anchoring
of the primary fusion device or the supplemental device. Finally,
spinal fusion can result in an absolute loss of relative movement
between vertebral bodies.
[0015] U.S. Pat. No. 5,496,318 to Howland, et al. teaches
supplemental devices for the stabilization of the spine for use
with surgical procedures to implant a primary fusion device.
Howland '318 teaches an H-shaped spacer having two pieces held
together by a belt, steel cable, or polytetrafluoroethane web
material, one or both ends of which includes an attachment device
fixedly connected with the respective end. Howland '318 teaches
that the vertebra are preferably surgically modified to include a
square notch to locate the fixation device in a preferred location.
Howland '318 has the further disadvantage that the belt, cable or
web material must be sized before implantation, increasing the
procedure time to include sizing time and reducing the precision of
the fit where both ends of the belt, cable or web material include
attachment devices (and as such are incrementally sized).
[0016] U.S. Pat. No. 5,609,634 to Voydeville teaches a prosthesis
including a semi-flexible interspinous block positioned between
adjacent spinous processes and a ligament made from the same
material. A physician must lace the ligament through the
interspinous block and around the spinous processes in a figure of
eight, through the interspinous block and around the spinous
processes in an oval, and suture the ligament to itself to fix the
interspinous block in place. Voydeville has the disadvantage of
requiring significant displacement and/or removal of tissue
associated with the spinous processes, potentially resulting in
significant trauma and damage. Voydeville has the further
disadvantage of requiring the physician to lace the interspinous
ligament through the interspinous block. Such a procedure can
require care and time, particularly because a physician's ability
to view the area of interest is complicated by suffusion of blood
in the area of interest.
[0017] It would be advantageous if a device and procedure for
limiting flexion and extension of adjacent vertebral bodies were as
simple and easy to perform as possible, and would preferably
(though not necessarily) leave intact all bone, ligament, and other
tissue which comprise and surround the spine. Accordingly, there is
a need for procedures and implants which are minimally invasive and
which can supplement or substitute for primary fusion devices and
methods, or other spine fixation devices and methods. Accordingly,
a need exists to develop spine implants that alleviate pain caused
by spinal stenosis and other such conditions caused by damage to,
or degeneration of, the spine. Such implants would distract
(increase) or maintain the space between the vertebrae to increase
the foraminal area and reduce pressure on the nerves and blood
vessels of the spine, and limit or block flexion to reduce pain
resulting from spondylosis and other such degenerative
conditions.
[0018] A further need exists for development of a minimally
invasive surgical implantation method for spine implants that
preserves the physiology of the spine. A still further need exists
for an implant that accommodates the distinct anatomical structures
of the spine, minimizes further trauma to the spine, and obviates
the need for invasive methods of surgical implantation.
Additionally, a need exists to address adverse spinal conditions
that are exacerbated by spinal extension and flexion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Further details of embodiments of the present invention are
explained with the help of the attached drawings in which:
[0020] FIG. 1 is a perspective view of an interspinous implant
capable of limiting or blocking relative movement of adjacent
spinous processes during extension of the spine.
[0021] FIG. 2A is a posterior view of the implant of FIG. 1
positioned between adjacent spinous processes.
[0022] FIG. 2B is a cross-sectional side view of a spacer of the
interspinous implant of FIGS. 1 and 2A positioned between spinous
processes.
[0023] FIG. 2C is a cross-sectional view of the spacer of FIG. 2B
during flexion of the spine.
[0024] FIG. 3A is a side view of an embodiment of an implant in
accordance with the present invention having a distraction guide, a
spacer, a brace, and a binder associated with the brace and fixable
in position by a capture device.
[0025] FIG. 3B is a side view of an alternative embodiment of an
implant in accordance with the present invention including a brace
wall having recesses for receiving lobes of a capture device.
[0026] FIG. 3C is a side view of still another embodiment of an
implant in accordance with the present invention including a
capture device having a spring-loaded cam for securing a binder
against a brace wall.
[0027] FIG. 3D is a side view of a still further embodiment of an
implant in accordance with the present invention including a
capture device having dual spring-loaded cams for securing a binder
in position.
[0028] FIG. 4A is an end view of the implant of FIG. 3A positioned
between adjacent spinous processes.
[0029] FIG. 4B is an end view of the implant of FIG. 3A positioned
between adjacent spinous processes.
[0030] FIG. 4C is an end view of the implant of FIG. 3A positioned
between adjacent spinous processes wherein the spinous processes
are surgically modified to receive a binder.
[0031] FIG. 5 is an end view of an alternative embodiment of an
implant in accordance with the present invention having a binder
that varies in shape along the binder's length.
[0032] FIG. 6A is an end view of the implant of FIG. 5 positioned
between adjacent spinous processes.
[0033] FIG. 6B is an opposite end view of the implant of FIG.
6A.
[0034] FIG. 6C is an end view of still another embodiment of an
implant in accordance with the present invention having a cord for
a binder.
[0035] FIG. 7A is a side view of an embodiment of an implant in
accordance with the present invention including a wing associated
with the distraction guide to further limit or block movement of
the implant.
[0036] FIG. 7B is a partial cross-sectional side view of an
alternative embodiment of an implant in accordance with the present
invention include an extendable wing associated with the
distraction guide, the extendable wing being in a retracted
position.
[0037] FIG. 7C is a partial cross-sectional side view of the
implant of FIG. 7B wherein the extendable wing is in an extended
position.
[0038] FIG. 7D is a partial cross-sectional side view of still
another embodiment of an implant in accordance with the present
invention including a spring-loaded wing associated with the
distraction guide, the wing being in an extended position.
[0039] FIG. 7E is a partial cross-sectional side view of the
implant of FIG. 7D wherein the spring-loaded wing is in a collapsed
position.
[0040] FIG. 8 is a top view of two implants in accordance with an
embodiment of the present invention positioned between the spinous
processes of adjacent vertebrae, one of the implants having a
binder arranged around the adjacent spinous processes.
