U.S. patent application number 16/600976 was filed with the patent office on 2020-02-06 for stabilization of vertebral bodies with bone particle slurry.
The applicant listed for this patent is Osteoagra LLC. Invention is credited to Neville Alleyne.
Application Number | 20200038083 16/600976 |
Document ID | / |
Family ID | 64659491 |
Filed Date | 2020-02-06 |
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United States Patent
Application |
20200038083 |
Kind Code |
A1 |
Alleyne; Neville |
February 6, 2020 |
STABILIZATION OF VERTEBRAL BODIES WITH BONE PARTICLE SLURRY
Abstract
A medical implant comprises a slurry of bone particles that are
injected into a vertebral body under pressure. The liquid component
of the slurry may be aspirated while the slurry is being injected
so that the bone particles of the slurry pack into the central area
of the vertebral body to provide structural support. The injected
slurry may be agitated during the procedure to maximize the
structural strength of the implant after the procedure.
Inventors: |
Alleyne; Neville; (La Jolla,
CA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Osteoagra LLC |
La Jolla |
CA |
US |
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|
Family ID: |
64659491 |
Appl. No.: |
16/600976 |
Filed: |
October 14, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16016635 |
Jun 24, 2018 |
10441336 |
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16600976 |
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PCT/US2018/037509 |
Jun 14, 2018 |
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16016635 |
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62519409 |
Jun 14, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A61F 2002/2835 20130101;
A61L 27/06 20130101; A61L 27/58 20130101; A61L 2400/06 20130101;
A61L 27/3608 20130101; A61F 2/30723 20130101; A61B 2217/005
20130101; A61B 17/8805 20130101; A61L 27/54 20130101; A61F 2/44
20130101; A61L 27/16 20130101; A61B 2017/8838 20130101; A61B
17/8816 20130101; A61F 2/2846 20130101; A61B 17/8833 20130101; A61L
27/025 20130101; A61F 2310/00359 20130101; A61B 17/8827 20130101;
A61B 17/8822 20130101; A61L 27/365 20130101; A61F 2002/30677
20130101; A61L 2430/38 20130101; A61L 27/50 20130101 |
International
Class: |
A61B 17/88 20060101
A61B017/88; A61L 27/50 20060101 A61L027/50; A61L 27/58 20060101
A61L027/58; A61L 27/54 20060101 A61L027/54; A61L 27/36 20060101
A61L027/36; A61L 27/16 20060101 A61L027/16; A61L 27/06 20060101
A61L027/06; A61L 27/02 20060101 A61L027/02; A61F 2/30 20060101
A61F002/30; A61F 2/28 20060101 A61F002/28 |
Claims
1. A surgical kit comprising: a cannula configured for accessing
the interior portion of a human vertebral body; a slurry of bone
particles; a slurry pump configured to force at least some of the
slurry of bone particles down the cannula and into the interior
portion of the vertebral body.
2. The surgical kit of claim 1, wherein the cannula has an inner
diameter of between 2.5 and 5 millimeters.
3. The surgical kit of claim 1, wherein the distal end of the
cannula comprises at least one slurry output opening.
4. The surgical kit of claim 3, wherein at least one slurry output
opening is positioned on the side of the cannula.
5. The surgical kit of claim 1, comprising a catheter having a
proximal end and a distal end, the catheter being configured to be
inserted into the vertebral body through the cannula.
6. The surgical kit of claim 5, wherein the catheter has an inner
diameter of between 1.5 and 2.5 millimeters.
7. The surgical kit of claim 5, wherein the distal end of the
catheter comprises at least one slurry output opening.
8. The surgical kit of claim 7, wherein at least one slurry output
opening is positioned on the side of the catheter.
9. The surgical kit of claim 1, wherein the slurry is 20-85% bone
by volume.
10. The surgical kit of claim 1, wherein the slurry consists
essentially of saline solution and bone particles.
11. The surgical kit of claim 1, wherein at least 90% of the bone
particles have a characteristic size of 50 micrometers to 1000
micrometers.
