U.S. patent application number 11/438683 was filed with the patent office on 2007-03-01 for bone probe apparatus and method of use.
Invention is credited to Richard W. Layne, Andrea Leung, Jeffrey D. Schwardt.
Application Number | 20070049849 11/438683 |
Document ID | / |
Family ID | 37452739 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070049849 |
Kind Code |
A1 |
Schwardt; Jeffrey D. ; et
al. |
March 1, 2007 |
Bone probe apparatus and method of use
Abstract
In one embodiment, an apparatus includes a probe configured to
be percutaneously deployed within an interior portion of a bone
structure. At least a portion of the probe is configured to contact
a portion of the interior portion of the bone structure when the
probe is actuated within the interior portion of the bone
structure. The apparatus also includes a pressure indicator that is
configured to provide pressure data associated with a pressure
externally exerted on the probe when the probe is actuated within
the interior portion of the bone structure. In some embodiments,
the probe includes an expandable member. In some embodiments, the
probe includes an expandable low-compliance balloon.
Inventors: |
Schwardt; Jeffrey D.; (Palo
Alto, CA) ; Leung; Andrea; (Milpitas, CA) ;
Layne; Richard W.; (Phoenix, AZ) |
Correspondence
Address: |
COOLEY GODWARD KRONISH LLP;ATTN: PATENT GROUP
THE BOWEN BUILDING
875 15TH STREET, N.W. SUITE 800
WASHINGTON
DC
20005-2221
US
|
Family ID: |
37452739 |
Appl. No.: |
11/438683 |
Filed: |
May 23, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60683803 |
May 24, 2005 |
|
|
|
Current U.S.
Class: |
600/587 |
Current CPC
Class: |
A61B 17/7097 20130101;
A61B 2017/00557 20130101; A61F 2/44 20130101; A61M 29/02 20130101;
A61B 17/8855 20130101 |
Class at
Publication: |
600/587 |
International
Class: |
A61B 5/103 20060101
A61B005/103 |
Claims
1. A method, comprising: inserting a probe into an interior portion
of a bone structure of a patient; actuating the probe such that at
least a portion of the probe contacts a portion of the interior
portion of the bone structure; and providing pressure data
associated with a pressure externally exerted on the probe while
the probe is within the interior portion of the bone structure.
2. The method of claim 1, further comprising: selecting a medical
device from a plurality of medical devices based on the pressure
data, the selected medical device configured to perform a procedure
within the interior portion of the bone structure.
3. The method of claim 1, wherein the probe includes a balloon, the
pressure indicator being coupled to the balloon, the actuating
includes inflating the balloon.
4. The method of claim 1, wherein: the probe includes a body and an
actuating tip movably coupled to the body; the pressure indicator
being disposed at the actuating tip; and the actuating includes
actuating the actuating tip.
5. The method of claim 1, further comprising: selecting a medical
device from a plurality of medical devices based on the pressure
data, the selected medical device configured to perform a procedure
within the interior portion of the bone structure, the medical
device including an expandable member; disposing the expandable
member within the interior portion of the bone structure; and
expanding the expandable member such that the expandable member
exerts pressure on at least a portion of the interior portion of
the bone structure.
6. The method of claim 1, wherein the bone structure is a vertebral
body.
7. The method of claim 1, wherein the actuating the probe includes
actuating the probe in a plurality of locations within the interior
portion of the bone structure, the method further comprising:
determining a profile of the interior portion of the bone structure
based on the pressure data associated with the plurality of
locations.
8. The method of claim 1, further comprising: selecting a medical
device from a plurality of medical devices based on the pressure
data, the selected medical device configured to perform a procedure
within the interior portion of the bone structure, the medical
device including an expandable member; disposing the expandable
member within the interior portion of the bone structure; and
expanding the expandable member, the expandable member having an
expanded size greater than a size of the probe.
9. The method of claim 1, further comprising: determining a
hardness of the interior portion of the bone structure based on the
pressure data.
10. An apparatus, comprising: a probe configured to be
percutaneously deployed within an interior portion of a bone
structure, at least a portion of the probe configured to contact a
portion of the interior portion of the bone structure when the
probe is actuated within the interior portion of the bone
structure; and a pressure indicator configured to provide pressure
data associated with a pressure externally exerted on the probe
when the probe is actuated within the interior portion of the bone
structure.
11. The apparatus of claim 10, wherein the probe includes an
expandable member, the pressure indicator being coupled to the
expandable member.
12. The apparatus of claim 10, wherein the probe includes a
low-compliance balloon, the pressure indicator being coupled to the
low-compliance balloon.
13. The apparatus of claim 10, wherein: the probe includes a body
and an actuating tip movably coupled to the body; and the pressure
indictor being disposed at the actuating tip.
14. The apparatus of claim 10, wherein the bone structure is a
vertebral body.
15. The apparatus of claim 10, wherein the pressure data is used to
identify a profile of the interior portion of the bone
structure.
16. The apparatus of claim 10, wherein the pressure indicator is a
first pressure indicator, the apparatus further comprising: a
second pressure indicator, the first pressure indicator and the
second pressure indicator each configured to contact a different
portion of the interior portion of the bone structure when the
probe is actuated within the interior portion of the bone
structure.
17. The apparatus of claim 10, wherein the pressure indicator is
configured to provide pressure data exerted on the expandable
member when the expandable member is in the expanded
configuration.
