U.S. patent application number 11/977532 was filed with the patent office on 2008-02-28 for systems and methods for treating bone using expandable bodies.
This patent application is currently assigned to Kyphon, Inc.. Invention is credited to Mark A. Reiley, Arie Scholten, Robert M. Scribner, Karen D. Talmadge.
Application Number | 20080051825 11/977532 |
Document ID | / |
Family ID | 37309554 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080051825 |
Kind Code |
A1 |
Reiley; Mark A. ; et
al. |
February 28, 2008 |
Systems and methods for treating bone using expandable bodies
Abstract
A vertebral body is selected for treatment. The vertebral body
has a cortical wall enclosing a cancellous bone volume. At least
one maximum dimension for the cancellous bone volume is
ascertained, and an expandable device is provided that has a
predefined dimension when substantially expanded that is less than
the maximum dimension. The expandable device is introduced into the
vertebral body through a percutaneous access path while in an
unexpanded condition. The expandable device is expanded while
disposed within the cancellous bone volume from the unexpanded
configuration toward the expanded configuration. An expansion
barrier is provided in association with the expandable device that
directs expansion of the expandable device in a desired direction
to create a cavity in the cancellous bone volume.
Inventors: |
Reiley; Mark A.; (Piedmont,
CA) ; Scholten; Arie; (Fremont, CA) ;
Talmadge; Karen D.; (Palo Alto, CA) ; Scribner;
Robert M.; (Los Altos, CA) |
Correspondence
Address: |
Daniel D. Ryan;RYAN, MAKI, MANN & HOHENFELDT, S.C.
Suite 1900
633 West Wisconsin Avenue
Milwaukee
WI
53203
US
|
Assignee: |
Kyphon, Inc.
|
Family ID: |
37309554 |
Appl. No.: |
11/977532 |
Filed: |
October 25, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11528163 |
Sep 27, 2006 |
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11977532 |
Oct 25, 2007 |
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10958600 |
Oct 5, 2004 |
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|
11528163 |
Sep 27, 2006 |
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|
09754451 |
Jan 4, 2001 |
6899719 |
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10958600 |
Oct 5, 2004 |
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|
08871114 |
Jun 9, 1997 |
6248110 |
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09754451 |
Jan 4, 2001 |
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08659678 |
Jun 5, 1996 |
5827289 |
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08871114 |
Jun 9, 1997 |
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08485394 |
Jun 7, 1995 |
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08659678 |
Jun 5, 1996 |
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08188224 |
Jan 26, 1994 |
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08485394 |
Jun 7, 1995 |
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Current U.S.
Class: |
606/192 ;
606/92 |
Current CPC
Class: |
A61F 2002/30285
20130101; A61F 2/2846 20130101; A61F 2002/2871 20130101; A61F
2230/0008 20130101; A61F 2002/2853 20130101; A61B 17/8855 20130101;
A61F 2002/30225 20130101; A61F 2002/4217 20130101; A61B 17/7097
20130101; A61F 2002/30599 20130101; A61B 2010/0258 20130101; A61B
2017/00539 20130101; A61B 17/8816 20130101; A61F 2002/2825
20130101; A61F 2002/30253 20130101; A61F 2230/0069 20130101; A61B
17/742 20130101; A61F 2002/30313 20130101; A61F 2002/30462
20130101; A61F 2002/2832 20130101; A61B 17/7061 20130101; A61F
2230/0065 20130101; A61B 17/8805 20130101; A61F 2002/30242
20130101; A61F 2230/0015 20130101; A61M 29/02 20130101; A61F
2002/30909 20130101; A61F 2002/4685 20130101; A61B 17/8811
20130101; A61B 90/94 20160201; A61B 17/7098 20130101; A61F
2250/0063 20130101; A61B 17/7291 20130101; A61B 90/39 20160201;
A61F 2002/2828 20130101; A61F 2002/30228 20130101; A61F 2002/30308
20130101; A61F 2220/005 20130101; A61M 2210/1003 20130101; A61B
10/0283 20130101; A61F 2/28 20130101; A61B 50/33 20160201; A61F
2310/0097 20130101; A61F 2002/30115 20130101; A61B 2017/0256
20130101; A61F 2230/0006 20130101; A61B 10/025 20130101; A61M 29/00
20130101; A61B 17/7258 20130101; A61F 2002/2835 20130101; A61F
2002/30677 20130101; A61F 2310/00293 20130101; A61M 2210/02
20130101; A61F 2230/0071 20130101; A61F 2002/30581 20130101; A61F
2310/00353 20130101; A61F 2002/30133 20130101; A61F 2002/302
20130101; A61F 2002/30448 20130101; A61M 25/10 20130101; A61M
25/1002 20130101; A61F 2002/2892 20130101; A61F 2/4601 20130101;
A61F 2002/30113 20130101; A61F 2002/30586 20130101; A61F 2220/0075
20130101; A61B 2050/3015 20160201; A61F 2/441 20130101; A61F 2/44
20130101; A61F 2/4611 20130101; A61F 2002/30245 20130101; A61F
2230/0063 20130101; A61B 2017/00544 20130101; A61B 2050/0065
20160201; A61F 2002/2817 20130101; A61F 2002/30288 20130101; A61F
2002/4635 20130101; A61F 2002/30125 20130101; A61B 17/00234
20130101; A61F 2002/4627 20130101; A61F 2230/0076 20130101; A61B
17/744 20130101 |
Class at
Publication: |
606/192 ;
606/092 |
International
Class: |
A61M 29/00 20060101
A61M029/00; A61B 17/58 20060101 A61B017/58 |
Claims
1. A method comprising: selecting a vertebral body for treatment
having a cortical wall enclosing a cancellous bone volume,
ascertaining a maximum anterior-to-posterior dimension for the
vertebral body measured between anterior and posterior cortical
walls, providing an expandable device including an expanded
configuration and an unexpanded configuration, the expandable
device having a predefined dimension when substantially expanded
that is less than the maximum anterior-to-posterior dimension,
introducing the expandable device into the vertebral body through a
percutaneous access path while in the unexpanded condition,
expanding the expandable device while disposed within the
cancellous bone volume from the unexpanded configuration toward the
expanded configuration, and providing an expansion barrier in
association with the expandable device that directs expansion of
the expandable device in a desired direction to create a cavity in
the cancellous bone volume.
2. A method according to claim 1 further including placing a volume
of filling material into the cavity.
3. A method according to claim 2 wherein the filling material
hardens within the cavity.
4. A method according to claim 2 wherein the filling material
comprises bone cement.
5. A method according to claim 1 wherein the expandable device
expands by inflation.
6. A method according to claim 1 wherein the expandable device
comprises a balloon.
7. A method according to claim 1 further including removing the
expandable device from the vertebral body.
8. A method according to claim 1 wherein the expansion barrier
comprises a device sized and configured to be introduced into the
vertebral body through a percutaneous access path and including a
platform region sized and configured to be disposed relative to the
expandable region of the first tool to define the expansion
barrier.
9. A method according to claim 8 wherein the platform region
comprises an expandable body.
10. A method according to claim 9 wherein the expandable body is
inflatable.
11. A method according to claim 1 wherein the expandable device and
the expansion barrier comprise parts of a single device.
12. A method according to claim 1 wherein the expandable device and
the expansion barrier comprise separate structures.
13. A method comprising selecting a vertebral body for treatment
having a cortical wall enclosing a cancellous bone volume,
ascertaining a maximum lateral dimension for the vertebral body
measured between lateral cortical walls, providing an expandable
device including an expanded configuration and an unexpanded
configuration, the expandable device having a predefined dimension
when substantially expanded that is less than the maximum lateral
dimension, introducing the expandable device into the vertebral
body through a percutaneous access path while in the unexpanded
condition, expanding the expandable device while disposed within
the cancellous bone volume from the unexpanded configuration toward
the expanded configuration, and providing an expansion barrier in
association with the expandable device that directs expansion of
the expandable device in a desired direction to create a cavity in
the cancellous bone volume.
14. A method according to claim 13 further including placing a
volume of filling material within the cavity.
15. A method according to claim 14 wherein the filling material
hardens within the cavity.
16. A method according to claim 14 wherein the filling material
comprises bone cement.
17. A method according to claim 13 wherein the expandable device
expands by inflation.
18. A method according to claim 13 wherein the expandable device
comprises a balloon.
19. A method according to claim 13 further including removing the
expandable device from the vertebral body.
20. A method according to claim 13 wherein the expansion barrier
comprises a device sized and configured to be introduced into the
vertebral body through a percutaneous access path and including a
platform region sized and configured to be disposed relative to the
expandable region of the first tool to define the expansion
barrier.
21. A method according to claim 20 wherein the platform region
comprises an expandable body.
22. A method according to claim 20 wherein the expandable body is
inflatable.
23. A method according to claim 20 wherein the expandable device
and the expansion barrier comprise parts of a single device.
24. A method according to claim 13 further including ascertaining a
maximum anterior-to-posterior dimension for the vertebral body
measured between anterior and posterior cortical walls, and wherein
the expandable device has a predefined dimension when substantially
expanded that is less than the maximum anterior-to-posterior
dimension and less than the maximum lateral dimension.
25. A method comprising: selecting a vertebral body for treatment
having a cortical wall enclosing a cancellous bone volume,
ascertaining a maximum dimension for the cancellous bone volume,
providing an expandable device including an expanded configuration
and an unexpanded configuration, the expandable device having a
predefined dimension when substantially expanded that is less than
the maximum dimension, introducing the expandable device into the
vertebral body through a percutaneous access path while in the
unexpanded condition, expanding the expandable device while
disposed within the cancellous bone volume from the unexpanded
configuration toward the expanded configuration, and providing an
expansion barrier in association with the expandable device that
directs expansion of the expandable device in a desired direction
to create a cavity in the cancellous bone volume, and placing a
volume of filling material into the cavity.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of co-pending U.S. patent
application Ser. No. 11/528,163, filed 27 Sep. 2006, and entitled
"Systems and Methods for Removing Tissue from a Cancellous Bone
Volume," which is a divisional of U.S. patent application Ser. No.
10/958,600, filed 5 Oct. 2004, and entitled "Systems and Methods
for Treating Fractured or Diseased Bone Using Expandable Bodies,"
which is a divisional of U.S. patent application Ser. No.
09/754,451, filed 4 Jan. 2001 (now U.S. Pat. No. 6,899,719), which
is a continuation of U.S. patent application Ser. No. 08/871,114,
filed 9 Jun. 1997 (now U.S. Pat. No. 6,248,110), which is a
continuation-in-part of U.S. patent application Ser. No.
08/659,678, filed Jun. 5, 1996 (now U.S. Pat. No. 5,827,289), which
is a continuation-in-part of U.S. patent application Ser. No.
08/485,394, filed Jun. 7, 1995 (now abandoned), which is a
continuation-in-part of U.S. patent application Ser. No.
08/188,224, filed Jan. 26, 1994 (now abandoned), each of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention relates to the treatment of bone conditions in
humans and other animals.
BACKGROUND OF THE INVENTION
[0003] When cancellous bone becomes diseased, for example, because
of osteoporosis, avascular necrosis, or cancer, the surrounding
cortical bone becomes more prone to compression fracture or
collapse. This is because the cancellous bone no longer provides
interior support for the surrounding cortical bone.
[0004] There are 2 million fractures each year in the United
States, of which about 1.3 million are caused by osteoporosis
alone. There are also other bone disease involving infected bone,
poorly healing bone, or bone fractured by severe trauma. These
conditions, if not successfully treated, can result in deformities,
chronic complications, and an overall adverse impact upon the
quality of life.