[0041] FIG. 9A is a perspective view of a further embodiment of an
implant in accordance with the present invention having a
distraction guide, a spacer, a brace, and a binder associated with
the brace and fixable in position by a capture device.
[0042] FIG. 9B is a perspective view the implant of FIG. 9A wherein
the capture device is arranged to secure a binder between the
capture device and the brace.
[0043] FIG. 9C is a side view of the implant of FIGS. 9A and
9B.
[0044] FIG. 10A is a cross-sectional top view of a binder loosely
positioned within the capture device of the implant of FIGS. 9A and
9B.
[0045] FIG. 10B is a cross-sectional top view of the binder secured
to the brace by the capture device of the implant of FIGS. 9A and
9B.
[0046] FIG. 10C is a cross-sectional top view of a binder loosely
positioned within an alternative embodiment of a capture device of
the implant of FIGS. 9A and 9B.
[0047] FIG. 10D is a cross-sectional top view of the binder and
capture device of FIG. 10C wherein the binder is secured to the
brace
[0048] FIG. 11 is an end view of the implant of FIGS. 9A and 9B
positioned between adjacent spinous processes.
[0049] FIG. 12 is a flow chart of a method of inserting an implant
according to an embodiment of the invention.
DETAILED DESCRIPTION
[0050] FIG. 1 is a perspective view of an implant as described in
U.S. Pat. No. 6,695,842 to Zucherman, et al., incorporated herein
by reference. The implant 100 has a main body 101. The main body
101 includes a spacer 102, a first wing 108, a lead-in tissue
expander 106 (also referred to herein as a distraction guide) and
an alignment track 103. The main body 101 is inserted between
adjacent spinous processes. Preferably, the main body 101 remains
(where desired) in place without attachment to the bone or
ligaments.
[0051] The distraction guide 106 includes a tip from which the
distraction guide 106 expands, the tip having a diameter
sufficiently small such that the tip can pierce an opening in an
interspinous ligament and/or can be inserted into a small initial
dilated opening. The diameter and/or cross-sectional area of the
distraction guide 106 then gradually increases until it is
substantially similar to the diameter of the main body 101 and
spacer 102. The tapered front end eases the ability of a physician
to urge the implant 100 between adjacent spinous processes. When
urging the main body 101 between adjacent spinous processes, the
front end of the distraction guide 106 distracts the adjacent
spinous processes and dilates the interspinous ligament so that a
space between the adjacent spinous processes is approximately the
diameter of the spacer 102.
[0052] The shape of the spacer 102 is such that for purposes of
insertion between the spinous processes, the spinous processes need
not be altered or cut away in order to accommodate the spacer 102.
Additionally, associated ligaments need not be cut away and there
is little or no damage to the adjacent or surrounding tissues. As
shown in FIG. 1, the spacer 102 is elliptically shaped in
cross-section, and can swivel about a central body (also referred
to herein as a shaft) extending from the first wing 108 so that the
spacer 102 can self-align relative to the uneven surfaces of the
spinous processes. Self-alignment can ensure that compressive loads
are distributed across the surface of the bone. As contemplated in
Zucherman '842, the spacer 102 can have, for example, a diameter of
six millimeters, eight millimeters, ten millimeters, twelve
millimeters and fourteen millimeters. These diameters refer to the
height by which the spacer distracts and maintains apart the
spinous process. For an elliptically shaped spacer, the selected
height (i.e., diameter) is the minor dimension measurement across
the ellipse. The major dimension is transverse to the alignment of
the spinous process, one above the other.
[0053] The first wing 108 has a lower portion 113 and an upper
portion 112. As shown in FIG. 1, the upper portion 112 is shaped to
accommodate the anatomical form or contour of spinous processes
(and/or laminae) of the L4 (for an L4-L5 placement) or L5 (for an
L5-S1 placement) vertebra. The same shape or variations of this
shape can be used to accommodate other motion segments. The lower
portion 113 can also be rounded to accommodate the spinous
processes. The lower portion 113 and upper portion 112 of the first
wing 108 act as a stop mechanism when the implant 100 is inserted
between adjacent spinous processes. The implant 100 cannot be
inserted beyond the surfaces of the first wing 108. Additionally,
once the implant 100 is inserted, the first wing 108 can prevent
side-to-side, or posterior-to-anterior movement of the implant
100.
[0054] The implant 100 further includes an adjustable wing 150
(also referred to herein as a second wing). The adjustable wing 150
has a lower portion 152 and an upper portion 153. Similar to the
first wing 108, the adjustable wing 150 is designed to accommodate
the anatomical form or contour of the spinous processes and/or
lamina. The adjustable wing 150 is secured to the main body 101
with a fastener 154. The adjustable wing 150 also has an alignment
tab 158. When the adjustable wing 150 is initially placed on the
main body 101, the alignment tab 158 engages the alignment track
103. The alignment tab 158 slides within the alignment track 103
and helps to maintain the adjustable wing 150 substantially
parallel with the first wing 108. When the main body 101 is
inserted into the patient and the adjustable wing 150 has been
attached, the adjustable wing 150 also can prevent side-to-side, or
posterior-to-anterior movement.
[0055] FIG. 2A illustrates an implant 100 positioned between
adjacent spinous processes extending from vertebrae of the lumbar
region. The implant 100 is positioned between inferior articular
processes 10 associated with the upper vertebrae and superior
articular processes 12 associated with the lower vertebrae. The
supraspinous ligament 6 connects the upper and lower spinous
processes 2,4. The implant 100 can be positioned without severing
or otherwise destructively disturbing the supraspinous ligament
6.