18. The apparatus of claim 10, wherein the probe includes a
low-compliance balloon configured to be expanded to a maximum
volume associated with a compressive strength of the bone structure
in which the balloon is disposed.
19. An apparatus, comprising: an elongate body; an expandable
member coupled to the elongate body, the expandable member having a
collapsed configuration and an expanded configuration, the
expandable member configured to be inserted into an interior
portion of a bone structure while the expandable member is in the
collapsed configuration; and a pressure indicator coupled to the
expandable member, the pressure indicator configured to contact at
least a portion of the interior portion of the bone structure when
the expandable member is in the expanded configuration, the
pressure indicator configured to transmit pressure data to a
location external to the bone structure.
20. The apparatus of claim 19, wherein the pressure indicator is
configured to detect pressure exerted on the expandable member when
the expandable member is in the expanded configuration.
21. The apparatus of claim 19, wherein the pressure indicator is a
first pressure indicator, the apparatus includes a second pressure
indicator, the first pressure indicator and the second pressure
indicator each configured to contact a different portion of the
interior portion of the bone structure when the expandable member
is in the expanded configuration within the interior portion of the
bone structure.
22. The apparatus of claim 19, wherein the expandable member
includes a low-compliance balloon.
23. The apparatus of claim 19, wherein: the expandable member
includes a body and an actuating tip movably coupled to the body;
and the pressure indicator is disposed at the actuating tip.
24. The apparatus of claim 19, wherein the bone structure is a
vertebral body.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to U.S. Provisional
Application No. 60/683,803 entitled "Low-Compliant Expandable
Medical Device," filed May 24, 2005, the disclosure of which is
incorporated herein by reference in its entirety.
BACKGROUND
[0002] The invention relates generally to medical devices and
procedures, and more particularly to a low-compliance expandable
medical device for use in medical procedures. For example, the
medical device may be inserted inside a bone structure to create a
cavity.
[0003] Inflatable devices are used in a variety of medical
procedures. Many inflatable medical devices are constructed with
elastic or highly-compliant materials that allow the inflatable
medical devices to expand within the particular space in which they
are deployed. The expansion path of the inflatable medical device
and the expanded shape of the device can at times be unpredictable,
as the device will typically expand within the space provided in a
path of least resistance. For example, for portions of a patient's
body having a non-uniform hardness, an inflatable medical device
may not expand in a predictable manner.
[0004] Thus, a need exists for different types of expandable
medical devices and methods for compacting or compressing tissue
(e.g., bone or soft tissue) within an interior area of a body of a
patient.
SUMMARY OF THE INVENTION
[0005] Apparatuses and methods for performing minimally-invasive
medical procedures are disclosed herein. In one embodiment, an
apparatus includes a probe configured to be percutaneously deployed
within an interior portion of a bone structure. At least a portion
of the probe is configured to contact a portion of the interior
portion of the bone structure when the probe is actuated within the
interior portion of the bone structure. The apparatus also includes
a pressure indicator that is configured to provide pressure data
associated with a pressure externally exerted on the probe when the
probe is actuated within the interior portion of the bone
structure. In some embodiments, the probe includes an expandable
member. In some embodiments, the probe includes an expandable
low-compliance balloon.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] The invention is described with reference to the
accompanying drawings. In the drawings, like reference numbers
indicate identical or functionally similar elements.
[0007] FIG. 1 is a side view of a medical device according to an
embodiment of the invention shown in an expanded configuration.
[0008] FIG. 2 is a side view of the medical device of FIG. 1 shown
in a collapsed configuration.
[0009] FIG. 3 is a partial cross-sectional side perspective view of
a medical device according to an embodiment of the invention shown
within a side perspective view of a vertebral body having a
cut-away portion.
[0010] FIG. 4 is an example of a graph of the expansion pressures
and inflation volumes for a high-compliance balloon and a
low-compliance balloon in a uniform surrounding medium.
[0011] FIG. 5 is a side view of an example of a high-compliance
balloon device in an expanded configuration shown positioned within
a cross-sectional view of a bone structure.
[0012] FIG. 6 is a side view of a portion of a medical device
according to an embodiment of the invention in an expanded
configuration and shown positioned within a cross-sectional view of
a bone structure.
[0013] FIG. 7 is a cross-sectional view of the bone structure of
FIG. 6 with the medical device shown expanded through a portion of
sclerotic bone within the bone structure.
[0014] FIG. 8 is a cross-sectional view of the bone structure of
FIG. 6 with the medical device shown expanded into contact with the
upper end plate of the bone structure.
[0015] FIG. 9 is a cross-sectional view of the bone structure of
FIG. 6 with the medical device shown expanded vertically such that
the upper/superior endplate of the bone structure is moved
upward.
[0016] FIG. 10 is an example of a graph illustrating expansion
pressures and inflation volumes associated with the expansion of a
low-compliance expandable member within a bone structure.
[0017] FIG. 11 is a side view of a bone probe according to an
embodiment of the invention shown positioned within a
cross-sectional view of a bone structure.
[0018] FIG. 12 is a side view of a bone probe according to an
embodiment of the invention shown positioned within a
cross-sectional view of a bone structure.
[0019] FIG. 13 is a side view of a bone probe according to another
embodiment of the invention shown positioned within a
cross-sectional view of a bone structure.
[0020] FIG. 14 is a side view of a platform portion according to an
embodiment of the invention positioned within a cross-sectional
view of a bone structure.
