U.S. patent application number 11/468421 was filed with the patent office on 2008-09-18 for cannula.
This patent application is currently assigned to DISC-O-TECH MEDICAL TECHNOLOGIES, LTD.. Invention is credited to Mordechay Beyar, Oren Globerman.
Application Number | 20080228192 11/468421 |
Document ID | / |
Family ID | 37768787 |
Filed Date | 2008-09-18 |
United States Patent
Application |
20080228192 |
Kind Code |
A1 |
Beyar; Mordechay ; et
al. |
September 18, 2008 |
Cannula
Abstract
A bone cement cannula, the cannula comprising: a tube including
a section adapted for plastic deformation; and a lumen in the tube
capable of resisting forces of a viscous material propelled
therethough at a pressure of at least 100 atmospheres.
Inventors: |
Beyar; Mordechay; (Caesarea,
IL) ; Globerman; Oren; (Kfar-Shmaryahu, IL) |
Correspondence
Address: |
NUTTER MCCLENNEN & FISH LLP
WORLD TRADE CENTER WEST, 155 SEAPORT BOULEVARD
BOSTON
MA
02210-2604
US
|
Assignee: |
DISC-O-TECH MEDICAL TECHNOLOGIES,
LTD.
Herzelia Pituach
IL
|
Family ID: |
37768787 |
Appl. No.: |
11/468421 |
Filed: |
August 30, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60763003 |
Jan 26, 2006 |
|
|
|
60721094 |
Sep 28, 2005 |
|
|
|
60762789 |
Jan 26, 2006 |
|
|
|
Current U.S.
Class: |
606/94 ;
606/93 |
Current CPC
Class: |
B01F 15/00506 20130101;
A61L 27/26 20130101; A61L 27/26 20130101; C08L 33/12 20130101; B01F
15/0278 20130101; A61B 17/8816 20130101; A61F 2/44 20130101; A61L
24/043 20130101; C08L 33/12 20130101; A61B 17/8811 20130101; A61B
2017/00539 20130101; A61F 2/4601 20130101; A61L 24/06 20130101;
A61F 2002/4693 20130101; A61B 17/3421 20130101; A61L 2430/38
20130101; A61B 2017/2905 20130101; B01F 7/30 20130101; B01F
15/00876 20130101; A61B 17/1671 20130101; A61B 2090/3937 20160201;
A61B 17/1604 20130101; A61B 17/8822 20130101; A61L 2430/02
20130101; A61B 17/8836 20130101; B01F 15/0279 20130101; A61L 24/043
20130101 |
Class at
Publication: |
606/94 ;
606/93 |
International
Class: |
A61F 2/28 20060101
A61F002/28 |
Claims
1. A bone cement cannula, the cannula comprising: (a) a tube
including a section adapted for plastic deformation; and (b) a
lumen in the tube capable of resisting forces of a viscous material
propelled therethough at a pressure of at least 100
atmospheres.
2. A cannula according to claim 1, wherein said section adapted for
plastic deformation comprises a series of separate joints formed in
an outer wall of the cannula.
3. A cannula according to claim 2, wherein at least one of said
joints is formed by at least one cut.
4. A cannula according to claim 3, wherein at least one of said
cuts is configured to close as the cannula deforms.
5. A cannula according to claim 2, wherein at least one of said
joints is formed by non-penetrating weakening of the cannula
wall.
6. A cannula according to claim 2, wherein said joints facilitate a
desired deformation configuration of the cannula.
7. A cannula according to claim 2, wherein said joints are
sealed.
8. A cannula according to claim 1, comprising an outer sealing
layer.
9. A cannula according to claim 1, comprising an inner sealing
layer.
10. A cannula according to claim 1, wherein said section is adapted
to remain outside of a body.
11. A cannula according to claim 1, wherein said section adapted
for plastic deformation comprises a deformable sleeve.
12. A cannula according to claim 1, wherein said section adapted
for plastic deformation comprises a flexible tube and a
configuration support for said tube.
13. A cannula, comprising: (a) a tube including a section adapted
for plastic deformation; and (b) a lumen in the tube, said lumen at
least partially filled with a bone filling material.