[0056] Referring to FIG. 2B, the spacer 102 of the implant 100 of
FIG. 2A is shown in cross-section. The spacer 102 defines a minimum
space between adjacent spinous processes 2,4. During extension the
spacer 102 limits or blocks relative movement between the adjacent
spinous processes 2,4, limiting or blocking the collapse of the
space between the spinous processes 2,4. Such support can alleviate
symptoms of degenerative disorders by preventing a reduction of the
foraminal area and compression of the nerve roots, or by avoiding
aggravation of a herniated disk, or by relieving other problems.
However, as shown in FIG. 2C, the implant 100 permits flexion,
which in some degenerative disorders (for example in cases of
spinal stenosis) can relieve some symptoms. As can be seen, during
flexion the spacer 102 can float between the spinous processes,
held in position by the interspinous ligament 8, and/or other
tissues and structures associated with the spine. The ability to
float between the spinous processes 2,4 also permits varying
degrees of rotation, as well as flexion. Implants as described in
Zucherman '842 thus have the advantage that they permit a greater
degree of movement when compared with primary and supplementary
spinal fusion devices.
[0057] In some circumstances, for example where a patient develops
spondylosis or other degenerative disorder that makes both flexion
and extension painful and uncomfortable, it can be desired that the
spinous processes be further immobilized, while providing the same
ease of implantation as provided with implants described above.
Referring to FIG. 3A, an embodiment of an implant 300 in accordance
with the present invention is shown. The implant 300 includes a
distraction guide 306, a spacer 302, and a brace 308. As shown, the
spacer 302 is rotatable about a central body 301 extending from the
brace 302, although in other embodiments the spacer 302 can be
fixed is position. A binder 330 can be fixedly connected with the
brace 308 at a proximal end 332 of the binder 330. The binder 330
is flexible, or semi-flexible, and can be positioned around
adjacent spinous processes so that the binder 308 engages the
spinous processes during flexion of the spine. Once positioned
around adjacent spinous processes, tension of the binder 330 can be
set when the binder 330 is secured to the brace 308 so that
relative movement of the adjacent spinous processes during flexion
is limited or prevented, as desired.
[0058] As can be seen in FIG. 3A, in an embodiment the brace 308
can include a first end having a slot 341 through which the
proximal end 332 of the binder 330 can be threaded and subsequently
sutured, knotted or otherwise bound so that the proximal end 332 of
the binder 330 cannot be drawn through the slot 341. In other
embodiments (not shown), the proximal end 332 can be looped or can
include a connector, such as a clasp or other device, and can be
fixed to the brace 308 via a fastener that engages the connector.
One of ordinary skill in the art can appreciate the myriad
different ways in which the proximal end 332 of the binder 330 can
be associated with the brace 308 so that tension can be applied to
the binder 330, and implants in accordance with the present
invention are not intended to be limited to those schemes described
in detail herein.
[0059] The brace 308 can include a height along the spine greater
than a height of the spacer 302 so that movement along a
longitudinal axis L in the direction of insertion is limited or
blocked by the brace 308 when the brace 308 contacts the lateral
surfaces of the spinous processes. In this way, the brace 308 can
function similarly to the wing 108 of the above described implant
100. In other embodiments, the brace 308 can have a height greater
or smaller than as shown. Once the binder 330 is positioned around
the spinous processes and secured, movement of the implant 300
relative to the spinous processes is limited by the binder 330
along the longitudinal axis as well as along the spinous processes
(i.e., anterior-to-posterior movement).
[0060] A free end of the binder 330 can be secured to the brace 308
by a capture device 320 associated with the brace 308. The brace
308 can include a flange 310 from which the capture device 320 can
extend. In the embodiment shown in FIG. 3A, the capture device 320
comprises a rotatable cam 321 having a fastener 322 and one or more
cut-outs 324. A tool can be mated with the cut-outs 324 and rotated
to pivot the rotatable cam 321. When the cam 321 is rotated, the
eccentric shape of the cam 321 causes a gap to close between the
cam 321 and a wall 314 of the brace 330 from which the flange 310
extends. When the binder 330 is positioned between the cam 321 and
the wall 314, the rotation of the cam 321 can pinch the binder 330
between the cam 321 and the wall 314, defining a secured end 336 of
the binder 330. Optionally, the fastener 322 can be screwed (i.e.,
rotated) so that the fastener 322 is further seated, tightening
against the cam 321 to fix the cam 321 in position. Further,
optionally, one or both of the wall 314 and the rotatable cam 321
can include knurls, or some other texture (e.g., teeth) to prevent
slippage (i.e., the slipping of the binder 330 between the cam 321
and the wall 314). The brace 308 can further include a guide 312,
such as a channel or slot (a slot as shown) at a second end of the
brace 308 to align the binder 330 with the capture device 320.
[0061] The binder 330 can comprise a strap, ribbon, tether, cord,
or some other flexible (or semi-flexible), and preferably
threadable structure. The binder 330 can be made from a
biocompatible material. In an embodiment, the binder 330 can be
made from a braided polyester suture material. Braided polyester
suture materials include, for example, Ethibond, Ethiflex,
Mersilene, and Dacron, and are nonabsorbable, having high tensile
strength, low tissue reactivity and improved handling. In other
embodiments, the binder 330 can be made from stainless steel (i.e.,
surgical steel), which can be braided into a tether or woven into a
strap, for example. In still other embodiments, the binder 330 can
be made from some other material (or combination of materials)
having similar properties.
[0062] The distraction guide 306 can optionally include a slot,
bore, cut-out or other cavity 309 formed in the distraction guide
306 through which the binder 330 can be threaded or positioned.
Such a cavity can allow on-axis positioning of the binder 330
(i.e., the binder can be substantially aligned with the
longitudinal axis L of the implant 300). Further, capturing the
binder 330 within a slot or bore can prevent or limit shifting of
the distraction guide 306 relative to the binder 330 to further
secure the implant 300 between the spinous processes.