[0021] FIG. 15 is a side view of a portion of a medical device
according to an embodiment of the invention positioned within a
cross-sectional view of a bone structure.
[0022] FIG. 16 is a flowchart of a method of performing a medical
procedure within a bone structure according to an embodiment of the
invention.
[0023] FIG. 17 is a flowchart of a method of performing a medical
procedure within a bone structure according to another embodiment
of the invention.
[0024] FIG. 18 is a flowchart of a method of performing a medical
procedure within a vertebral body according to another embodiment
of the invention.
DETAILED DESCRIPTION
[0025] In at least some embodiments, the medical devices described
herein are configured for percutaneous deployment within an
interior area of a patient's body, such as within a bone structure
or soft tissue area of a patient. For example, a medical device
according to an embodiment of the invention may include an
expandable member configured to compact and forcibly displace bone
material (e.g., cancellous bone) within a bone structure, such as a
vertebra, of the patient when expanded. A medical device according
to an embodiment of the invention may also include an expandable
member configured to be movably disposed within a cannula.
[0026] Note that, as used in this specification and the appended
claims, the singular forms "a," "an" and "the" include plural
referents unless the context clearly dictates otherwise. Thus, for
example, the term "a lumen" is intended to mean a single lumen or a
combination of lumens. Furthermore, the words "proximal" and
"distal" refer to direction closer to and away from, respectively,
an operator (e.g., surgeon, physician, nurse, technician, etc.) who
would insert the medical device into the patient, with the tip-end
(i.e., distal end) of the device inserted inside a patient's body.
Thus, for example, the catheter end inserted inside the patient's
body would be the distal end of the catheter, while the catheter
end outside the patient's body would be the proximal end of the
catheter.
[0027] In one variation, an apparatus includes an elongate body and
an expandable member coupled to the elongate body. The expandable
member has a collapsed configuration, an unfolded configuration and
an expanded configuration. The expandable member is configured to
be percutaneously inserted into an interior portion of a bone
structure when the expandable member is in the collapsed
configuration. The expandable member when in the expanded
configuration is configured to exert a pressure in a vertical
direction on a first portion of the bone structure in contact with
the expandable member greater than a pressure exerted in a lateral
direction on a second portion of the bone structure in contact with
the expandable member when the expandable member transitions from
the unfolded configuration to the expanded configuration.
[0028] In another embodiment, an apparatus includes an elongate
body and an expandable member constructed with low-compliance
material releasably coupled to the elongate body. The expandable
member has a collapsed configuration and an expanded configuration.
The expandable member is configured to be percutaneously disposed
entirely within an interior portion of a single vertebral body. The
expandable member in the expanded configuration is configured to be
released from the elongate body and remain within the interior
portion of the vertebral body after the elongate body has been
removed from the vertebral body.
[0029] In yet another embodiment, an apparatus includes an elongate
body that defines a longitudinal axis, and an expandable member
constructed with low-compliance material. The expandable member is
configured to be disposed within an interior portion of a vertebral
body. The expandable member has a collapsed configuration and an
expanded configuration. The expandable member when in the expanded
configuration has a width substantially perpendicular to the
longitudinal axis and greater than a length substantially parallel
to the longitudinal axis. The expandable member when in the
expanded configuration is configured to exert a pressure on
cancellous bone disposed between the expandable member and an
endplate of the vertebral body.
[0030] In one embodiment, an expandable member, when in the
expanded configuration, is configured to exert forces in the
inferior-superior direction within a collapsed vertebral body to
restore the endplates to a proper anatomical position. The
expandable member is configured to undergo highly constrained
expansion in a lateral direction to prevent undesired force
exertion on the lateral cortices of the vertebral body.
[0031] The term "expandable member" is used here to mean a
component of the medical device that is configured to be changed or
moved from a collapsed configuration to an expanded configuration
in which the expandable member is larger than in the collapsed
configuration. The expandable member can be expanded, for example,
by introducing a medium such as fluid and/or gas into the interior
of the expandable member. The expandable member can be, for
example, a balloon configured to expand from a collapsed
configuration to an expanded configuration.
[0032] The term "cannula" is used here to mean a component of the
medical device having one or more channels configured to receive a
device therethrough and provide access to an interior region of a
patient's body. For example, the cannula can be substantially
tubular. The cannula can be a variety of different shapes and size,
such as having a round or octagonal outer perimeter, and can
include any suitable number of channels. In addition, the
channel(s) can be a variety of different shapes and sizes, such as
square, round, triangular, or any other suitable shape.
[0033] The term "elongate body" is used here to mean a component of
the medical device that is coupled to the expandable member. The
elongate body can be a variety of different shapes and size, such
as having a round or octagonal outer perimeter and can include one
or more channels. Alternatively, the elongate body can be solid
(i.e., no channels). The elongate body can also be configured to
provide the means to expand the expandable member with fluid or
gas. The elongate body can be, for example, a catheter.