14. A bone cement cannula, the cannula comprising: (a) a tube
including a tube lumen providing a channel of fluid communication
between at least one injection aperture and a connector body; and
(b) at least two inlet ports defined in said tube.
15. A cannula according to claim 14, wherein one of said ports is
axially oriented.
16. A cannula according to claim 14, wherein at least one of said
ports is trans-axially oriented.
17. A cannula according to claim 14, including a port path selector
adapted to selectively allow flow from one of said ports.
18. A cannula according to claim 14, including a port path blocker
adapted to selectively allow block back-flow out of one of said
ports.
19. A manufacturing process for a surgical tool, the method
comprising: (a) determining a pattern of cuts which will impart a
desired deformability to a work piece; (b) imparting the desired
plastic deformability to the work piece by incising the pattern of
cuts therein to produce a surgical tool; and (c) forming said work
piece into a cannula suitable for bone cement injection.
20. A method of delivering cement, comprising: (a) providing a
cannula with an axial guide-wire exiting through an axial hole
thereof and said cannula including a side exit port; (b) inserting
said cannula into a bone; (c) removing said guide-wire; and (d)
injecting cement through said cannula such that less than 20% of
the cement exits through the axial hole.
21. A method of injecting a viscous material into a patient,
comprising: (a) inserting a cannula into a patient; (b) bending
said cannula over a length of at least 20 mm; and (c) injecting a
viscous material through said cannula.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit under 119(e) of a US
provisional application titled "Cannula", filed on Jan. 26, 2006,
and having Ser. No. 60/763,003, the disclosure of which is
incorporated herein by reference.
[0002] This application also claims the benefit under 119(e) of a
US provisional application titled "Tools and methods for treating
bones", filed on Sep. 28, 2005, and having Ser. No. 60/721,094, the
disclosure of which is incorporated herein by reference.
[0003] This application also claims the benefit under 119(e) to
U.S. application 60/762,789 entitled "Methods, Materials and
Apparatus for Treating Bone and other Tissue" filed Jan. 26, 2006,
with the same inventors as this application, the disclosure of
which is incorporated herein by reference.
[0004] This application also claims priority from U.S. application
Ser. No. 11/360,251 entitled "Methods, materials, and apparatus for
treating bone and other tissue filed on Feb. 22, 2006 the
disclosure of which is incorporated herein by reference.
[0005] This application is related to PCT Applications Nos.
PCT/IL00/00056, filed Jan. 27, 2000, published as WO 00/44321;
PCT/IL00/00058, filed Jan. 27, 2000, published as WO 00/44319;
PCT/IL2004/000527, filed Jun. 17, 2004, published as WO 04110300;
PCT/IL2005/000812, filed Jul. 31, 2005; the disclosures of all of
which are incorporated herein by reference.
FIELD OF INVENTION
[0006] The present invention relates to devices and methods for
delivery of material into an organ, for example cannulae for
delivery of bone cement during an orthopedic procedure.
BACKGROUND OF THE INVENTION
[0007] Surgical and/or interventional treatment of fractured bones,
osteoporotic bones, deformed bones and the like occasionally
includes the use of various types of bone fillers, in order to
reinforce and stabilize the bone, restore its original
configuration and alleviate pain.
[0008] Vertebral fractures, for example, may be treated using the
vertebroplasty technique, during which bone cement (e.g. PMMA) is
injected into the vertebral body through a cannula with a diameter
of approximately 1 to 4 mm. Current vertebroplasty procedures
typically rely upon a needle and stylet assembly, such as a
Jamshidi needle.
[0009] The currently available needle and stylet are typically made
of a rigid inflexible material, e.g., metal. A typical procedure
includes approaching the bone, under fluoroscopy, with a needle and
cannula assembly, followed by removal of the stylet. The remaining
cannula serves as a channel through which the bone cement is
delivered into the bone from a reservoir connected to the cannula.
Most commonly employed bone cements are not X-ray transparent.
[0010] US patent application 2004/0054377 by Foster teaches a
flexible cannula made from a single continuous piece of tubing. The
proximal end of the cannula is made flexible by removing material
from the wall of the cannula, preferably in a spiral pattern. The
disclosure of this application is fully incorporated herein by
reference. Foster's cannula has a grasping device at the distal end
and is designed and constructed for removal of objects from soft
tissue. Foster contemplates neither delivery of cement via the
cannula nor use of the cannula in orthopedic procedures.