12. The surgical kit of claim 1, wherein the bone particles include
at least two populations of bone particles having different mean
characteristic sizes, each population comprising at least 10% by
mass of the bone particles.
13. The surgical kit of claim 12, wherein the particle size
distribution is characterized by a uniformity coefficient D60/D10
of at least 2.
14. The surgical kit of claim 5, wherein the slurry of bone
particles is pre-packed in the catheter and/or the slurry pump.
15. The surgical kit of claim 1, wherein at least 90% of the bone
particles are cortical bone particles.
16. The surgical kit of claim 1, comprising two separate cannulas,
two separate slurries of bone particles, and two separate slurry
pumps.
17. A medical implant for use in structurally supporting vertebral
bodies, the implant comprising a slurry of bone particles, wherein
the slurry comprises 30% to 85% bone by mass, wherein at least 90%
of the bone particles have a characteristic size of 1 micrometer to
1000 micrometers, wherein the bone particles include at least two
populations of bone particles having different mean characteristic
sizes, each population comprising at least 10% by mass of the bone
particles, and wherein the particle size distribution has a
uniformity coefficient D60/D10 of at least 2.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. patent application
Ser. No. 16/016,635, now U.S. Pat. No. 10,441,336, filed on Jun.
24, 2018, which is a continuation-in-part of International
Application PCT/US2018/37509, filed on Jun. 14, 2018. This
application also claims priority to U.S. Provisional Application
No. 62/519,409 filed on Jun. 14, 2017. The entire contents of both
the above applications are hereby incorporated by reference.
BACKGROUND
[0002] Osteoporosis has continued to be a ubiquitous problem,
especially in our elderly population. It is said that osteoporosis
sufferers outnumber patients in the United States who have had
MI's, stroke, and breast cancer combined. Osteoporosis can result
in compression fractures of the vertebral bodies of the spinal
column. As shown in FIG. 1, these fractures 10 generally occur in
the anterior portion of the vertebra, with this portion compressing
to a smaller height than a normal vertebral body. With increasing
numbers of osteoporotic compression fractures of the thoracic and
lumbar spine, it is felt that 1 in 3 women and 1 in 5 men will have
an osteoporotic fracture in their lifetime. By the date 2020,
osteoporosis is expected to affect approximately 14 million people
in the United States. These fractures become more common obviously
in older population and current treatment recommendations include
vertebroplasty which can be done as an outpatient and kyphoplasty,
which requires an in hospital stay of approximately one day.
[0003] PMMA, poly methacrylate, is the substance used in both
vertebroplasty and kyphoplasty. This material has been used
throughout orthopedics for over 35 years. The first total hip
replacements done by Dr. Charnley in Boston and utilized a
methacrylate. This material is also known as bone cement and its
modulus of elasticity is much higher than that of cancellous or
cortical bone. When this material is placed into a vertebral body
and is allowed to cure, it creates an exothermic reaction, which
can sometimes deaden or destroy nociceptin fibers and once it is
hardened, it provides rigid support of the vertebra. Unfortunately,
the remaining part of the vertebra and the part in which the cement
has been placed cannot grow new bone. The exothermic reaction, if
it is close to the endplate, can cause avascular necrosis and
result in endplate fracture and adjacent segment collapse. Some of
the issues that are associated with the use of PMMA include, but
are not limited to, cord compression from ectopic cement extending
from the vertebral body into the spinal canal, extrusion of cement
through the cartilaginous endplate into the disc, allergic reaction
to PMMA, coagulopathy, PMMA getting into the basivertebral sinus
resulting in pulmonary emboli and infection because of the foreign
body. These are some of the related complications that can occur
with vertebroplasty or kyphoplasty. Furthermore, what we have seen
over the years is that the cement, which does decrease pain, also
appears to cause adjacent segment fractures at a later date. Some
as early as a few months and others within a few years. The reason
for these compression fractures is: 1) Underlying osteoporosis
throughout the vertebral bodies. 2) Cement having a higher density
than the cortical or cancellous bone and adjacent microfracturing,
which may not have been detected at the time of the initial
procedure involving the adjacent vertebra. In addition, compression
fractures at TS or above are technically difficult due to the small
pedicle and the parallel orientation of these pedicles. The
thoracic spine is also very vulnerable in the event the cement is
extruded, which could result in myelopathy or paresis or
plegia.