[0063] As will be readily apparent to one of skill in the art,
implants in accordance with the present invention provide
significant benefits to a physician by simplifying an implantation
procedure and reducing procedure time, while providing an implant
that can limit or block flexion and extension of the spine. A
physician can position an implant between adjacent spinous
processes and can position a binder 330 connected with the brace
308 around the spinous processes without requiring the physician to
measure an appropriate length of the binder 330 prior to
implantation. The capture device 320 allows the binder 330 to be
secured to the brace 308 anywhere along a portion of the binder
330, the portion being between a distal end 334 of the binder 330
and the proximal end 332. The physician can secure the binder 330
to the brace 308 to achieve the desired range of movement (if any)
of the spinous processes during flexion.
[0064] The capture device 320 and brace 308 can have alternative
designs to that shown in FIG. 3A. A side view of an implant 400 in
accordance with an alternative embodiment of the present invention
is shown in FIG. 3B, the implant 400 including a capture device 420
comprising a cam 421 positioned within a ring 426 having one or
more lobes 423 corresponding with one or more recesses 413 in a
wall 414 of the brace 408. The binder 330 is positioned between the
capture device 420 and the brace 408. Once the binder 330 is
positioned as desired, the fastener 422 and cam 421 can be rotated
using an appropriate tool, with the cam 421 forcing the lobes 423
of the ring 426 to mate with the recesses 413 of the brace 408,
preventing the ring 426 from shifting in position and defining a
secure end 336 of the binder 330. Rotating the fastener 422 rotates
and optionally tightens down the cam 421. Such a capture device 420
can provide a physician a visual indication that the binder 330 is
properly secured to the brace 408, as well as preventing
slippage.
[0065] Referring to FIGS. 3C and 3D, in still other embodiments,
the implant can include a capture device comprising a spring-loaded
mechanism. FIG. 3C illustrates an implant 500 including a capture
device 520 comprising a single spring-loaded cam 521 pivotally
connected with the flange 310 and biased to rotate in one
direction. The distance between the pivot point of the cam 510 and
the wall 314 is sufficiently narrow that the rotation of the cam
521 in the direction of bias is blocked (or nearly blocked) by the
wall 314. The eccentricity of the cam 521 is large enough that a
maximum gap between the wall 314 and the cam 521 is sufficiently
wide as to allow the binder 330 to be threaded between the cam 521
and the wall 314. A physician can position the binder 330 between
the cam 521 and the wall 514 by overcoming the spring-force of the
spring-loaded cam 521. Once the binder 330 is position as desired,
the physician need only allow the bias force of the spring-loaded
cam 520 to force the cam 521 against the wall 314, so that the cam
521 pinches and secures the binder 330 between the cam 521 and the
wall 314. Optionally, one or both of the cam 521 and the wall 314
can be knurled or otherwise textured to limit or prevent slippage.
Further, the wall 314 can optionally include a recess (not shown)
to receive the cam 521 so that the binder 330 is pinched within the
recess (similar to the lobe and recess arrangement of FIG. 3B),
thereby further limiting slippage.
[0066] FIG. 3D illustrates an implant 600 including a capture
device 620 comprising dual spring-loaded cams 621, the dual
spring-loaded cams 621 being pivotally connected with the flange
310. The dual spring-loaded cams 621 are biased in opposition to
one another so that the cams 621 abut one another, similar to cam
cleats commonly used for securing rope lines on boats. During
surgery, the binder 330 can be loosely positioned around the
adjacent spinous processes and threaded between the cams 621.
Tension can be applied to the binder 330, as desired, by drawing
the binder 330 through the cams 621. The force of the binder 330
being pulled through the cams 621 can overcome the bias force to
allow the binder 330 to be tightened, while releasing the binder
330 can define a secure end 336 of the binder 330 as the cams 621
swivel together. As above, one or both of the cams 621 can be
knurled or otherwise textured to limit or prevent slippage.
[0067] Embodiments of implants have been described in FIGS. 3A-3D
with some level of specificity; however, implants in accordance
with the present invention should not be construed as being limited
to such embodiments. Any number of different capture devices can be
employed to fix a binder to a brace by defining a secure end of the
binder, and such capture devices should not be construed as being
limited to capture devices including cams, as described above. The
capture device need only be a device that allows a physician to fit
a binder having a generic size, or estimated size, around adjacent
spinous processes with a desired level of precision in tension.
[0068] FIGS. 4A and 4B are an opposite end views of the implant of
FIG. 3A positioned between adjacent spinous processes extending
from vertebrae of the lumbar region. The contours of a space
between adjacent spinous processes can vary between patients, and
between motion segments. A rotatable spacer 302 can rotate to best
accommodate the shape of the space so that the implant 300 can be
positioned as desired along the spinous processes. For example, it
can be desirable to position the spacer 302 as close to the
vertebral bodies as possible (or as close to the vertebral bodies
as practicable) to provide improved support. Once the implant 300
is positioned as desired, the binder 330 can be threaded through
interspinous ligaments associated with motion segments (i.e., pairs
of adjacent vertebrae and associated structures and tissues) above
and below the targeted motion segment so that the binder 330 is
arranged around the upper and lower spinous processes 2,4. The
binder 330 can then be threaded through the slot 312 of the brace
308 and positioned between the capture device 320 and the brace
wall 314. A first tool (not shown) can be inserted into the
incision formed to insert the implant 300 between the spinous
processes 2,4. Though not shown, the spacer 302 can include a
notch, similar to a notch 190 of the spacer 102 of FIG. 1, and the
brace 308 can include recesses, similar to recesses 192 of the
first wing 108 of FIG. 1, that can be engaged by the first tool for
grasping and releasing the implant 300 during insertion. (See U.S.
Pat. No. 6,712,819, which is incorporated herein by reference.)