[0011] U.S. Pat. No. 6,719,761 to Reiley teaches use of steering
wires to deflect (curve) a distal end of a cannula for injecting
bone cement, apparently low viscosity cement is used. The
disclosure of this patent is fully incorporated herein by
reference.
[0012] U.S. Pat. No. 6,875,219 to Arramon teaches a cannula with a
deformable distal tip. Deformation is achieved by inserting the
cannula over a curved guide. The disclosure of this patent is fully
incorporated herein by reference.
[0013] US patent application publication number 2004/0260303 to
Carrison, the disclosure of which is incorporated herein by
reference, describes a pivoting cannula attachment to a reservoir,
with the pivot adjacent a connector to the reservoir.
SUMMARY OF THE INVENTION
[0014] An aspect of some embodiments of the invention relates to a
plastically deformable bone cement cannula. Optionally, plastic
deformation of the cannula by hand permits a desired positioning of
a cement reservoir attached thereto, relative to the cannula,
imaging equipment and/or the patient. Optionally, a rigid stylet
prevents plastic deformation of the cannula during insertion. Such
stylet is optionally provided as a straight stylet or as a curved
stylet. In an exemplary embodiment of the invention, the
deformation uses less than 2 Kg force. Optionally, the deformation
does not damage tissues inside the body as the cannula is
deformed.
[0015] In an exemplary embodiment of the invention, insertion in a
straight line is provided by the cannula in an un-deformed
configuration, which may be easier, and then the cannula is
distorted to a form suitable for another use, for example, during
injection and/or imaging.
[0016] In an exemplary embodiment of the invention, the cannula is
stiff enough so that it maintains its deformation during injection
of material therethrough. Optionally, the injected material is
viscous, for example, viscous bone cement, injected at a high
pressure, for example, at least 50 Atmospheres, at least 100
Atmospheres, at least 150 Atmospheres, at least 200 Atmospheres
and/or intermediate or smaller numbers. In an exemplary embodiment
of the invention, the viscosities used are between 100 and 3000
Pascal-second, for example 300-2000, for example, between 500 and
1000. Intermediate values may be used as well. In an exemplary
embodiment of the invention, the cannula includes a series of
joints which facilitate plastic deformation in a desired manner. In
an exemplary embodiment of the invention, the joints are provided
as joint areas including patterns of cuts and/or other weakening in
the cannula body material. Optionally, the cuts are discrete.
Optionally, the cuts are through cuts. Alternatively, at least some
of the cuts are notches or other thinning of the cannula material.
Optionally, another weakening type is provided, for example, by
chemical treatment and/or mechanical and/or heat treatment.
[0017] In an exemplary embodiment of the invention, the cuts and/or
weakening are designed to designate particular parts of the cannula
to act as plastically deformed segments, at which a significant
portion of the overall deformation is provided.
[0018] In an exemplary embodiment of the invention, the cuts and/or
weakening are designed to facilitate a particular direction and/or
degree of deformation or range of degrees. Optionally, the cuts are
designed to reduce spacings in the cannula body, for example,
spacings between lips of cuts.
[0019] Optionally such design includes one or more of cut shape,
cut size, number of cuts, depth, radial profile, number of groups
of cuts, relative size of cuts in different groups and/or relative
position of cuts in different groups.
[0020] In an exemplary embodiment of the invention, cut/weakening
design and/or distribution takes into account expected applied
forces.
[0021] In an exemplary embodiment of the invention, at least some
of the cuts tend to at least partially close during deformation.
Optionally, the tendency to partially close is related to a degree
of bending the cut is subjected to. Optionally, partial closing
reduces leaking of a material injected through the cannula.
Optionally, the cuts are covered to reduce leaking of a material
injected through the cannula. In an exemplary embodiment of the
invention, a covering which substantially reduces leaking through
the slits at a pressure of 100 to 200 or 300 atmospheres is
provided. The covering may be, for example, internal or external,
for example, of Teflon. Optionally, a more viscous cement is used
with the cannula, to reduce leakage. In an exemplary embodiment of
the invention, a cement is selected which reduces leakage in other
means, for example, the cement may include a liquid phase and a
solid phase, with the solid particles being of the order of the
narrow dimensions of the slits or larger. Optionally, leakages is
reduced once the solid particles are at least 10%, at least 35%, at
least 60%, at least 80% or larger of such narrow dimensions, for
example, being at least 0.01 mm, 0.05 mm, 0.1 mm, 0.3 mm, or
intermediate or greater in size.
