U.S. patent application number 12/869101 was filed with the patent office on 2010-12-16 for systems and methods for forming a cavity in cancellous bone.
This patent application is currently assigned to KYPHON S RL. Invention is credited to Michael L. Reo, Robert M. Scribner.
Application Number | 20100318087 12/869101 |
Document ID | / |
Family ID | 25430918 |
Filed Date | 2010-12-16 |
United States Patent
Application |
20100318087 |
Kind Code |
A1 |
Scribner; Robert M. ; et
al. |
December 16, 2010 |
SYSTEMS AND METHODS FOR FORMING A CAVITY IN CANCELLOUS BONE
Abstract
A cavity creating device having a cavity creating axis is
introduced through a percutaneous access path into a cancellous
bone volume, e.g., within a vertebral body. The cavity creating
device is manipulated to form a cavity in the cancellous bone
volume. The manipulation includes deflecting the cavity creating
device along the cavity creating axis relative to the axis of the
access path. A material, such as bone cement, can be conveyed into
the cavity.
Inventors: |
Scribner; Robert M.; (Niwot,
CO) ; Reo; Michael L.; (Redwood City, CA) |
Correspondence
Address: |
MEDTRONIC;Attn: Noreen Johnson - IP Legal Department
2600 Sofamor Danek Drive
MEMPHIS
TN
38132
US
|
Assignee: |
KYPHON S RL
Neuchatel
CH
|
Family ID: |
25430918 |
Appl. No.: |
12/869101 |
Filed: |
August 26, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11527861 |
Sep 27, 2006 |
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12869101 |
|
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|
10436551 |
May 13, 2003 |
7156861 |
|
|
11527861 |
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|
09918942 |
Jul 31, 2001 |
6623505 |
|
|
10436551 |
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|
09404662 |
Sep 23, 1999 |
6280456 |
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09918942 |
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08911827 |
Aug 15, 1997 |
5972015 |
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09404662 |
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Current U.S.
Class: |
606/79 ;
606/191 |
Current CPC
Class: |
A61B 17/74 20130101;
A61F 2230/0008 20130101; A61F 2230/0063 20130101; A61F 2002/30288
20130101; A61F 2230/0069 20130101; A61F 2002/2832 20130101; A61F
2002/2853 20130101; A61F 2002/4685 20130101; A61F 2230/0006
20130101; A61F 2/28 20130101; A61F 2002/2817 20130101; A61B 90/94
20160201; A61F 2002/30285 20130101; A61F 2002/30581 20130101; A61F
2310/00293 20130101; A61F 2002/30245 20130101; A61F 2002/30242
20130101; A61B 17/7275 20130101; A61B 17/7258 20130101; A61B
2017/00544 20130101; A61F 2220/0075 20130101; A61F 2230/0065
20130101; A61F 2/44 20130101; A61F 2002/2871 20130101; A61B 10/025
20130101; A61B 17/12136 20130101; A61F 2002/30225 20130101; A61B
17/744 20130101; A61F 2002/30599 20130101; A61B 2017/00539
20130101; A61B 17/12099 20130101; A61F 2002/30115 20130101; A61F
2002/30125 20130101; A61F 2002/302 20130101; A61B 17/8855 20130101;
A61B 50/33 20160201; A61F 2/4611 20130101; A61F 2002/4627 20130101;
A61B 17/00234 20130101; A61F 2230/0015 20130101; A61F 2002/30113
20130101; A61F 2002/30462 20130101; A61F 2002/30586 20130101; A61F
2002/30253 20130101; A61F 2/441 20130101; A61B 17/1204 20130101;
A61F 2230/0076 20130101; A61F 2002/30133 20130101; A61F 2002/2892
20130101; A61F 2002/30448 20130101; A61F 2002/4217 20130101; A61F
2310/00353 20130101; A61F 2002/30228 20130101; A61F 2250/0063
20130101; A61F 2220/005 20130101; A61B 17/12109 20130101; A61B
2050/3015 20160201; A61F 2/2846 20130101; A61B 2010/0258 20130101;
A61F 2002/30308 20130101; A61F 2310/0097 20130101; A61B 2050/0065
20160201; A61F 2002/4635 20130101; A61F 2002/30909 20130101; A61B
90/39 20160201; A61F 2002/2825 20130101; A61F 2/4601 20130101; A61F
2002/2828 20130101; A61F 2002/30313 20130101; A61F 2002/30677
20130101; A61F 2002/2835 20130101; A61F 2230/0071 20130101 |
Class at
Publication: |
606/79 ;
606/191 |
International
Class: |
A61B 17/16 20060101
A61B017/16; A61M 29/00 20060101 A61M029/00 |
Claims
1-14. (canceled)
15. An instrument for forming a cavity in cancellous bone
comprising: a generally straight catheter tube having a proximal
end, a distal end, a first lumen and a second lumen; an expandable
structure disposed at the distal end of the catheter tube, the
expandable structure having a distal end and communicating with the
first lumen of the catheter tube; and a generally straight
stiffening stylet inserted into the second lumen of the catheter
tube; wherein the second lumen extends through the first lumen of
the catheter tube to the distal end of the expandable
structure.
16. The instrument according to claim 1, wherein the expandable
structure is made from an elastic material.
17. The instrument according to claim 1, wherein the stylet is
removable from the second lumen.
18. The instrument according to claim 1, wherein the stylet is
formed from metal.
19. The instrument according to claim 1, wherein the stylet is
formed from plastic.
20. An instrument for forming a cavity in cancellous bone
comprising: a generally straight outer catheter tube including a
distal end and a first lumen; a generally straight inner catheter
tube extending within the outer catheter tube and including a
distal end and a second lumen, wherein the distal end of the inner
catheter tube extends beyond the distal end of the outer catheter
tube; an expandable structure communicating with the first lumen;
and a generally straight stiffening stylet sized for insertion into
the second lumen.
21. The instrument of claim 20 wherein the expandable structure
includes a proximal end and distal end and wherein the distal end
of the expandable structure is attached to the distal end of the
inner catheter tube.
22. The instrument of claim 20 wherein the stylet is formed of
metal.
23. The instrument of claim 20 wherein the stylet is formed of
plastic.
24. The instrument of claim 20 wherein the stylet includes a region
with a preformed memory.
25. The instrument of claim 20 further comprising a guide sheath
sized for through passage of the stylet and catheter tubes.