[0005] U.S. Pat. Nos. 4,969,888 and 5,108,404 disclose apparatus
and methods for the fixation of fractures or other conditions of
human and other animal bone systems, both osteoporotic and
non-osteoporotic. The apparatus and methods employ an expandable
body to compress cancellous bone and provide an interior cavity.
The cavity receives a filling material, which hardens and provides
renewed interior structural support for cortical bone.
[0006] The better and more efficacious treatment of bone disease
that these patents promise can be more fully realized with improved
systems and methods for making and deploying expandable bodies in
bone.
SUMMARY OF THE INVENTION
[0007] The invention provides improved systems and methods for
treating bone, including vertebral bodies, as well as in other bone
types, using one or more expandable bodies.
[0008] One aspect of the invention provides a method for treating a
vertebral body that has a cortical wall enclosing a cancellous bone
volume. The method includes ascertaining at least one maximum
dimension for the cancellous bone volume. The method includes
providing an expandable device that has a predefined dimension when
substantially expanded that is less than the maximum dimension. The
method includes introducing the expandable device into the
vertebral body through a percutaneous access path while in an
unexpanded condition. The method includes expanding the expandable
device while disposed within the cancellous bone volume from the
unexpanded configuration toward the expanded configuration. The
method includes providing an expansion barrier in association with
the expandable device that directs expansion of the expandable
device in a desired direction to create a cavity in the cancellous
bone volume
[0009] Features and advantages of the inventions are set forth in
the following Description and Drawings, as well as in the appended
Claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a side view of the spinal column of a human;
[0011] FIG. 2 is coronal view of a lumbar vertebra, partially cut
away and in section, taken generally along line 2-2 in FIG. 1;
[0012] FIG. 3 is a vertical section of lumbar vertebrae;
[0013] FIG. 4 is a plan view of a probe including a catheter tube
carrying an expandable body intended to treat bone;
[0014] FIGS. 5A to 5P are a series of coronal views of a vertebra,
partially cut away and in section, showing the steps of
introducing, via transpedicular access, an expandable body to
compress cancellous bone and create a cavity within a vertebral
body, and of then conveying a filling material into the cavity to
restore interior integrity to cortical bone;
[0015] FIG. 5Q is a lateral view, with parts broken away, of the
vertebra shown in coronal view in FIG. 5P;
[0016] FIG. 6 is a coronal view of a vertebral body in which an
expandable body, restrained by an external sealing element,
compresses cancellous bone to form a cavity;
[0017] FIG. 7 is a coronal view, partially broken away and in
section, of a vertebral body in which an expandable body is being
collapsed after having formed a cavity, while an injector tip, also
within the vertebral body, is simultaneously injecting filling
material into the cavity;
[0018] FIG. 8A is a coronal view of a vertebral body, partially
broken away and in section, showing a tool that integrates an
injector tube and an integral expandable body to create a cavity in
cancellous bone, and also showing the injection of filling material
simultaneous with collapse of the expandable body;
[0019] FIG. 8B is a side view of the tool shown in FIG. 8A, located
outside bone;
[0020] FIG. 8C is sectional view of the tool shown in FIG. 8B,
taken generally along line 8C-8C in FIG. 8B;
[0021] FIG. 9 is a coronal view of a vertebral body showing
multiple expandable bodies separately introduced by transpedicular
approach;
[0022] FIG. 10 is a view of the distal end of a probe in which two
catheter tubes, each carrying an expandable body, are joined to
form a symmetric array, when substantially expanded outside a
bone;
[0023] FIG. 11 is a view of the distal end of a probe in which two
catheter tubes, each carrying an expandable body, are joined to
form an asymmetric array, when substantially expanded outside a
bone;
[0024] FIG. 12 is a coronal view, partially broken away and in
section, of a vertebral body into which multiple expandable bodies
have been deployed by dual transpedicular access;
[0025] FIG. 13 is a coronal view of a vertebral body, partially
broken away and in section, into which multiple expandable bodies
have been deployed by contralateral posterolateral access;
[0026] FIG. 14 is a coronal view of a vertebral body, partially
broken away and in section, in which multiple expandable bodies
have formed multiple cavities which join to form a single cavity to
receive filling material;
[0027] FIG. 15 is a coronal view of a vertebral body, partially
broken away and in section, in which multiple expandable bodies
have formed multiple separate cavities to receive filling
material;
[0028] FIG. 16 is an anterior-posterior view of a region of the
spine, showing multiple expandable bodies present within a targeted
vertebral body using ipsilateral postereolateral access;
[0029] FIG. 17 is an anterior-posterior view of a vertebral body,
partially broken away and in section, in which multiple expandable
bodies, introduced using ipsilateral postereolateral access, have
formed multiple cavities which are joined to form a single cavity
to receive filling material;
[0030] FIG. 18 is an anterior-posterior view of a vertebral body,
partially broken away and in section, in which multiple expandable
bodies, introduced using an ipsa posterolateral access, have formed
multiple separate cavities to receive filling material;
[0031] FIG. 19 is a coronal view of a vertebral body, partially
broken away and in section, in which multiple expandable bodies
have been introduced by both transpedicular and posterolateral
access;
[0032] FIG. 20 is a perspective view of one representative
embodiment of an expandable body having a stacked doughnut-shaped
geometry;
[0033] FIG. 21 is a view of another representative embodiment of an
expandable body having an oblong-shaped geometry;
[0034] FIG. 22 is an elevation view of another representative
embodiment of an expandable body showing three stacked bodies and
string-like restraints for limiting the expansion of the bodies
during inflation;
[0035] FIG. 23 is a perspective view of another representative
embodiment of an expandable body having a kidney bean-shaped
geometry;
[0036] FIG. 24 is a top view of another representative embodiment
of an expandable body having a kidney bean-shaped geometry with
several compartments by a heating element or branding tool;
[0037] FIG. 25 is a cross-sectional view taken along line 25-25 of
FIG. 24;
[0038] FIG. 26 is a perspective, lateral view of a vertebral body,
partially broken away to show the presence of an expandable body,
and also showing the major reference dimensions for the expandable
body;
[0039] FIG. 27 is a dorsal view of a representative expandable body
having a humpback banana-shaped geometry in use in a right distal
radius;
[0040] FIG. 28 is a cross sectional view of the expandable body
shown in FIG. 27, taken generally along line 28-28 of FIG. 27;
[0041] FIG. 29A is a representative expandable body having a
spherical shape with a base, located in a proximal humerus and
viewed from the front (anterior) of the left proximal humerus;
[0042] FIG. 29B is a representative expandable body having a
cylindrical shape, located in a proximal humerus and viewed from
the front (anterior) of the left proximal humerus;
[0043] FIG. 30A is a representative embodiment of an expandable
body located, as shown in a front (anterior) view of the proximal
tibia, introduced beneath the medial tibial plateau;
[0044] FIG. 30B is a side elevation view of the expandable body
shown in FIG. 30A;
[0045] FIG. 30C is a top perspective view of the expandable body
shown in FIG. 30A, showing its generally cylindrical geometry;
[0046] FIG. 31 is a top plan view of another representative
embodiment of an expandable body for use in treating tibial plateau
fractures, having a generally elliptical geometry;
[0047] FIG. 32 is a side view of multiple expandable bodies stacked
on atop another for use, for example, in treating tibial plateau
fractures;
[0048] FIG. 33 is another representative embodiment of an
expandable body having an egg-shaped geometry located, as shown in
a front (anterior) view of the proximal tibia, introduced beneath
the medial tibial plateau;
[0049] FIG. 34 is a representative embodiment of an expandable body
having a spherical-shaped geometry for treating avascular necrosis
of the head of the femur (or humerus), which is shown from the
front (anterior) of the left hip;
[0050] FIG. 35 is a side view of another representative embodiment
of an expandable body having a hemispherically-shaped geometry for
treating avascular necrosis of the head of the femur (or
humerus);
[0051] FIG. 36A is a view of a representative expandable body
having a bent-geometry for preventing hip fracture, as seen from
the front (anterior) of the left hip;
[0052] FIG. 36B is a view of multiple expandable bodies
individually deployed through multiple access points into the left
hip for preventing hip fracture;
[0053] FIG. 37A is a view of a representative expandable body
having an asymmetric bow tie-shape for use in treating fracture of
the calcaneus bone, shown in lateral view within the calcaneus;
[0054] FIG. 37B is a perspective top view of the expandable body
shown in FIG. 37A when substantially expanded outside the
calcaneus;
[0055] FIG. 38 shows a representative embodiment of an expandable
body having a spherical or egg-shaped geometry shown in lateral
view deployed within the calcaneus;
[0056] FIGS. 39A to 39D show a multiple stage process of
introducing filling material into a cavity formed by an expandable
body in cancellous bone, to prevent or impede flow or seepage of
filling material from the interior of the bone;
[0057] FIG. 40 is an elevation view of an injector tip for filling
material, over which a mesh is draped, which, when deployed in a
cavity formed by an expandable body, impedes or prevents seepage of
the material from the cavity;
[0058] FIG. 41 is a coronal view of a vertebra, with parts broken
away and in section, showing the deployment of the mesh shown in
FIG. 40 within the vertebral body;
[0059] FIGS. 42A to 42 C are schematic illustrations of a
representative method and system for delivering a therapeutic
substance to a bone using an expandable body;
[0060] FIG. 43 is an illustration of the human skeleton, showing
regions of long bone that can be treated using expandable
bodies;
[0061] FIG. 44 is a representative embodiment of multiple
expandable bodies located, as shown in a front (anterior) view,
within the proximal tibia, both introduced beneath the medial
tibial plateau, one of the bodies being substantially expanded to
form an interior barrier and serve as a platform for the other
body, which is shown substantially collapsed;
[0062] FIG. 45 is a front (anterior) view of the multiple
expandable bodies, shown in FIG. 44, with both bodies in
substantially expanded conditions to form a cavity within the
proximal tibia beneath the medial tibial plateau;
[0063] FIG. 46 is an enlarged front (anterior) perspective view of
the multiple expandable bodies shown in FIG. 45, with the lower
expandable body serving as a platform for the upper expandable
body;
[0064] FIG. 47 is diagrammatic view of a system for harvesting bone
marrow in a bone-marrow producing bone using an expandable
body;
[0065] FIG. 48 is a section view of the catheter tube associated
with the system shown in FIG. 48, taken generally along line 48-48
of FIG. 47; and
[0066] FIG. 49 is an enlarged view of the expandable body
associated with the system shown in FIG. 47 inside a bone for the
purpose of harvesting bone marrow.
[0067] The invention may be embodied in several forms without
departing from its spirit or essential characteristics. The scope
of the invention is defined in the appended claims, rather than in
the specific description preceding them. All embodiments that fall
within the meaning and range of equivalency of the claims are
therefore intended to be embraced by the claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0068] This Specification describes new systems and methods to
treat bones using expandable bodies. The use of expandable bodies
to treat bones is disclosed in U.S. Pat. Nos. 4,969,888 and
5,108,404, which are incorporated herein by reference. Improvements
in this regard are disclosed in U.S. patent application Ser. No.
08/188,224, filed Jan. 26, 1994; U.S. patent application Ser. No.
08/485,394, filed Jun. 7, 1995; and U.S. patent application Ser.
No. 08/659,678, filed Jun. 5, 1996, which are each incorporated
herein by reference.
[0069] The new systems and methods will be first described with
regard to the treatment of vertebra. It should be appreciated,
however, the systems and methods so described are not limited in
their application to vertebrae. As will be described in greater
detail later, the systems and methods are applicable to the
treatment of diverse bone types.