SUMMARY
[0004] In one implementation, a surgical kit comprises a cannula
configured for accessing the interior portion of a human vertebral
body, a catheter having a proximal end and a distal end configured
to be inserted into the vertebral body through the cannula, a
slurry of bone particles, and a slurry pump configured to force at
least some of the slurry of bone particles down the catheter and
into the interior portion of the vertebral body. The slurry pump
may comprise an inflation syringe. The slurry pump may comprise an
auger extruder.
[0005] In another implementation, a method of structurally
supporting a vertebral body comprises forming one or more openings
to a central portion of a vertebral body and placing a cannula
through a first opening of the one or more openings. A catheter is
inserted into the central portion of the vertebral body through the
cannula, and a slurry of bone particles is injected into the
vertebral body through the catheter. The slurry is pressurized
during and/or after the injecting to force bone particles of the
slurry into direct contact with bone tissue inside the vertebral
body. After the pressurizing, the catheter and cannula may be
removed, and a plug may be inserted into the first opening.
[0006] In another implementation, a medical implant for use in
structurally supporting vertebral bodies is provided. The implant
comprises a slurry of bone particles. Furthermore, the slurry
comprises 30% to 85% bone by mass, wherein at least 90% of the bone
particles have a characteristic size of 1 micrometer to 1000
micrometers. The bone particles include at least two populations of
bone particles having different characteristic sizes, each
population comprising at least 10% by mass of the slurry, and
wherein the particle size distribution is characterized by a
uniformity coefficient D60/D10 of at least 2.
BRIEF DESCRIPTION OF THE DRAWING
[0007] FIG. 1 illustrates a vertebral body with a compression
fracture.
[0008] FIG. 2 is a schematic block diagram of one implementation of
a system in accordance with the present disclosure.
[0009] FIG. 3 is a block diagram of a method that may be performed
with the system of FIG. 2.
[0010] FIG. 4 illustrates a conceptual example of a bone particle
size distribution.
[0011] FIG. 5 is a schematic block diagram of another
implementation of a system in accordance with the present
disclosure including two cannulas and two catheters.
[0012] FIG. 6 is a schematic block diagram of another
implementation of a system in accordance with the present
disclosure including an aspirator.
DETAILED DESCRIPTION
General Considerations
[0013] In order to be successful in stabilizing these fractures,
bone should be inserted, not be a foreign body like PMMA. By
inserting cortical allograft or autologous bone particles, we are
able to gradually, steadily, increase the bone density within the
vertebral body and allow the body to perform its normal healing by
not destroying the bone matrix within the vertebral body. PMMA,
when it is allowed to cure, creates an exothermic reaction, which
then destroys the bone and does not allow bone to incorporate into
it. Our material, cortical bone microspheres, allograft or
autologous bone will allow the natural healing processes of bone to
not only stabilize the fracture, but to heal the fracture with
bone. The vertebral bodies receive their blood supply from
surrounding tissues and the lumbar spine, lumbar vertebral
arteries, the segmental arteries, come off the aorta and supply the
blood to the vertebral body to allow it to heal. When PMMA is
introduced into a compressed vertebra, yes, it does help to
stabilize that vertebra, but in the end, there is no healing that
occurs and if the PMMA is very close to the cartilaginous endplate,
it may create fractures due to migration of the PMMA or the heat
may create osteonecrosis which will then lead to fracturing of the
endplate and adjacent segment collapse.
