U.S. patent application number 11/450264 was filed with the patent office on 2006-10-12 for vertebral body having an altered native cancellous bone volume and related treatment methods.
Invention is credited to Mark A. Reiley, Arie Scholten, Karen Talmadge.
Application Number | 20060229631 11/450264 |
Document ID | / |
Family ID | 22692257 |
Filed Date | 2006-10-12 |
United States Patent
Application |
20060229631 |
Kind Code |
A1 |
Reiley; Mark A. ; et
al. |
October 12, 2006 |
Vertebral body having an altered native cancellous bone volume and
related treatment methods
Abstract
The native cancellous bone volume of a vertebral body is altered
to comprise a region of cancellous bone that has been compressed to
form a compressed bone region that peripherally defines a cavity
and another region of substantially uncompressed cancellous bone
occupying at least a portion of the remaining native cancellous
bone volume. A bone filling material occupies the cavity.
Inventors: |
Reiley; Mark A.; (Piedmont,
CA) ; Scholten; Arie; (Fremont, CA) ;
Talmadge; Karen; (Palo Alto, CA) |
Correspondence
Address: |
COOLEY GODWARD LLP;ATTN: PATENT GROUP
THE BOWEN BUILDING
875 15TH STREET, N.W. SUITE 800
WASHINGTON
DC
20005-2221
US
|
Family ID: |
22692257 |
Appl. No.: |
11/450264 |
Filed: |
June 12, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11214652 |
Aug 30, 2005 |
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11450264 |
Jun 12, 2006 |
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|
10747547 |
Dec 29, 2003 |
6981981 |
|
|
11214652 |
Aug 30, 2005 |
|
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|
10411573 |
Apr 10, 2003 |
|
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|
10747547 |
Dec 29, 2003 |
|
|
|
10200674 |
Jul 22, 2002 |
6663647 |
|
|
10411573 |
Apr 10, 2003 |
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|
09059796 |
Apr 13, 1998 |
6423083 |
|
|
10200674 |
Jul 22, 2002 |
|
|
|
08788786 |
Jan 23, 1997 |
6235043 |
|
|
09059796 |
Apr 13, 1998 |
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08188224 |
Jan 26, 1994 |
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08788786 |
Jan 23, 1997 |
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Current U.S.
Class: |
606/93 |
Current CPC
Class: |
A61F 2/28 20130101; A61F
2/441 20130101; A61F 2/4611 20130101; A61F 2002/30308 20130101;
A61F 2230/0013 20130101; A61F 2230/0065 20130101; A61B 17/742
20130101; A61F 2002/30253 20130101; A61M 2210/02 20130101; A61F
2002/2853 20130101; A61B 90/39 20160201; A61F 2002/30133 20130101;
A61F 2002/30586 20130101; A61F 2002/3611 20130101; A61M 2025/1072
20130101; Y10S 606/91 20130101; A61F 2230/0015 20130101; A61F
2/3601 20130101; A61F 2002/2828 20130101; A61F 2220/005 20130101;
A61B 2050/0065 20160201; A61F 2230/0071 20130101; A61M 25/10
20130101; A61B 17/8855 20130101; A61B 17/7258 20130101; A61F
2002/2871 20130101; A61F 2002/2825 20130101; A61F 2250/0058
20130101; A61F 2002/30909 20130101; A61M 25/1002 20130101; A61F
2/2846 20130101; A61F 2002/30288 20130101; A61F 2002/2835 20130101;
A61F 2002/4635 20130101; A61B 50/33 20160201; A61F 2002/30115
20130101; A61F 2002/30535 20130101; A61M 2210/1003 20130101; A61B
17/7097 20130101; A61B 17/7275 20130101; A61F 2002/2817 20130101;
A61F 2002/30677 20130101; A61M 29/02 20130101; A61F 2002/4062
20130101; A61B 2017/00544 20130101; A61F 2002/4627 20130101; A61B
10/025 20130101; A61F 2220/0075 20130101; A61B 17/744 20130101;
A61F 2002/30242 20130101; A61B 2017/0256 20130101; A61F 2002/30285
20130101; A61B 90/94 20160201; A61B 2017/00539 20130101; A61F
2002/30225 20130101; A61F 2310/0097 20130101; A61B 17/00234
20130101; A61F 2002/4217 20130101; A61F 2230/0008 20130101; A61M
2025/105 20130101; A61F 2/44 20130101; A61F 2002/30599 20130101;
A61B 2010/0258 20130101; A61F 2002/2892 20130101; A61F 2002/30462
20130101; A61M 25/1011 20130101; A61F 2002/30686 20130101; A61F
2002/2832 20130101; A61F 2/4601 20130101; A61F 2002/30125 20130101;
A61F 2002/30131 20130101; A61F 2002/30313 20130101; A61B 2017/00557
20130101; A61F 2002/30581 20130101; A61F 2002/3625 20130101; A61F
2002/4685 20130101; A61F 2310/00293 20130101; A61F 2002/30245
20130101; A61F 2230/0076 20130101; A61F 2230/0063 20130101; A61F
2230/0069 20130101; A61F 2310/00353 20130101; A61B 17/8866
20130101; A61F 2/389 20130101; A61F 2002/30113 20130101; A61F
2002/30228 20130101; A61B 2050/3015 20160201; A61B 17/025 20130101;
A61F 2002/30448 20130101; A61F 2002/302 20130101; A61F 2230/0006
20130101; A61F 2250/0063 20130101 |
Class at
Publication: |
606/093 |
International
Class: |
A61F 2/00 20060101
A61F002/00 |
Claims
1-5. (canceled)
6. An apparatus, comprising: a catheter; and an expandable member
coupled to the catheter and configured to move cancellous bone in a
vertebral body, the expandable member having a first expandable
region, a second expandable region and a substantially
non-expanding region, the substantially non-expanding region being
disposed between the first expandable region and the second
expandable regions.
7. The apparatus of claim 6, wherein the first expandable region
and the second expandable region are movable from a collapsed
configuration to an expanded configuration, the first expandable
region having a height in the collapsed configuration and a height
in the expanded configuration different from the height in a
collapsed configuration, the substantially non-expanding region
having a height that is less than the height of the first
expandable region in the expanded configuration.
8. The apparatus of claim 6, wherein the substantially
non-expanding region includes a crimp disposed between the first
expandable region and the second expandable region.
9. The apparatus of claim 6, wherein the substantially
non-expanding region defines a lumen between the first expandable
region and the second expandable region.