26. The instrument of claim 20 wherein the inner catheter tube is
formed from a material more compliant than the material from which
the outer catheter tube is formed.
Description
RELATED APPLICATIONS
[0001] This application is divisional of co-pending U.S. patent
application Ser. No. 10/436,551, filed May 13, 2003, which is a
divisional of U.S. patent application Ser. No. 09/918,942, filed
Jul. 31, 2001 (now U.S. Pat. No. 6,623,505), which is a divisional
of U.S. patent application Ser. No. 09/404,662, filed Sep. 23,
1999, now U.S. Pat. No. 6,280,456, which is a divisional of U.S.
patent application Ser. No. 08/911,827, filed Aug. 15, 1997, now
U.S. Pat. No. 5,972,015, each of which is incorporated herein by
reference.
FIELD OP THE INVENTION
[0002] The invention, relates to expandable structures, which, in
use, are deployed in interior body regions of humans and other
animals.
BACKGROUND OF THE INVENTION
[0003] The deployment of expandable structures into interior body
regions is well known. For example, expandable structures,
generically called "balloons," are deployed during angioplasty to
open occluded blood vessels. As another example, U.S. Pat. Nos.
4,969,888 and 5,108,404 disclose apparatus and methods the use of
expandable structures for the fixation of fractures or other
osteoporotic and non-osteoporotic conditions of human and animal
bones.
[0004] Many interior regions of the body, such as the vasculature
and interior bone, possess complex, asymmetric geometries. Even if
an interior body region is somewhat more symmetric, it may still be
difficult to gain access along the natural axis of symmetry.
[0005] For example, deployment of an expandable structure in the
region of branched arteries or veins can place the axis of an
expandable structure off-alignment with the axis of the blood
vessel which the structure is intended to occupy. As another
example, insertion of an expandable structure into bone can require
forming an access portal that is not aligned with the natural
symmetry of the bone. In these instances, expansion of the
structure is not symmetric with respect to the natural axis of the
region targeted for treatment. As a result, expansion of the body
is not symmetric with respect to the natural axis of the targeted
region.
[0006] It can also be important to maximize the size and surface
area of an expandable structure when deployed in an interior body
region. Current medical balloons manufactured by molding techniques
are designed to be guided into a narrow channel, such as a blood
vessel or the fallopian tube, where they are then inflated. In this
environment, the diameter of the balloon is critical to its
success, but the length is less so. Such balloons only need to be
long enough to cross the area of intended use, with few constraints
past the effective portion of the inflated balloon. This allows
conventional balloons to be constructed in three molded pieces,
comprising a cylindrical middle section and two conical ends,
bonded to a catheter shaft. As a practical matter, neither the
length of the conical end, nor the length of the bond of the
balloon to the catheter shaft, affect the function of conventional
balloons, and these regions on conventional balloons are often 1 cm
in length or more. Indeed, the larger the balloon diameter, the
longer the end cone, which creates a tradeoff between maximum
effective length and maximum effective diameter. This tradeoff
makes optimization of conventional structures problematic in
interior structures with defined lengths, such as bone.
SUMMARY OF THE INVENTION
[0007] One aspect of the invention provides a device comprising a
shaft having an elongated shaft axis and a proximal end portion and
a distal end portion. The elongated shaft is sized and configured
for passage through a percutaneous access path into a cancellous
bone region. The device also includes a cavity forming structure
carried on the distal end of the shaft. The cavity forming device
is sized and configured to be manipulated to form a cavity in the
cancellous bone region. The cavity forming structure has an
elongated cavity forming axis. The device further includes a
mechanism for deflecting the cavity forming structure along the
elongated cavity forming axis, to shift the elongated cavity
forming axis relative to the elongated shaft axis.
[0008] Another aspect of the invention provides a method that
provides a percutaneous access path having an axis into bone having
an interior volume occupied, at least in part, by cancellous bone.
The method introduces a cavity creating device having a cavity
creating axis through the access path into the cancellous bone
volume. The method manipulates the cavity creating device to form a
cavity in the cancellous bone volume. The manipulation includes
deflecting the cavity creating device along the cavity creating
axis relative to the axis of the access path.
[0009] In one embodiment, a material, e.g., bone cement, is
introduced into the cavity.
[0010] In one embodiment, the cavity creating device is also
expanded to form the cavity.
[0011] In one embodiment, bone comprises a vertebral body.
[0012] 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
[0013] FIG. 1 is a lateral view, partially broken away and in
section, of a lumbar vertebra taken generally along line 1-1 in
FIG. 2;
[0014] FIG. 2 is a coronal view of the lumbar vertebra, partially
cut away and in section, shown in FIG. 1;
[0015] FIG. 3 is a top view of a probe including a catheter tube
carrying a tubular expandable structure of conventional
construction, shown in a substantially collapsed condition;
[0016] FIG. 4 is an enlarged side view of the tubular expandable
structure carried by the probe shown in FIG. 3, shown in a
substantially expanded condition;
[0017] FIG. 5 is a lateral view of the lumbar vertebra shown in
FIGS. 1 and 2, partially cut away and in section, with the
expandable structure shown in FIGS. 3 and 4 deployed by
transpedicular access when in a substantially collapsed
condition;
[0018] FIG. 6 is a coronal view of the transpedicular access shown
in FIG. 5, partially cut away and in section;
[0019] FIG. 7 is a lateral view of the transpedicular access shown
in FIG. 5, with the expandable structure shown in FIGS. 3 and 4 in
a substantially expanded condition, forming a cavity that is not
centered with respect to the middle region of the vertebral
body;
[0020] FIG. 8 is a coronal view of the transpedicular access shown
in FIG. 7, partially cut away and in section;
[0021] FIG. 9 is a coronal view of the lumbar vertebra shown in
FIGS. 1 and 2, partially cut away and in section, with the
expandable structure shown in FIGS. 3 and 4 deployed by
postero-lateral access when in a substantially collapsed
condition;
[0022] FIG. 10 is a coronal view of the postero-lateral access
shown in FIG. 9, with the expandable structure shown in a
substantially expanded condition, forming a cavity that is not
centered with respect to the middle region of the vertebral
body;
[0023] FIGS. 11A and 11B are side views of improved expandable
structures, each having an axis of expansion that is offset by an
acute angle and not aligned with the axis of the supporting
catheter tube;
[0024] FIG. 12 is a lateral view of the lumbar vertebra shown in
FIGS. 1 and 2, partially cut away and in section, with the offset
expandable structure shown in FIG. 11A deployed by transpedicular
access and being in a substantially expanded condition, forming a