[0070] I. Treatment of Vertebral Bodies
[0071] As FIG. 1 shows, the spinal column 10 comprises a number of
uniquely shaped bones, called the vertebrae 12, a sacrum 14, and a
coccyx 16 (also called the tail bone). The number of vertebrae 12
that make up the spinal column 10 depends upon the species of
animal. In a human (which FIG. 1 shows), there are twenty-four
vertebrae 12, comprising seven cervical vertebrae 18, twelve
thoracic vertebrae 20, and five lumbar vertebrae 22.
[0072] When viewed from the side, as FIG. 1 shows, the spinal
column 10 forms an S-shaped curve. The curve serves to support the
head, which is heavy. In four-footed animals, the curve of the
spine is simpler.
[0073] As FIGS. 1 to 3 show, each vertebra 12 includes a vertebral
body 26, which extends on the anterior (i.e., front or chest) side
of the vertebra 12. As FIGS. 1 to 3 show, the vertebral body 26 is
in the shape of an oval disk. As FIGS. 2 and 3 show, the vertebral
body 26 includes an exterior formed from compact cortical bone 28.
The cortical bone 28 encloses an interior volume 30 of reticulated
cancellous, or spongy, bone 32 (also called medullary bone or
trabecular bone). A "cushion," called an intervertebral disk 34, is
located between the vertebral bodies 26.
[0074] An opening, called the vertebral foramen 36, is located on
the posterior (i.e., back) side of each vertebra 12. The spinal
ganglion 39 pass through the foramen 36. The spinal cord 38 passes
through the spinal canal 37.
[0075] The vertebral arch 40 surrounds the spinal canal 37. The
pedicle 42 of the vertebral arch 40 adjoins the vertebral body 26.
The spinous process 44 extends from the posterior of the vertebral
arch 40, as do the left and right transverse processes 46.
[0076] A. Deployment of an Expandable Body
[0077] FIG. 4 shows a tool 48 for preventing or treating
compression fracture or collapse of a vertebral body using an
expandable body.
[0078] The tool 48 includes a catheter tube 50 having a proximal
and a distal end, respectively 52 and 54. The distal end 54 carries
an expandable body 56.
[0079] The body 56 includes an exterior wall 58, which, in FIG. 4,
is shown in a collapsed geometry. The collapsed geometry permits
insertion of the body 56 into the interior volume 30 of a targeted
vertebral body 26.
[0080] The insertion of the body 56 into the interior volume 30 of
a targeted vertebral body 26 can be accomplished in various ways.
FIGS. 5A to 5Q show the insertion of the body 56 using a
transpedicular approach, which can be performed either with a
closed, minimally invasive procedure or with an open procedure.
[0081] In the described procedure, a patient lies on an operating
table, while the physician introduces a conventional spinal needle
assembly 60 into soft tissue in the patient's back. The patient can
lie facedown on the table, or on either side, or at an oblique
angle, depending upon the physician's preference. Indeed, the
procedure can be performed through an open anterior procedure or an
endoscopic anterior procedure, in which case the tool 48 may be
introduced from the anterior aspect of the vertebral body.
[0082] The spinal needle assembly 60 comprises a stylet 62 slidable
housed within a stylus 64. The assembly 60 typically has, for
example, about an 18 gauge diameter. Other gauge diameters can and
will be used to accommodate appropriate guide pins, as will be
described in greater detail later.
[0083] Under radiologic, CT, or MRI monitoring, the physician
advances the assembly 60 through soft tissue (designated S in FIG.
5A) down to and into the targeted vertebra 12, as FIG. 5A shows.
The physician will typically administer a local anesthetic, for
example, lidocaine, through assembly 60. In some cases, the
physician may prefer other forms of anesthesia.
[0084] The physician directs the spinal needle assembly 60 to
penetrate the cancellous bone 32 of the targeted vertebra 12.
Preferably the depth of penetration is about 60% to 95% of the
vertebral body 26.
[0085] FIG. 5A shows gaining access to cancellous bone 32 through
the pedicle 42, which is called transpedicular access. However,
posterolateral access, through the side of the vertebral body 12
(designated P-L and shown in phantom lines in FIG. 5A), may be
indicated, if a compression fracture has collapsed the vertebral
body 26 below the plane of the pedicle 42, or for other reasons
based upon the preference of the physician.
[0086] After positioning the spinal needle assembly 60 in
cancellous bone 32, the physician holds the stylus 64 and withdraws
the stylet 62 (see FIG. 5B). Still holding the stylus 64, the
physician slides a guide pin 66 through the stylus 64 and into the
cancellous bone 32 (see FIG. 5C). The physician now removes the
stylus 64, leaving the guide pin 66 deployed within the cancellous
bone 32, as FIG. 5D shows.
[0087] As FIG. 5E shows the physician makes a small incision
(designated I in FIG. 5E) in the patient's back to accommodate a
trocar 68. The physician inserts the trocar 68 through the soft
tissue S along the guide pin 66 down to the pedicle 42. The
physician taps the distal end 70 of the trocar 68 into the pedicle
42 to secure its position.
[0088] As FIG. 5F shows, the physician next slides an outer guide
sheath 72 over the trocar 68. The distal end 74 of the outer guide
sheath 72 is likewise tapped into the pedicle 42. The physician
removes the trocar 68, leaving the guide pin 66 and outer guide
sheath 72 in place, as FIG. 5G shows. Alternatively, the trocar 68
and guide sheath 72 can be introduced together in one step.
[0089] As FIG. 5H shows, the physician advances a drill bit 76 (for
example, 5 mm in diameter) over the guide pin 66 through the outer
guide sheath 72. Under X-ray control (or using another external
visualizing system), the physician operates the drill bit 76 to
open a passage 78 through the pedicle 42 and into the cancellous
bone 32. The drilled passage 78 preferable extends no more than 95%
across the vertebral body 26.
[0090] As FIG. 5I shows, the physician removes drill bit 76 and
guide pin 66, leaving the outer guide sheath 72. The passage 78
made by the drill bit 76 remains, passing through the pedicle 42
and into the cancellous bone 32.
[0091] As FIG. 5J(1) shows, the physician next advances the
catheter tube 50 and expandable body 56 through the outer guide
sheath 72 and into the drilled passage 78 in the cancellous bone
32. As best shown in FIG. 5J(2), the body 56 is maintained in a
straightened, collapsed condition distally beyond the end of the
catheter tube 50 during transport through the guide sheath 72 and
into the drilled passage 78 by a generally rigid, external
protective sleeve 73, which surrounds the body 56. Alternatively,
an internal stiffening member (not shown) can extend within the
body 56, to keep the body 56 in the desired distally straightened
condition during passage through the guide sheath 72. Once the body
56 is located in the desired location within the passage 78, the
physician pulls the sleeve 73 back, to uncover the body 56. The
expandable body 56 can be dipped into thrombin prior to its
introduction into the vertebral body 26 to facilitate in situ
coagulation.
[0092] The materials for the catheter tube 50 are selected to
facilitate advancement of the body 56 into cancellous bone through
the guide sheath 72. The catheter tube 50 can be constructed, for
example, using standard flexible, medical grade plastic materials,
like vinyl, nylon, polyethylenes, ionomer, polyurethane, and
polyethylene tetraphthalate (PET). The catheter tube 50 can also
include more rigid materials to impart greater stiffness and
thereby aid in its manipulation. More rigid materials that can be
used for this purpose include Kevlar.TM. material, PEBAX.TM.
material, stainless steel, nickel-titanium alloys (Nitinol.TM.
material), and other metal alloys.
[0093] Once the protective sheath 73 is withdrawn, the wall 58 of
the body 56 is capable of assuming an expanded geometry within the
interior volume 30 (generally shown in FIG. 5K(1)). To accommodate
expansion of the body 56, the catheter tube 50 includes a first
interior lumen 80 (see FIG. 4). The lumen 80 is coupled at the
proximal end of the catheter tube 50 to a pressurized source of
fluid 82. The fluid 82 is preferably radio-opaque to facilitate
visualization. For example, Renograffin.TM. can be used for this
purpose.
[0094] The lumen 80 conveys the fluid 82 into the body 56 under
pressure. As a result, the wall 58 expands, as FIG. 5K(1) shows.
Because the fluid 82 is radio-opaque, body expansion can be
monitored fluoroscopically or under CT visualization. Using real
time MRI, the body 56 may be filled with sterile water, saline
solution, or sugar solution.
[0095] Expansion of the wall 58 enlarges the body 56 and compacts
cancellous bone 32 within the interior volume 30. As FIG. 5K(2)
shows, the presence of the sheath 73 serves to keep the proximal
end of the body 56 away from edge-contact with the distal end of
the catheter tube 50.
[0096] The compaction of cancellous bone 32 forms a cavity 84 in
the interior volume 30 of the vertebral body 26. The compaction of
cancellous bone also exerts interior force upon cortical bone,
making it possible to elevate or push broken and compressed bone
back to or near its original prefracture position. Using a single
transpedicular access (as FIG. 5K(1) shows), the cavity 84 occupies
about one-half of the interior volume 30. As will be described in
greater detail later, using multiple accesses, e.g., one through
each pedicle, a cavity 84 occupying substantially all of the
interior volume 30 can be created.
[0097] As FIG. 4 shows, the proximal end of the catheter tube 50 is
preferably coupled by tubing to a source of negative air pressure
86. The negative pressure is conveyed through a second interior
lumen 81 to one or more suction holes 88 on the distal end of the
catheter tube 50. Prior to and during the expansion of the body 56,
suction is applied to remove fats and other debris through the
suction holes 88 for disposal. A separate suction-irrigation tool
can be deployed through the guide sheath 72 for this purpose, if
desired.
[0098] The body 56 is preferably left inflated for an appropriate
waiting period, for example, three to five minutes, to allow
coagulation inside the vertebral body 26. After the appropriate
waiting period, the physician collapses the body 56 and removes it
through the outer guide sheath 72 (see FIG. 5L). To facilitate
removal, the exterior surface of the body 56 can be treated, e.g.,
by ion beam-based surface treatment, to reduce friction during
passage through the outer guide sheath 72. As FIG. 5L shows, upon
removal of the body 56, the formed cavity 84 remains in the
interior volume 30.
[0099] A suction-irrigation tool (not shown) can be introduced
through the outer guide sheath 72, to further flush and clear
debris from the formed cavity 84 after removal of the body 56.
[0100] As FIG. 5M shows, an injector nozzle or tip 90, coupled by
an injector tube 92 to an injector gun 94, is inserted through the
outer guide sheath 72 into the formed cavity 84. The injector gun
94 carries a filling material 96. The filling material 96
comprises, for example, methylmethacrylate cement or a synthetic
bone substitute.
[0101] The injector gun 94 can comprise a cement gun made, for
example, by Stryker Corporation (Kalamazoo, Mich.). This particular
injector gun 94 has a manually operated injection grip 98 with a
mechanical advantage of about 9 to 1. Other injection guns may be
used, having more or less mechanical advantage. Non-manually
operated injection guns can also be used.
[0102] The injector tip 90 can be, for example, about 4.9 mm in
diameter, to accommodate the flow a relatively viscous material 96
into the cavity 84.
[0103] As FIG. 5M shows, the injector gun 94 pushes the filling
material 96 into the cavity 84. While injecting the material 96,
the physician preferably begins with the injector tip 90 positioned
at the anterior region of the cavity 84 (as FIG. 5M shows). The
physician progressively moves the tip 90 toward the posterior
region of the cavity 84 (as FIG. 5N shows), away from the flow of
the material 96 as it enters and fills the cavity 84. The physician
observes the progress of the injection fluoroscopically.