[0014] In addition, on complex deformity, correction, in which
thoracolumbar or thoracolumbar sacral or thoracolumbar sacroiliac
fixation is utilized. The cephalad vertebra can also undergo
collapse, kyphosis and fracture. On these long constructs,
orthopedic and neurosurgeons have angled the most cephalad screws
in a more angled trajectory pointing down at the inferior endplate
of the top vertebral body. This angulation of screw is to minimize
the forces at the apex and minimize the cut out of these pedicle
screws in this very fragile osteoporotic bone for surgical
procedures that are complex deformity correction. In addition, some
surgeons have extended bone graft above the level of the top screw
to minimize fracturing or proximal junctional kyphosis. However,
none of these are foolproof because of the diffuse osteopenia or
osteoporosis in all of the vertebral bodies. It is therefore
contemplated that stabilization above the level of a long construct
may prove to be beneficial by inserting PMMA,
polymethylmethacrylate, either as a vertebroplasty augmentation or
kyphoplasty augmentation. It is our thought process that PMMA will
not allow that fracture to heal or that vertebral body to heal. It
is purely for stability. Therefore, it is much more prudent to
insert these cortical microspheres or cortical cancellous
microspheres of autologous or allograft bone into the vertebral
body to minimize proximal junctional kyphosis. In addition, this
bone graft material can be inserted into the sacrum in order to
help increase the bone density in the sacrum or into the ilium or
any other bone. Osteoporosis can occur in any bone in the human
body. There are 206 bones in the adult of which bones in the foot
and ankle are susceptible to fracture and complex open reduction
internal fixation is required with bone graft and sometimes
methacrylate. In those cases, instead of methacrylate, pressurized
microspheres of allograft cortical bone or autologous cortical bone
can be used to strengthen the fracture.
[0015] Most thoracic and lumbar burst fractures are not treated and
matter of fact, is contraindicated for vertebroplasty or
kyphoplasty; however, in stable burst fractures our technology by
inserting pressurized cortical microspheres of allograft or
autologous bone under pressure can be done safely to stabilize
burst fractures and minimize the need for surgery. Unstable burst
fractures with bone fragments in the canal is still a
contraindication even for our technology; however, once the
stability has been achieved, the adjacent segments to the fracture,
if osteoporotic, can be augmented with our particles of cortical
bone whether it be autologous or allograft.
[0016] Given the 700,000 to 800,000 vertebral compression fractures
that occur each year, the estimated cost for their treatment is
anywhere from 13-21 billion dollars per year. The ability to treat
these in an effort to allow the natural processes of healing to
occur within the vertebral body will allow the vertebral body
itself to fill in with bone. Given the blood supply and the
compression that exist by placing these particles pressurized
through the interstices of the cancellous marrow of the said
vertebra, the vertebra may gradually increase its vertebral height
and its vertebral bone density. In addition, the vertebral body can
be expanded by gradual, steady pressure and be seen under
visualization by fluoroscopy, x-ray, CT, ultrasound, MRI. In
addition, the particles can, but need not necessarily, be
impregnated with a barium compound such as ISOVUE which will allow
the vertebral body to be well visualized when the particles are
being injected into the vertebra. Moreover, the use of ultrasound
to show improved bone density can be performed to look at pre- and
post-procedure bone density and vertebral height. With some of the
kyphoplasties, early and/or late collapse of the vertebra can occur
due to loss of the distraction by the cement or adjacent fracturing
of the superior and inferior endplate of said vertebra. With the
installation of bone particles, autologous or allograft, we should
be able to maintain the vertebral body height and density since
bone will attempt to heal within the interstices of the
particles.
[0017] The present intervention comprises a method and apparatus
for spinal stabilization of weak or fractured vertebral bodies or
any bone with cortical, autologous or allograft particles via a
novel injection apparatus that is capable of measuring pressure and
density of the vertebral body. The microspheres can come in a
plurality of geometric shapes, that can vary in size or be uniform.
The diameter of these microspheres can vary from one micron to 1000
microns diameter, with about 100-200 microns diameter being one
specific example size range. In addition, these microspheres can be
embedded with barium to allow for better visualization and can vary
in the diameter depending on the degree of osteoporosis or
collapse. We feel by utilizing incremental impaction bone
augmentation through our apparatus, we will be able to deliver
significant enough bone material to stabilize the fracture and also
increase some of the vertebral height, if not all, as well as
allowing the fracture to heal with bone and not allowing the
fracture to remain unhealed because of a foreign material, poly
methacrylate, in the center or within the vertebral body, which
would inhibit in healing.