Alternatively, some other technique for grasping and releasing the
implant 300 can be employed. Once the implant 300 is positioned and
the binder 330 is arranged as desired, a second tool (not shown),
such as a forked tool having spaced apart tines, can engage the cam
321 of the capture device 320 to rotate the cam 321, thereby
securing the binder 330 to the brace 308. A hex wrench can tighten
down the fastener 322 if desired. Alternatively, a single tool can
be employed to perform both the function of insertion of the
implant 300 and rotation of the cam 321, as depicted in the above
referenced patent. Optionally, the binder 330 can then be trimmed
so that the distal end 334 of the binder 330 does not extend
undesirably away from the brace 308. As can be seen, the spacer 302
is rotated relative to the distraction guide 306 and the brace 308.
Because the spacer 302 can rotate relative to the distraction guide
306 and the brace 308, the brace 308 can be positioned so that the
binder 330 can be arranged around the upper and lower spinous
processes 2,4 without twisting the binder 330. The binder 330 is
positioned around the lower spinous process 4, threaded or
positioned at least partially within a slot 309 of the distraction
guide 306, and positioned around the upper spinous process 2 so
that the binder 330 can be secured to the brace 308, as described
above.
[0069] Implants in accordance with the present invention can enable
a physician to limit or block flexion and extension in a targeted
motion segment while minifying invasiveness of an implantation
procedure (relative to implantation procedures of the prior art).
However, such implants can also be used where more extensive
implantation procedures are desired. For example, as shown in FIG.
4C, it can be desired that the adjacent spinous processes 2,4 be
surgically modified to receive the binder 330, thereby insuring
that the binder 330 does not shift or slide relative to the spinous
processes 2,4. The binder 330 is threaded directly through the
respective spinous processes 2,4 rather than through the
interspinous ligaments of adjacent motion segments. The amount of
bone removed from the spinous processes 2,4 can be reduced where a
cord or tether is used as a binder 330 rather than a strap. While
such applications fall within the contemplated scope of implants
and methods of implantation of the present invention, such
application may not realize the full benefit that can be achieved
using such implants due to the modification of the bone.
[0070] Still another embodiment of an implant 700 in accordance
with the present invention is shown in the end view of FIG. 5. In
such an embodiment the binder 430 can comprise a first portion 431
formed as a strap for arrangement around one of the upper and lower
spinous processes 2,4, and that tapers to a second portion 433
formed as a cord. The distraction guide 406 can include a bore 409
or other cavity for receiving the second portion 433. As can be
seen in FIG. 6A, once the binder 430 is threaded through the
distraction guide 406, a pad 436 of biocompatible material can be
associated with the binder 430, for example by slidably threading
the binder 430 through a portion of the pad 436, and the pad 436
can be arranged between the binder 430 and the respective spinous
process 2 so that a load applied by the binder 430 is distributed
across a portion of the surface of the spinous process 2. Referring
to FIG. 6B, once the binder 430 is arranged as desired relative to
the adjacent spinous processes 2,4, the binder 330 can be secured
by the brace 708. The brace 708 as shown is still another
embodiment of a brace for use with implants of the present
invention. In such an embodiment, the brace 708 includes a capture
device 720 comprising a clip including a spring-loaded button 721
having a first hole therethrough and a shell 723 in which the
button 721 is disposed, the shell 723 having a second hole. A
physician depresses the button 721 so that the first and second
holes align. The binder 430 can then be threaded through the holes,
and the button 721 can be released so that the spring forces the
holes to misalign, pinching the binder 430 and defining a secure
end of the binder 430.
[0071] FIG. 6C is an end view of a still further embodiment of an
implant 800 in accordance with the present invention. In such an
embodiment the binder 530 can comprise a cord. An upper pad 536 and
a lower pad 538 can be slidably associated with the binder 530 and
arranged so that a load applied by the binder 530 is distributed
across a portion of the upper and lower spinous processes 2,4. As
can be seen, such an embodiment can include a brace 808 having a
substantially different shape than braces previously described. It
should be noted that the brace 808 of FIG. 6C is shown, in part, to
impress upon one of ordinary skill in the art that a brace and
capture device for use with implants of the present invention can
include myriad different shapes, mechanisms and arrangements, and
that the present invention is meant to include all such variations.
As shown, the footprint of the brace 808 is reduced by shaping the
wall 814 of the brace 808 to taper at an upper end to form a guide
812 for aligning the binder 530 and to taper at a lower end to an
eyelet 841 for capturing a proximal end 532 of the binder 530. The
brace 808 includes a height from eyelet 841 to guide 812 such that
movement of the implant 800 in the direction of insertion is
blocked or limited by the brace 808.
[0072] Use of a binder to limit or prevent flexion can provide an
additional benefit of limiting movement along the longitudinal axis
L (shown in FIG. 3A). However, implants in accordance with the
present invention can optionally further include a second wing for
limiting or blocking movement in the direction opposite insertion.
Inclusion of such a structure can ensure that the implant remains
in position, for example where the binder slips out of a slot of
the distraction guide, or where the binder becomes unsecured.
[0073] Referring to FIG. 7A, an implant in accordance with an
embodiment can include a second wing 450 connected with the
distraction guide 406 of the implant 900 by a fastener 454. The
second wing 450 is similar to the second wing 150 described above
in reference to FIG. 1. The second wing 450 can include an
alignment tab 458 allowing a position of the second wing 450 to be
adjusted along a longitudinal axis L of the implant 900, and a
fastener 454 (for example a hex headed bolt) for affixing the
second wing 450 to the implant 900 in the position along the
longitudinal axis L desired. The distraction guide 406 can include
an alignment groove (not shown) corresponding to the alignment tab
458. The alignment tab 458 fits within, and is movable along, the
alignment groove so that a contact surface 455 of the second wing
450 can be arranged as desired. As shown, the second wing 450
includes a substantially planar contact surface arranged so that
the contact surface 455 of the second wing 450 is perpendicular to
the longitudinal axis L. However, in other embodiments, the contact
surface 455 need not be planar, and can be shaped and oriented to
roughly correspond with a contact surface of the upper and lower
spinous processes. Likewise, a contact surface 315 of the binder
308 can be shaped and oriented to roughly correspond with a contact
surface of the upper and lower spinous processes. As shown, the
upper portion 453 and the lower portion 452 of the second wing 450
do not extend from the distraction guide 406 as substantially as
the upper portion 153 and lower portion 152 of the second wing 150
of FIG. 1. As such, the second wing 450 includes a height H along
the spine smaller than that of the second wing 150 of FIG. 1. It
has been observed that benefits can be gained by including a wing
450, though the wing 450 does not extend from the distraction guide
406 as significantly as shown in FIG. 1 (i.e., the wing 450
includes "nubs" extending above and/or below the height of the
spacer 302). Such wings 450 will also be referred to herein as
winglets. Including a second wing 450 having an overall height
along the spine smaller than that of FIG. 1 can limit movement
along the longitudinal axis without interfering with (or being
interfered by) the arrangement of the binder 330.