[0104] The physician can also check, using, for example, x-ray, for
leakage of the material through cortical bone 28. Systems and
methods for impeding or preventing such leakage will be described
in greater detail later.
[0105] The physician flows material 96 into the cavity 84, until
the material 96 reaches the distal end 74 of the outer guide sheath
72 (as FIG. 50 shows).
[0106] Upon removing the injector tube 92 from the outer guide
sheath 72, the physician may, if necessary, tamp residual filling
material 96 from the distal end 74 of the outer guide sheath 72
into the cavity 84. If fluoroscopic examination reveals void
regions in the cavity 84, the physician may again insert the
injector tube 92 to add more filling material 96 into the cavity
84.
[0107] FIG. 7 shows an alternative technique for filling the
cavity. In this technique, the injector tip 90 occupies the cavity
84 while the expandable body 56 is collapsing within the cavity 84.
As the body 56 collapses, the tip 90 injects material 96 into the
part of the cavity 84 that the collapsing body 56 no longer
occupies. The increasing volume of the cavity 84 not occupied by
the collapsing body 56 is thereby progressively filled by an
increasing volume of material 96. The presence of the body 56,
partially expanded while the tip 90 injects the material 96, serves
to compact and spread the injected material 96 within the cavity
84.
[0108] As filling of the cavity 84 progresses, preferably under
fluoroscopic monitoring, the physician progressively retracts the
injector tip 90 from the anterior region of the cavity 84, toward
the outer guide sheath 72, allowing the material 96 to
progressively enter and fill the cavity 84 with the collapse of the
body 56.
[0109] FIGS. 8A to 8C show a preferred embodiment of a tool 650
which integrates the injection tube and expandable body in a single
structure. As FIG. 8B shows, the tool 650 includes a catheter tube
652 having a proximal end 654 and a distal end 656. The distal end
carries an expandable body 662.
[0110] As FIG. 8C shows, the catheter tube 652 has concentric inner
and outer lumens, respectively 658 and 660. The inner lumen 658
communicates, by proximal tubing 664, with an injector gun 94, of
the type previously described. The inner lumen 658 also
communicates with an injector nozzle or tip 666 at the distal
catheter tube end 656. Operation of the gun 94 serves to inject
filling material 96 through the nozzle 666 (as FIG. 8A shows).
[0111] The outer lumen 660 communicates, via proximal tubing 668,
with a source 82 of pressurized liquid. The outer lumen 660 also
communicates with ports 670 formed on the distal catheter tube end
656 underlying the expandable body 662. Operation of the source 82
serves to inject pressurized liquid into the body 662 to expand it,
in the manner previously described.
[0112] As FIG. 8A shows, the physician introduces the tool 650 into
the cancellous bone 32. The physician expands the body 662 to
create the cavity 84. Once the cavity 84 is formed, the physician
begins to collapse the body 662, while injecting the filling
material 96 through the nozzle 666. The volume of the cavity 84
occupied by the collapsing body 662 is progressively filled by the
increasing volume of filling material 96 injected through the
nozzle 666.
[0113] As earlier described, the collapsing body 662 serves to
compact and spread the filling material 96 more uniformly within
the cavity 84. Under fluoroscopic monitoring, the physician
progressively retracts the distal end 656 of the tool 650 from the
anterior region of the cavity 84 toward the outer guide sheath 72,
allowing the material 96 to enter and fill the cavity 84.
[0114] Upon filling the cavity 84 with the material 96, the
physician removes the outer guide sheath 72, as FIGS. 5P and 5Q
show. The incision site is sutured or otherwise closed (designated
by ST in FIG. 5P).
[0115] In time, the filling material 96 sets to a hardened
condition within the cavity 84 (see FIGS. 5P and 5Q). The hardened
material 96 provides renewed interior structural support for the
cortical bone 28.
[0116] The above described procedure, carried out in a minimally
invasive manner, can also be carried out using an open surgical
procedure. Using open surgery, the physician can approach the bone
to be treated as if the procedure is percutaneous, except that
there is no skin and other tissues between the surgeon and the bone
being treated. This keeps the cortical bone as intact as possible,
and can provide more freedom in accessing the interior volume 30 of
the vertebral body.
[0117] B. Material Selection for the Expandable Body
[0118] The material of the body wall 58 can be selected according
to the therapeutic objectives surrounding its use. For example,
materials including vinyl, nylon, polyethylenes, ionomer,
polyurethane, and polyethylene tetraphthalate (PET) can be used.
The thickness of the body wall 58 is typically in the range of
2/1000ths to 25/1000ths of an inch, or other thicknesses that can
withstand pressures of up to, for example, 250-500 psi.
[0119] If desired, the material for the wall 58 can be selected to
exhibit generally elastic properties, like latex. Alternatively,
the material can be selected to exhibit less elastic properties,
like silicone. Using expandable bodies 56 with generally elastic or
generally semi-elastic properties, the physician monitors the
expansion to assure that over-expansion and wall failure do not
occur. Furthermore, expandable bodies 56 with generally elastic or
generally semi-elastic properties will require some form of
external or internal restraints to assure proper deployment in
bone.
[0120] For example, expandable bodies 56 with generally elastic
properties will exhibit the tendency to backflow or creep into the
outer guide sheath 72 during their expansion. It is therefore
necessary to internally or externally restrain a body 56 that is
subject to creeping, to keep it confined within the interior bone
region. In FIG. 6, an exterior sealing element 100 is provided for
this purpose. In FIG. 6, the sealing element 100 takes the form of
a movable o-ring.
[0121] The physician advances the o-ring 100 along the catheter
tube 50 inside the guide sheath 72 using a generally stiff stylet
102 attached to the o-ring 100. The physician locates the o-ring
100 at or near the distal end 54 of the catheter tube 50 prior to
conveying the liquid 82 to expand the body 56. The o-ring 100 is
held in place by the generally stiff stylet 102, which provides a
counter force to prevent backward movement of the o-ring 100 in the
guide sheath 72 as the body 56 expands. The o-ring 100 thereby
keeps all or a substantial portion of the generally elastic body 26
confined inside the interior volume 30. The body 56 thereby serves
to compact as much of the cancellous bone 32 as possible.
[0122] The use of an external sealing element 100 to restrain the
expandable body 56 may not be necessary when relatively inelastic
materials are selected for the body 56. For example, the material
for the body wall 58 can be selected to exhibit more inelastic
properties, to limit expansion of the wall 58 prior to wall
failure. The body wall 58 can also include one or more restraining
materials, particularly when the body wall 58 is itself made from
more elastic materials. The restraints, made from flexible,
inelastic high tensile strength materials, limit expansion of the
body wall 58 prior to wall failure. Representative examples of
generally inelastic wall structures will be described in greater
detail later.
[0123] C. Selection of Shape and Size for the Expandable Body
[0124] As will also be demonstrated later, when relatively
inelastic materials are used for the body wall 58, or when the body
wall 58 is otherwise externally restrained to limit its expansion
prior to failure, a predetermined shape and size can be imparted to
the body 56, when it is substantially expanded. The shape and size
can be predetermined according to the shape and size of the
surrounding cortical bone 28 and adjacent internal structures, or
by the size and shape of the cavity 84 desired to be formed in the
cancellous bone 32.
[0125] In one embodiment, which is generally applicable for
treating bones experiencing or prone to fracture, the shape and
size of the body 56, when substantially expanded, can be designed
to occupy at least about 30% of the volume of cancellous bone 32 in
the interior volume 30. A body 56 having a substantially expanded
size and shape in the range of about 40% to about 99% of the
cancellous bone volume is preferred.
[0126] In another embodiment, which is applicable for treating
bones having more localized regions of fracture or collapse caused,
for example, by avascular necrosis, the shape and size of the body
56 can be designed to occupy as little as about 10% of the
cancellous bone volume. In this embodiment, the drilled passage 78
extends directly to the localized site of injury, to enable
targeted introduction of the body 26.
[0127] The shape of the cancellous bone 32 to be compressed, and
the presence of surrounding local anatomic structures that could be
harmed if cortical bone were moved inappropriately, are generally
understood by medical professionals using textbooks of human
skeletal anatomy, along with their knowledge of the site and its
disease or injury. The physician is also able to select the
materials and geometry desired for the body 56 based upon prior
analysis of the morphology of the targeted bone using, for example,
plain films, spinous process percussion, or MRI or CRT scanning.
The materials and geometry of the body 56 are selected to create a
cavity 84 of desired size and shape in cancellous bone 32 without
applying harmful pressure to the outer cortical bone 28 or
surrounding anatomic structures.
[0128] In some instances, it is desirable, when creating the cavity
84, to move or displace the cortical bone 28 to achieve the desired
therapeutic result. Such movement is not per se harmful, as that
term is used in this Specification, because it is indicated to
achieve the desired therapeutic result. By definition, harm results
when expansion of the body 56 results in a worsening of the overall
condition of the bone and surrounding anatomic structures, for
example, by injury to surrounding tissue or causing a permanent
adverse change in bone biomechanics.
[0129] D. Deployment of Multiple Expandable Bodies
[0130] Formation of a desired cavity geometry in cancellous bone 32
using an expandable body 56 can be accomplished in diverse ways to
achieve the desired therapeutic effect. The foregoing disclosure
envisions the deployment of a single expandable body 56 to compact
cancellous bone 32 and, by itself, form a cavity 84 having a
desired shape and size to receive a filling material 96.
[0131] Alternatively, a cavity 84 having a desired shape and size
in cancellous bone 32 can be formed by the deployment of more than
one expandable body 56 in a targeted region of cancellous bone 32,
either sequentially or simultaneously.
[0132] FIG. 9 shows the representative deployment of multiple
expandable bodies 56A and 56B through a single outer guide sheath
72, which is arranged to provide transpedicular access. It should
be understood that deployment of multiple expandable bodies can
likewise be achieved through an outer guide sheath 72 arranged to
provide a posterolateral access, through the side of the vertebral
body 26 (as shown as P-L in phantom lines in FIG. 9). In FIG. 9,
the expandable bodies 56A and 56B are carried by separate catheter
tubes 50A and 50B, which are not joined together.
[0133] In the alternative embodiment shown in FIG. 10, a tool 109
comprising an array 108 of catheter tubes 50A and 50B is provided.
Each catheter tube 50A and 50B each carries an expandable body 56A
and 56B, which are shown in FIG. 10 in a collapsed condition. In
FIG. 10, the distal ends of the catheter tubes 50A and 50B are
joined by a connector 106, for simultaneous deployment through an
outer guide sheath 72 into the vertebral body 26, as FIG. 9 shows.
As before described, a slidable protective sheath 73 encloses the
bodies 56A and 56B during passage through the guide sheath 72. Upon
withdrawal of the protective sheath 73, expansion of the bodies 56A
and 56B, either simultaneously or sequentially, creates a cavity
84. If desired, the connector 106 can permit relative adjustment of
the catheter tubes 50A and SOB, so that, when deployed, one
expandable body is located more distal to another expandable
body.
[0134] For the sake of illustration, FIGS. 9 and 10 show two
catheter tubes 50A and 50B, but more than two catheter tubes can be
deployed in the vertebral body 26, either as separate tools (as
FIG. 9 shows), or joined to form a composite array 108 (as FIG. 10
shows).