Example Systems and Methods
[0018] Referring now to FIGS. 2 and 3, one exemplary apparatus and
method of vertebral body stabilization will be described. The
system of FIG. 2 includes a cannula 22 and a catheter 23 having a
proximal end 23a and a distal end 23b. The cannula 22 is configured
for accessing the interior portion of a human vertebral body. The
cannula 22 may have an inner diameter in the range of 2.5 to 5 mm,
8 or 10 gauge rigid tubing for example, which is in the range used
in conventional vertebroplasty and kyphoplasty procedures. FIG. 2
shows the cannula 22 installed through a transpedicular opening
into the interior portion 26 of a vertebral body 25. This is a
common location for cannula insertion in currently performed
vertebroplasty and kyphoplasty procedures, although a more lateral
approach is sometimes utilized. It is also conceived that such a
cannula can be inserted through the cartilaginous endplate into the
vertebral body.
[0019] The catheter 23 is configured to be inserted into the
central portion 26 of the vertebral body 25 through the cannula 22
and FIG. 2 illustrates the catheter 23 so positioned. The term
catheter as used herein means any form of tube, rigid or flexible,
made of any suitable material, whether polymer or metal or both.
The catheter may have an inner diameter in the range of 1.5 to 3
mm. At least the distal portion may be formed as a 12, 13, or 14
gauge metal needle for example. The distal end 23b of the catheter
23 includes one or more openings 29a, 29b, 29c. One or more of
these openings, such as opening 29a and 29b may be in the side of
the catheter to inject material substantially perpendicular to the
longitudinal extend of the catheter. An opening 29c may also be
provided in the distal tip to inject material parallel with the
longitudinal axis of the catheter.
[0020] The system of FIG. 2 also includes a slurry reservoir 24.
The slurry reservoir 24 contains a slurry of bone particles to be
implanted into the inner portion 26 of the vertebral body. A slurry
pump 28 may be coupled to the slurry reservoir 24 and catheter 23
to force at least some of the slurry of bone particles down the
catheter and into the interior portion 26 of the vertebral body 25.
In use, the components of FIG. 2 including the cannula 22, catheter
23, slurry of bone particles 24 and slurry pump 28 may be provided
to a physician as part or all of a surgical kit. In such a kit, the
slurry reservoir could be made part of the catheter 23 or the
slurry pump 28 and be pre-filled with a slurry of bone particles.
The volume needed for such a reservoir is the volume of slurry that
contains about 5 cc volume of bone particles.
[0021] FIG. 3 is a block diagram of a surgical method that can be
performed with the apparatus of FIG. 2. At block 30, one or more
openings to a central region of a vertebral body are created. This
can be done by the same methods that are used in conventional
arthroplasty and kyphoplasty procedures such as with a stylet or
trocar and/or a bone drill. At block 31, this procedure will leave
a cannula behind extending through the opening as shown, for
example, in FIG. 2. Also at block 31, a catheter is positioned
inside the vertebral body through the cannula. At block 32, a
slurry of bone particles is injected into the vertebral body
through the catheter. At block 35, the slurry is pressurized. This
may occur in conjunction with the injecting of block 32.
Pressurizing the slurry can increase the height of the vertebral
body as slurry is injected. It is advantageous if this is performed
without a bag or other structure enclosing or confining the slurry
that is being injected. This can allow direct contact and healing
between the implanted bone particles and the bone tissue inside the
fractured and/or weakened vertebral body in, for example, a spinal
compression fracture, while additionally providing immediate
stabilization resulting from the compressed bone particles
interlocked in a `granular mechanic` structure of packed granules
resisting further compression or movement and enclosed by the
spinal bony fracture fragments and the remainder of the outer shell
of the vertebral body.