[0022] In an exemplary embodiment of the invention, the joints each
comprises an asymmetric cut design, in which a greater spacing
between lips is provided on one side of the cut, so that bending in
the direction of that side, tends to reduce the spacing.
[0023] In an exemplary embodiment of the invention, the joints are
arranged in a line parallel to the cannula axis.
[0024] In an exemplary embodiment of the invention, a manufacturing
process imparts flexibility to a workpiece by incising a series of
cuts therein. Optionally, the process is carried out by an
automated machine including control circuitry. Incision of cuts may
be, for example, by one or more of lasers, chemical etching, water
jets and rotating abrasive discs.
[0025] In an exemplary embodiment of the invention, the joints
(e.g., cuts and/or weakening) are designed to support deformation
outside a body or adjacent to a point of entry of the cannula into
the body (e.g., at a proximal end thereof).
[0026] In an exemplary embodiment of the invention, each joint
permits a deformation of 5, optionally 10, optionally 15 degrees or
lesser or greater or intermediate values. Optionally, a total
deformation of 45, optionally 90, optionally 135, optionally 180
degrees or smaller, intermediate values or greater is achieved
and/or is designated as a design set point where there is minimal
leakage. The length of cannula subject to deformation may vary with
the total deformation implemented and/or the number of slits
employed, for example, being 20 mm, 30 mm, 40 mm, or greater,
smaller or intermediate in size. In an exemplary embodiment of the
invention, 13 cuts provide a total deformation of 130 degrees.
Greater or smaller numbers of cuts/deformation regions may be
provided, for example, 7, 10, 15 or smaller, intermediate or
greater numbers.
[0027] Optionally, the degree of supported deformation of a
deforming segment is selected to reduce leakage and/or
straightening behavior. Optionally, leakage is reduced by
increasing the number of joints to the point where the product of
the joint by the leakage through the joint is minimized. In
general, for a desired bending angle, as the number of joints
increases, the leakage is typically reduced.
[0028] In an exemplary embodiment of the invention, the cannula
includes a plastically deformable tube. Optionally, the tube is a
flexible tube which contains internal and/or external supports to
counteract change after deformation. Optionally, the supports are
designed for a particular degree and/or direction of plastic
deformation.
[0029] An aspect of some embodiments of the invention relates to a
bone cement cannula with at least two fill ports. Optionally, the
fill ports are deployed at different angles with respect to the
main cannula axis. In an exemplary embodiment of the invention, a
single port is used for injection of cement. Optionally, the other
port is used for guiding of a stylet or other guide tool through
the cannula.
[0030] In an exemplary embodiment of the invention, unused ports
are covered, plugged and/or removed from a cement flow path by a
stopcock.
[0031] An aspect of some embodiments of the invention relates to a
stylet, at least part of the stylet being flexible, so that angled
insertion of the stylet into the patient's body is facilitated. In
an exemplary embodiment of the invention, the stylet and/or a
cannula is introduced into a bone, for example a vertebra. In yet
another exemplary embodiment of the invention, the device is
introduced into the body during laparoscopic surgery. Optionally,
the stylet and/or cannula comprise a handle at their proximal end.
Optionally, said handles are made of a polymer. Optionally, said
handles interlock with each other. In an exemplary embodiment of
the invention, the interlocking arranges the parts in a correct
orientation. Optionally, the interlocking prevents inadvertent
rotation or axial motion of one part relative to the other.
[0032] An aspect of some embodiments of the invention relates to a
device, intended to serve as a channel for the delivery of material
and/or devices/instruments into the body. In an exemplary
embodiment of the invention, bone void filler, such as PMMA, is
delivered via the device into a bone, for example a vertebral body.