Description
RELATED APPLICATIONS
[0001] This application is a divisional of co-pending application
Ser. No. 10/747,547, filed Dec. 29, 2003, which is a divisional of
application Ser. No. 10/411,573, filed Apr. 10, 2003 (now
abandoned), which is a divisional of application Ser. No.
10/200,674, filed Jul. 22, 2002 (now U.S. Pat. No. 6,663,647),
which is a divisional of Ser. No. 09/059,796, filed Apr. 13, 1998
(now U.S. Pat. No. 6,423,083), which is a divisional of application
Ser. No. 08/788,786, filed Jan. 23, 1997 (now U.S. Pat. No.
6,235,043), which is a continuation of application Ser. No.
08/188,224, filed on Jan. 26, 1994 (now abandoned).
FIELD OF THE INVENTION
[0002] This invention relates to improvements in the surgical
treatment of bone conditions of the human and other animal bone
systems and, more particularly, to an inflatable balloon-like
device for use in treating such bone conditions. Osteoporosis,
avascular necrosis and bone cancer are diseases of bone that
predispose the bone to fracture or collapse. There are 2 million
fractures each year in the United States, of which about 1.3
million are caused by osteoporosis. Avascular necrosis and bone
cancers are more rare but can cause bone problems that are
currently poorly addressed.
BACKGROUND OF THE INVENTION
[0003] In U.S. Pat. Nos. 4,969,888 and 5,108,404, an apparatus and
method are disclosed for the fixation of fractures or other
conditions of human and other animal bone systems, both
osteoporotic and non-osteoporotic. The apparatus and method are
especially suitable for use in the fixation of, but not limited to,
vertebral body compression fractures, Colles fractures and
fractures of the proximal humerus.
[0004] The method disclosed in these two patents includes a series
of steps which a surgeon or health care provider can perform to
form a cavity in pathological bone (including but not limited to
osteoporotic bone, osteoporotic fractured metaphyseal and
epiphyseal bone, osteoporotic vertebral bodies, fractured
osteoporotic vertebral bodies, fractures of vertebral bodies due to
tumors especially round cell tumors, avascular necrosis of the
epiphyses of long bones, especially avascular necrosis of the
proximal femur, distal femur and proximal humerus and defects
arising from endocrine conditions).
[0005] The method further includes an incision in the skin (usually
one incision, but a second small incision may also be required if a
suction egress is used) followed by the placement of a guide pin
which is passed through the soft tissue down to and into the
bone.
[0006] The method further includes drilling the bone to be treated
to form a cavity or passage in the bone, following which an
inflatable balloon-like device is inserted into the cavity or
passage and inflated. The inflation of the inflatable device causes
a compacting of the cancellous bone and bone marrow against the
inner surface of the cortical wall of the bone to further enlarge
the cavity or passage. The inflatable device is then deflated and
then is completely removed from the bone. A smaller inflatable
device (a starter balloon) can be used initially, if needed, to
initiate the compacting of the bone marrow and to commence the
formation of the cavity or passage in the cancellous bone and
marrow. After this has occurred, a larger, inflatable device is
inserted into the cavity or passage to further compact the bone
marrow in all directions.
[0007] A flowable biocompatible filling material, such as
methylmethacrylate cement or a synthetic bone substitute, is then
directed into the cavity or passage and allowed to set to a
hardened condition to provide structural support for the bone.
Following this latter step, the insertion instruments are removed
from the body and the incision in the skin is covered with a
bandage.
[0008] While the apparatus and method of the above patents provide
an adequate protocol for the fixation of bone, it has been found
that the compacting of the bone marrow and/or the trabecular bone
and/or cancellous bone against the inner surface of the cortical
wall of the bone to be treated can be significantly improved with
the use of inflatable devices that incorporate additional
engineering features not heretofore described and not properly
controlled with prior inflatable devices in such patents. A need
has therefore arisen for improvements in the shape, construction
and size of inflatable devices for use with the foregoing apparatus
and method, and the present invention satisfies such need.
Prior Techniques for the Manufacture of Balloons for In-Patient
Use
[0009] A review of the prior art relating to the manufacture of
balloons shows that a fair amount of background information has
been amassed in the formation of guiding catheters which are
introduced into cardiovascular systems of patients through the
brachial femoral arteries. However, there is a scarcity of
disclosures relating to inflatable devices used in bone, and none
for compacting bone marrow in vertebral bodies and long bones.
[0010] In a dilatation catheter, the catheter is advanced into a
patient until a balloon is properly positioned across a lesion to
be treated. The balloon is inflated with a radiopaque liquid at
pressures above four atmospheres to compress the plaque of the
lesion to thereby dilate the lumen of the artery. The balloon can
then be deflated, then removed from the artery so that the blood
flow can be restored through the dilated artery.
[0011] A discussion of such catheter usage technique is found and
clearly disclosed in U.S. Pat. No. 5,163,989. Other details of
angioplasty catheter procedures, and details of balloons used in
such procedures can be found in U.S. Pat. Nos. 4,323,071,
4,332,254, 4,439,185, 4,168,224, 4,516,672, 4,538,622, 4,554,929,
and 4,616,652.
[0012] Extrusions have also been made to form prism shaped balloons
using molds which require very accurate machining of the interior
surface thereof to form acceptable balloons for angioplastic
catheters. However, this technique of extrusion forms parting lines
in the balloon product which parting lines are limiting in the
sense of providing a weak wall for the balloon itself.
[0013] U.S. Pat. No. 5,163,989 discloses a mold and technique for
molding dilatation catheters in which the balloon of the catheter
is free of parting lines. The technique involves inflating a
plastic member of tubular shape so as to press it against the inner
molding surface which is heated. Inflatable devices are molded into
the desired size and shape, then cooled and deflated to remove it
from the mold. The patent states that, while the balloon of the
present invention is especially suitable for forming prism-like
balloons, it can also be used for forming balloons of a wide
variety of sizes and shapes.
[0014] A particular improvement in the catheter art with respect to
this patent, namely U.S. Pat. No. 4,706,670, is the use of a
coaxial catheter with inner and outer tubing formed and reinforced
by continuous helical filaments. Such filaments cross each other
causing the shaft of the balloon to become shorter in length while
the moving portion of the shank becomes longer in length. By
suitably balancing the lengths and the angle of the weave of the
balloon and moving portions of the filaments, changes in length can
be made to offset each other. Thus, the position of the inner and
outer tubing can be adjusted as needed to keep the balloon in a
desired position in the blood vessel.