[0034] FIG. 1 is a side view of a medical device 20 according to an
embodiment of the invention. Medical device 20 includes an elongate
body 22 having a proximal end portion (not shown) and a distal end
portion 26. An expandable member 28 is coupled to the distal end
portion 26 of the elongate body 22. The elongate body 22 defines a
longitudinal axis A1 and can be configured to provide, for example,
fluid or gas to expandable member 28. In some embodiments, the
expandable member 28 is configured to be expanded with a solid
material such as, for example, bone chips. The expandable member 28
can be moved between a collapsed configuration, as shown in FIG. 2,
and an expanded configuration, as shown in FIG. 1. In the collapsed
configuration, the medical device 20 can be percutaneously inserted
into a patient's body. The expandable member 28 can be expanded by
introducing gas, fluid, solids or other suitable material into an
interior area of the expandable member. In one embodiment, the
expandable member 28 is configured to expand a greater distance in
a direction substantially perpendicular to the axis A1 than in a
direction substantially parallel to the axis A1.
[0035] In an alternative embodiment, a medical device according to
an embodiment of the invention can also include a cannula 30, such
as medical device 120 shown in FIG. 3. The cannula 30 defines an
axis A2 and can include one or more channels 32 in which the
elongate body 22 and the expandable member 28 can be movably
disposed when the expandable member 28 is in the collapsed
configuration. The cannula 30 is configured to provide percutaneous
access to an interior portion of a patient through the channel 32.
For example, the cannula 30 can be used to provide access to an
interior portion of a bone structure, such as a vertebral body B of
a patient as shown in FIG. 3, to perform a medical procedure within
the bone structure.
[0036] The expandable member 28 is constructed with a
low-compliance material, which provides the expandable member 28
with more predictable expanding characteristics than inflatable
devices constructed with high-compliance materials.
[0037] Because the expandable member 28 is constructed with
low-compliance materials, the expandable member 28 can be
configured such that it will expand in a predictable manner. For
example, the expandable member can be configured to expand to a
predetermined profile (shape and size), in a predetermined
direction. The expandable member 28 can also have a predetermined
pressure in an unfolded configuration, a predetermined compressive
stress or exerted pressure in an expanded configuration, and a
predetermined expansion height. Thus, the expandable member 28 can
be pre-calibrated for the particular body area, type of body
composition (e.g., soft or hard bone, soft or hard tissue, or a
region of bone or tissue having varying hardness through the
region) and type of procedure to be performed. The low-compliance
material of the expandable member 28 is also more puncture
resistant, as well as monomer resistant, than a high-compliance
material. In some embodiments, the expandable member 28 can be
constructed with low-compliance material having varying compliancy
as a function, for example, of time and/or temperature.
[0038] A low-compliance balloon, such as expandable member 28, has
different performance characteristics than a high-compliance
balloon. For example, FIG. 4 illustrates an example graph comparing
pressure vs. volume during expansion of a low-compliance balloon
and a high-compliance balloon within a uniform surrounding medium
(e.g., air). The vertical axis is the pressure (measured in pounds
per square inch (PSI)) within the interior of the balloon. The
pressure the balloon exerts on the surrounding medium may be the
same or different from the pressure within the interior of the
balloon depending upon the situation. For example, the pressure the
balloon exerts on the surrounding medium can be the same as the
pressure in the interior of the balloon when the balloon is
expanded at a substantially constant rate. In addition, in
situations where the balloon is expanded in a non-uniform medium,
the pressure exerted on the medium may be different at different
portions of the medium. For example, in relatively softer bone or
tissue structures the pressure may be relatively low, and in
relatively harder bone structures the pressure may be relatively
high.
[0039] The horizontal axis of the graph illustrated in FIG. 4 is
the inflation volume (measured in cubic centimeters (cc)) within
the balloons as they are inflated. As shown in the graph, the
pressure of a high-compliance balloon increases quickly as the
balloon unfolds or starts to expand (region F), then levels off to
a substantially constant pressure (region G) as more volume is
introduced into the balloon. Because a high-compliance balloon
stretches as the volume introduced into the balloon increases, the
pressure remains relatively constant once the high-compliance
balloon is unfolded. As more volume is introduced, instead of
pressure building up within the balloon, the balloon stretches to
accommodate the increased volume. Thus, after a high-compliance
balloon is fully unfolded (point H) the pressure is substantially
the same as when the high-compliance balloon is fully expanded
(point I).
[0040] In contrast, the pressure of a low-compliance balloon will
increase at a slow rate initially as the balloon unfolds (region
J). When the low-compliance balloon is substantially unfolded
(point K), the pressure will be relatively low. For example, during
the unfolding, when the balloon is partially unfolded and without
contacting an obstruction, the balloon can exert a relatively low
pressure in a lateral and/or vertical direction. When the balloon
encounters an obstruction (i.e., a material or portion harder than
another material or portion within the surrounding medium),
however, the balloon can exert a relatively low pressure in one
direction (e.g., the horizontal direction (lateral or longitudinal)
and a relatively high pressure in a different direction (e.g., the
vertical direction). In such a case, the balloon can be, for
example, fully unfolded in the lateral direction and only partially
unfolded in the vertical direction. Here, the balloon transitions
from the unfolded configuration to the expanded configuration in
the sense that lateral expansion is limited by the low-compliance
material of the balloon and vertical expansion is limited by the
obstruction. In other cases, the balloon transitions from the
unfolded configuration to the expanded configuration when the
balloon is fully unfolded and additional volume is introduced into
the balloon.