[0022] It is beneficial to monitor the slurry injection under
fluoroscopy to visualize the increased density in the vertebral
body interior as well as the expansion of the endplates. This may
be done without a contrast medium as the accumulation of the denser
cortical bone will be visible under fluoroscopy. As explained
further below, it is also possible to incorporate a radiopaque
contrast medium to the slurry to enhance this visualization.
[0023] At the conclusion of the injection, the bone particles will
support the vertebral body in its expanded state. Advantageously,
this support function can be essentially immediate, similar to a
conventional kyphoplasty where the PMMA curing process takes a few
hours or even less. After injecting the slurry, the catheter and
cannula are removed at block 36. If desired, as shown in block 37,
a plug may be placed in the opening that the cannula entered the
vertebral body through. Such a plug can be made of a variety of
materials including, but not limited to, stainless steel, titanium,
cobalt chrome molybdenum, TLA, PGA, PMMA, methylcellulose, or
cortical allograft bone.
[0024] It may be noted here that the procedure may optionally
include the insertion of an inflatable balloon bone tamp prior to
injecting slurry. The use of such a bone tamp to create a cavity
inside the vertebral body is a familiar part of conventional
kyphoplasty procedures.
[0025] The slurry of bone particles can take a variety of forms. As
used herein, the term "slurry" refers to a flowable mixture of
solid particles in a liquid carrier. With respect material content,
one suitable slurry composition is bone particles suspended in pure
water or saline without any functionally significant additional
substances. The slurry may contain 20% to 85% bone by volume. At
the lower end of this range, extrusion is more like that of the
liquid carrier, and the particles may not interact appreciably in
the catheter as the slurry is injected. At the higher end, there
will be significant particle to particle contact when the slurry is
forced through the catheter. This requires more force to extrude
from the catheter, but the material being delivered is closer to
its final compacted post-injection form. In some implementations,
the slurry may be 40% to 60% bone by volume. Although saline alone
can be advantageous, other carriers and/or supplemental substances
can be included in some implementations such as blood, platelets,
contrast agent, stem cells, and growth factor. Hyaluronic acid can
be provided as an extrusion lubricant. As other examples, the
particles can be impregnated with biphosphonates, forteo, prolia
and fosemax on the surface or as separate substances mixed into the
slurry. Other substances such as antibiotics (e.g. vancomycin),
chemotherapeutic agents, and the like can also be added to the
surface of the particles or as separate substances in the slurry.
Particles made of materials other than bone can also form part of
the slurry in some implementations.
[0026] The bone particles themselves may comprise cortical or
cancellous bone, whether allograft, xenograft, or autologous.
Cortical bone has favorable compressive strength to perform the
desired structural support function. In some implementations, at
least 90% of the bone particles are non-demineralized cortical bone
particles. Regarding the size distribution of the particles, they
can be no larger than the inner diameter of the catheter, and as
noted above, may potentially be anywhere in the range of 1
micrometer to 1 millimeter. In some implementations, at least 90%
of the bone particles have a characteristic size in the range of 50
to 1000 micrometers. Conceptually, bone particles in this size
range may be analogized to grains of sand of varying coarseness.
Because the particles may not be entirely spherical, the
"characteristic size" of a given particle as defined herein is the
diameter of a sphere having a volume equal to that of the actual
particle.
[0027] A slurry containing substantially uniform particle
characteristic sizes in the 50 to 1000 micrometer range may be
used, wherein substantially uniform means that the distribution of
characteristic sizes (full width at half maximum of a histogram) is
within .+-.10% of the mean characteristic size of the particles in
the mixture. Alternatively, the slurry may contain bone particles
with two or more different sizes, where two particles are
considered to have different sizes if the characteristic size of
the larger divided by the characteristic size of the smaller is
more than 1.5. Particle size distributions may be characterized by
a parameter that may be referred to as the uniformity coefficient.
This may be defined as D60/D10, where D60 means 60% of the
particles by mass have equal to or smaller characteristic size.
Similarly, D10 means that 10% of the particles by mass have equal
to or smaller characteristic size. For example, a set of particles
half of which (by mass) are 1000 micrometers and the other half (by
mass) are 500 micrometers, would have a uniformity coefficient of
2. It can also be seen that a mixture of particles of uniform size
would have a uniformity coefficient of 1. Generally, a higher
uniformity coefficient corresponds to a greater range of particle
characteristic sizes in the particle mixture.