[0015] Other disclosures relating to the insertion of inflatable
devices for treating the skeleton of patients include the
following:
[0016] U.S. Pat. No. 4,313,434 relates to the fixation of a long
bone by inserting a deflated flexible bladder into a medullary
cavity, inflating the balloon bladder, sealing the interior of the
long bone until healing has occurred, then removing the bladder and
filling the opening through which the bladder emerges from the long
bone.
[0017] U.S. Pat. No. 5,102,413 discloses the way in which an
inflatable bladder is used to anchor a metal rod for the fixation
of a fractured long bone.
[0018] Other references which disclose the use of balloons and
cement for anchoring of a prosthesis include U.S. Pat. Nos.
5,147,366, 4,892,550, 4,697,584, 4,562,598, and 4,399,814.
[0019] A Dutch patent, NL 901858, discloses a means for fracture
repair with a cement-impregnated bag which is inflated into a
preformed cavity and allowed to harden.
[0020] It can be concluded from the foregoing review of the prior
art that there is little or no substantive information on
inflatable devices used to create cavities in bone. It does not
teach the shape of the balloon which creates a cavity that best
supports the bone when appropriately filled. It does not teach how
to prevent balloons from being spherical when inflated, when this
is desired. Current medical balloons can compress bone but are too
small and generally have the wrong configuration and are generally
not strong enough to accomplish adequate cavity formation in either
the vertebral bodies or long bones of the body.
[0021] U.S. Pat. Nos. 4,969,888 and 5,108,404 disclose a
checker-shaped balloon for compressing cancellous bone, but does
not provide information on how this balloon remains in its shape
when inflated.
[0022] Thus, the need continues for an improved inflatable device
for use with pathological bones and the treatment thereof.
SUMMARY OF THE INVENTION
[0023] The native cancellous bone volume of a vertebral body is
altered to comprise a region of cancellous bone that has been
compressed to form a compressed bone region that peripherally
defines a cavity and another region of substantially uncompressed
cancellous bone occupying at least a portion of the remaining
native cancellous bone volume. A bone filling material occupies the
cavity.
[0024] In one embodiment, a void creating device is introduced into
the native cancellous bone volume and manipulated to compress the
region of cancellous bone and form the cavity. In one embodiment,
the void creation device is expanded to compress the region of
cancellous bone and form the cavity.
[0025] Other objects of the present invention will become apparent
as the following specification progresses, reference being had to
the accompanying drawings for an illustration of the invention.
DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a perspective view of a first embodiment of the
balloon of the present invention, the embodiment being in the shape
of a stacked doughnut assembly.
[0027] FIG. 2 is a vertical section through the balloon of FIG. 1
showing the way in which the doughnut portions of the balloon of
FIG. 1, fit into a cavity of a vertebral body.
[0028] FIG. 3 is a schematic view of another embodiment of the
balloon of the present invention showing three stacked balloons and
string-like restraints for limiting the expansion of the balloon in
directions of inflation.
[0029] FIG. 4 is a top plan view of a spherical balloon having a
cylindrical ring surrounding the balloon.
[0030] FIG. 5 is a vertical section through the spherical balloon
and ring of FIG. 4.
[0031] FIG. 6 shows an oblong-shaped balloon with a catheter
extending into the central portion of the balloon.
[0032] FIG. 6A is a perspective view of the way in which a catheter
is arranged relative to the inner tubes for inflating the balloon
of FIG. 6.
[0033] FIG. 7 is a suction tube and a contrast injection tube for
carrying out the inflation of the balloon and removal of debris
caused by expansion from the balloon itself.
[0034] FIG. 8 is a vertical section through a balloon after it has
been deflated and as it is being inserted into the vertebral body
of a human.
[0035] FIGS. 9 and 9A are side elevational views of a cannula
showing how the protective sleeve or guard member expands when
leaving the cannula.
[0036] FIG. 9B is a vertical section through a vertebral bone into
which an access hole has been drilled.
[0037] FIG. 10 is a perspective view of another embodiment of the
balloon of the present invention formed in the shape of a kidney
bean.
[0038] FIG. 11 is a perspective view of the vertebral bone showing
the kidney shaped balloon of FIG. 10 inserted in the bone and
expanded.
[0039] FIG. 12 is a top view of a kidney shaped balloon formed of
several compartments by a heating element or branding tool.
[0040] FIG. 13 is a cross-sectional view taken along line 13-13 of
FIG. 12 but with two kidney shaped balloons that have been
stacked.
[0041] FIG. 14 is a view similar to FIG. 11 but showing the stacked
kidney shaped balloon of FIG. 13 in the vertebral bone.
[0042] FIG. 15 is a top view of a kidney balloon showing outer
tufts holding inner strings in place interconnecting the top and
bottom walls of the balloon.
[0043] FIG. 16 is a cross sectional view taken along lines 16-16 of
FIG. 15.
[0044] FIG. 17A is a dorsal view of a humpback banana balloon in a
right distal radius.
[0045] FIG. 17B is a cross sectional view of FIG. 17A taken along
line 17B-17B of FIG. 17A.
[0046] FIG. 18 is a spherical balloon with a base in a proximal
humerus viewed from the front (anterior) of the left proximal
humerus.
[0047] FIG. 19A is the front (anterior) view of the proximal tibia
with the elliptical cylinder balloon introduced beneath the medial
tibial plateau.
[0048] FIG. 19B is a three quarter view of the balloon of FIG.
19A.
[0049] FIG. 19C is a side elevational view of the balloon of FIG.
19A.
[0050] FIG. 19D is a top plan view of the balloon of FIG. 19A.
[0051] FIG. 20 is a spherically shaped balloon for treating
avascular necrosis of the head of the femur (or humerus) as seen
from the front (anterior) of the left hip.
[0052] FIG. 20A is a side view of a hemispherically shaped balloon
for treating avascular necrosis of the head of the femur (or
humerus).
DETAILED DESCRIPTION
[0053] The present invention is directed to a balloon-like
inflatable device or balloon for use in carrying out the apparatus
and method of the above-mentioned U.S. Pat. Nos. 4,969,888 and
5,108,404. Such inflatable devices, hereinafter sometimes referred
to as balloons, have shapes for compressing cancellous bone and
marrow (also known as medullary bone or trabecular bone) against
the inner cortex of bones whether the bones are fractured or
not.