[0041] As shown in FIG. 4, once fully or substantially unfolded, as
more volume is introduced into the balloon, the pressure will
increase (region L) to a maximum level (point M) in which the
balloon is in a substantially expanded configuration. For example,
during the expanding from the fully unfolded configuration to the
expanded configuration, the balloon can exert a relatively high
pressure on the surrounding medium. During this transition and once
at the maximum level (fully expanded), the balloon may only be able
to expand or stretch some nominal amount (e.g., approximately 5%)
before bursting. Because a low-compliance balloon is only able to
stretch a minimal amount, the low-compliance balloon exerts a
relatively high pressure for a very short period of time and then
drops to a substantially zero pressure when it burst as shown on
the graph at region N.
[0042] In some embodiments, the predetermined shape and size of a
low-compliance balloon can be selected so that when the balloon is
substantially unfolded within a bone structure or other tissue, it
will be positioned adjacent to a region of bone or tissue having a
relatively hard portion that a medical practitioner seeks to
compress, move or break. By fully expanding the balloon to an
expanded configuration when adjacent to such a hard region of bone
or tissue, the hard region of bone or tissue will be subject to a
relatively high pressure of the expanding balloon (see, for
example, region L of FIG. 10). As a result, a relatively high
pressure can be applied to a desired region of bone or tissue with
minimal risk that the low-compliance balloon will expand into an
undesired direction or distance (e.g., through a vertebral endplate
or cortical lateral wall).
[0043] An expandable member 28 can be constructed and calibrated
such that the expandable member 28 has sufficient strength and can
apply sufficient pressure to break through relatively harder bone
(e.g., recalcitrant fractures, sclerotic bone, cortical bone). An
expandable member 28 can also be constructed and calibrated such
that the expandable member 28 has lower exertion pressures for use
in softer bone and tissue areas. An expandable member 28 can be
constructed and calibrated such that it expands vertically a
greater distance than it expands laterally, and can be constructed
and calibrated to expand to a variety of different profiles (shapes
and sizes), including a variety of different expansion heights
and/or widths. Thus, a variety of different low-compliance
expandable members 28 can be constructed having a variety of
different calibrations.
[0044] In an exemplary application of the medical device 20 (120)
according to an embodiment of the invention, the medical device 20
(120) is used to repair a collapsed vertebral body. As shown in
FIGS. 5-9, which illustrate cross-sectional views of a vertebral
body B, an upper endplate E of the vertebral body B may become
damaged or collapsed, for example, by a fracture in a cortical
lateral wall L causing the upper endplate E to partially collapse.
Known medical procedures can be performed to raise the upper
endplate E and restore the vertebral height using one of a variety
of different expandable devices. An interior portion of the
vertebral body B may also become damaged during or after the
collapse of the upper endplate E. After the damage has healed, a
portion of the interior of the vertebral body B may form a scarred
bone area, known as sclerotic bone S, as shown in FIGS. 5-9. The
sclerotic bone S is hard bone that a high-compliance balloon may,
in certain circumstances, be unable to penetrate or compact upon
expansion within the vertebral body B. The soft cancellous bone
within the interior of a vertebral body can be compacted with
approximately 5 MPa of pressure, whereas as sclerotic bone may
require approximately 80 MPa. A typical high-compliance balloon may
be unable to push through the sclerotic bone S, and will instead
expand in a path of least resistance, such as expanding laterally
and/or downwardly within the vertebral body B, as shown in FIG. 5.
FIG. 5 illustrates an example of a high-compliance balloon HB that
has expanded within the vertebral body B in a path of least
resistance. This type of expansion within a vertebral body can, in
this example, increase the risk of the balloon fracturing the lower
endplate E or lateral walls L of the vertebral body B. In such a
case, a high-compliance balloon will not be able to penetrate
through the sclerotic bone S to gain access to the collapsed upper
endplate E.
[0045] A low-compliance expandable member 28 described herein can
be configured, for example, to penetrate through the sclerotic bone
S and gain access to the upper endplate E, as shown in FIGS. 6-9.
Thus, the risk of fracturing or breaking through the lower endplate
or lateral walls of the vertebral body during expansion of the
expandable member is substantially reduced. In one embodiment, a
first medical device 20 (120) can be selected having an expandable
member 28 with selected calibration parameters, such as expansion
height, expansion profile, and expansion pressure, to allow it to
penetrate through the sclerotic bone S. The first medical device 20
(120) can be inserted into the vertebral body B and the expandable
member 28 expanded to an unfolded configuration in which it exerts
pressure and compacts at least a portion (e.g., a lower portion
below the sclerotic bone) of the cancellous bone C within the
vertebral body B, as shown in FIG. 6. Thus, a cavity can be created
within the interior of the vertebral body B below the sclerotic
bone S. Such a cavity may be created, for example, for insertion of
bone cement or other suitable material into the cavity. The
expandable member 28 can then be expanded to an expanded
configuration in which it exerts a greater pressure than in the
unfolded configuration such that the sclerotic bone S is penetrated
or broke-through, as shown in FIG. 7. The expandable member 28 can
then be expanded further such that it expands in a vertical
direction and contacts the upper end plate as shown in FIG. 8. The
upper endplate E will be moved upwardly reducing the fracture and
restoring at least a portion of the vertebral height, as shown in
FIG. 9. In some situations, the original vertebral height will be
restored. As an alternative to the above procedure, after the
expandable member 28 has broke through the sclerotic bone, a second
medical device 20 (120) having a differently calibrated expandable
member can be inserted into the vertebral body B and expanded such
that it contacts the upper endplate E. The second expandable member
can be further expanded such that the expandable member forces the
upper endplate E to be moved upwardly reducing the fracture and
restoring at least a portion of the vertebral height.