[0028] FIG. 4 shows a conceptual illustration of a particle
distribution that may be suitable for the present application. The
example of FIG. 4 may be referred to as "open graded," which
generally means that there is a range of particle sizes, but there
are few extremely small particles that would substantially fill in
the voids between the larger and medium sized particles when they
are packed together. In a packed mixture like this, structural
support is provided by both the larger particles and the smaller
particles. This may be more structurally sound than a substantially
uniform particle mixture with fewer points of contact between
particles.
[0029] In an open graded particle mixture, the open voids may
comprise 15% to 25% of the total volume of the packed material.
These voids can make the packed bone particle structure water
permeable, making it easier and faster for the excess water from
the injected slurry to be absorbed or removed as the bone particles
pack together on the inside of the vertebral body. These voids also
form pores that can be useful for bone ingrowth. Thus, it can be
advantageous for the bone particles in the slurry to have a D60/D10
uniformity coefficient of at least 2. In some implementations, the
uniformity coefficient is between 2 and 6. In some implementations,
the uniformity coefficient is greater than 6. In some
implementations, the range of characteristic sizes is limited to
reliably produce pores in the packed material such as are shown in
FIG. 4. For example, in some implementations, the mean
characteristic size of the largest 10% by mass of the particles is
no more than 5 times the mean characteristic size of the smallest
10% by mass of the particles.
[0030] It is possible to use more complex forms of bone particles
as a component of the slurry as well. For example, flexible and
compressible spongy webs of bone tissue that may be used as
bioscaffolds have been created and are commercially available.
Pieces of this type of bone material could be compressed while
being injected in the slurry and can expand after exiting to the
interior of the vertebral body.
[0031] The slurry pump 28 used for delivery of the particle slurry
may be similar to a caulking gun or other pressurization device
with a knob or trigger or the like to gradually and steadily
pressurize the vertebral body with the slurry. The slurry pump may
also have a pressure gauge to identify to the surgeon or treating
physician how much pressure is being exerted by the slurry pump
when performing the slurry injection. The slurry pump 28 should be
able to create a pressure at the distal outlet(s) of the catheter
inside the vertebral body of about 5-20 psi above ambient
atmospheric pressure, similar to the intervertebral pressures that
occur in conventional vertebroplasty and kyphoplasty procedures.
How much pressure this requires at the proximal end of the catheter
near or at the output of the slurry pump 28 will depend on the
specific properties of the slurry such as viscosity, as well as the
length, lumen diameter, and internal surface characteristics of the
catheter. These factors will affect the pressure drop from the
input to the output of the catheter. Balloon inflation syringes
that are currently used in kyphoplasty procedures that have an
output pressure capability of 200 to 700 psi and one of these types
of inflation syringes could be used as the slurry pump 28. An
electrical rotating auger drive pump could also be used as the
slurry pump 28.
[0032] FIG. 5 illustrates a possible bi-pedicular approach, where
two openings, two cannulas, and two catheters are used. In this
implementation, slurry can be injected into the vertebra at the
same time through two catheters. In FIG. 5 two slurry reservoirs
and two slurry pumps are also illustrated. This may be convenient
for separate monitoring and control of the slurry injection in the
two catheters. Also, it distributes the pressurization duty across
two separate systems. It will be appreciated, however, that these
could be combined into a single reservoir and single pump if
desired.