[0054] In particular, the present invention is directed to a
balloon for use in treating a bone predisposed to fracture or to
collapse. The balloon comprises an inflatable, non-expandable
balloon body for insertion into said bone. The body has a
predetermined shape and size when substantially inflated sufficient
to compress at least a portion of the inner cancellous bone to
create a cavity in the cancellous bone and to restore the original
position of the outer cortical bone, if fractured or collapsed. The
balloon body is restrained to create said predetermined shape and
size so that the fully inflated balloon body is prevented from
applying substantial pressure to the inner surface of the outer
cortical bone if said bone is unfractured or uncollapsed.
[0055] In addition to the shape of the inflatable device itself,
another aspect of importance is the construction of the wall or
walls of the balloon such that proper inflation the balloon body is
achieved to provide for optimum compression of all the bone marrow.
The material of the balloon is also desirably chosen so as to be
able to fold the balloon so that it can be inserted quickly and
easily into a bone using a guide pin and a cannula, yet can also
withstand high pressures when inflated. The balloon can also
include optional ridges or indentations which are left in the
cavity after the balloon has been removed, to enhance the stability
of the filler. Also, the inflatable device can be made to have an
optional, built-in suction catheter. This is used to remove any fat
or fluid extruded from the bone during balloon inflation in the
bone. Also, the balloon body can be protected from puncture by the
cortical bone or canula by being covered while inside the canula
with an optional protective sleeve of suitable material, such as
Kevlar or PET or other polymer or substance that can protect the
balloon. The main purpose of the inflatable device, therefore, is
the forming or enlarging of a cavity or passage in a bone,
especially in, but not limited to, vertebral bodies.
[0056] The primary object of the present invention is to provide an
improved balloon-like inflatable device for use in carrying out a
surgical protocol of cavity formation in bones to enhance the
efficiency of the protocol, to minimize the time prior to
performing the surgery for which the protocol is designed and to
improve the clinical outcome. These balloons approximate the inner
shape of the bone they are inside of in order to maximally compress
cancellous bone. They have additional design elements to achieve
specific clinical goals. Preferably, they are made of inelastic
material and kept in their defined configurations when inflated, by
various restraints, including (but not limited to) use of inelastic
materials in the balloon body, seams in the balloon body created by
bonding or fusing separate pieces of material together, or by
fusing or bonding together opposing sides of the balloon body,
woven material bonded inside or outside the balloon body, strings
or bands placed at selected points in the balloon body, and
stacking balloons of similar or different sizes or shapes on top of
each other by gluing or by heat fusing them together. Optional
ridges or indentations created by the foregoing structures, or
added on by bonding additional material, increases stability of the
filler. Optional suction devices, preferably placed so that if at
least one hole is in the lowest point of the cavity being formed,
will allow the cavity to be cleaned before filling.
[0057] Among the various embodiments of the present invention are
the following:
[0058] 1. A doughnut (or torus) shaped balloon with an optional
built-in suction catheter to remove fat and other products extruded
during balloon expansion.
[0059] 2. A balloon with a spherical outer shape surrounded by a
ring-shaped balloon segment for body cavity formation.
[0060] 3. A balloon which is kidney bean shaped in configuration.
Such a balloon can be constructed in a single layer, or several
layers stacked on top of each other.
[0061] 4. A spherically shaped balloon approximating the size of
the head of the femur (i.e. the proximal femoral epiphysis). Such a
balloon can also be a hemisphere.
[0062] 5. A balloon in the shape of a humpbacked banana or a
modified pyramid shape approximating the configuration of the
distal end of the radius (i.e. the distal radial epiphysis and
metaphysis).
[0063] 6. A balloon in the shape of a cylindrical ellipse to
approximate the configuration of either the medial half or the
lateral half of the proximal tibial epiphysis. Such a balloon can
also be constructed to approximate the configuration of both halves
of the proximal tibial epiphysis.
[0064] 7. A balloon in the shape of sphere on a base to approximate
the shape of the proximal humeral epiphysis and metaphysis with a
plug to compress cancellous bone into the diaphysis, sealing it
off.
[0065] 8. A balloon device with optional suction device.
[0066] 9. Protective sheaths to act as puncture guard members
optionally covering each balloon inside its catheter.
[0067] The present invention, therefore, provides improved,
inflatable devices for creating or enlarging a cavity or passage in
a bone wherein the devices are inserted into the bone. The
configuration of each device is defined by the surrounding cortical
bone and adjacent internal structures, and is designed to occupy
about 70-90% of the volume of the inside of the bone, although
balloons that are as small as about 40% and as large as about 99%
are workable for fractures. In certain cases, usually avascular
necrosis, the balloon size may be as small as 10% of the cancellous
bone volume of the area of bone being treated, due to the localized
nature of the fracture or collapse. The fully expanded size and
shape of the balloon is limited by additional material in selected
portions of the balloon body whose extra thickness creates a
restraint as well as by either internal or external restraints
formed in the device including, but not limited to, mesh work, a
winding or spooling of material laminated to portions of the
balloon body, continuous or non-continuous strings across the
inside held in place at specific locations by glue inside or by
threading them through to the outside and seams in the balloon body
created by bonding two pieces of body together or by bonding
opposing sides of a body through glue or heat. Spherical portions
of balloons may be restrained by using inelastic materials in the
construction of the balloon body, or may be additionally restrained
as just described. The material of the balloon is preferably a
non-elastic material, such as polyethylene tetraphthalate (PET),
Kevlar or other patented medical balloon materials. It can also be
made of semi-elastic materials, such as silicone or elastic
material such as latex, if appropriate restraints are incorporated.
The restraints can be made of a flexible, inelastic high tensile
strength material including, but not limited, to those described in
U.S. Pat. No. 4,706,670. The thickness of the balloon wall is
typically in the range of 2/1000ths to 25/1000ths of an inch, or
other thicknesses that can withstand pressures of up to 250-400
psi.
[0068] A primary goal of percutaneous vertebral body augmentation
of the present invention is to provide a balloon which can create a
cavity inside the vertebral body whose configuration is optimal for
supporting the bone. Another important goal is to move the top of
the vertebral body back into place to retain height where possible,
however, both of these objectives must be achieved without
fracturing the cortical wall of the vertebral body. This feature
could push vertebral bone toward the spinal cord, a condition which
is not to be desired.
[0069] The present invention satisfies these goals through the
design of inflatable devices to be described. Inflating such a
device compresses the calcium-containing soft cancellous bone into
a thin shell that lines the inside of the hard cortical bone
creating a large cavity.