[0135] In FIG. 10, the bodies 56A and 56B of the array 108 have
generally the same geometry, when substantially expanded, thereby
providing a symmetric arrangement for compacting cancellous bone
32. A generally symmetric cavity 84 results.
[0136] Alternatively, as shown in FIG. 11, the bodies 56A and 56B
possess different geometries when substantially expanded, thereby
presenting an asymmetric arrangement for compacting cancellous bone
32. A generally asymmetric cavity 84 results. By mutually adjusting
catheter tubes through a connector 106 (as previously described),
the distal extensions of expandable bodies relative to each other
can be made to differ, thereby also resulting in asymmetric cavity
formation.
[0137] The selection of size and shape of the array 108, whether
symmetric or asymmetric, depends upon the size and shape of the
targeted cortical bone 28 and adjacent internal structures, or by
the size and shape of the cavity 84 desired to be formed in the
cancellous bone 32. The deployment of multiple expandable bodies 56
makes it possible to form cavities 84 having diverse and complex
geometries within bones of all types. Multiple expandable bodies
having generally the same geometry can be deployed in different
ways to create cavities of different geometries.
[0138] It should be appreciated that the various styles of multiple
expandable bodies 56 shown in FIGS. 9 to 11 are deployed in a
distally straightened condition (as FIGS. 10 and 11 show) by using,
e.g., a relatively stiff, surrounding sheath 73 (shown in phantom
lines in FIG. 10), which is manipulated in the same as previously
described in connection with FIG. 5J(1) and 5J(2). There are, of
course, other ways to straighten the bodies 56 for deployment into
bone, such as through the use of internal stiffening elements.
[0139] Access for expandable bodies 56 can be achieved through
multiple access sites and in many different ways. For example,
multiple expandable bodies can access the vertebral body from
different regions of a targeted vertebra.
[0140] FIG. 12 shows a representative dual transpedicular access,
in which two outer guide sheaths 72A and 72B are used to provide
separate access for two or more expandable bodies 56A and 56B
through different sides of the pedicle 42A and 42B of the vertebral
body 26.
[0141] FIG. 13 shows a representative dual contra lateral
posterolateral access, in which two outer guide sheaths 72A and 72B
are used to provide separate access for multiple expandable bodies
56A and 56B from different lateral sides of the vertebral body
26.
[0142] Deployed from dual access sites as shown in FIGS. 12 and 13,
the multiple expandable bodies 56A and 56B each forms a cavity 84A
and 84B (shown in FIG. 14). The cavities 84A and 84B are
transversely spaced within the cancellous bone 32. The transversely
spaced cavities 84A and 84B may adjoin to form a single combined
cavity (designated C in FIG. 14), into which the filling material
96 is injected. Alternatively, as FIG. 15 shows, the transversely
spaced cavities 84A and 84B may remain separated by a region of
cancellous bone (designated by numeral 110 in FIG. 13). In this
arrangement, the filling material 96 is injected into multiple,
individual cavities 84A and 84B within the interior volume.
[0143] As another example, multiple expandable bodies 56A and 56B
can access the vertebral body 26 from the same general region of
the vertebra. FIG. 16 shows a representative dual ipsilateral
posterolateral access, in which two outer guide sheaths 72A and 72B
are used to provide separate access from the same lateral sides of
the vertebral body 26.
[0144] Deployed from these access sites (see FIG. 17), the multiple
expandable bodies 56A and 56B form vertically spaced, or stacked,
cavities 84A and 84B. The vertically spaced cavities 84A and 84B
may adjoin to form a single combined cavity (designated C in FIG.
17), into which the filling material 96 is injected. Alternatively
(see FIG. 18), the vertically spaced cavities 84A and 84B may be
separated by a region of cancellous bone (designated by numeral 110
in FIG. 18), forming multiple individual cavities 84A and 84B
within the interior volume, each of which is individually filled
with a filling material 96A and 96B.
[0145] By way of another example, FIG. 19 shows a first outer guide
sheath 72A arranged to provide a transpedicular access and a second
outer guide sheath 72B to provide a posterolateral access.
[0146] Systems for treating bone using multiple expandable bodies
can include directions 79 (see FIG. 12) for deploying the first and
second expandable bodies. For example, the directions 79 can
instruct the physician to insert a first expandable body into the
interior volume through a first access path through cortical bone,
while inserting a second expandable body into the interior volume
through a second access path through cortical bone different than
the first access path.
[0147] In any of the above-described examples, each guide sheath
72A or 72B can itself accommodate a single expandable body or
multiple expandable bodies. The size and shape of the bodies may be
the same, or they may vary, according to the desired objectives of
the physician for the targeted vertebral body.
[0148] E. Representative Embodiments of Expandable Bodies to Treat
Vertebrae
[0149] i. Constrained Donut-Shaped Geometries
[0150] FIG. 20 shows a representative embodiment of an expandable
body, which is broadly denoted by the numeral 210. The body 210
comprises a pair of hollow, inflatable, non-expandable parts 212
and 214 of flexible material, such as PET or Kevlar. Parts 12 and
14 have a suction tube 216 therebetween for drawing fats and other
debris by suction into tube 216 for transfer to a remote disposal
location. The catheter tube 216 has one or more suction holes so
that suction may be applied to the open end of tube 216 from a
suction source (not shown).
[0151] The parts 212 and 214 are connected together by an adhesive
which can be of any suitable type. Parts 212 and 214 are
doughnut-shaped, as shown in FIG. 20 and have tubes 218 and 220
which communicate with and extend away from the parts 212 and 214,
respectively, to a source of inflating liquid under pressure (not
shown). The liquid expands the body 210 as already described.
[0152] FIG. 21 shows a modified doughnut shape body 280 of the type
shown in FIG. 20, except the doughnut shapes of body 280 are not
stitched onto one another. In FIG. 21, body 280 has a pear-shaped
outer convex surface 282 which is made up of a first hollow part
284 and a second hollow part 285. A tube 288 is provided for
directing liquid into the two parts along branches 290 and 292 to
inflate the parts after the parts have been inserted into the
interior volume of a bone. A catheter tube 216 may or may not be
inserted into the space 296 between two parts of the balloon 280 to
provide irrigation or suction. An adhesive bonds the two parts 284
and 285 together.
[0153] FIG. 22 shows another representative embodiment of an
expandable body, designated 309. The body 309 has a generally round
geometry and three expandable body units 310, 312 and 314. The body
units 310, 312, and 314 include string-like external restraints
317, which limit the expansion of the body units 310, 312, and 314
in a direction transverse to the longitudinal axes of the body
units 310, 312, and 314. The restraints 317 are made of the same or
similar material as that of the body units 310, 312, and 314, so
that they have some resilience but substantially no expansion
capability.
[0154] A tubes 315 direct liquid under pressure into the body units
310, 312 and 314 to expand the units and cause compaction of
cancellous bone. The restraints 317 limit expansion of the body
units prior to failure, keeping the opposed sides 377 and 379
substantially flat and parallel with each other.
[0155] ii. Constrained Kidney-Shaped Geometries
[0156] FIG. 23 shows another representative embodiment of an
expandable body 230, which has a kidney-shaped geometry. The body
230 has a pair of opposed kidney-shaped side walls 232 and a
continuous end wall 234. A tube 238 directs liquid into the body to
expand it within the vertebral body.
[0157] FIG. 24 shows another representative embodiment of an
expandable body 242, which also has a kidney-shaped geometry. The
body 242 is initially a single chamber bladder, but the bladder is
branded along curved lines or strips 241 to form attachment lines
244 which take the shape of side-by-side compartments 246 which are
kidney shaped as shown in FIG. 25. A similar pattern of strips as
in 240 but in straight lines would be applied to a body that is
square or rectangular. The branding causes a welding of the two
sides of the bladder to occur.
[0158] The details of these and other expandable bodies usable to
treat vertebral bodies are described in U.S. patent application
Ser. No. 08/188,224, filed Jan. 26, 1994, which is incorporated
herein by reference.
[0159] F. Selection of Desired Geometry
[0160] The eventual selection of the size and shape of a particular
expandable body or bodies to treat a targeted vertebral body 26 is
based upon several factors. When multiple expandable bodies are
used, the total combined dimensions of all expandable bodies
deployed, when substantially expanded, should be taken into
account.
[0161] The anterior-posterior (A-P) dimension (see FIG. 26) for the
expandable body or bodies is selected from the CT scan or plain
film or x-ray views of the targeted vertebral body 26. The A-P
dimension is measured from the internal cortical wall of the
anterior cortex to the internal cortical wall of the posterior
cortex of the vertebral body. In general, the appropriate A-P
dimension for the expandable body or bodies is less than this
anatomic measurement.
[0162] The appropriate side to side dimension L (see FIG. 26) for
an expandable body or bodies is also selected from the CT scan, or
from a plain film or x-ray view of the targeted vertebral body. The
side to side distance is measured between the internal cortical
walls laterally across the targeted vertebral body. In general, the
appropriate side to side dimension L for the expandable body is
less than this anatomic measurement.
[0163] The lumbar vertebral body tends to be much wider in side to
side dimension L then in A-P dimension. In thoracic vertebral
bodies, the side to side dimension and the A-P dimensions are
almost equal.
[0164] The height dimensions H of the expandable body or bodies
(see FIG. 26) is chosen by the CT scan or x-ray views of the
vertebral bodies above and below the vertebral body to be treated.
The height of the vertebral bodies above and below the vertebral
body to be treated are measured and averaged. This average is used
to determine the appropriate height dimension of the chosen
expandable body.
[0165] The dimensions of expandable body or bodies for use in
vertebrae are patient specific and will vary across a broad range,
as summarized in the following table: TABLE-US-00001 Side to
Posterior Side Height (H) (A-P) Dimension Dimension Dimension (L)
of of Typical of Typical Typical Expandable Expandable Expandable
Vertebra Body or Body or Body or Type Bodies Bodies Bodies Lumbar
0.5 cm to 0.5 cm to 0.5 cm to 4.0 cm 4.0 cm 5.0 cm Thoracic 0.5 cm
to 0.5 cm to 0.5 cm to 3.5 cm 3.5 cm 4.0 cm
[0166] A preferred expandable body 56 for use in a vertebral body
is stacked with two or more expandable members of unequal height
(see FIG. 26), where each member can be separately inflated through
independent tube systems. The total height of the stack when fully
inflated should be within the height ranges specified above. Such a
design allows the fractured vertebral body to be returned to its
original height in steps, which can be easier on the surrounding
tissue, and it also allows the same balloon to be used in a wider
range of vertebral body sizes.
[0167] II. Treatment of Long Bones
[0168] Like vertebrae, the interior regions of long bones
substantially occupied by cancellous bone can be treated with the
use of one or more expandable bodies. FIG. 43 shows representative
regions of the human skeleton 600, where cancellous bone regions of
long bones can be treated using expandable bodies. The regions
include the distal radius (Region 602); the proximal tibial plateau
(Region 604); the proximal humerus (Region 606); the proximal
femoral head (Region 608); and the calcaneus (Region 610).
[0169] As for vertebral bodies, expandable bodies possess the
important attribute of being able, in the course of forming
cavities by compressing cancellous bone, to also elevate or push
broken or compressed cortical bone back to or near its normal
anatomic position. This is a particularly important attribute for
the successful treatment of compression fractures or cancellous
bone fractures in the appendicular skeleton, such as the distal
radius, the proximal humerus, the tibial plateau, the femoral head,
hip, and calcaneus.
[0170] Representative examples of expandable bodies for the
treatment of cancellous bone regions of long bones will be next
described.
[0171] A. Expandable Body for the Distal Radius
[0172] The selection of an appropriate expandable to treat a
fracture of the distal radius (Region 602 in FIG. 43) will depend
on the radiological size of the distal radius and the location of
the fracture.