cavity that is substantially centered with respect to the middle
region of the vertebral body;
[0025] FIG. 13 is a coronal view of the lumbar vertebra shown in
FIGS. 1 and 2, partially cut away and in section, with the offset
expandable structure shown in FIG. 11 deployed by postero-lateral
access and being in a substantially expanded condition, forming a
cavity that is substantially centered with respect to the middle
region of the vertebral body;
[0026] FIGS. 14A and 14B are side views of other embodiments of
improved expandable structures, each having an axis of expansion
that is offset by a distance from the axis of the supporting
catheter tube;
[0027] FIG. 15 is a side view of a conventional expandable
structure shown in FIG. 4, enlarged to show further details of its
geometry when substantially expanded;
[0028] FIG. 16 is a side view of an improved expandable structure,
when in a substantially expanded condition, which includes end
regions having compound curvatures that reduce the end region
length and thereby provide the capability of maximum bone
compaction substantially along the entire length of the
structure;
[0029] FIG. 17 is a side view of an improved expandable structure,
when in a substantially expanded condition, which includes end
regions having compound curvatures that invert the end regions
about the terminal regions, where the structure is bonded to the
supporting catheter tube, to provide the capability of maximum bone
compaction substantially along the entire length of the
structure;
[0030] FIG. 18 is a side section view of an improved expandable
structure, when in a substantially expanded condition, which
includes end regions that have been tucked or folded about the
terminal regions, where the structure is bonded to the supporting
catheter tube, to provide the capability of maximum bone compaction
substantially along the entire length of the structure;
[0031] FIG. 19 is a side section view of a tubular expandable
structure having a distal end bonded to an inner catheter tube and
a proximal end bonded to an outer catheter tube, the inner catheter
tube being slidable within the outer catheter tube;
[0032] FIG. 20 is a side section view of the tubular expandable
structure shown in FIG. 19, after sliding the inner catheter tube
within the outer catheter tube to invert the end regions of the
structure about the distal and proximal bonds, to thereby provide
the capability of maximum bone compaction substantially along the
entire length of the structure;
[0033] FIG. 21 is a side section view of a tubular expandable
structure having a distal end bonded to an inner catheter tube and
a proximal end bonded to an outer catheter tube, the inner catheter
tube and structure being made of a more compliant material than the
outer catheter tube to provide proportional length and diameter
expansion characteristics;
[0034] FIG. 22 is an enlarged plan view of a branched blood
vasculature region, in which an occlusion exists;
[0035] FIG. 23 is a further enlarged view of the branched blood
vasculature region shown in FIG. 22, in which an asymmetric
expandable structure of the type shown in FIG. 11 is deployed to
open the occlusion;
[0036] FIG. 24 is a plan view of a sterile kit to store a single
use probe, which carries an expandable structure as previously
shown;
[0037] FIG. 25 is an exploded perspective view of the sterile kit
shown in FIG. 24;
[0038] FIG. 26 is a side view, with parts broken away and in
section, of an expandable structure having an enclosed stiffening
member, to straighten the structure during passage through a guide
sheath into an interior body region; and
[0039] FIG. 27 is a side view of the expandable structure shown in
FIG. 27, after deployment beyond the guide sheath and into the
interior body region, in which the stiffening member includes a
distal region having a preformed bend, which deflects the structure
relative to the axis of the guide sheath.
[0040] 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
[0041] The preferred embodiment first describes improved systems
and methods that embody features of the invention in the context of
treating bones. This is because the new systems and methods are
advantageous when used for this purpose.
[0042] Another preferred embodiment describes the improved systems
and methods in the context of relieving constrictions or blockages
within branched blood vessels. This is because the vasculature also
presents an environment well suited to receive the benefits of the
invention.
[0043] The two environments are described for the purpose of
illustration. However, it should be appreciated that the systems
and methods as described are not limited to use in the treatment of
bones or the vasculature. The systems and methods embodying the
invention can be used virtually in any interior body region that
presents an asymmetric geometry, or otherwise requires an access
path that is not aligned with the natural axis of the region.
I. Deployment in Bones
[0044] The new systems and methods will be first described in the
context of the treatment of human vertebra. Of course, other human
or animal bone types, e.g., long bones, can be treated in the same
or equivalent fashion.
[0045] FIG. 1 shows a lateral (side) view of a human lumbar
vertebra 12. FIG. 2 shows a coronal (top) view of the vertebra. The
vertebra 12 includes a vertebral body 26, which extends on the
anterior (i.e., front or chest) side of the vertebra 12. The
vertebral body 26 is in the shape of an oval disk. The geometry of
the vertebral body 26 is generally symmetric arranged about its
natural mid-anterior-posterior axis 66, natural mid-lateral axis
67, and natural mid-top-to-bottom axis 69. The axes 66, 67, and 69
intersect in the middle region or geometric center of the body 26,
which is designated MR in the drawings.
[0046] As FIGS. 1 and 2 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).
[0047] The spinal canal 36 (see FIG. 2), is located on the
posterior (i.e., back) side of each vertebra 12. The spinal cord
(not shown) passes through the spinal canal 36. The vertebral arch
40 surrounds the spinal canal 36. Left and right pedicles 42 of the
vertebral arch 40 adjoin 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.
[0048] 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
structure to compress cancellous bone and provide an interior
cavity. The cavity receives a filling material, e.g., bone cement,
which hardens and provides renewed interior structural support for
cortical bone. 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, or other desired condition.
[0049] FIG. 3 shows a tool 48, which includes a catheter tube 50
having a proximal and a distal end, respectively 52 and 54. The
catheter tube 50 includes a handle 51 to facilitate gripping and
maneuvering the tube 50. The handle 51 is preferably made of a foam
material secured about the catheter tube 50.
[0050] The distal end 54 carries an expandable structure 56, which
FIG. 3 shows to be of conventional construction. The structure 56
is shown in FIG. 3 in a substantially collapsed geometry. The
structure 56 conventionally comprises an elongated tube, formed,
for example, by standard polymer extrusion and molding processes.
The tubular structure 56 is bonded at its opposite ends 58 to the
catheter tube 50, using, for example, an adhesive. When
substantially collapsed, the structure 56 can be inserted into an
interior body region.