[0070] At the same time, the biological components (red blood
cells, bone progenitor cells) within the soft bone are pressed out
and removed by rinsing during the procedure. The body recreates the
shape of the inside of an unfractured vertebral body, but optimally
stops at approximately 70 to 90% of the inner volume. The balloons
of the present invention are inelastic, so maximally inflating them
can only recreate the predetermined shape and size. However,
conventional balloons become spherical when inflated. Spherical
shapes will not allow the hardened bone cement to support the spine
adequately, because they make single points of contact on each
vertebral body surface (the equivalent of a circle inside a square,
or a sphere inside a cylinder). The balloons of the present
invention recreate the flat surfaces of the vertebral body by
including restraints that keep the balloon in the desired shape.
This maximizes the contacts between the vertebral body surfaces and
the bone cement, which strengthens the spine. In addition, the
volume of bone cement that fills these cavities creates a thick
mantle of cement (4 mm or greater), which is required for
appropriate compressive strength. Another useful feature, although
not required, are ridges in the balloons which leave their imprint
in the lining of compressed cancellous bone. The resulting bone
cement "fingers" provide enhanced stability.
[0071] The balloons which optimally compress cancellous bone in
vertebral bodies are the balloons listed as balloon types 1, 2 and
3 above. These balloons are configured to approximate the shape of
the vertebral body. Since the balloon is chosen to occupy 70 to 90%
of the inner volume, it will not exert undue pressure on the sides
of the vertebral body, thus the vertebral body will not expand
beyond its normal size (fractured or unfractured). However, since
the balloon has the height of an unfractured vertebral body, it can
move the top, which has collapsed, back to its original
position.
[0072] One aspect of the invention provides a device for insertion
into a vertebral body to apply a force capable of compacting
cancellous bone and moving fractured cortical bone. The device
includes a catheter extending along an axis and having a distal end
sized and configured for insertion through a cannula into the
vertebral body. The catheter carries near its distal end an
inflatable body having a wall sized and configured for passage
within the cannula into the vertebral body when the inflatable body
is in a collapsed condition. The wall is further sized and
configured to apply the in response to expansion of the inflatable
body within the vertebral body. The wall includes, when inflated,
opposed side surfaces extending along an elongated longitudinal
axis that is substantially aligned with the axis of the catheter.
The inflatable body has a height of approximately 0.5 cm to 3.5 cm,
an anterior to posterior dimension of approximately 0.5 cm to 3.5
cm, and a side to side dimension of approximately 0.5 cm to 5.0
cm.
[0073] In a representative embodiment, the inflatable body
comprises a balloon and the cannula is a percutaneious cannula.
[0074] In another aspect of the invention, the wall includes
changes in wall thickness which restrain the opposed sided surfaces
from expanding beyond a substantially flat condition.
[0075] According to another aspect of the invention, the wall
includes an internal restraint which restrains the opposed side
surfaces from expanding beyond a substantially flat condition. The
internal restraint may include a mesh material, a string material,
a woven material, a seam, or an essentially non-elastic
material.
[0076] In yet another aspect of the invention, the wall includes an
external restraint which restrains the opposed side surfaces from
expanding beyond a substantially flat condition. The internal
restraint may include a mesh material, a string material, a woven
material, a seam, or an essentially non-elastic material.
[0077] A primary goal of percutaneous proximal humeral augmentation
is to create a cavity inside the proximal humerus whose
configuration is optimal for supporting the proximal humerus.
Another important goal is to help realign the humeral head with the
shaft of the humerus when they are separated by a fracture. Both of
these goals must be achieved by exerting pressure primarily on the
cancellous bone, and not the cortical bone. Undue pressure against
the cortical bone could conceivably cause a worsening of a shoulder
fracture by causing cortical bone fractures.
[0078] The present invention satisfies these goals through the
design of the inflatable devices to be described. Inflating such a
device compresses the cancellous bone against the cortical walls of
the epiphysis and metaphysis of the proximal humerus thereby
creating a cavity. In some cases, depending on the fracture
location, the balloon or inflatable device may be used to extend
the cavity into the proximal part of the humeral diaphysis.
[0079] Due to the design of the "sphere on a stand" balloon
(described as number 7 above), the cavity made by this balloon
recreates or approximates the shape of the inside cortical wall of
the proximal humerus. The approximate volume of the cavity made by
the "spherical on a stand balloon" is 70 to 90% that of the
proximal humeral epiphysis and metaphysis, primarily, but not
necessarily exclusive of, part of the diaphysis. The shape
approximates the shape of the humeral head. The "base" is designed
to compress the trabecular bone into a "plug" of bone in the distal
metaphysis or proximal diaphysis. This plug of bone will prevent
the flow of injectable material into the shaft of the humerus,
improving the clinical outcome. The sphere can also be used without
a base.
[0080] A primary goal of percutaneous distal radius augmentation is
to create a cavity inside the distal radius whose configuration is
optimal for supporting the distal radius. Another important goal is
to help fine tune fracture realignment after the fracture has been
partially realigned by finger traps. Both of these goals must be
achieved by exerting pressure primarily on the cancellous bone and
not on the cortical bone. Excessive pressure against the cortical
bone could conceivably cause cortical bone fractures, thus
worsening the condition.
[0081] The present invention satisfies these goals through the
design of inflatable devices either already described or to be
described.
[0082] The design of the "humpbacked banana", or modified pyramid
design (as described as number 5 above), approximates the shape of
the distal radius and therefore, the cavity made by this balloon
approximates the shape of the distal radius as well. The
approximate volume of the cavity to be made by this humpbacked
banana shaped balloon is 70 to 90% that of the distal radial
epiphysis and metaphysis primarily of, but not necessarily
exclusive of, some part of the distal radial diaphysis. Inflating
such a device compresses the cancellous bone against the cortical
walls of the epiphysis and metaphysis of the distal radius in order
to create a cavity. In some cases, depending on the fracture
location, the osseous balloon or inflatable device may be used to
extend the cavity into the distal part of the radial diaphysis.
[0083] A primary goal of percutaneous femoral head (or humeral
head) augmentation is to create a cavity inside the femoral head
(or humeral head) whose configuration is optimal for supporting the
femoral head. Another important goal is to help compress avascular
(or aseptic) necrotic bone or support avascular necrotic bone is
the femoral head. This goal may include the realignment of
avascular bone back into the position it previously occupied in the
femoral head in order to improve the spherical shape of the femoral
head. These goals must be achieved by exerting pressure primarily
on the cancellous bone inside the femoral head.