[0173] FIGS. 27 and 28 show a representative expandable body 260
for use in the distal radius. The body 260, which is shown deployed
in the distal radius 252, has a shape which approximates a pyramid
but more closely can be considered the shape of a humpbacked
banana. The geometry of the body 260 substantially fills the
interior of the space of the distal radius to compact cancellous
bone 254 against the inner surface 256 of cortical bone 258.
[0174] The body 260 has a lower, conical portion 259 which extends
downwardly into the hollow space of the distal radius 252. This
conical portion 259 increases in cross section as a central distal
portion 261 is approached. The cross section of the body 260 is
shown at a central location (FIG. 27), which is near the widest
location of the body 260. The upper end of the body 260, denoted by
the numeral 262, converges to the catheter tube 288 for directing a
liquid into the body 260 to expand it and force the cancellous bone
against the inner surface of the cortical bone.
[0175] The shape of the body 260 is determined and restrained by
tufts formed by string restraints 265. These restraints are
optional and provide additional strength to the body 260, but are
not required to achieve the desired configuration.
[0176] The body 260 is placed into and taken out of the distal
radius in the same manner as that described above with respect to
the vertebral bone.
[0177] Typical dimensions of the distal radius body vary as
follows:
[0178] The proximal end of the body 260 (i.e. the part nearest the
elbow) is cylindrical in shape and will vary from 0.4.times.0.4 cm
to 1.8.times.1.8 cm.
[0179] The length of the distal radius body will vary from 1.0 cm
to 12.0 cm.
[0180] The widest medial to lateral dimension of the distal radius
body, which occurs at or near the distal radio-ulnar joint, will
measure from 0.5 cm to 2.5 cm.
[0181] The distal anterior-posterior dimension of the distal radius
body will vary from 0.4 to 3.0 cm.
[0182] B. Expandable Body for Proximal Humerus Fracture
[0183] The selection of an appropriate expandable body 266 to treat
a given proximal humeral fracture (Region 606 in FIG. 43) depends
on the radiologic size of the proximal humerus and the location of
the fracture.
[0184] FIG. 29A shows a representative embodiment of an expandable
body 266 for use in the proximal humerus 269. The body 266 is
spherical for compacting the cancellous bone 268 in a proximal
humerus 269. If surrounding cortical bone has experienced
depression fracture, expansion of the body 266 also serves to
elevate or move the fractured cortical bone back to or near its
anatomic position before fracture.
[0185] A mesh 270, embedded or laminated and/or winding, may be
used to form a neck 272 on the body 266. A second mesh 270a may be
used to conform the bottom of the base 272a to the shape of the
inner cortical wall at the start of the shaft. These mesh
restraints provide additional strength to the body 266, but the
configuration can be achieved through molding of the body.
[0186] The body 266 has a catheter tube 277 into which liquid under
pressure is forced into the body to expand it to compact the
cancellous bone in the proximal humerus. The body 266 is inserted
into and taken out of the proximal humerus in the same manner as
that described above with respect to the vertebral bone.
[0187] Typical dimensions of the expandable body 266 shown in FIG.
29A for proximal humerus fracture vary as follows:
[0188] The spherical end of the body will vary from 0.6.times.0.6
cm to 3.0.times.3.0 cm.
[0189] The neck of the proximal humeral fracture body will vary
from 0.5.times.0.5 cm to 3.0.times.3.0 cm.
[0190] The width of the base portion or distal portion of the
proximal numeral fracture body will vary from 0.5.times.0.5 cm to
2.5.times.2.5 cm.
[0191] The length of the body will vary from 3.0 cm to 14.0 cm.
[0192] FIG. 29B shows another representative embodiment of an
expandable body 266' for use in the proximal humerus 269. Instead
of being spherical, the body 266' shown in FIG. 29B has a generally
cylindrical geometry for compacting the cancellous bone 268 in a
proximal humerus 269. Alternatively, the cylindrical body 266' can
be elongated to form an elliptical or football-shaped geometry.
Typical dimensions for a cylindrical or elliptical body vary from
0.6 cm to 3.0 cm in diameter to 3.0 cm to 14.0 cm in length.
[0193] C. Expandable Body for Proximal Tibial Plateau Fracture
[0194] The selection of an expandable body to treat a given tibial
plateau fracture (Region 604 in FIG. 43) will depend on the
radiological size of the proximal tibial and the location of the
fracture.
[0195] FIG. 30A shows a representative expandable body 280 for
treating a tibial plateau fracture. The body 280 may be introduced
into the tibia from any direction, as desired by the physician, for
example, from the top, or medial, lateral, anterior, posterior, or
oblique approach. In FIG. 30A, the body 280 has been introduced
into cancellous bone 284 from the anterior side of the tibia 283
and is shown position in one side 282 of the tibia 283.
[0196] The body 280, when substantially inflated (as FIG. 30A
shows), compacts the cancellous bone in the layer 284 surrounding
the body 280. If the tibia plateau has experienced depression
fracture, expansion of the body 280 also serves to move the tibia
plateau back to or near its anatomic elevation before fracture, as
FIG. 30A shows. Fractures on both the medial and lateral sides of
the tibia can be treated in this manner.
[0197] As FIG. 30B shows, the body 280 has a pair of opposed sides
285 and 287. The sides 285 and 287 are interconnected by restraints
288, which pass through the body 280. FIG. 30C shows the tied-off
ends 291 of the restraints 288.
[0198] The restraints 288 can be in the form of strings or flexible
members of any suitable construction.
[0199] The restraints 288 limit expansion of the body 280 prior to
failure. The restraints 288 make the sides 285 and 287, when the
body 280 is substantially expanded, substantially parallel with
each other and, thereby, non-spherical.
[0200] A tube 290 is coupled to the body 280 to direct liquid into
and out of the body to expand it. The body is inserted into and
taken out of the tibia in the same manner as that described above
with respect to the vertebral bone. FIG. 30C shows a substantially
circular configuration for the body 280, although the body 280 can
also be substantially elliptical, as FIG. 31 shows.
[0201] Other geometries and configurations can also be used. For
example, as FIG. 32 shows, two or more expandable bodies 280(1),
280(2), and 280(3) can be stacked one atop another to produce a
different cavity geometry and to enhance plateau fracture
displacement. The multiple bodies 280(1), 280(2), and 280(3) can
comprise separate units or be joined together for common
deployment. When deployed as separate units, the bodies 280(1),
280(2), and 280(3) can enter through the same access point or from
different access points.
[0202] As another example, as FIG. 33 shows, the body 280' can
assume an egg shape when substantially inflated, to form a cavity
and reshape broken bones. Other geometries, such as cylindrical or
spherical, can also be used for the same purpose. Typical
dimensions of the body 280 for treating proximal tibial plateau
fracture vary as follows:
[0203] The thickness or height of the body will vary from 0.3 cm to
5.0 cm.
[0204] The anterior-posterior (front to back) dimension will vary
from 1.0 cm to 6.0 cm.
[0205] The medial to lateral (side-to-side) dimension will vary
from 1.0 cm to 6.0 cm.
[0206] FIGS. 44 and 45 show multiple expandable zones 614, and 616
deployed in cancellous bone 620. One zone 614 serves as a platform
to confine and direct the expansion of the other zone 616. For the
purpose of illustration, FIGS. 44 and 45 show the multiple zones
614 and 616 used for this purpose to treat a tibial plateau
fracture 622.
[0207] In the embodiment shown in FIGS. 44 and 45, the zones 614
and 616 comprise separate expandable bodies. It should be
appreciated, however, that the zone 614 and 616 can comprise parts
of a single expandable body.
[0208] In the illustrated embodiment (as FIG. 44 shows), the first
expandable body 614 is deployed through a first outer guide sheath
618(1) into cancellous bone 620 below the fracture 622. As FIG. 44
shows, when substantially expanded, the first body 614 expands more
along its horizontal axis 624 (i.e., in a side-to-side direction)
than along its vertical axis 626 (i.e., in a top-to-bottom
direction). The greater expanded side-to-side geometry of the first
body 614 compacts cancellous bone in a relatively thin region,
which extends substantially across the interior volume 628 occupied
by the first body 614. The geometric limits of the body 614 will
typically fall just inside the inner cortical walls of the proximal
tibia, or whatever bone in which the first body 614 is
deployed.
[0209] The expanded first body 614 creates a barrier 630 within the
interior region 628. Due to the less expanded top-to-bottom
geometry of the first body 614, a substantially uncompacted region
632 of cancellous bone is left above the body 614, which extends
from the formed barrier 630 upward to the fracture 622. In a
representative deployment, the uncompacted region 632 extends about
2 cm below the tibial plateau fracture 622.
[0210] As FIG. 44 shows, a second expandable body 616 is deployed
through a second outer guide sheath 618(2) into the uncompacted
region 632 left between the first body 614, when substantially
expanded, and the targeted tibial plateau fracture 622.
[0211] As FIG. 45 shows, the second expandable body 616 has a
geometry, substantially like that shown in FIGS. 30A to 30C. When
substantially inflated, the second body 616 compacts a large
percentage of the cancellous bone in the region 632 above the first
expandable body 614. The presence of the barrier 630, which the
expanded first body 614 creates (see FIG. 46 also), prevents
expansion of the second body 616 in a direction away from the
tibial platform fracture 622. Instead, the barrier 630 directs
expansion of the second body 616 toward the fracture 622.
Buttressed by the barrier 630, the expansion of the body 616 is
directed against the fractured plateau 622, restoring it to its
normal anatomic position, as FIGS. 45 and 46 show.
[0212] It should be appreciated that one or more expandable bodies
can be used as platforms or barriers to direct the expansion of one
or more other expandable bodies in other localized interior bone
regions. The barrier makes possible localized cavity formation in
interior bone regions. Use of the barrier preserves healthy regions
of cancellous bone, while directing the main compacting body toward
localized fractures or localized regions of diseased cancellous
bone.
[0213] D. Expandable Body for Femoral Head
[0214] The size of an expandable body for use in the femoral head
(Region 608 in FIG. 43) is chosen based upon the radiological or CT
scan size of the head of the femur and the location and size of the
avascular necrotic bone.
[0215] FIG. 34 shows a representative embodiment of an expandable
body 300 introduced inside the cortical bone 302 of the femoral
head. As FIG. 34 shows, the femoral head is thin at the outer end
304 of the femur and increases in thickness at the lower end 306 of
the femur. A tube 309 directs liquid to expand the body 300. The
tube 309 extends along the femoral neck and into the femoral head.
The expandable body 300 compacts the cancellous bone 307 in this
bone region, while also moving fractured cortical bone back to or
near its normal anatomic position.
[0216] The femoral head is generally spherical in configuration,
and the body 300 can have either a hemispherical (see FIG. 35) as
well as spherical geometry (as FIG. 34 shows). The hemispherical
shape is maintained in FIG. 34 by bonding overlapping portions of
the body 300, creating pleats 300b.
[0217] The body 300 is inserted into and taken out of the femoral
head in the same manner as that described with respect to the
vertebral bone.
[0218] Typical dimensions of an expandable body for use in treating
the femoral head vary as follows:
[0219] The diameter of the expandable body will vary from 0.5 cm to
up to 4.5 cm. The dimensions of the hemispherical body (FIG. 35)
are the same as the those of the spherical body (FIG. 34), except
that approximately one half is provided.
[0220] E. Expandable Body for Prevention of Hip Fracture
[0221] Patients with bone density in the hip (Region 612 in FIG.
43) below a threshold value are at increased risk of hip fracture,
and lower densities create greater risk. Patient selection is done
through a bone density scan.