[0051] Tubular bodies of the type shown in FIG. 3 are made from
polymer materials and are commonly deployed in veins and arteries,
e.g., in angioplasty applications. FIG. 4 shows an enlarged view of
the structure 56 when in a substantially expanded geometry. As FIG.
4 shows, the middle region 64 of the tubular structure 56, when
substantially expanded, assumes a generally cylindrical shape,
which is symmetric about the main axis 60 of the catheter tube 50.
Expansion stretches the polymer material of the structure 56 near
its bonded ends 58 to form generally conical end portions 62.
[0052] The structure 56 can be inserted into bone in accordance
with the teachings of the above described U.S. Pat. Nos. 4,969,888
and 5,108,404. For a vertebral body 26, access into the interior
volume 30 can be accomplished, for example, by drilling an access
portal 43 through either pedicle 42. This is called a
transpedicular approach, which FIG. 5 shows in lateral view and
FIG. 6 shows in coronal view. As FIG. 5 shows, the access portal 43
for a transpedicular approach enters at the top of the vertebral
body 26, where the pedicle 42 is relatively thin, and extends at an
angle downward toward the bottom of the vertebral body 26 to enter
the interior volume 30. As FIGS. 5 and 6 show, in a typical
transpedicular approach, the access portal 43 aligns the catheter
tube axis 60 obliquely with respect to all natural axes 66, 67, or
69 of the vertebral body 26.
[0053] As the conventional structure 56 expands within the interior
volume 30 (as FIGS. 7 and 8 show, respectively, in lateral and
coronal views for the transpedicular approach), the structure 56
symmetrically expands about the catheter tube axis 60, compressing
cancellous bone 32 to form a cavity 68. However, since the catheter
tube axis 60 is oriented obliquely relative to all natural axes 66,
67, or 69, the formed cavity is not centered with respect to the
middle region MR. Instead, the cavity 68 is offset on one lateral
side of the middle region MR (as FIG. 8 shows) and also extends
from top to bottom at oblique angle through the middle region MR
(as FIG. 7 shows).
[0054] Due to these, asymmetries, the cavity 68 will not provide
optimal support to the middle region MR when filled with bone
cement. Since the bone cement volume is not centered about the
middle region MR, the capability of the vertebral body 26 to
withstand loads is diminished. The asymmetric compaction of
cancellous bone 32 in the interior volume 30 may also exert unequal
or nonuniform interior forces upon cortical bone 32, making it
difficult to elevate or push broken and compressed bone.
[0055] As FIG. 9 shows, access to the interior volume 30 of the
vertebral body 26 also can be achieved by drilling an access portal
45 through a side of the vertebral body 26, which is called a
postero-lateral approach. The portal 45 for the postero-lateral
approach enters at a posterior side of the body 26 and extends at
angle forwardly toward the anterior of the body 26.
[0056] As FIG. 9 shows, the orientation of the portal 45 in a
typical postero-lateral approach does not permit parallel or
perpendicular alignment of the catheter tube axis 60 with either
the mid-lateral axis 67 or the mid-anterior-posterior axis 66 of
the vertebral 26. As a result, symmetric expansion of the
conventional structure 56 about the catheter tube axis 60 forms an
off-centered cavity 68', which extends obliquely across the middle
region MR of the body 26, as FIG. 10 view shows. As with the cavity
68 formed by the structure 56 using transpedicular access, the
off-centered cavity 68' formed by the structure 56 using
postero-lateral access also fails to provide optimal support to the
middle region MR when filled with bone cement.
[0057] A. Optimal Orientation for Cancellous Bone Compaction
[0058] FIG. 11A shows an improved bone treating tool 14, which
includes a catheter tube 16 carrying at its distal end 18 an
expandable structure 20. The catheter tube 16 can, at its proximal
end, be configured like the tube 50 shown in FIG. 3, with a handle
51 made of, e.g., a foam material.
[0059] FIG. 11A shows the structure 20 in a substantially expanded
condition, in which the structure comprises a cylinder 21 with
generally conical portions 34, each having a top 25 and a base 27.
The tops 25 of conical portions 34 are secured about the catheter
tube 16 and, in this respect, are generally aligned with the
catheter tube axis 24. However, unlike the expandable structure 56
shown in FIG. 4, the main axis 22 of the cylinder 21 and the axis
24 of the catheter tube 16 are not aligned. Instead, the cylinder
axis 22 is offset at an angle A from the catheter tube axis 24. As
a result, the structure 20, when substantially expanded (as FIG.
11A shows), is not symmetric with respect to the catheter tube axis
24.
[0060] In FIG. 11A, the bases 27 of the conical portions 34 extend
generally perpendicularly to the cylinder axis 22. In this
orientation, the tops 25 and the bases 27 are not parallel to each
other. Other orientations are possible. For example, in FIG. 11B,
the bases 27 of the conical portions 34 extend generally
perpendicularly to the catheter tube axis 24. In this orientation,
the tops 25 and the bases 27 are generally parallel to each
other.
[0061] FIG. 12 shows in lateral view, the offset structure 20 shown
in FIG. 11A deployed by a transpedicular approach in the interior
volume 30 of a vertebral body 26. As before shown in FIGS. 7 and 8,
the transpedicular approach in FIG. 12 does not align the catheter
tube axis 24 with any of the natural axes 66, 67, and 69 of the
body 26. However, as FIG. 12 shows, the expansion of the offset
cylinder 21 of the structure 20 about its axis 22 is not symmetric
with respect to the catheter tube axis 24. Instead, expansion of
the offset structure 20 is generally aligned with the natural axes
66 and 69 of the vertebral body 26. As FIG. 12 shows, a single
offset structure 20 introduced by transpedicular access, forms a
cavity 38 that, while still laterally offset to one side of the
middle region MR (as shown in FIG. 8), is nevertheless symmetric in
a top-to-bottom respect with the middle region MR. A matching,
adjacent cavity can be formed by transpedicular deployment of a
second offset structure 20 on the opposite lateral side of the
vertebral body 26. The composite cavity, formed by the two offset
bodies 20, introduced simultaneously or in succession by dual
transpedicular access, is substantially centered in all respects
about the middle region MR.