[0046] The second medical device 20 (120) may be calibrated such
that it expands vertically a greater distance than the first
medical device 20 (120) allowing it to contact the upper endplate
E. In addition, because the second medical device 20 (120) is being
deployed after the sclerotic bone S has been broke-through, the
required expansion pressure of the second medical device 20 (120)
can be less than what was required of the first medical device 20
(120). For example, the second medical device 20 (120) may compact
cancellous bone above the sclerotic bone S, while exerting a
relatively low pressure during the unfolding. Because the second
medical device 20 (120) does not have to penetrate sclerotic bone,
the second medical device 20 (120) can alternatively have an
expandable member constructed with high-compliance material.
[0047] In the embodiment described above with reference to FIGS.
6-9, where only one medical device 20 (120) is used, the expandable
member 28 can be formed with sufficient calibration parameters to
allow the expandable member 28 to penetrate the sclerotic bone
within a vertebral body. The expandable member 28 can be
constructed and calibrated with a size and pressure such that it
can penetrate the sclerotic bone and expand to a sufficient
vertical height while expanding to the expanded configuration. The
use of only one medical device 20 (120) may also be sufficient
where the pressure needed to break through sclerotic bone S is such
that unfolding is sufficient.
[0048] FIG. 10 is a graphical representation of an example of the
interior inflation pressures and volumes of a low-compliance
expandable member as it is expanded within a non-uniform medium
such as a vertebral body as described above with reference to FIGS.
6-9. Regions 6, 7, 8, and 9 on the graph represent the interior
volume and pressure that corresponds to the expansion of the
expandable member 28 illustrated in FIGS. 6-9, respectively. As the
expandable member is being unfolded within the vertebral body, the
expandable member will have a relatively small interior volume and
a relatively low interior pressure, as indicated at region 6 in
FIG. 10. When the expandable member contacts the sclerotic bone,
the pressure within the expandable member will build up to a peak
pressure indicated at P1 until the expandable member breaks through
the sclerotic bone. At the time the expandable member breaks
through the sclerotic bone, the pressure within the expandable
member will drop as indicated at region 7 on the graph. As the
expandable member is further expanded within the vertebral body,
the interior pressure will again begin to increase, as shown at
region 8, until it reaches a relatively high pressure as indicated
at region 9. If the expandable member were to continue to be
expanded, the expandable member would eventually reach a maximum
volume and corresponding maximum pressure P2. If the expandable
member is expanded beyond the maximum volume, the expandable member
will typically burst, dropping the volume and pressure to
substantially zero. That said, the example contemplated by FIGS.
6-10 and typically used would not involve the balloon bursting.
[0049] A low-compliance expandable member (or balloon as
hereinafter referred) can be manufactured with a variety of
materials, such as PET, Nylons, cross-linked Polyethylene,
Polyurethanes, and PVC that provide the balloon with the necessary
characteristics to effectively compact bone material. Some
parameters of low-compliance balloons include the tensile strength,
the compliance, the stiffness, the profile (i.e., the relative size
of the balloon when in its collapsed configuration prior to use)
and the maximum rated pressure (psi) of the balloon. A comparison
of various parameters for some example low-compliance balloon
materials is provided in the table below. The ratings (e.g. high,
medium, low) listed in the table are relative to low-compliance
balloons. TABLE-US-00001 Tensile Materials Strength Compliance
Stiffness Profile PET High-Very Low- High Low High Medium Nylons
Medium- Medium Medium Low- High Medium PE Low High Low High
cross-linked and other polyolefins Polyurethanes Low- Medium- Low-
Medium- Medium High Medium High PVC Low High Low High
(flexible)
Such parameters can also depend on structural specifications, such
as balloon wall thickness and length, width and/or other dimensions
of a balloon.
[0050] Low-compliance balloons can be manufactured with such
processes as an extrusion process or a blow molding process. A
variety of parameters can have an effect on the mechanical
properties of balloons manufactured with an extrusion process. Some
extrusion parameters include the temperature profile from the
feeding zone of the screw to the tooling, the tooling geometry, the
temperature of the cooling bath, the tubing dimensions, the
distance between the tooling and the cooling bath that affects the
degree of crystallization (the faster the tubing is cooled, the
more amorphous (more compliant) the final product), and the
rotational speed of the gear.
[0051] In a blow molding process, a variety of parameters also can
influence the balloon properties, such as the temperature of the
heating jaws, the pre-pressure/warm-up time, the forming pressure,
and the distal and proximal stretching. Among the above balloon
forming parameters, the forming pressure can be a parameter for
producing a balloon with a high burst pressure. For example,
increasing the forming pressure from 200 psi to 300 psi can
increase the burst pressure by 30 psi and can also shorten the
cycle time for manufacturing the balloon. In addition, the wall
thickness is a function of the forming pressure, the forming
temperature, and the warm-up time.
[0052] In some medical procedures, it may be desirable to determine
the shape and/or profile of the interior of a bone structure, as
well as the bone quality, prior to performing a procedure with the
medical device 20 (120) described above. Typically, an imaging
device, such as an X-ray or CT is used to obtain an image of the
bone structure to be treated. A biopsy may also be taken to
evaluate the bone quality. Using the image, a physician or other
medical professional can determine the size of balloon to use for a
particular medical procedure. Likewise, the biopsy may provide
information on the pressure that will be required to compact an
interior area of the bone.