In one embodiment of the invention, the device comprises at least a
cannula. Optionally, the device comprises a cannula and stylet, and
may be used for accessing the target organ as well. In an exemplary
embodiment of the invention, the cannula and stylet are assembled
and interlocked. Optionally, cannula and stylet are interlocked at
proximal handles thereof.
[0033] In an exemplary embodiment of the invention, the device is
constructed from biocompatible materials. Optionally, the device is
constructed from metal, such as stainless steel or a
nickel-titanium alloy such as NiTinol. Optionally, at least a
portion of device is formed form a polymer.
[0034] In an exemplary embodiment of the invention, the deformable
cannula is designed to withstand the loads acting on it during
usage, for example torque during insertion into a bone and/or
removal therefrom.
[0035] Optionally, a proximal end of the cannula includes a
connection means for attaching to a delivery device, for example a
Luer-lock type connector.
[0036] Optionally, the cannula comprises at least one marker, for
instance to indicate insertion depth and/or facilitated cannula
bending direction. Such marking may be, for example, visible to
human eye and/or under imaging, such as x-ray imaging.
[0037] In an exemplary embodiment of the invention, the cannula
tapers at its distal end and/or is otherwise shaped, for example,
to serve as a trocar.
[0038] An aspect of some embodiments of the invention relates to a
cement provision cannula with an axial hole suitable for a stylet
and through which cement leakage is reduced or absent. Optionally,
the size of the hole reduces leakage. Alternatively or
additionally, the properties of the cement used reduce leakage, for
example, viscosity and/or grain size. Alternatively or
additionally, the cannula and/or delivery system include a plug
which selectively closes the axial hole once the stylet is
removed.
[0039] There is also provided in accordance with an exemplary
embodiment of the invention, a bone cement cannula, the cannula
comprising:
(a) a tube including a section adapted for plastic deformation; (b)
a lumen in the tube capable of resisting forces of a viscous
material propelled therethough at a pressure of at least 100
atmospheres.
[0040] Optionally, said section adapted for plastic deformation
comprises a series of separate joints formed in an outer wall of
the cannula. Optionally, at least one of said joints is formed by
at least one cut. Optionally, at least one of said cuts is
configured to close as the cannula deforms.
[0041] In an exemplary embodiment of the invention, at least one of
said joints is formed by non-penetrating weakening of the cannula
wall.
[0042] In an exemplary embodiment of the invention, said joints
facilitate a desired deformation configuration of the cannula.
[0043] In an exemplary embodiment of the invention, said joints are
sealed.
[0044] In an exemplary embodiment of the invention, the cannula
comprises an outer sealing layer.
[0045] In an exemplary embodiment of the invention, the cannula
comprises an inner sealing layer.
[0046] In an exemplary embodiment of the invention, said section is
adapted to remain outside of a body.
[0047] There is also provided in accordance with an exemplary
embodiment of the invention, a cannula, comprising:
(a) a tube including a section adapted for plastic deformation; (b)
a lumen in the tube, said lumen at least partially filled with a
bone filling material.
[0048] In an exemplary embodiment of the invention, said section
adapted for plastic deformation comprises a deformable sleeve.
[0049] In an exemplary embodiment of the invention, said section
adapted for plastic deformation comprises a flexible tube and a
configuration support for said tube.
[0050] There is also provided in accordance with an exemplary
embodiment of the invention, a bone cement cannula, the cannula
comprising:
(a) a tube including a tube lumen providing a channel of fluid
communication between at least one injection aperture and a
connector body; and (b) at least two inlet ports defined in said
tube.
[0051] Optionally, one of said ports is axially oriented.
[0052] Optionally, at least one of said ports is trans-axially
oriented.
[0053] In an exemplary embodiment of the invention, the cannula
comprises a port path selector adapted to selectively allow flow
from one of said ports.
[0054] In an exemplary embodiment of the invention, the cannula
comprises a port path blocker adapted to selectively allow block
back-flow out of one of said ports.
[0055] There is also provided in accordance with an exemplary
embodiment of the invention, a manufacturing process for a surgical
tool, the method comprising:
(a) determining a pattern of cuts which will impart a desired
deformability to a work piece; (b) imparting the desired plastic
deformability to the work piece by incising the pattern of cuts
therein to produce a surgical tool; and (c) forming said work piece
into a cannula suitable for bone cement injection.