[0222] FIG. 36A shows a representative embodiment of an expandable
body 410 having a "boomerang" geometry for use in preventing hip
fracture. When substantially expanded. (as FIG. 36A, shows), the
body 410 forms a cylinder, which gradually bends in the middle,
like a boomerang, and extends from about 0.5 cm from the end of the
femoral head 411 through the femoral neck 412 and down into the
proximal femoral diaphysis 413 about 5 to 7 cm past the lesser
trochanter 414.
[0223] Expansion of the body 410 is limited to achieve the
described geometry by rings 430 of inelastic material. The rings
430 are held in a spaced apart relationship along one side of the
body 410 by attachment to an inelastic band 416, which runs the
length of that side of body 410. The rings 430 are held in a
farther spaced apart relationship along the opposite side of the
body 410 by attachment to another, longer inelastic band 417, which
runs the length of the opposite side of the body 410. A tube 419
conveys liquid to inflate the body 410.
[0224] Prior to deployment within the body, the body 410 is
collapsed and rolled up and held against the inflation tube 419
using, for example, with frangible connectors that will break as
the body is subject to expansion. To deploy the body 410 into the
hip, the surgeon uses a power drill under radiographic guidance to
create a cavity 420, which is, for example, about 4 to 6 mm wide
starting at the lateral femoral cortex 421 and proceeding into the
femoral head 411. The body 410 is deployed through a guide sheath
423, following the cavity 420. The body 410 is deployed, prior to
expansion, facing the lesser trochanter 414, so that expansion
occurs toward the femoral diaphysis 413, and not toward the greater
trochanteric region 422.
[0225] The expansion of the body 410 is guided by the rings 430 and
bands 416 and 417, which cause bending of the body 410 downward
into the lesser trochanter 414. Optionally, a second cavity can be
drilled down into the diaphysis 413, starting from the same entry
point or from the other side.
[0226] The body length is chosen by the physician to extend about
0.5 cm from the end of the femoral head, through the femoral neck
and into the proximal femoral diaphysis, usually about 4 to 8 cm
below the lesser trochanter. The body diameter is chosen by
measuring the inner cortical diameter of the femoral neck (the most
narrow area) and subtracting 0.5 cm. The preferred dimensions of
the body 410 are a total length of 10-20 cm 41- and a diameter of
about 1.0-2.5 cm.
[0227] Patients having the lowest bone densities in the femoral
head may require greater compacting in the femoral head, which may,
for example, be provided by using two bodies, one after the other:
the bent body 410 followed by the femoral head body (inserted at
the same point and expanded prior to inserting any supporting
material). Alternatively, the bent body 410 may be adapted to have
a distal portion that approximates the shape of the femoral head
body.
[0228] The geometry of the single, restrained body 410 can be
approximated by multiple expandable bodies deployed separately, or
coupled together, or stacked together. FIG. 36B shows a
representative embodiment of the use of multiple expandable bodies
in the hip region.
[0229] As FIG. 36B shows, a first expandable body 410(1) is
introduced through a first outer guide sheath 423(1) in the
proximal lateral cortex of the femoral shaft. The first body 419(1)
is deployed across the femoral neck 480 into the femoral head
482.
[0230] A second expandable body 410(2) is introduced through a
second outer guide sheath 423(2) in the greater trochanter 422 of
the femur. The first body 419(1) is deployed in the direction of
the femoral diaphysis 413.
[0231] Other approaches can be used. For example, one body can be
introduced through the femoral neck 480, and the other body can be
introduced along the shaft of the femur.
[0232] One or both of the bodies 410(1) and 41b(2) can include
external restraints to limit expansion, in the manner described
with regard to the body 410. Expansion of the bodies 410(1) and
410(2) compacts cancellous bone to form a cavity having a geometry
approximating that formed by the single body 410.
[0233] F. Expandable Body for Calcaneus Fracture
[0234] The size of an expandable body for use in treating fracture
of the calcaneus (heel bone) (Region 610 in FIG. 43) is chosen
based upon the radiological or CT scan size of the calcaneus and
the location and size of the fracture.
[0235] FIGS. 37A and 37B show a representative expandable body 450
for treating fracture of the calcaneus 452. A tube 464 conveys
liquid into the body 450 to expand it.
[0236] In FIG. 37A, the body 450 is deploy into the calcaneus 452
by a posterior approach, through the tuberosity. Other approaches
can be used, as desired by the physician. A power drill opens a
passage 466 through the tuberosity into the calcaneus. An outer
guide sheath 470 is positioned within the passage 466, abutting the
posterior of the calcaneus, in the manner previously described in
obtaining access to a vertebral body. The body 450 is introduced
through the guide sheath 470 and formed passage 466 into the
calcaneus.
[0237] Expansion of the body 450 is limited within the confines of
the calcaneus by inelastic peripheral bands 454 (see FIG. 37B). The
bands 454 constrain expansion of the body 450 to an asymmetric,
pear-shaped geometry, best shown in FIG. 37B. The pear-shaped
geometry has a major dimension H1 occupying the region of the
posterior facet 454. The major dimension H1 is located here,
because the part of the calcaneus most likely to require elevation
and realignment during expansion of the body 450 is the depressed
part of the posterior facet 454 of the calcaneus, where the
posterior facet 454 abuts the talus 456.
[0238] The pear-shaped geometry has a smaller, minor dimension
occupying the region of the anterior facet 458 of the calcaneus,
near the calcaneal-cuboid joint 460, between the calcaneus and
cuboid bone 462.
[0239] Expansion of the body 410 compacts cancellous bone 470
within the calcaneus 452. The expansion also lifts a depression
fracture of the posterior facet 454 back to or near its original
anatomic elevation adjacent the talus 456. When collapsed and
removed, the body 410 leaves a cavity in cancellous bone into which
filling material can be introduced in the manner previously
described.
[0240] FIG. 38 shows another representative embodiment of an
expandable body 450' for use in treating fractures in the
calcaneus. The body 450' in FIG. 38 has a more spherical or
egg-shaped geometry than the pear-shaped body 450 shown in FIG.
37B. Like the pear-shaped body 450, the body 450', when expanded
within the calcaneus, forms a cavity within cancellous bone and
realigns fractured cortical bone at or near its normal anatomic
position.
[0241] III. Selection of Other Expandable Bodies (Further
Overview)
[0242] Different sizes and/or shapes of expandable bodies may be
used at sites not specified above, such as the jaw bones, the
midshaft of the arm and leg bones, the cervical vertebral bodies,
the foot and ankle bones, the pelvis, the ribs, and the like.
[0243] The choice of the shape and size of a expandable body takes
into account the morphology and geometry of the site to be treated.
As before stated, the shape of the cancellous bone to be
compressed, and the local structures that could be harmed if bone
were moved inappropriately, are generally understood by medical
professionals using textbooks of human skeletal anatomy along with
their knowledge of the site and its disease or injury. Precise
dimensions for a given patient can be further determined by x-ray
of the site to be treated.
[0244] As one general guideline, the selection of the geometry of
the expandable body should take into account that at least 40% of
the cancellous bone volume needs to be compacted in cases where the
bone disease causing fracture (or the risk of fracture) is the loss
of cancellous bone mass (as in osteoporosis). The preferred range
is about 30% to 90% of the cancellous bone volume. Compacting less
of the cancellous bone volume can leave too much of the diseased
cancellous bone at the treated site. The diseased cancellous bone
remains weak and can later collapse, causing fracture, despite
treatment.
[0245] Another general guideline for the selection of the geometry
of the expandable body is the amount that the targeted fractured
bone region has been displaced or depressed. The expansion of the
body within the cancellous bone region inside a bone can elevate or
push the fractured cortical wall back to or near its anatomic
position occupied before fracture occurred.
[0246] However, there are times when a lesser amount of cancellous
bone compaction is indicated. For example, when the bone disease
being treated is localized, such as in avascular necrosis, or where
local loss of blood supply is killing bone in a limited area, the
expandable body can compact a smaller volume. This is because the
diseased area requiring treatment is smaller.
[0247] Another exception lies in the use of an expandable body to
improve insertion of solid materials in defined shapes, like
hydroxyapatite and components in total joint replacement. In these
cases, the body shape and size is defined by the shape and size of
the material being inserted.
[0248] Yet another exception is the delivery of therapeutic
substances, which will be described in greater detail later. In
this case, the cancellous bone may or may not be diseased or
adversely affected. Healthy cancellous bone can be sacrificed by
significant compaction to improve the delivery of a drug or growth
factor which has an important therapeutic purpose. In this
application, the size of the expandable body is chosen by the
desired amount of therapeutic substance sought to be delivered. In
this case, the bone with the drug inside is supported while the
drug works, and the bone heals through exterior casting or current
interior or exterior fixation devices.
[0249] Generally speaking, providing relatively inelastic
properties for the expandable body, while not always required, is
nevertheless preferred when maintaining a desired shape and size
within the bone is important, for example, in bone graft placement
or in a vertebral body, where the spinal cord is nearby. Using
relatively inelastic bodies, the shape and size can be better
predefined, taking into account the normal dimensions of the
outside edge of the cancellous bone.
[0250] Use of relatively inelastic materials also more readily
permits the application of pressures equally in all directions to
compress cancellous bone. Still, substantially equivalent results
can usually be achieved by the use of multiple expandable bodies
having highly elastic properties, if expansion is controlled by
either internal or external restraints, as previously
disclosed.
[0251] IV. Confinement of Filling Material
[0252] A. Dual Stage Filling
[0253] FIGS. 39A to 39D show a multiple stage process for
introducing filling material into a cavity formed by an expandable
body in cancellous bone. The process is shown in association with
treating a vertebral body. This is for the purpose of illustration.
It should be appreciated that the process can be used in the
treatment of all bone types.
[0254] Use of the multi-stage process is indicated when
pre-examination of the targeted bone reveals that a portion of the
cortical wall 28 has fractured or failed (as FIG. 39A shows at the
anterior region of the vertebral body 26). The failed cortical wall
28 creates gaps and cracks (designated G in FIG. 39A). Typically,
remnant chips 500 of the failed cortical bone 28 may lay in the
cancellous bone 32 in the region where cortical wall-failure has
occurred. Filling material can flow or seep through these gaps or
cracks C outside of the interior volume of the bone.
[0255] The process begins at the point where the outer guide sheath
72 has been positioned and the guide pin removed in the manner
previously described. The physician introduces a first expandable
body 502 into the cancellous bone 32 near the failed cortical bone
region, as FIG. 39A shows. The first expandable body 502 is sized,
when substantially expanded, to occupy a relatively small volume
(i.e., less than about 20%) of the volume of cancellous bone 32 in
interior volume 30.
[0256] The physician expands the first expandable body 502,
compacting a relatively small region of cancellous bone. Upon
collapse and removal of the first body 502, a small cavity 504,
caused by the compaction, remains (as FIG. 39B shows).
[0257] The physician introduces the injector tip 90 and injects an
aliquot of filling material 96(1) (for example, about 1 cc to about
9 cc) into the formed small cavity 504 (as FIG. 39B shows).
[0258] In a short time interval (before the filling material 96(1)
is allowed to substantially set and harden), the physician
withdraws the injector tip 90 and introduces a second expandable
body 506 into the cancellous bone 32 (see FIG. 39C). The second
expandable body 506 is larger than the first body 502. The second
body 506 is sized to create the desired geometry for the
therapeutic main cavity 508 in cancellous bone 32.