[0053] In another embodiment of the invention, and as an
alternative to the above described procedures to evaluate the bone
quality, a bone probe can be used in conjunction with the medical
device 20 (120). Prior to using a medical device 20 (120), a bone
probe can be deployed within the interior portion of a bone
structure. As shown in FIG. 11, a bone probe 40 can include a small
low-compliance expandable member (e.g., balloon) 42 as described
above, coupled to a pressure indicator 44. The pressure indicator
44 can be, for example, coupled to an inflation syringe 45 that is
also coupled to the balloon 42, as shown schematically in FIG. 11.
As the balloon 42 is expanded within the interior area of a bone
structure (or other interior area of the patient), the pressure
indicator 44 can detect the internal pressure of the balloon 42,
and transmit or output the pressure information to a location
external to the patient. For example, the pressure data can be
provided via a digital output, an analog output (e.g., dial
indicator) or other visual pressure display. The information (e.g.,
pressure data) can be used to determine the bone quality (e.g.,
stiffness, force and/or stress). For example, the higher the
pressure within the balloon, the stronger the bone quality. The
bone probe 40 could also be configured to transmit location and/or
size information regarding the interior area of the bone structure.
The pressure required to expand the probe balloon to its maximum
volume can relate to the ultimate compressive strength of the bone
structure in which the balloon is disposed. This can provide
information on the density of the bone within the bone structure in
the particular region where, for example, height restoration and/or
fracture reduction, may be desired. Such a bone probe balloon can
be calibrated to correlate inflation pressure at full volume to
bone compressive strength, which can then aid the physician and/or
other medical professional in selecting a medical device 20 (120)
having an expandable member 28 with the desired calibration
parameters to perform the particular procedure.
[0054] In another embodiment, a probe can include an expandable
member and a pressure indicator coupled directly to the expandable
member. As shown in FIG. 12, a probe 140 can include an expandable
member 142, and a pressure indicator 144 coupled to the expandable
member 142. In such an embodiment, when the probe 140 is actuated
within a bone structure B, the pressure indicator 142 contacts an
interior portion of the bone structure B. The pressure indicator
142 can transmit pressure data to a location exterior to the bone
structure as with the previous embodiment.
[0055] In an alternative embodiment, a bone probe 240 can include
an expandable mechanical member 242, instead of balloon 42 or 142,
as shown in FIG. 13. For example, the expandable mechanical member
242 can have a plunger body 246 having an actuating tip 248 on a
distal end. The tip 248 includes a pressure indicator 244 and is
configured to tap or push against the bone to determine, for
example, the force, stiffness, or stress of the bone and output the
information to a visual output (e.g., digital output, analog
output, etc.) external to the patient, as with the previous
embodiment.
[0056] In some medical procedures, for example, a procedure
performed on a vertebral body, it may be desirable to perform a
first procedure to create a platform within the bone structure on
which a medical device 20 (120) can be supported. For example, a
procedure may include inserting a device, such as a medical device
20 (120) or other suitable medical device, into the vertebral body
and actuating or expanding the device such that it compacts the
cancellous bone in the interior of the vertebral body and creates a
cavity. Once the cavity is created, bone cement or other suitable
material is introduced into the cavity to create a solid or hard
platform portion P within the vertebral body B, as shown in FIG.
14. A medical device 20 (120) can then be inserted into the
interior area of the vertebral body using the platform portion P as
a base support, as shown in FIG. 15. This type of procedure may be
desirable, for example, where it is determined that the sclerotic
bone S is strong in comparison to the lower endplate E. In such a
case, to ensure that the endplate E is not fractured during the
expansion of the expandable member 28 of medical device 20 (120), a
platform portion P may be created for added support.
[0057] In another embodiment of the invention, a kit can be
provided including multiple medical devices 20 (120) and/or
multiple expandable members 28. The kit can include expandable
members having various constructions and calibrations. A physician
or other medical professional can select from the kit the
appropriate medical device(s) 20 (120) to use for the particular
patient and/or procedure. The kit can include replacement
expandable members 28 configured to be removably attached to a
cannula and/or other medical device. In some embodiments the kit
can also include one or more bone probes 42 (142). As described
above, a particular medical procedure may require the use of one or
more medical devices 20 (120) and or the use of a bone probe 42
(142). A kit provides the physician or other medical professional
with a variety of optional medical devices 20 (120) to select from
depending on the particular procedure to be performed.
[0058] FIG. 16 is a flowchart illustrating a method of performing a
medical procedure within a bone structure according to an
embodiment of the invention. A method can include inserting an
expandable member while in a collapsed configuration into an
interior portion of a bone structure, such as a vertebral body, at
40. In some embodiments, prior to inserting the expandable member
into the interior of the bone structure, a cannula can optionally
be inserted into the interior portion of the bone structure at 38.
The expandable member can then be inserted through the cannula when
the expandable member is inserted into the interior of the bone
structure. The expandable member can be constructed with a
low-compliance material. The expandable member can be expanded
while inserted in the interior portion of the bone structure such
that the expandable member expands to an unfolded configuration at
42. At 44, the expandable member can be expanded while inserted in
the interior portion of the bone structure such that the expandable
member moves from the unfolded configuration to an expanded
configuration and such that the expandable member exerts a pressure
in a vertical direction on a first portion of the interior portion
of the bone structure in contact with the expandable member greater
than a pressure exerted in a lateral direction on a second portion
of the bone structure in contact with the expandable member. In
some embodiments, when expanding the expandable member to move the
expandable member from the unfolded configuration to the expanded
configuration, the expandable member expands a greater distance in
a direction perpendicular to a longitudinal axis defined by the
elongate body than in a direction parallel to the axis.