[0074] In other embodiments, implants in accordance with the
present invention can include a second wing (or an upper portion
and/or lower portion) extendable from the distraction guide. In
this way an implant and a device for limiting or blocking movement
along a longitudinal axis of the implant can be included in a
single piece, possibly simplifying implantation. Referring to FIGS.
7B and 7C, implants 1000 in accordance with the present invention
can include a distraction guide 506 having a selectably extendable
upper portion 553 and lower portion 552 disposed within a cavity of
the distraction guide 506. The upper and lower portions 553,552 can
be extended by actuating a nut, knob or other mechanism operably
associated with a gear 556 so that the gear 556 rotates. The teeth
of the gear 556 engage teeth of the upper and lower portions
553,552, causing the upper and lower portions 553,552 to extend
sufficiently that the upper and lower portions 553,552 form
winglets for preventing motion of the implant 1000 in a direction
opposite insertion (shown in FIG. 7C). Rotating the gear 556 in an
opposite direction can retract the upper and lower portions
553,552.
[0075] In an alternative embodiment, implants 1100 in accordance
with the present invention can include spring-loaded upper and/or
lower portions 653,652 such as shown in FIGS. 7D and 7E. In such an
embodiment the upper and lower portions 653,652 can be fin-shaped,
having sloping forward surfaces 655,654 and being spring-biased to
an extended position, as shown in FIG. 7D. As the implant 1100 is
positioned between adjacent spinous processes, the spinous
processes and/or related tissues can contact the forward surface
655,654 of the upper and lower portions 653,652, causing the upper
and lower portions 653,652 to pivot about respective hinge points
657,656 and collapse into cavities disposed within the distraction
guide 606, as shown in FIG. 7E. Once the implant 1100 clears the
obstruction, the upper and lower portions 653,652 re-extend out of
the distraction guide 650. A slot and pin mechanism 660,661 or
other mechanism can lock the upper and lower portion 653,652 in
place once extended, disallowing over-extension of the upper and
lower portion 653,652 in the direction of bias. The extended upper
and lower portions 653,652 limit or block movement of the implant
1100 in an a direction opposite insertion.
[0076] In still further embodiments, implants in accordance with
the present invention can optionally employ some other additional
mechanism for limiting or blocking motion along the longitudinal
axis of the implant. Mechanisms shown and described in FIGS. 7A-7E
are merely provided as examples of possible mechanisms for use with
such implants, and are not intended to be limiting.
[0077] FIG. 8 is a top-down view of still another embodiment of an
implant in accordance with the present invention including a brace
708 arranged at an angle along the spinous process relative to the
longitudinal axis L of the implant 1200. The brace 708 is arranged
at such an angle to roughly correspond to a general shape of the
adjacent spinous processes. Such a general shape can commonly be
found in spinous processes extending from vertebrae of the cervical
and thoracic region, for example. The implant 1200 further includes
a second wing 752 extending from distraction guide 706 at an angle
roughly corresponding to a general shape of the adjacent spinous
processes. Identical implants 1200, one above the other, are shown.
The lower implant 1200 includes a binder 330 arranged around the
adjacent spinous processes (only the upper spinous process is
shown) and positioned in a slot 309 of the distraction guide 706.
The binder 330 includes a capture device 320 for securing the
binder 330 to the brace 708, and a channel formed by guides 712 on
the brace 708 for aligning the binder 330 with the capture device
320. Unlike previously illustrated embodiments, the brace wall
includes a recess 717 to accommodate rotation of the rotatable
spacer 302. Alternatively, the implants can include fixed spacers,
for example integrally formed with the brace 708 and the
distraction guide 706.
[0078] FIGS. 9A and 9B are perspective views, and FIG. 9C is a side
view of a still further embodiment of an implant in accordance with
the present invention. The implant 1300 includes a distraction
guide 806, a rotatable spacer 302, and a brace 908. As above, a
binder 330 can be fixedly connected with the brace 908 at a
proximal end 332 of the binder 330. Once positioned around adjacent
spinous processes, tension of the binder 330 can be set when the
binder 330 is secured to the brace 908 so that relative movement of
the adjacent spinous processes during flexion is limited or
prevented, as desired.
[0079] As can be seen in FIG. 9A, the brace 908 can include a first
end having an eyelet 941 through which the proximal end 332 of the
binder 330 can be threaded and subsequently sutured, knotted or
otherwise bound, or alternatively looped through the eyelet 941 and
secured to itself (e.g., using a clasp) so that the proximal end
332 of the binder 330 cannot be drawn through the eyelet 941. One
of ordinary skill in the art can appreciate the myriad different
ways in which the proximal end 332 of the binder 330 can be
associated with the brace 908 so that tension can be applied to the
binder 330. As in previous embodiments, a free end of the binder
330 can be secured to the brace 908 by a capture device 820
associated with the brace 908. The capture device 820 of FIGS.