[0259] As FIG. 39C shows, expansion of the second body 506
displaces the earlier injected aliquot of filling material 96(1) in
the cavity 504 toward the failed cortical wall region. The aliquot
of filling material 96(1) will envelop remnant chips 500 of
cortical bone lying in its path. The material 96(1) and enveloped
chips 500 are pressed against the failed cortical bone region as
expansion of the second body 506 progresses. The first aliquot of
filling material 96(1) will begin to set and harden as the main
therapeutic cavity 508 is being formed by the expansion of the
second body 506. The second body 506 is collapsed and removed,
leaving the main cavity 508.
[0260] As FIG. 39D shows, the first aliquot of filling material
96(1) provides a viscous or (in time) hardened boarder region along
the anterior edge of the cavity 508. As subsequent injection of
additional filling material 96(2) into the main cavity 508
proceeds, as FIG. 39D shows, the viscous or hardened boarder region
96(1) impedes passage of the additional filling material 96(2) as
it fills the main cavity 508. The viscous or hardened boarder
region 96(1) serves as a dam, keeping the additional filling
material 96(2) entering the main cavity 508 from seeping from the
vertebral body 26.
[0261] B. Interior Mesh
[0262] FIGS. 40 and 41 show the use of an interior mesh 510 in
association with the introduction of filling material into a cavity
formed by an expandable body in cancellous bone. The mesh 510 is
shown in association with treating a vertebral body, but it should
be appreciated that the process can be used in the treatment of all
bone types.
[0263] Use of the mesh 510 is indicated when pre-examination of the
targeted bone reveals a failed cortical bone region (as FIG. 41
shows at the anterior region of the vertebral body 26), coupled
with the lack of enough bone matter, due to advanced disease or a
complex fracture, to adequately fill the failed cortical bone
region by compacting using an expandable body. Flowable cement
material can flow or seep through the unfilled gaps or cracks
(designated G in FIG. 41) present in the failed cortical bone
region.
[0264] The mesh 510 comprises a woven structure made from
biocompatible material like Goretex.TM. material, Nitinol.TM.
material, or Dacron.TM. material. The mesh presents a surface area,
which is about 1/3rd to 1/2 of the interior area of the main
therapeutic cavity 84 formed by the selected expandable body.
[0265] Before deploying the injector tip 90 into the formed cavity
84 (which is deployed in FIG. 41 by posterolateral access), the
physician drapes the mesh 510 over the tip 90, as FIG. 40 shows. As
FIG. 41 shows, the viscous flow of filling material 96 injected
from the tip 90 carries the mesh 510 into the cavity 84 in advance
of the filling material 96. The mesh 510 is urged by the filling
material 96 into contact with the anterior region of the bone,
including the failed cortical bone region. The mesh 510, permeated
with viscous material 96 and resting over the failed cortical bone
region, impedes passage of filling material, until hardening
occurs.
[0266] V. Delivery of Therapeutic Materials
[0267] A cavity created in cancellous bone by any of the expandable
bodies described above can be filled with a medically-appropriate
formulation of a drug or a growth factor.
[0268] An expandable body can compact infected cancellous bone to
create a space which can be filled with the antibiotic gel in an
open or minimally invasive procedure. The cavity places and holds
the required amount of drug right at the site needing treatment,
and protects the drug from being washed away by blood or other
fluids.
[0269] Not only can the dose be optimized, but additional doses can
be applied at later times without open surgery, enhancing the
therapeutic outcome. If the required cavity for the optimal drug
dose weakens the bone, the bone can be protected from future
fracture with a cast or with current internal or external metal or
plastic fixation devices.
[0270] The therapeutic substance put into bone may act outside the
bone as well. A formulation containing chemotherapeutic agent could
be used to treat local solid tumors, localized multiple myeloma or
even a nearby osteosarcoma or other tumor near that bone.
[0271] The cavity formed by an expandable body can be filled with
an appropriate supporting material, like acrylic bone cement or
biocompatible bone substitute, which carries a therapeutic
substance. Alternatively, the therapeutic substance can be
separately delivered before injection of the filling material.
Thus, using an expandable body, the physician is able to treat a
fracture while also delivering a desired therapeutic substance
(like an antibiotic, bone growth facer or osteoporosis drug) to the
site.
[0272] As an alternative, to deliver therapeutic substances, bodies
can be dipped in a medical formulation (often a dry powder, liquid
or gel) containing a medically-effective amount of any desired
antibiotic, bone growth factor or other therapeutic agent to coat
the body with the above-mentioned substance before it is inserted
into a bone being treated. Optionally, the body can be wholly or
partially expanded before the coating is performed. Optionally, the
coated body can be dried with air or by other means when the
applied formulation is wet, such as a liquid or a gel. The body is
refolded as required and either used immediately or stored, if
appropriate and desired. Coated on the body, therapeutic substances
can be delivered while cancellous bone is being compressed, or with
an additional body once the cavity is made.
[0273] The methods described above can also be used to coat Gelfoam
or other agents onto the body before use. Inflating the
Gelfoam-coated body inside bone will further fill any cracks in
fractured bone not already filled by the compressed cancellous
bone.
[0274] FIGS. 42A to 42C schematically illustrate one system and
method for delivering a therapeutic substance to the bone using an
expandable body 529. The body 529 is carried at the end of the
catheter tube 530, which conveys liquid to expand the body 529, as
previously described.
[0275] As shown in FIG. 42A, the expandable body 529, in a
substantially expanded condition, is stabilized with a clip 531
that couples the catheter tube 530 to a wire 532. As shown in FIG.
42B, a measured amount of gel formulation containing the desired
amount of substance 533 is uniformly dispensed from a container
534, preferably in thin lines 535, onto the outer surface of the
body 536. The coating substance can be the desired compound alone
in its natural state (solid, liquid or gas) or in an appropriate
formulation, including a dry powder, an aerosol or a solution. As
shown in FIG. 42C, the coated body 537 is collapsed and allowed to
dry until the gel sets. Alternatively, the body 536 can also be
coated without prior expansion. The optional drying time will, of
course, depend on the nature of the compound and its formulation.
The coated body 237 is suitable for packaging for use by a
surgeon.
[0276] Delivering a therapeutic substance on the outside of
expandable body used to compact the bone, or with an expandable
body introduced after the bone is compacted, is qualitatively
different than putting formulated drug into the cavity. When
delivered while the bone is compressed, the therapeutic substance
becomes incorporated into the compacted bone. This can serve as a
way to instantly formulate a slow release version of the substance.
The cavity formed by the expandable body can be filled with an
appropriate supporting material, like acrylic bone cement or
biocompatible bone substitute, as before described.
[0277] Medically-effective amounts of therapeutic substances are
defined by their manufacturers or sponsors and are generally in the
range of 10 nanograms to 50 milligrams per site, although more or
less may be required in a specific case.
[0278] For example, the cavity can accommodate a typical dose of
the antibiotic, gentamicin, to treat a local osteomyelitis (bone
infection). A typical dose is about 1 gram, although the
therapeutic range for gentamicin is far greater, from 1 nanogram to
100 grams, depending on the condition being treated and the size of
the area to be covered. A medically-suitable gel formulated with
appropriate gel materials, such as Polyethylene glycol, can contain
1 gram of gentamicin in a set volume of gel, such as 10 cc.
[0279] Other antibiotics that can be used to treat bone infection
include, for example, ancef, nafcillin, erythromycin, tobramycin,
and gentamicin. Typical bone growth factors are members of the Bone
Morphogenetic Factor, Osteogenic Protein, Fibroblast Growth Factor,
Insulin-Like Growth Factor and Transforming Growth Factor alpha and
beta families. Chemotherapeutic and related agents include
compounds such as cisolatin, doxcrubicin, daunorubicin,
methotrexate, taxol and tamoxifen. Osteoporosis drugs include
estrogen, calcitonin, diphosphonates, and parathyroid hormone
antagonists.
[0280] VI. Delivery of Biomaterials
[0281] A cavity created in cancellous bone by any of the expandable
bodies described above can also be filled with biomaterials.
[0282] Biomaterials which do not flow into the formed cavity, like
hydroxyapatite granules or bone mineral matrix, can be pushed down
a tube with a long pin whose diameter is slightly more narrow than
the inner-diameter of the outer guide sheath, using the
minimally-invasive procedure. During open surgery, the physician
can approach the bone in the same way.
[0283] If the biomaterial to be inserted does not flow and should
not be pushed into the cavity through the guide sheath (as in the
case of the hydroxyapatite block, because that can cause damage),
the physician can form the cavity using a minimally invasive
approach, then punch a hole using standard tools (such as a punch,
gouge or rasp) into one side of the cortical bone to allow
insertion of the block.
[0284] VII. Bone Marrow Harvesting
[0285] Any of the expandable bodies described above can also be
used in the harvesting of bone marrow for diagnostic or therapeutic
purposes, for example, in the diagnosis of multiple myeloma or in
the treatment of advanced cancers with bone marrow transplants.
[0286] FIG. 47 shows a system 700 for harvesting bone marrow in a
bone-marrow producing bone 702. The bone 702, which is shown
diagrammatically in FIG. 47, can comprise, for example, the pelvis,
or a vertebral body, or a distal radius.
[0287] The system 700 employs a bone marrow harvesting tool 704.
The tool 704 includes a catheter tube 706, which carries an
expandable body 708 at its distal end. The tool 704 can be deployed
into the bone 702 using a minimally invasive approach, as
previously described.
[0288] The catheter tube 706 has three concentric and independent
lumens 710, 712, and 714 (see FIG. 48). The outer lumen 710
communicates with the interior of the body 78 and is coupled to a
source 718 of an inflation liquid. The middle lumen 712
communicates with a source 720 of rinse liquid and a distal opening
716 on the catheter tube 706. The center lumen 714 communicates
with a collection container 722 and a second distal opening 724 on
the catheter tube 706.
[0289] The body 708 is deployed in a substantially collapsed
condition, as already described. Inflation liquid, which is
preferably radiopaque, is convey from the source 718 into the body
708 to expand it. As FIG. 48 shows, the body 708 is constrained by
selection of relatively inelastic materials or by exterior
restraints (as previously described) to assume an elongated shape.
Expansion of the body 708 creates a relatively shallow area of
compaction 726 in cancellous bone 728 along a relatively long
length. The size and shape of the body 708 will depend upon the
geometry of the harvest site and the amount of bone marrow
required. In long bones, like the distal radius, and in bones with
narrow width but large area, such as the ribs or pelvis, the body
728 is shaped to compress a large area but not a great depth of
cancellous bone 728.
[0290] As FIG. 48 also shows, as the body 708 expands, rinse
liquid, which can be saline or another suitable biocompatible
liquid, is conveyed from the source 720 into the area 726 (shown by
arrows 730 in FIG. 48). The rinse liquid loosens up biological
components (such as red blood cells, bone cells, and immune-.beta.
cells) within the defined area 726, forming component-rich
suspension 732.
[0291] The body 708 is collapsed, and suction is applied through
the lumen 714. The suction draws the component-rich suspension 732
from the area 726 into the collection container 722.
[0292] The above sequence of expansion, rinsing, collapse, and
aspiration can be repeated to collect additional component-rich
suspension 732 in the container 722. The position of the expandable
body 708 in the bone 702 can be changed, if desired, to maintain a
component-rich suspension 732 for harvesting.
[0293] Use of the expandable body 708 to form the long but shallow
compaction area 726 permits the harvest of a significant
concentration of therapeutic biological components with less damage
to bone that conventional harvesting methods. If desired, standard
casts or other fixation devices can be applied to the bone 702
after bone marrow harvesting until the bone 702 heals.
[0294] The features of the invention are set forth in the following
claims.
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