[0084] The present invention satisfied these goals through the
design of inflatable devices either already described or to be
described.
[0085] The design of the spherical osseous balloon (described as
balloon type 4 above) approximates the shape of the femoral head
and therefore creates a cavity which approximates the shape of the
femoral head as well. (It should be noted that the spherical shape
of this inflatable device also approximates the shape of the
humeral head and would, in fact, be appropriate for cavity
formation in this osseous location as well.) Inflating such a
device compresses the cancellous bone of the femoral head against
its inner cortical walls in order to create a cavity. In some
cases, depending upon the extent of the avascular necrosis, a
smaller or larger cavity inside the femoral head will be formed. In
some cases, if the area of avascular necrosis is small, a small
balloon will be utilized which might create a cavity only 10 to 15%
of the total volume of the femoral head. If larger areas of the
femoral head are involved with the avascular necrosis, then a
larger balloon would be utilized which might create a much larger
cavity, approaching 80 to 90% of the volume of the femoral
head.
[0086] The hemispherical balloon approximates the shape of the top
half of the femoral (and humeral) head, and provides a means for
compacting cancellous bone in an area of avascular necrosis or
small fracture without disturbing the rest of the head. This makes
it easier to do a future total joint replacement if required.
[0087] A primary goal of percutaneous proximal tibial augmentation
is to create a cavity inside the proximal tibia whose configuration
is optimal for supporting either the medial or lateral tibial
plateaus. Another important goal is to help realign the fracture
fragments of tibial plateau fractures, particularly those features
with fragments depressed below (or inferior to) their usual
location. Both of these objectives must be achieved by exerting
pressure on primarily the cancellous bone and not the cortical
bone. Pressure on the cortical bone could conceivably cause
worsening of the tibial plateau fracture.
[0088] The present invention satisfies these goals through the
design of the inflatable devices to be described. Inflating such a
device compresses the cancellous bone against the cortical walls of
the medial or lateral tibial plateau in order to create a
cavity.
[0089] Due to the design of the "elliptical cylinder" balloon
(described as balloon type 6 above) the cavity made by this balloon
recreates or approximates the shape of the cortical walls of either
the medial or lateral tibial plateaus. The approximate volume of
the cavity to be made by the appropriate elliptical cylindrical
balloon is 50 to 90% of the proximal epiphyseal bone of either the
medial half or the lateral half of the tibial.
[0090] Balloons for Vertebral Bodies
[0091] A first embodiment of the balloon (FIG. 1) of the present
invention is broadly denoted by the numeral 10 and includes a
balloon body 11 having a pair of hollow, inflatable, non-expandable
parts 12 and 14 of flexible material, such as PET or Kevlar. Parts
12 and 14 have a suction tube 16 therebetween for drawing fats and
other debris by suction into tube 16 for transfer to a remote
disposal location. Catheter 16 has one or more suction holes so
that suction may be applied to the open end of tube 16 from a
suction source (not shown).
[0092] The parts 12 and 14 are connected together by an adhesive
which can be of any suitable type. Parts 12 and 14 are
doughnut-shaped as shown in FIG. 1 and have tubes 18 and 20 which
communicate with and extend away from the parts 12 and 14,
respectively, to a source of inflating liquid under pressure (not
shown). The liquid can be any sterile biocompatible solution. The
liquid inflates the balloon 10, particularly parts 12 and 14
thereof after the balloon has been inserted in a collapsed
condition (FIG. 8) into a bone to be treated, such as a vertebral
bone 22 in FIG. 2. The above-mentioned U.S. Pat. Nos. 4,969,888 and
5,108,404 disclose the use of a guide pin and cannula for inserting
the balloon into bone to be treated when the balloon is deflated
and has been inserted into a tube and driven by the catheter into
the cortical bone where the balloon is inflated.
[0093] FIG. 8 shows a deflated balloon 10 being inserted through a
cannula 26 into bone. The balloon in cannula 26 is deflated and is
forced through the cannula by exerting manual force on the catheter
21 which extends into a passage 28 extending into the interior of
the bone. The catheter is slightly flexible but is sufficiently
rigid to allow the balloon to be forced into the interior of the
bone where the balloon is then inflated by directing fluid into
tube 88 whose outlet ends are coupled to respective parts 12 and
14.
[0094] In use, balloon 10 is initially deflated and, after the bone
to be filled with the balloon has been prepared to receive the
balloon with drilling, the deflated balloon is forced into the bone
in a collapsed condition through cannula 26. The bone is shown in
FIG. 2. The balloon is oriented preferably in the bone such that it
allows minimum pressure to be exerted on the bone marrow and/or
cancellous bone if there is no fracture or collapse of the bone.
Such pressure will compress the bone marrow and/or cancellous bone
against the inner wall of the cortical bone, thereby compacting the
bone marrow of the bone to be treated and to further enlarge the
cavity in which the bone marrow is to be replaced by a
biocompatible, flowable bone material.
[0095] The balloon is then inflated to compact the bone marrow
and/or cancellous bone in the cavity and, after compaction of the
bone marrow and/or cancellous bone, the balloon is deflated and
removed from the cavity. While inflation of the balloon and
compaction occurs, fats and other debris are sucked out of the
space between and around parts 12 and 14 by applying a suction
force to catheter tube 16. Following this, and following the
compaction of the bone marrow, the balloon is deflated and pulled
out of the cavity by applying a manual pulling force to the
catheter tube 21.
[0096] The second embodiment of the inflatable device of the
present invention is broadly denoted by the numeral 60 and is shown
in FIGS. 4 and 5. Balloon 60 includes a central spherical part 62
which is hollow and which receives an inflating liquid under
pressure through a tube 64. The spherical part is provided with a
spherical outer surface 66 and has an outer periphery which is
surrounded substantially by a ring shaped part 68 having tube
segments 70 for inflation of part 68. A pair of passages 69
interconnect parts 62 and 68. A suction tube segment 72 draws
liquid and debris from the bone cavity being formed by the balloon
60.