[0062] FIG. 13 shows the offset expandable structure 20 deployed by
a postero-lateral approach in the interior volume 30 of a vertebral
body 26. As before shown in FIG. 9, the postero-lateral approach in
FIG. 13 does not align the catheter tube axis 24 with the natural
axes 66 and 67 of the body 26. The expansion of the offset
structure 20, which is asymmetric about the catheter tube axis 24,
is nevertheless generally symmetric with respect to all natural
axes 66, 67, and 69 of the vertebral body 26. A single offset
structure 20, deployed by postero-lateral access, forms a cavity
38', which is substantially centered about the middle region
MR.
[0063] A cavity centered with respect to the middle region MR
provides support uniformly across the middle region MR when filled
with bone cement. The capability of the vertebral body 26 to
withstand loads is thereby enhanced. The symmetric compaction of
cancellous bone 32 in the interior volume 30 that a centered cavity
provides also exerts more equal and uniform interior forces upon
cortical bone 32, to elevate or push broken and compressed
bone.
[0064] FIGS. 14A and 14B show an expandable structure 200 having an
offset, asymmetric geometry different than the geometry of the
offset expandable structure 20 shown in FIGS. 11A and 11B. In FIGS.
11A and 11B, the offset angle A between the cylinder axis 22 and
the catheter tube axis 24 is an acute angle. As a result, the axis
22 of the structure 20 is offset in a nonparallel dimension or
plane relative to the catheter tube axis 24. In FIGS. 14A and 14B,
the offset angle A between the cylinder axis 220 and the catheter
tube axis 240 is zero, as the axis 220 of the cylinder 210 is
offset at a distance from and in a generally parallel dimension or
plane relative to the catheter tube axis 240. The catheter tube 160
can, at its proximal end, be configured like the tube 50 shown in
FIG. 3, with a handle 51 made of, e.g., a foam material.
[0065] As in FIGS. 11A and 11B, the tops 250 of conical portions
340 are secured about the catheter tube 160 and, in this respect,
are generally aligned with the catheter tube axis 240. In FIGS. 14A
and 14B, the orientation of the bases 270 of the conical portions
340 differ. In FIG. 14A, the bases 270 of the conical portions 340
extend generally perpendicularly to the catheter tube axis 240, and
are therefore generally parallel to the tops 250 (comparable to the
orientation shown in FIG. 11B). In FIG. 14B, the bases 270 of the
conical portions 340 extend at an angle B to the catheter tube axis
240. In this orientation, the tops 250 and the bases 270 are not
parallel to each other.
[0066] FIGS. 11A and 11B and 14A and 14B show that it is possible,
by adjustment of the offset angle A, as well as adjustment of the
orientation of the conical end bases, to achieve virtually any
desired offset geometry, and thereby tailor the orientation of the
expandable structure to the particular geometry of the point of
use.
[0067] B. Maximizing Cancellous Bone Compaction
[0068] Referring back to FIG. 4, when the conventional tubular
structure 56 shown in FIG. 4 is substantially expanded, material of
the structure is stretched into conical sections 62 near the ends
58, which are bonded to the catheter tube 50. FIG. 15 shows the
geometry of expanded tubular structure 56 in greater detail. The
conical portions 62 extend at a cone angle .alpha. from the bonded
ends 58. The expanded structure 56 therefore presents the generally
cylindrical middle region 64, where the maximum diameter of the
structure 56 (BODY.sub.DIA) exists, and the conical portions 62,
which comprise regions of diameter that decreases with distance
from the middle region 64 until reaching the diameter of the
catheter tube (TUBE.sub.DIA).
[0069] Due to the geometry shown in FIG. 15, maximum cancellous
bone compaction does not occur along the entire length (L2) of the
conventional structure 56, as measured between the bonded ends 58.
Instead, maximum cancellous bone compaction occurs only along the
effective length (L1) of the cylindrical middle region 64 of the
structure 56, where the structure 56 presents its maximum diameter
BODY.sub.DIA. Cancellous bone compaction diminishes along the
length of the conical portions 62, where the structure's diameter
progressively diminishes. At the bonded ends 58, and portions of
the catheter tube 50 extending beyond the bonded ends 58, no bone
compaction occurs. The catheter tube 50 can, at its proximal end,
be configured like the tube 50 shown in FIG. 3, with a handle 51
made of, e.g., a foam material.
[0070] The lengths (Lc) of the conical regions 62 and bonded ends
58 relative to the entire length of the structure 56 (L2) are
important indications of the overall effectiveness of the structure
56 for compacting cancellous bone. The effective bone compaction
length (L1) of any expandable structure having conical end regions,
such as structure 56 shown in FIG. 15, can be expressed as
follows:
L1=L2-2(Lc)
[0071] where the length of a given conical region (Lc) can be
expressed as follows:
Lc = h tan .alpha. 2 ##EQU00001##
where:
h = BODY DIA - TUBE DIA 2 ##EQU00002##
[0072] where (see FIG. 15): [0073] BODY.sub.DIA is the maximum
diameter of the middle region 64, when substantially expanded,
[0074] TUBE.sub.DIA is the diameter of the catheter tube 50, and
[0075] .alpha. is the angle of the conical portion.
[0076] As the foregoing expressions demonstrate, for a given
conical angle .alpha., the length Lc of the conical portions 62
will increase with increasing maximum diameter BODY.sub.DIA of the
middle region 64. Thus, as BODY.sub.DIA is increased, to maximize
the diameter of the formed cavity, the lengths Lc of the conical
portions 62 also increase, thereby reducing the effective length L1
of maximum cancellous bone compaction.
[0077] The bone compaction effectiveness of an expandable structure
of a given maximum diameter increases as L1 and L2 become more
equal. The geometry of a conventional tubular structure 56 shown in
FIG. 15 poses a tradeoff between maximum compaction diameter and
effective compaction length. This inherent tradeoff makes
optimization of the structure 56 for bone compaction application
difficult.
[0078] FIG. 16 shows an improved structure 70 having a geometry,
when substantially expanded, which mitigates the tradeoff between
maximum compaction diameter and effective compaction length. The
structure 70 includes a middle region 72, where BODY.sub.DIA
occurs. The structure 70 also includes end regions 74, which extend
from the middle region 72 to the regions 76, where the material of
the structure is bonded to the catheter tube 78, at TUBE.sub.DIA.
The catheter tube 78 can, at its proximal end, be configured like
the tube 50 shown in FIG. 3, with a handle 51 made of, e.g., a foam
material.