[0056] There is also provided in accordance with an exemplary
embodiment of the invention, a method of delivering cement,
comprising:
(a) providing a cannula with an axial guide-wire exiting through an
axial hole thereof and said cannula including a side exit port; (b)
inserting said cannula into a bone; (c) removing said stylet; and
(d) injecting cement through said cannula such that less than 20%
of the cement exits through the axial hole.
[0057] There is also provided in accordance with an exemplary
embodiment of the invention, a method of injecting a viscous
material into a patient, comprising:
(a) inserting a cannula into a patient; (b) bending said cannula
over a length of at least 20 mm; and (c) injecting a viscous
material through said cannula.
BRIEF DESCRIPTION OF DRAWINGS
[0058] In the Figures, identical structures, elements or parts that
appear in more than one Figure are generally labeled with the same
numeral in all the Figures in which they appear. Dimensions of
components and features shown in the Figures are chosen for
convenience and clarity of presentation and are not necessarily
shown to scale. The Figures are listed below.
[0059] FIG. 1 is a flow diagram illustrating a cement provision
method, in accordance with an exemplary embodiment of the
invention;
[0060] FIG. 2 is a front view of a deformable cement cannula with
stylet inserted, in accordance with some exemplary embodiments of
the present invention;
[0061] FIG. 3A is a perspective view of a deformable cement cannula
prior to deformation in accordance with some exemplary embodiments
of the present invention;
[0062] FIG. 3B (inset) is magnification of a portion of the
exemplary cannula showing slits according to the embodiment
illustrated in FIG. 3A;
[0063] FIGS. 4A and 4B illustrate the cannula depicted in FIGS. 3A
and 3B after deformation, in accordance with an exemplary
embodiment of the invention;
[0064] FIG. 4C is a diagrammatic representation of slits according
to FIGS. 3B and 4B illustrating exemplary geometric
considerations;
[0065] FIG. 5 is a plan view of the cannula of FIG. 3A;
[0066] FIG. 6 illustrates a deformed cannula including a sleeve
according to an exemplary embodiment of the invention;
[0067] FIG. 7 is a perspective view of a deformable cement cannula
prior to deformation in accordance with some exemplary embodiments
of the present invention illustrating a lateral ejection port and a
penetrating distal tip;
[0068] FIG. 8A is a perspective view of a deformable cement cannula
including external support prior to deformation in accordance with
an exemplary embodiment of the invention;
[0069] FIG. 8B is a perspective view of the cannula of FIG. 8A,
after deformation in accordance with an exemplary embodiment of the
invention;
[0070] FIGS. 9A and 9B are side cross-sectional views of a
plastically deformable cannula according to exemplary embodiments
of the invention before and after plastic deformation
respectively;
[0071] FIGS. 10A and 10B are side cross-sectional views of a
cannula with multiple fill ports according to exemplary embodiments
of the invention without and with a port cover respectively;
[0072] FIGS. 10C and 10D are side cross-sectional views of a
cannula with multiple fill ports according to exemplary embodiments
of the invention with a port closure valve open and closed
respectively;
[0073] FIGS. 10E and 10F are side cross-sectional views of a
cannula with multiple fill ports according to exemplary embodiments
of the invention with a stopcock directed towards an axial and a
radial port respectively;
[0074] FIG. 11 is a flow diagram illustrating a method of
manufacture according to exemplary embodiments of the invention;
and
[0075] FIG. 12 is a schematic side cross-sectional view of a
sealed-tip cannula, with an axial aperture for a stylet, in
accordance with an exemplary embodiment of the invention.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
Overview of Method
[0076] FIG. 1 is a flow diagram illustrating a method 100 of cement
provision, in accordance with an exemplary embodiment of the
invention. At 102, a cannula is inserted, optionally with or
without the aid of a stylet. Such stylet may be, for example, rigid
or flexible, straight or bent. Optionally, insertion 102 is
monitored 104 via a medical imaging apparatus such as, for example,
a fluoroscope or conventional X-ray camera. If the optional stylet
has been employed, it may be removed 106 at this stage.