[0097] Provision can be made for a balloon sleeve 71 for balloon 60
and for all balloons disclosed herein. A balloon sleeve 71 (FIG. 9)
is shiftably mounted in an outer tube 71a and can be used to insert
the balloon 60 when deflated into a cortical bone. The sleeve 71
has resilient fingers 71b which bear against the interior of the
entrance opening 71c of the vertebral bone 22 (FIG. 9A) to prevent
tearing of the balloon. Upon removal of the balloon sleeve, liquid
under pressure will be directed into tube 64 which will inflate
parts 62 and 68 so as to compact the bone marrow within the
cortical bone. Following this, balloon 60 is deflated and removed
from the bone cavity.
[0098] FIGS. 6 and 6A show several views of a modified doughnut
shape balloon 80 of the type shown in FIGS. 1 and 2, except the
doughnut shapes of balloon 80 are not stitched onto one another. In
FIG. 6, balloon 80 has a pear-shaped outer convex surface 82 which
is made up of a first hollow part 84 and a second hollow part 85. A
tube 88 is provided for directing liquid into the two parts along
branches 90 and 92 to inflate the parts after the parts have been
inserted into the medullary cavity of a bone. A catheter tube 16 is
inserted into the space 96 between two parts of the balloon 80. An
adhesive bonds the two parts 84 and 85 together at the interface
thereof.
[0099] FIG. 6A shows the way in which the catheter tube 16 is
inserted into the space or opening 96 between the two parts of the
balloon 80.
[0100] FIG. 7 shows tube 88 of which, after directing inflating
liquid into the balloon 80, can inject contrast material into the
balloon 80 so that x-rays can be taken of the balloon with the
inflating material therewithin to determine the proper placement of
the balloon. Tube 16 is also shown in FIG. 6, it being attached in
some suitable manner to the outer side wall surface of tube 88.
[0101] Still another embodiment of the invention is shown in FIG. 3
which is similar to FIG. 1 except that it is round and not a
doughnut and includes an inflatable device 109 having three balloon
units 110, 112 and 114 which are inflatable and which have
string-like restraints 117 which limit the expansion of the balloon
units in a direction transverse to the longitudinal axes of the
balloon units. The restraints are made of the same or similar
material as that of the balloon so that they have some resilience
but substantially no expansion capability.
[0102] A tube system 115 is provided to direct liquid under
pressure into balloon units 110, 112 and 114 so that liquid can be
used to inflate the balloon units when placed inside the bone in a
deflated state. Following the proper inflation and compaction of
the bone marrow, the balloon can be removed by deflating it and
pulling it outwardly of the bone being treated. The restraints keep
the opposed sides 77 and 79 substantially flat and parallel with
each other.
[0103] In FIG. 10, another embodiment of the inflatable balloon is
shown. The device is a kidney shaped balloon body 130 having a pair
of opposed kidney shaped side walls 132 which are adapted to be
collapsed and to cooperate with a continuous end wall 134 so that
the balloon 130 can be forced into a bone 136 shown in FIG. 11. A
tube 138 is used to direct inflating liquid into the balloon to
inflate the balloon and cause it to assume the dimensions and
location shown vertebral body 136 in FIG. 11. Device 130 will
compress the cancellous bone if there is no fracture or collapse of
the cancellous bone. The restraints for this action are due to the
side and end walls of the balloon.
[0104] FIG. 12 shows a balloon 140 which is also kidney shaped and
has a tube 142 for directing an inflatable liquid into the tube for
inflating the balloon. The balloon is initially a single chamber
bladder but the bladder can be branded along curved lines or strips
141 to form attachment lines 144 which take the shape of
side-by-side compartments 146 which are kidney shaped as shown in
FIG. 13. The branding causes a welding of the two sides of the
bladder to occur since the material is standard medical balloon
material, which is similar to plastic and can be formed by
heat.
[0105] FIG. 14 is a perspective view of a vertebral body 147
containing the balloon of FIG. 12, showing a double stacked balloon
140 when it is inserted in vertebral bone 147.
[0106] FIG. 15 is a view similar to FIG. 10 except that tufts 155,
which are string-like restraints, extend between and are connected
to the side walls 152 of inflatable device 150 and limit the
expansion of the side walls with respect to each other, thus
rendering the side walls generally parallel with each other. Tube
88 is used to fill the kidney shaped balloon with an inflating
liquid in the manner described above.
[0107] The dimensions for the vertebral body balloon will vary
across a broad range. The heights (H, FIG. 11) of the vertebral
body balloon for both lumbar and thoracic vertebral bodies
typically range from 0.5 cm to 3.5 cm. The anterior to posterior
(A, FIG. 11) vertebral body balloon dimensions for both lumbar and
thoracic vertebral bodies range from 0.5 cm to 3.5 cm. The side to
side (L, FIG. 11) vertebral body dimensions for thoracic vertebral
bodies will range from 0.5 cm to 3.5 cm. The side to side vertebral
body dimensions for lumbar vertebral bodies will range from 0.5 cm
to 5.0 cm.
[0108] The eventual selection of the appropriate balloon for, for
instance, a given vertebral body is based upon several factors. The
anterior-posterior (A-P) balloon dimension for a given vertebral
body is selected from the CT scan or plain film x-ray views of the
vertebral body. The A-P dimension is measured from the internal
cortical wall of the anterior cortex to the internal cortical wall
of the posterior cortex of the vertebral body. In general, the
appropriate A-P balloon dimension is 5 to 7 millimeters less than
this measurement.
[0109] The appropriate side to side balloon dimensions for a given
vertebral body is selected from the CT scan or from a plain film
x-ray view of the vertebral body to be treated. The side to side
distance is measured from the internal cortical walls of the side
of the vertebral bone. In general, the appropriate side to side
balloon dimension is 5 to 7 millimeters less than this measurement
by the addition of the lumbar vertebral body tends to be much wider
than side to side dimension then their A-P dimension. In thoracic
vertebral bodies, the side to side dimension and their A-P
dimensions are almost equal.
[0110] The height dimensions of the appropriate vertebral body
balloon for a given vertebral body is chosen by the CT scan or
x-ray views of the vertebral bodies above and below the vertebral
body to be treated. The height of the vertebral bodies above and
below the vertebral body to be treated are measured and averaged.
This average is used to determine the appropriate height dimension
of the chosen vertebral body balloon.
[0111] Balloons for Long Bones
[0112] Long bones which can be treated with the use of balloons of
the present invention include distal radius (larger arm bone at the
wrist), proximal tibial plateau (leg bone just below the knee),
proximal humerus (upper end of the arm at the shoulder), and
proximal femoral head (leg bone in the hip).