9A-11 is arranged at a second end of the brace 908 opposite the
eyelet 941, rather than approximately centered along the brace wall
914. The brace 908 can optionally include a locking pin hole 915
that can be engaged by a locking pin of an insertion instrument
(not shown), for example as described in U.S. Pat. No. 6,712,819 to
Zucherman, et al., incorporated herein by reference. Further,
similar to implants described in Zucherman '819, the brace wall 914
can optionally include one or more holes 916 (shown in FIG. 11)
adapted to receive alignment pins of such an insertion instrument,
and the spacer 402 can include a spacer engagement hole 403 adapted
to receive a spacer engagement pin of such an insertion instrument.
When a spacer engagement pin engages the spacer engagement hole
403, rotation of the spacer 402 can be limited or blocked. Once the
spacer engagement pin is released from the spacer engagement hole
403, the spacer 402 can rotate and/or swivel about a central body
917 without impedance from the spacer engagement pin. Such an
arrangement can provide a physician additional control over the
positioning of the implant 1300, although in other embodiments the
spacer 402 need not include an engagement hole 403. Arranging the
captured device 820 at a second end of the brace 908 can allow an
insertion instrument, having a configuration as described in
Zucherman '819 or having some other configuration, to releasably
engage the implant 1300 to assist in implantation without
interference from the capture device 820.
[0080] The distraction guide 806 of the implant 1300 can be
wedge-shaped, as described above, or approximately conical, as
shown in FIGS. 9A-9C, and can include a slot 809 disposed through
the distraction guide 806 and adapted to receive the binder 330
during implantation. Also as described above, the rotatable spacer
402 can be elliptical in cross-section, or otherwise shaped, and
can rotate relative to the distraction guide 806 to roughly conform
with a contour of a space between the targeted adjacent spinous
processes.
[0081] The capture device 820 is shown in cross-section in FIGS.
10A and 10B. The capture device 820 can comprise, for example, two
pieces slidably associated with one another by an adjustable
fastener 822 (as shown, the adjustable fastener is a hex screw). A
fixed piece 821 of the capture device can extend from the brace
wall 914. The fixed piece 821 can include a beveled surface 823
that can function as a ramp. A slidable piece 827 of the capture
device can be slidably associated with the fixed piece 821, and can
likewise included a beveled surface 829 positioned in opposition to
the beveled surface 823 of the fixed piece 821. As shown, the
slidable piece 827 is associated with the fixed piece 821 via an
adjustable fastener 822. The fastener 822 can be positioned within
slots 890,892 of the fixed piece 821 and the slidable piece 827 and
can include a threaded shaft 880, a head 882, and a nut 884. The
head 882 of the fastener 822 can engage an anterior surface 894 of
the fixed piece 821 and the nut 884 can be threaded onto the
threaded shaft 880 so that the nut 884 can engage a posterior
surface 896 of the slidable piece 827. The slidable piece 827 is
free to slide along the beveled surface 823 of the fixed piece 821
until both the nut 884 engages the posterior surface 896 and the
head 882 engages the anterior surface 894, blocking further
movement in one direction. The distance between the anterior
surface 894 and the posterior surface 896 increases or decreases as
the slidable piece 827 slides along the beveled surface 823 and a
distance between a capture surface 898 of the slidable piece 827
and the brace wall 914 likewise increases or decreases. The maximum
distance the slidable piece 827 can travel can be defined by the
distance between the nut 884 and the head 882. A physician can
adjust the maximum distance by rotating the nut 884 so that the nut
884 travels closer to, or farther from the head 882 along the
threaded shaft 880, possibly urging the capture surface 898 toward
the brace wall 914. Thus, when the implant 1300 is positioned
between spinous processes, the physician can set the maximum
distance so that the free end of the binder 330 can be threaded
between the capture surface 898 and the brace wall 914. As shown in
FIG. 10B, the physician can then adjust the fastener 822 so that
the posterior surface 896 and the anterior surface 894 are urged
together, the maximum distance decreases and the distance between
the capture surface 898 and the brace wall 914 decreases, thereby
pinching the binder 330 between the capture surface 898 and the
brace wall 914 and defining a secure end of the binder 330. In some
embodiments, one or both of the capture surface 898 and the brace
wall 914 can include texture so that the binder 330 is further
prevented from sliding when the binder 330 is placed under
increasing tension (e.g., during flexion).
[0082] The slidable piece 827 can optionally further include a
guide 912 extending from the slidable piece 827 so that the guide
912 overlaps a portion of the brace 908. The guide 912 can extend,
for example, a distance roughly similar to the maximum distance
between the capture surface 898 and the brace wall 914, and can
help ensure that the binder 330 is captured between the capture
surface 898 and the brace wall 914. In other embodiments, the
capture device 820 of FIGS. 9A-10B can include some other shape or
configuration and still fall within the contemplated scope of the
invention. For example, the fastener need not include a nut. In one
embodiment, shown in FIGS. 10C and 10D, the fastener 922 can
include a threaded shaft 980 associated with a sleeve 984. As one
of the threaded shaft 980 and the sleeve 984 is rotated, the
distance between a head 982 of the threaded shaft 980 and the head
985 of the sleeve 984 can decrease or increase. In still other
embodiments, the fastener need not include a threaded shaft, but
rather can include a smooth shaft having a retaining clip
frictionally associated with the smooth shaft. One of ordinary
skill in the art will appreciate the myriad different devices that
can be employed to selectively close a gap between a capture
surface 898 and the brace wall 914.
[0083] FIG. 11 is an end view of the implant 1300 of FIGS. 9A-10D
positioned between adjacent spinous processes. As shown, the binder
530 is a cord, but in other embodiments can have some other
geometry. As described above in reference to previous embodiments,
where a cord, a tether, or the like is used as a binder, a pad 536
can be arranged along a contact surface of the respective spinous
process so that a load applied to the contact surface by the
tension in the binder 530 can be distributed across a portion of
the contact surface wider than the binder 530, thereby reducing
stress on the portion. The capture device 820 is arranged so that
the slidable piece 827 is posteriorly located relative to the fixed
piece 821. A fastener 822 can be accessed by the physician using a
substantially posterior approach.