[0033] FIG. 6 illustrates another implementation of the
bi-pedicular access also illustrated in FIG. 5. In the
implementation of FIG. 6, the second catheter may not be used as
another injection pathway for slurry. Instead, the distal end of
the second catheter comprises a filtered opening 62. The proximal
end of the second catheter is coupled to an aspirator 64 which can
be used to aspirate excess slurry liquid as the bone particles of
the slurry settle and pack within the vertebral body. Alternatively
or additionally, the aspirator 64 can provide an agitation function
that can agitate the injected slurry material within the vertebral
body as the bone particles of the slurry settle and pack within the
vertebral body. This can help ensure that bone particles of
different sizes in the slurry remain more homogeneously distributed
settle and pack within the vertebral body. To perform agitation and
aspiration, the aspirator/agitator may alternate between fluid
injection and fluid aspiration. For example, it may inject 0.1 cc,
then aspirate 0.2 cc, and so on in rapid succession. The aspiration
and agitation functions could also be completely separate. An
implantation like this may include reciprocating fins on the second
catheter for example. As a further technique for agitation of the
slurry as it is injected, the slurry pump 28 could have a mechanism
to vibrate or reciprocate the distal end of either or both of the
first or second catheters and/or cannulas such as with ultrasound,
piezoelectric transducers, or other mechanical means.
Additional Embodiments
[0034] The cannula or needle apparatus can also have a distraction
device to create a cavity if need be within the vertebral body;
however, with gradual pressurization and movement of the needle in
multiple directions, the cavitation may not be necessary. Such
cavitation if performed, can be done with a spring within the
needle sheath to expand the needle in multiple directions or a
balloon to expand the fractured vertebra cancellous bone or a
cortical cap that can be placed onto the shaft of the needle or
cannula that can be used to distract the endplates that have
fractured and fill in the bone interstices with our cortical
allograft for autologous microspheres. This cortical bone cap may
be on the needle or cannula and can be deployed with spring loaded
compression to push the endplates back into normal position. This
would be the first time that bone would be utilized to distract the
compressed vertebra and allow the microspheres to maintain its
height and eventually allow the vertebral body to heal. This method
of incremental bone impaction can also be utilized at the cephalad
or caudal end of a surgical construct such as a posterolateral
instrumented fusion to prevent proximal junctional kyphosis or
minimize fracture of the sacrum, ileum or lower lumbar spine or any
bone.
[0035] In the above described specific implementation, there is a
separate slurry injection catheter that is inserted into the
vertebral body through a cannula placed in the access opening to
the inside of the vertebral body. It will be appreciated that it
would also be possible to use the cannula directly as an injection
and/or aspiration path without using a separate catheter within a
cannula, combining the functions of both described above into one
element.
[0036] In some implementations, the bone particle slurry may
additionally contain particles of material other than bone. For
example, these non-bone particles incorporated into the bone
particle slurry may comprise metal particles such as titanium
particles or polymer particles such as PMMA particles, or any
mixture of non-bone particles of different types. In some
implementations, these non-bone particles may be of relatively
small size, such as having a characteristic size of less than 100
micrometers, less than 50 micrometers, or less than 20 micrometers.
In these implementations, multiple non-bone particles can become
incorporated into the voids illustrated in FIG. 4. In some
implementations, such a slurry may be "gap graded" where there are
bone particles having a relatively narrow range of large
characteristic sizes, and non-bone particles having a relatively
narrow range of much smaller characteristic sizes. For example, the
mean characteristic size of the smallest 10% of the bone particles
in the slurry may be at least five time larger than the mean
characteristic size of the largest 10% of the non-bone particles.
In these implementations, the non-bone particles can be configured
to elute therapeutic substances such as chemotherapy drugs,
antibiotics, or the like. Some or all of the non-bone particles may
be resorbable. Such a mixture of bone and non-bone particles can
provide a desirable combination of structural support with bone
material having good compressive modulus properties, and
therapeutic support with non-bone material that may easily be made
to incorporate therapeutic substances in know manners.
[0037] Although the present disclosure has been described in terms
of certain preferred features, other features of the disclosure
including variations in dimensions, configuration and materials
will be apparent to those of skill in the art in view of the
disclosure herein. In addition, all features detailed in connection
with any one aspect herein can be readily adapted for use in other
aspects herein. The use of different terms or reference numerals
for similar features in different embodiments does not imply
differences other than those which may be expressly set forth.
Accordingly, the present disclosure is intended to be described
solely by reference to the appended claims, and not limited to the
preferred embodiments disclosed herein.
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