[0113] Distal Radius Balloon
[0114] For the distal radius, a balloon 160 is shown in the distal
radius 152 and the balloon has a shape which approximates a pyramid
but more closely can be considered the shape of a humpbacked banana
in that it substantially fills the interior of the space of the
distal radius to force cancellous bone 154 lightly against the
inner surface 156 of cortical bone 158.
[0115] The balloon 160 has a lower, conical portion 159 which
extends downwardly into the hollow space of the distal radius 152,
and this conical portion 159 increases in cross section as a
central distal portion 161 is approached. The cross section of the
balloon 160 is shown at a central location (FIG. 17B) and this
location is near the widest location of the balloon. The upper end
of the balloon, denoted by the numeral 162, converges to the
catheter 88 for directing a liquid into the balloon for inflating
the same to force the cancellous bone against the inner surface of
the cortical bone. The shape of the balloon 160 is determined and
restrained by tufts formed by string restraints 165. These
restraints are optional and provide additional strength to the
balloon body 160, but are not required to achieve the desired
configuration. The balloon is placed into and taken out of the
distal radius in the same manner as that described above with
respect to the vertebral bone.
[0116] The dimensions of the distal radius balloon vary as
follows:
[0117] The proximal end of the balloon (i.e. the part nearest the
elbow) is cylindrical in shape and will vary from 0.5.times.0.5 cm
to 1.8.times.1.8 cm.
[0118] The length of the distal radius balloon will vary from 1.0
cm to 12.0 cm.
[0119] The widest medial to lateral dimension of the distal radius
balloon, which occurs at or near the distal radio-ulnar joint, will
measure from 1.0 cm to 2.5 cm.
[0120] The distal anterior-posterior dimension of the distal radius
balloon will vary from 0.5 to 3.0 cm.
[0121] Proximal Humerus Fracture Balloon
[0122] The selection of the appropriate balloon size to treat a
given fracture of the distal radius will depend on the radiological
size of the distal radius and the location of the fracture.
[0123] In the case of the proximal humerus 169, a balloon 166 shown
in FIG. 18 is spherical and has a base design. It compacts the
cancellous bone 168 in a proximal humerus 169. A mesh 170, embedded
or laminated and/or winding, may be used to form a neck 172 on the
balloon 166, and second mesh 170a may be used to conform the bottom
of the base 172a to the shape of the inner cortical wall at the
start of the shaft. These restraints provide additional strength to
the balloon body, but the configuration can be achieved through
molding of the balloon body. This is so that the cancellous bone
will be as shown in the compacted region surrounding the balloon
166 as shown in FIG. 18. The cortical bone 173 is relatively wide
at the base 174 and is thin-walled at the upper end 175. The
balloon 166 has a feed tube 177 into which liquid under pressure is
forced into the balloon to inflate it to lightly compact the
cancellous bone in the proximal humerus. The balloon is inserted
into and taken out of the proximal humerus in the same manner as
that described above with respect to the vertebral bone.
[0124] The dimensions of the proximal humerus fracture balloon vary
as follows:
[0125] The spherical end of the balloon will vary from
1.0.times.1.0 cm to 3.0.times.3.0 cm.
[0126] The neck of the proximal humeral fracture balloon will vary
from 0.8.times.0.8 cm to 3.0.times.3.0 cm.
[0127] The width of the base portion or distal portion of the
proximal numeral fracture balloon will vary from 0.5.times.0.5 cm
to 2.5.times.2.5 cm.
[0128] The length of the balloon will vary from 4.0 cm to 14.0
cm.
[0129] The selection of the appropriate balloon to treat a given
proximal humeral fracture depends on the radiologic size of the
proximal humerus and the location of the fracture.
[0130] Proximal Tibial Plateau Fracture Balloon
[0131] The tibial fracture is shown in FIG. 19A in which a balloon
180 is placed in one side 182 of a tibia 183. The balloon, when
inflated, compacts the cancellous bone in the layer 184 surrounding
the balloon 180. A cross section of the balloon is shown in FIG.
19C wherein the balloon has a pair of opposed sides 185 and 187
which are interconnected by restraints 188 which can be in the form
of strings or flexible members of any suitable construction. The
main purpose of the restraints is to make the sides 185 and 187
substantially parallel with each other and non-spherical. A tube
190 is coupled to the balloon 180 to direct liquid into and out of
the balloon. The ends of the restraints are shown in FIGS. 19B and
19D and denoted by the numeral 191. The balloon is inserted into
and taken out of the tibia in the same manner as that described
above with respect to the vertebral bone. FIG. 19B shows a
substantially circular configuration for the balloon; whereas, FIG.
19D shows a substantially elliptical version of the balloon.
[0132] The dimensions of the proximal tibial plateau fracture
balloon vary as follows:
[0133] The thickness or height of the balloon will vary from 0.5 cm
to 5.0 cm.
[0134] The anterior/posterior (front to back) dimension will vary
from 1.0 cm to 6.0 cm.
[0135] The side to side (medial to lateral) dimension will vary
from 1.0 cm to 6.0 cm.
[0136] The selection of the appropriate balloon to treat a given
tibial plateau fracture will depend on the radiological size of the
proximal tibial and the location of the fracture.
[0137] Femoral Head Balloon
[0138] In the case of the femoral head, a balloon 200 is shown as
having been inserted inside the cortical bone 202 of the femoral
head which is thin at the outer end 204 of the femur and which can
increase in thickness at the lower end 206 of the femur. The
cortical bone surrounds the cancellous bone 207 and this bone is
compacted by the inflation of balloon 200. The tube for directing
liquid for inflation purposes into the balloon is denoted by the
numeral 209. It extends along the femoral neck and is directed into
the femoral head which is generally spherical in configuration.
FIG. 20A shows that the balloon, denoted by the numeral 200a, can
be hemispherical as well as spherical, as shown in FIG. 20. The
balloon 200 is inserted into and taken out of the femoral head in
the same manner as that described with respect to the vertebral
bone. The hemispherical shape is maintained in this example by
bonding overlapping portions of the bottom, creating pleats 200b as
shown in FIG. 20A.
[0139] The dimensions of the femoral head balloon vary as
follows:
[0140] The diameter of the femoral head balloon will vary from 1.0
cm to up to 4.5 cm. The appropriate size of the femoral head
balloon to be chosen depends on the radiological or CT scan size of
the head of the femur and the location and size of the avascular
necrotic bone. The dimensions of the hemispherical balloon are the
same as those of the spherical balloon, except that approximately
one half is provided.
* * * * *