[0079] In the embodiment shown in FIG. 16, the end regions are
molded or stressed to provide a non-conical diameter transformation
between BODY.sub.DIA and TUBE.sub.DIA. The diameter changes over
two predefined radial sections r1 and r2, forming a compound curve
in the end regions 74, instead of a cone. The non-conical diameter
transformation of radial sections r1 and r2 between BODY.sub.DIA
and TUBE.sub.DIA reduces the differential between the effective
bone compaction length L1 of the structure 70 and the overall
length L2 of the structure 70, measured between the bond regions
76.
[0080] FIG. 17 shows another improved expandable structure 80
having a geometry mitigating the tradeoff between maximum
compaction diameter and effective compaction length. Like the
structure 70 shown in FIG. 16, the structure 80 in FIG. 16 includes
a middle region 82 of BODY.sub.DIA and end regions 84 extending
from the middle region to the bonded regions 86, at TUBE.sub.DIA.
As the structure 70 in FIG. 16, the end regions 84 of the structure
80 make a non-conical diameter transformation between BODY.sub.DIA
and TUBE.sub.DIA. In FIG. 17, the predefined radial sections r1 and
r2 are each reduced, compared to the radial section r1 and r2 in
FIG. 16. As a result, the end regions 84 take on an inverted
profile. As a result, the entire length L2 between the bonded
regions 86 becomes actually less than the effective length L1 of
maximum diameter BODY.sub.DIA. The catheter tube can, at its
proximal end, be configured like the tube 50 shown in FIG. 3, with
a handle 51 made of, e.g., a foam material.
[0081] The structures 70 and 80, shown in FIGS. 16 and 17, when
substantially inflated, present, for a given overall length L2,
regions of increasingly greater proportional length L1, where
maximum cancellous bone compaction occurs.
[0082] Furthermore, as in FIG. 17, the end regions 84 are inverted
about the bonded regions 86. Due to this inversion, bone compaction
occurs in cancellous bone surrounding the bonded regions 86.
Inversion of the end regions 84 about the bonded regions 86
therefore makes it possible to compact cancellous bone along the
entire length of the expandable structure 80.
[0083] FIG. 18 shows another embodiment of an improved expandable
structure 90. Like the structure 80 shown in FIG. 17, the structure
90 includes a middle region 92 and fully inverted end regions 94
overlying the bond regions 96. The structure 80 comprises, when
substantially collapsed, a simple tube. At least the distal end of
the tubular structure 80 is mechanically tucked or folded inward
and placed into contact with the catheter tube 98. As shown in FIG.
18, both proximal and distal ends of the tubular structure are
folded over and placed into contact with the catheter tube 98. The
catheter tube 98 can, at its proximal end, be configured like the
tube 50 shown in FIG. 3, with a handle 51 made of, e.g., a foam
material.
[0084] The catheter tube 98 is dipped or sprayed beforehand with a
material 102 that absorbs the selected welding energy, for example,
laser energy. The folded-over ends 94 are brought into abutment
against the material 102. The welding energy transmitted from an
external source through the middle region 92 is absorbed by the
material 102. A weld forms, joining the material 102, the
folded-over ends 94, and the catheter tube 50. The weld constitutes
the bond regions 96.
[0085] The inverted end regions 94 of the structure 90 achieve an
abrupt termination of the structure 90 adjacent the distal end 104
of the catheter tube 98, such that the end regions 94 and the
distal catheter tube end 104 are coterminous. The structure 90
possesses a region of maximum structure diameter, for maximum
cancellous bone compaction, essentially along its entire length.
The structure 90 presents no portion along its length where bone
compaction is substantially lessened or no cancellous bone
compaction occurs.
[0086] FIGS. 19 and 20 show another embodiment of an expandable
structure 110. As FIG. 20 shows, the structure 110 includes a
middle region 112 of maximum diameter BODY.sub.DIA and inverted end
regions 114, which overlie the bonded regions 116.
[0087] FIG. 19 shows the structure 110 before the end regions 114
have been inverted in the manufacturing process. As FIG. 19 shows,
the structure 110 comprises, when substantially collapsed, a simple
tube. To facilitate formation of the inverted end regions 114 and
bonded regions 116, a two-piece catheter tube is provided,
comprising an outer catheter tube 118 and an inner catheter tube
120. The inner catheter tube 120 slides within the outer catheter
tube 118. The catheter tube 118 can, at its proximal end, be
configured like the tube 50 shown in FIG. 3, with a handle 51 made
of, e.g., a foam material.
[0088] As FIG. 19 shows, during the manufacturing process, the
inner catheter tube 120 is moved a first distance d1 beyond the
outer catheter tube 118. In this condition, the proximal and distal
ends 122 and 124 of the tubular structure 110 are bonded, without
folding over or tucking in, about the inner catheter tube 118 and
the outer catheter tube 120, respectively. The unfolded ends 122
and 124 of the tubular structure 110 can then be directly exposed
to conventional adhesive or melt bonding processes, to form the
bonded regions 116.
[0089] Once the bonded regions 116 are formed, the inner catheter
tube 120 is moved (see arrow 130 in FIG. 20) to a distance d2
(shorter than d1) from the end of the outer catheter tube 118. The
shortening of the inner tube 120 relative to the outer tube 120
inverts the ends 122 and 124. The inversion creates double jointed
end regions 116 shown in FIG. 20, which overlie the bonded regions
116. The relative position of the outer and inner catheter tubes
118 and 120 shown in FIG. 20 is secured against further movement,
e.g., by adhesive, completing the assemblage of the structure
110.
[0090] The double jointed inverted ends 114 of the structure 110 in
FIG. 20, like single jointed inverted ends 94 of the structure 90
in FIG. 18, assure that no portion of the catheter tube protrudes
beyond the expandable structure. Thus, there is no region along
either structure 94 or 114 where cancellous bone compaction does
not occur. Like the structure 90 shown in FIG. 18, the structure
110 in FIG. 20 presents a maximum diameter for maximum cancellous
bone compaction essentially along its entire length.
[0091] FIG. 21 shows another embodiment of an improved expandable
structure 300 well suited for deployment in an interior body
region. Like the structure 110 shown in FIGS. 19 and 20, the
structure 300 in FIG. 21 includes an inner catheter tube 304
secured within an outer catheter tube 302. Like the structure 110
shown in FIGS. 19 and 20, the distal end 310 of the inner catheter
tube 304 in FIG. 21 extends beyond the distal end 308 of the outer
catheter tube 302.