[0084] A method of surgically implanting an implant 1300 in
accordance with an embodiment as described above in FIGS. 9A-11 of
the present invention is shown as a block diagram in FIG. 12. The
method can include forming an incision at the target motion
segment, and enlarging the incision to access the target motion
segment (Step 100). The interspinous ligament between targeted
adjacent spinous processes can then be distracted by piercing or
displacing the interspinous ligament with the distraction guide 106
(Step 102) and urging the implant 1300 between the adjacent spinous
processes (Step 104). As the interspinous ligament is displaced,
the spacer 302 can be positioned between the spinous processes such
that the spacer 302 can rotate to assume a preferred position
between the spinous processes (Step 106). Once the implant 1300 is
positioned, the binder 330 can be threaded between interspinous
ligaments of adjacent motion segments so that the targeted adjacent
spinous processes are disposed within a loop formed by the binder
330 (Step 108). The physician can then thread the binder 330
between the capture surface 898 of the capture device 820 and the
brace wall 914 (Step 110). Once a desired tension of the binder 330
is applied (Step 112), the physician can adjust the fastener 822 of
the capture device 820 so that the binder 330 is secured between
the captured surface 898 and the brace wall 914 (Step 114). The
incision can subsequently be closed (Step 116).
Materials For Use in Implants of The Present Invention
[0085] In some embodiments, the implant can be fabricated from
medical grade metals such as titanium, stainless steel, cobalt
chrome, and alloys thereof, or other suitable implant material
having similar high strength and biocompatible properties.
Additionally, the implant can be at least partially fabricated from
a shape memory metal, for example Nitinol, which is a combination
of titanium and nickel. Such materials are typically radiopaque,
and appear during x-ray imaging, and other types of imaging.
Implants in accordance with the present invention, and/or portions
thereof can also be fabricated from somewhat flexible and/or
deflectable material. In these embodiments, the implant and/or
portions thereof can be fabricated in whole or in part from medical
grade biocompatible polymers, copolymers, blends, and composites of
polymers. A copolymer is a polymer derived from more than one
species of monomer. A polymer composite is a heterogeneous
combination of two or more materials, wherein the constituents are
not miscible, and therefore exhibit an interface between one
another. A polymer blend is a macroscopically homogeneous mixture
of two or more different species of polymer. Many polymers,
copolymers, blends, and composites of polymers are radiolucent and
do not appear during x-ray or other types of imaging. Implants
comprising such materials can provide a physician with a less
obstructed view of the spine under imaging, than with an implant
comprising radiopaque materials entirely. However, the implant need
not comprise any radiolucent materials.
[0086] One group of biocompatible polymers is the
polyaryletherketone group which has several members including
polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). PEEK
is proven as a durable material for implants, and meets the
criterion of biocompatibility. Medical grade PEEK is available from
Victrex Corporation of Lancashire, Great Britain under the product
name PEEK-OPTIMA. Medical grade PEKK is available from Oxford
Performance Materials under the name OXPEKK, and also from CoorsTek
under the name BioPEKK. These medical grade materials are also
available as reinforced polymer resins, such reinforced resins
displaying even greater material strength. In an embodiment, the
implant can be fabricated from PEEK 450 G, which is an unfilled
PEEK approved for medical implantation available from Victrex.
Other sources of this material include Gharda located in Panoli,
India. PEEK 450 G has the following approximate properties:
TABLE-US-00001 Property Value 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
[0087] PEEK 450 G has appropriate physical and mechanical
properties and is suitable for carrying and spreading a physical
load between the adjacent spinous processes. The implant and/or
portions thereof can be formed by extrusion, injection, compression
molding and/or machining techniques.
[0088] It should be noted that the material selected can also be
filled. Fillers can be added to a polymer, copolymer, polymer
blend, or polymer composite to reinforce a polymeric material.
Fillers are added to modify properties such as mechanical, optical,
and thermal properties. For example, carbon fibers can be added to
reinforce polymers mechanically to enhance strength for certain
uses, such as for load bearing devices. In some embodiments, other
grades of PEEK are available and contemplated for use in implants
in accordance with the present invention, such as 30% glass-filled
or 30% carbon-filled grades, 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 unfilled PEEK. The
resulting product is known to be ideal for improved strength,
stiffness, or stability. Carbon-filled PEEK is known to have
enhanced compressive strength and stiffness, and a lower expansion
rate relative to unfilled PEEK. Carbon-filled PEEK also offers wear
resistance and load carrying capability.
[0089] 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. As mentioned, the implant can be
comprised of polyetherketoneketone (PEKK). Other material that can
be used include polyetherketone (PEK),
polyetherketoneetherketoneketone (PEKEKK),
polyetheretherketoneketone (PEEKK), and generally a
polyaryletheretherketone. Further, other polyketones can be used as
well as other thermoplastics. Reference to appropriate polymers
that can be used in the implant 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." 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.
[0090] As described above, the binder can be made from a
biocompatible material. In an embodiment, the binder can be made
from a braided polyester suture material. Braided polyester suture
materials include, for example, Ethibond, Ethiflex, Mersilene, and
Dacron, and are nonabsorbable, having high tensile strength, low
tissue reactivity and improved handling. In other embodiments, the
binder can be made from stainless steel (i.e., surgical steel),
which can be braided into a tether or woven into a strap, for
example. In still other embodiments, the binder can be made from
some other material (or combination of materials) having similar
properties.
[0091] The foregoing description of the present invention have been
presented for 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 practitioners skilled in this 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 for various
embodiments and with various modifications as are suited to the
particular use contemplated. It is intended that the scope of the
invention be defined by the following claims and their
equivalents.
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