[0077] At 108, plastic deformation of the cannula is performed (it
is noted that the cannula can be deformed before insertion), for
example to be curved. At 110 a bone cement reservoir and/or
delivery system are attached to a proximal end of the cannula. The
order in which 108 and 110 are performed is optionally reversed. In
some cases, the reservoir is integral with the cannula.
[0078] An injection 112 of cement or other viscous material is then
performed.
[0079] Plastic deformation 108 and attachment 110 are optionally
performed in consideration of subsequent injection monitoring 114.
Because the bone cement and/or injection reservoir may not be X-ray
transparent, deformation 108 is performed so that an attached
cement reservoir will be outside of a relevant portion of a field
of view of an X-ray image taken during injection 112. X-rays are
often obtained from a directional perpendicular to the body, e.g.,
along the axis of the unbent cannula, but this is not always the
case and the cannula deformation may be changed.
[0080] Injection 112 may be undertaken using a suitable injection
device connected to the cement reservoir. In an exemplary
embodiment of the invention, a high viscosity bone cement is
employed and a high pressure injection device is employed, for
example as described in U.S. application Ser. No. 11/360,251, the
disclosure of which is incorporated herein by reference.
Alternatively, a syringe or other delivery system is used. The
delivered material may be, for example, PMMA or calcium-based
material (such as calcium phosphate or calcium sulfate).
[0081] Optionally, a vibrator is attached to the cannula, for
example, at a connector of the reservoir thereto, to facilitate
flow of cement therethrough.
[0082] Optional injection 112 is monitored via a medical imaging
apparatus such as, for example, a fluoroscope or conventional X-ray
camera. Such monitoring may be, for example, periodically or
throughout the injection 114.
[0083] When injection 112 is complete as indicated by monitoring
114, the cement reservoir is disconnected 116 and the cannula is
removed 118. The order in which 116 and 118 are performed is
optionally reversed.
Plastic Deformation
[0084] A cannula according to exemplary embodiments of the
invention is plastically deformable, as opposed to flexible.
"Plastic deformation" as used herein refers to a change in shape
which requires an input energy to implement, and another energy
input, for example, of similar order, to reverse. In an exemplary
embodiment of the invention, the input energy required for plastic
deformation is sufficiently small that it can be applied manually,
optionally with one hand. Optionally, once deformed, the cannula
will not un-deform under forces applied to it by injecting cement
therethrough and/or without external forces.
[0085] In an exemplary embodiment of the invention, the deformation
is facilitated to be in a certain direction and/or one plane.
Optionally, once the cannula is deformed, a weight of a cement
reservoir attached thereto will tend to preserve the deformation
and/or assist in resisting forces applied by injection of cement
therethrough.
[0086] In an exemplary embodiment of the invention, the deformation
is limited in extent and/or degree. Optionally, a desired maximum
angle of deformation is facilitated by the construction and/or
design of the cannula. While application of excessive force may
cause additional bending beyond this maximum angle, such additional
bending would be beyond the scope of designed deformation. Such
additional bending may cause kinking of the cannula and/or leakage
therefrom. In an exemplary embodiment of the invention, a weight of
a cement reservoir attached to the cannula does not provide
excessive force sufficient to deform and/or over-deform the
cannula. Optionally, the reservoir provides sufficient force to
deform the cannula until the reservoir rests against the patient
and/or other support.
[0087] The degree of plastic deformability may be governed to some
extent by materials employed in construction of the cannula. Some
materials have a higher degree of plasticity than others. Some
materials have an elastic memory which causes them to tend to
return to their original shape when a deforming force is removed.
In exemplary embodiments of the invention, such as described below,
deformation is facilitated by the geometry/structure of the cannula
and/or supports provided thereto.
Slit Cannula
[0088] FIG. 2 is a front view of an assembled Cannula/stylet
apparatus 200 according to an exemplary embodiment of the
invention, showing a partial cross-section view of handles thereof.
In an exemplary embodiment of the invention, the handle orientation
is matched to the slit orientation (described below), so that in
typical use, the forces applied by a doctor to insert the cannula
will not be in the same direction as forces that are used to bend
the cannula. Optionally, the handle direction is used to indicate
the desired deformation direction.
[0089] Cannula 212 includes a series of slits 224 designed to
impart a desired plastic deformation capability to a specific
portion of the cannula. Cannula 212 optionally includes a handle
222 at its proximal end.