[0092] The outer diameter of the inner catheter tube 304 is
likewise smaller than the inner diameter of the outer catheter tube
302. A flow passage 312 is defined by the space between the two
catheter tubes 302 and 304.
[0093] The proximal end 314 of an expandable body 306 is bonded to
the distal end 308 of the outer catheter tube 302. The distal end
316 of the expandable body 306 is bonded to the distal end 310 of
the inner catheter tube 304. An inflation medium 318 is conveyed
into the body 306 through the flow passage 312, causing expansion
of the body 306.
[0094] In FIG. 21, the physical properties of the structure 300 at
the proximal body end 314 differ from the physical properties of
the structure 300 at the distal body end 316. The different
physical properties are created by material selection. More
particularly, materials selected for the inner catheter tube 304
and the expandable body 306 are more compliant (i.e., more elastic)
than the materials selected for the outer catheter tube 302. In a
preferred embodiment, materials selected for the expandable body
306 and the inner catheter tube 304 possess hardness properties of
less than about 90 Shore A and ultimate elongation of greater than
about 450%, e.g., more compliant polyurethanes. In a preferred
embodiment, materials selected for the outer catheter tube 302
possess hardness properties of greater than about 45 Shore D and
ultimate elongation of less than about 450%, e.g., less compliant
polyurethanes or polyethylenes.
[0095] Due to the differential selection of materials, the lack of
compliance of the outer catheter tube 302 at the proximal body end
314 is counterpoised during expansion of the body 306 against the
compliance of the inner catheter tube 304 at the distal, body end
316. The different compliance characteristics causes the body 306,
during expansion, to increase in length in proportion to its
increase in diameter during expansion. By virtue of the more
compliant body 306 and inner catheter tube 304, the structure 300
shown in FIG. 21 is elastic enough to conform to an interior body
region, like inside a bone. Nevertheless, the structure 300 is
constrained from over-expansion by attachment of the proximal end
314 of the body 306 to the less elastic outer catheter tube
302.
[0096] The bond between a given expandable structure and its
associated catheter tube can be strengthened by using a CO2 or
NdYAG laser to weld the structure and tube materials together.
Factors influencing joint strength include energy wave length,
energy pulse width, pulse period, head voltage, spot size, rate of
rotation, working distance, angle of attack, and material
selection.
[0097] The catheter tube 302 can, at its proximal end, be
configured like the tube 50 shown in FIG. 3, with a handle 51 made
of, e.g., a foam material.
II. Deployment in the Vasculature
[0098] FIG. 22 shows a blood vasculature region 400. The region 400
includes a first blood vessel 402, which extends along a first axis
404. The region 400 also includes a second blood vessel 406, which
branches from the first blood vessel 402 along a second axis 408
offset from the first axis 404.
[0099] FIG. 22 also shows the presence of an occlusion 410 adjacent
the second blood vessel 406. The occlusion 410 can comprise, e.g.,
plaque buildup along the interior wall of the second blood vessel
406.
[0100] FIG. 23 shows the distal end of a tool 412, which has been
introduced into the vascular region 400 for the purpose of opening
the occlusion 410. The tool 412 comprises a catheter tube 416,
which carries at its distal end an expandable structure 420 of the
type shown in FIG. 11. The catheter tube 416 can, at its proximal
end, be configured like the tube 50 shown in FIG. 3, with a handle
51 made of, e.g., a foam material.
[0101] The catheter tube 416 is introduced by conventional vascular
introducer and, with fluoroscopic monitoring, steered to the
targeted region 400 along a guidewire 430 deployed within the first
and second vessels 402 and 406. The structure 420 is expanded using
a sterile fluid, like saline or a radio-contrast medium. FIG. 23
shows the structure 420 in a substantially expanded condition.
[0102] Like the expandable structure 20 shown in FIG. 11, the main
axis 422 of the structure 420 shown in FIG. 23 and the axis 424 of
the catheter tube 416 are not aligned. Instead, the structure axis
422 is offset at a selected acute angle A from the catheter tube
axis 424. Due to the offset angle A, the structure 420, when
substantially expanded (as FIG. 23 shows), is not symmetric with
respect to the catheter tube axis 424.
[0103] As FIG. 23 shows, the asymmetric expansion of the structure
420 allows the physician to maintain the catheter tube 416 in axial
alignment with the first blood vessel 402, while maintaining the
expandable structure 420 in axial alignment with the second blood
vessel 406. In this orientation, expansion of the structure 420
within the second blood vessel 406 opens the occlusion 410. The
asymmetry of the structure 420 relative to the catheter tube 416
thereby permits access to branched blood vessels without complex
manipulation and steering.
III. Deflection of the Structure
[0104] In all of the foregoing embodiments, a length of the
associated catheter tube extends within the expandable structure.
In the embodiments shown in FIGS. 4, 11A/B, 14A/B, and 15 to 18,
the enclosed catheter tube comprises an extension of the main
catheter tube. In the embodiments shown in FIGS. 19 to 21, the
enclosed catheter tube comprises a separate catheter tube carried
by the main catheter tube.
[0105] Regardless of the particular construction (see FIG. 26), the
enclosed length of catheter tube 600 provides an interior lumen 602
passing within the expandable structure 604. The lumen 602
accommodates the passage of a stiffening member or stylet 606 made,
e.g., from stainless steel or molded plastic material.
[0106] The presence of the stylet 606 serves to keep the structure
604 in the desired distally straightened condition during passage
through an associated guide sheath 608 toward the targeted body
region 610, as FIG. 26 shows. Access to the target body region 610
through the guide sheath 608 can be accomplished using a closed,
minimally invasive procedure or with an open procedure.
[0107] As shown in FIG. 27, the stylet 606 can have a preformed
memory, to normally bend the distal region 612 of the stylet 606.
The memory is overcome to straighten the stylet 606 when confined
within the guide sheath 608, as FIG. 26 shows. However, as the
structure 604 and stylet 606 advance free of the guide sheath 608
and pass into the targeted region 610, the preformed memory bends
the distal stylet region 612. The bend of the distal stylet region
612 bends the tube 600 and thereby shifts the axis 614 of the
attached expandable structure 604 relative to the axis 616 of the
access path (i.e., the guide sheath 608). The prebent stylet 606,
positioned within the interior of the structure 604, further aids
in altering the geometry of the structure 604 in accordance with
the orientation desired when the structure 604 is deployed for use
in the targeted region 610.