[0059] In some embodiments, the expandable member is releasably
coupled to an elongate body. In such an embodiment, the expandable
member can optionally be released from the elongate body while the
expandable member is within the interior of the bone structure and
the elongate body can be removed from the interior of the bone
structure at 46, leaving the expandable member within the interior
of the bone structure.
[0060] FIG. 17 is a flowchart illustrating another method for
performing a medical procedure within a bone structure according to
an embodiment of the invention. A method includes at 50, inserting
a probe into an interior portion of a bone structure of a patient.
In some embodiments, the probe can include an expandable member
coupled to a pressure indicator. In some embodiments, the probe
includes a body and an actuating tip movably coupled to the body.
In such an embodiment, the pressure indicator can be disposed at
the actuating tip. At 52, the probe can be actuated such that at
least a portion of the probe contacts a portion of the interior
portion of the bone structure. In some embodiments, the probe can
be actuated multiple times at different locations. At 54, pressure
data can be provided that is associated with a pressure exerted
externally on the probe while inserted within the interior of the
bone structure. At 56, a profile of the interior portion of the
bones structure can optionally be determined based on the pressure
data. The hardness of the interior portion of the bone structure
can also optionally be determined at 58.
[0061] In some embodiments, a medical device configured to perform
a procedure within the bone structure can optionally be selected
based on the pressure data at 60. In some embodiments, the medical
device can include an expandable member. The expandable member of
the medical device can optionally be inserted into the bone
structure at 62. The expandable member can optionally be expanded
at 64 such that the expandable member exerts a pressure on at least
a portion of the interior of the bone structure. The expandable
member can have an expanded size greater than the probe.
[0062] FIG. 18 is a flowchart illustrating a method for performing
a medical procedure within a vertebral body according to the
invention. A method includes at 70 inserting an expandable member
into an interior portion of a bone structure, such as a vertebral
body, having a first portion of bone with a density and a second
portion of bone with a density less than the density of the first
portion. The expandable member can be constructed, for example,
with a low-compliance material. The first portion of the bone is
disposed apart from a cortical endplate of the vertebral body. For
example, the first portion of the bone can be sclerotic, cortical
or recalcitrant bone and the second portion of the bone can be
cancellous bone. At 72, the expandable member can be expanded while
disposed within the interior of the vertebral body such that the
expandable member exerts a pressure on the first portion of bone
sufficient to cause the first portion of bone to move. In some
embodiments, the expandable member can be coupled to an elongate
body that defines a longitudinal axis and when the expandable
member is expanded it can expand a greater distance in a direction
substantially perpendicular to the axis than in a direction
substantially parallel to the axis. At 74, after expanding the
expandable member to exert pressure on the first portion of bone,
the expandable member can optionally be expanded such that the
expandable member exerts pressure on an upper cortical endplate of
the vertebral body. At 76, in some embodiments, prior to inserting
the expandable member into the vertebral body, another expandable
member can optionally be inserted into the interior portion of the
vertebral body and expanded such that it exerts pressure on the
second portion of bone within the vertebral body. Such an
expandable member can have a set of pre-calibrated parameters
different from a set of pre-calibrated parameters of the other
expandable member. At 78, prior to inserting an expandable member
into the vertebral body, a cannula can optionally be inserted into
the vertebral body. The cannula can provide access to the interior
portion of the vertebral body.
[0063] While various embodiments of the invention have been
described above, it should be understood that they have been
presented by way of example only, and not limitation. Where methods
and steps described above indicate certain events occurring in
certain order, those of ordinary skill in the art having the
benefit of this disclosure would recognize that the ordering of
certain steps may be modified and that such modifications are in
accordance with the variations of the invention. Additionally,
certain of the steps may be performed concurrently in a parallel
process when possible, as well as performed sequentially as
described above. The invention has been particularly shown and
described with reference to specific embodiments thereof, but it
will be understood that various changes in form and details may be
made.
[0064] For example, in some embodiments, the expandable member 28
may be configured to be removably coupled to the elongate body 22
such that it can be released within the interior of a bone
structure of a patient and remain within the patient's body after
the medical procedure has been performed. In such an embodiment,
the expandable member 28 may be constructed with a low-compliance,
permeable material and expanded via the insertion of bone chips as
previously described. The permeability of the expandable member can
allow for bone growth to occur between the bone chips and the
surrounding bone structure.
[0065] In addition, more than one medical device 20 (120) may be
used to perform a medical procedure. For example, a first medical
device 20 (120) and a second medical device 20 (120) can be
inserted into a vertebral body and each expanded to create a
cavity. The first medical device 20 (120) can be removed, while the
second medical device 20 (120) remains in place within the
vertebral body. Bone cement or other suitable material may then be
inserted into the cavity created by the first medical device 20
(120). Thus, multiple medical devices 20 (120) can be used either
simultaneously or sequentially depending on the particular
procedure to be performed. Each of the medical devices 20 (120) can
have an expandable member 28 constructed with either low-compliance
or high-compliance material depending on the particular use of the
medical device 20 (120).
* * * * *