IV. Material Selection
[0108] In any of the foregoing embodiments, the material of the
expandable structure 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
structure 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.
[0109] If desired, the material for the structure 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 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 with generally elastic or
generally semi-elastic properties may require some form of external
or internal restraints to assure proper deployment in bone. The use
of internal or external restraints in association with expandable
bodies used to treat bone is discussed in greater detail in
copending U.S. patent application Ser. No. 08/485,394, filed Jun.
7, 1995, which is incorporated herein by reference.
[0110] Generally speaking, for use in treating bone, providing
relatively inelastic properties for the expandable structure, while
not always required, is nevertheless preferred, when maintaining a
desired shape and size within the bone is important, for example,
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. Use of relatively inelastic
materials also more readily permits the application of pressures
equally in a defined geometry to compress cancellous bone.
[0111] When treating bone, the choice of the shape and size of an
expandable structure takes into account the morphology and geometry
of the site to be treated. 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. The
physician is also able to select the materials and geometry desired
for the structure 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 structure are selected to optimize the formation of a cavity
that, when filled with bone cement, provide support across the
middle region of the bone being treated.
[0112] In some instances, it is desirable, when creating a cavity,
to also move or displace the cortical bone 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 structure 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.
[0113] As one general guideline, the selection of the geometry of
the expandable structure 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.
[0114] Another general guideline for the selection of the geometry
of the expandable structure is the amount that the targeted
fractured bone region has been displaced or depressed. The
expansion of the structure 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.
[0115] 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 structure can compact a smaller volume of total bone.
This is because the diseased area requiring treatment is
smaller.
[0116] Another exception lies in the use of an expandable structure
to improve insertion of solid materials in defined shapes, like
hydroxyapatite and components in total joint replacement. In these
cases, the structure shape and size is defined by the shape and
size of the material being inserted.
[0117] Yet another exception lays the use of expandable bodies in
bones to create cavities to aid in the delivery of therapeutic
substances, as disclosed in copending U.S. patent application Ser.
No. 08/485,394, previously mentioned. 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 structure 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.
[0118] The materials for the catheter tube are selected to
facilitate advancement of the expandable structure into cancellous
bone. The catheter tube 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 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 stainless steel, nickel-titanium alloys
(Nitinol.TM. material), and other metal alloys.
V. Single Use
[0119] Expansion of any one of the expandable structures described
herein during first use in a targeted body region generates stress
on the material or materials which make up the structure. The
material stress created by operational loads during first use in a
targeted body region can significantly alter the molded morphology
of the structure, making future performance of the structure
unpredictable.
[0120] For example, expansion within bone during a single use
creates contact with surrounding cortical and cancellous bone. This
contact can damage the structure, creating localized regions of
weakness, which may escape detection. The existence of localized
regions of weakness can unpredictably cause overall structural
failure during a subsequent use.
[0121] In addition, exposure to blood and tissue during a single
use can entrap biological components on or within the structure or
the associated catheter tube. Despite cleaning and subsequent
sterilization, the presence of entrapped biological components can
lead to unacceptable pyrogenic reactions.
[0122] As a result, following first use, the structure can not be
relied upon to reach its desired configuration during subsequent
use and may not otherwise meet established performance and
sterilization specifications. The effects of material stress and
damage caused during a single use, coupled with the possibility of
pyrogen reactions even after resterilization, reasonably justify
imposing a single use restriction upon devices which carry these
expandable structures for deployment in bone.
[0123] To protect patients from the potential adverse consequences
occasioned by multiple use, which include disease transmission, or
material stress and instability, or decreased or unpredictable
performance, the invention also provides a kit 500 (see FIGS. 24
and 25) for storing a single use probe 502, which carries an
expandable structure 504 described herein prior to deployment in
bone.
[0124] In the illustrated embodiment (see FIGS. 24 and 25), the kit
500 includes an interior tray 508. The tray 508 holds the probe 502
in a lay-flat, straightened condition during sterilization and
storage prior to its first use. The tray 508 can be formed from die
cut cardboard or thermoformed plastic material. The tray 508
includes one or more spaced apart tabs 510, which hold the catheter
tube 503 and expandable structure 504 in the desired lay-flat,
straightened condition. As shown, the facing ends of the tabs 510
present a nesting, serpentine geometry, which engages the catheter
tube 503 essentially across its entire width, to securely retain
the catheter tube 503 on the tray 508.
[0125] The kit 500 includes an inner wrap 512, which is
peripherally sealed by heat or the like, to enclose the tray 508
from contact with the outside environment. One end of the inner
wrap 512 includes a conventional peal-away seal 514 (see FIG. 25),
to provide quick access to the tray 508 upon instance of use, which
preferably occurs in a sterile environment, such as within an
operating room.
[0126] The kit 500 also includes an outer wrap 516, which is also
peripherally sealed by heat or the like, to enclosed the inner wrap
512. One end of the outer wrap 516 includes a conventional
peal-away seal 518 (see FIG. 25), to provide access to the inner
wrap 512, which can be removed from the outer wrap 516 in
anticipation of imminent use of the probe 502, without compromising
sterility of the probe 502 itself.
[0127] Both inner and outer wraps 512 and 516 (see FIG. 25) each
includes a peripherally sealed top sheet 520 and bottom sheet 522.
In the illustrated embodiment, the top sheet 520 is made of
transparent plastic film, like polyethylene or MYLAR.TM. material,
to allow visual identification of the contents of the kit 500. The
bottom sheet 522 is made from a material that is permeable to EtO
sterilization gas, e.g., TYVEC.TM. plastic material (available from
DuPont).
[0128] The sterile kit 500 also carries a label or insert 506,
which includes the statement "For Single Patient Use Only" (or
comparable language) to affirmatively caution against reuse of the
contents of the kit 500. The label 506 also preferably
affirmatively instructs against resterilization of the probe 502.
The label 506 also preferably instructs the physician or user to
dispose of the probe 502 and the entire contents of the kit 500
upon use in accordance with applicable biological waste procedures.
The presence of the probe 502 packaged in the kit 500 verifies to
the physician or user that probe 502 is sterile and has not be
subjected to prior use. The physician or user is thereby assured
that the expandable structure 504 meets established performance and
sterility specifications, and will have the desired configuration
when expanded for use.
[0129] The features of the invention are set forth in the following
claims.
* * * * *