[0090] Stylet 214 is inserted through cannula 212 via an inner
lumen of the cannula. A cutting tip 218 of stylet 214 optionally
protrudes from a distal end of cannula 212. Distal tip 218 is
optionally adapted to puncture and penetrate the skin, soft tissue
and/or cortical bone. Tip 218 may be, for example, of diamond type,
drill type, bevel type or J-type, or of other tip types known in
the art.
[0091] Optionally, a distal tip of the cannula is formed of a radio
opaque material of different opacity and/or there is a step in
diameter between the cannula and the stylet, so that transition is
clearer on an x-ray image.
[0092] Optionally, stylet 214 is equipped with a proximal handle
220. In an exemplary embodiment of the invention, handles 222 and
220 engage one another via an engagement mechanism 216, for example
a threaded connection. Optionally, a spring is provided to
elastically couple the components. An alternative locking mechanism
217 is shown as well, in which a tongue on one handle snap-locks to
a groove on the other handle. Such snap-locking may be, for
example, by rotation or by axial motion.
[0093] In an exemplary embodiment of the invention, stylet 214 is
rigid. Optionally, a rigid stylet supports cannula 212 during
insertion and prevents deformation of cannula 212 until such
deformation is desired. In an exemplary embodiment of the
invention, the stylet is removed before deformation is undertaken.
Optionally, a lumen of cannula 212 is adapted to comply with a
diameter of stylet 214. For example, an inner cannula lumen of 2.7
mm may be provided with a stylet of 2.6 mm.
[0094] In an alternative embodiment, stylet 214 is curved.
Alternatively or additionally, stylet 214 is flexible, for example,
at a portion corresponding to slit series 224.
[0095] In an exemplary embodiment of the invention, stylet 214 has
a preferred orientation (e.g., is beveled) which optionally matches
an angled/beveled tip of the cannula.
[0096] In an exemplary embodiment of the invention designed for use
in a fractured vertebral body, stylet 214 has a diameter of about
1.4-2.6 mm. It is noted that viscous material may be provided to
other bone sand/or other parts of the body using the apparatus and
methods described herein. The cannula optionally has an inner
diameter of about 2.7 mm and an outer diameter of about 3 mm. When
employed in a vertebroplasty procedure, the assembled cannula
stylet 200 is introduced into the body, so distal tip 218
penetrates skin, soft tissue and vertebra. Stylet 214 is then
disconnected from cannula 212 which remains in situ as described
with regard to method 100 (FIG. 1).
[0097] FIG. 3A illustrates an exemplary cannula 212 with stylet 214
removed. The straight configuration of cannula 212 is optionally
used for device introduction. Cannula 212 comprises a series of
slits 224, which facilitate plastic deformation. FIG. 3B (inset) is
an enlargement of part of series of slits 224 showing the slits in
greater detail.
[0098] The pattern of the slits enlarged in FIG. 3B includes two
rows of slits 226, 228 and 230, 232. The rows are displaced 180
degrees relative to each other with respect to the circumference of
cannula 212. In the depicted exemplary embodiment, each row
includes 12 slits, but other numbers may be provided. The slits may
penetrate the cannula wall completely, or they may be perforations
or grooves etched in the cannula wall.
[0099] FIGS. 4A and 4B (inset) illustrate plastic deformation of
cannula 212 of FIGS. 3A and 3B. As seen most clearly in inset 4B,
slits 230 and 232 on the inner side of the bend caused by the
deformation tend to close as a result of the deformation. Slits 226
and 228 on the outer side of the bend caused by the deformation
tend to remain the same size or open slightly as a result of the
deformation. The closing is explained in greater detail with
regards to FIGS. 4C and 5.
[0100] In an exemplary embodiment of the invention, slits 226 and
228 are characterized by a width of, for example, 0.03 mm. Cannula
thickness can be, for example, 0.03 mm. During plastic deformation,
this width increases, for example to about 0.3 mm, for some of the
slits or sections thereof (e.g., the outer slits). In the exemplary
embodiment of the invention depicted in FIGS. 3A; 3B; 4A and 4B,
the initial width of slits in the row along the inside of the curve
produced by plastic deformation (230, 232) is larger than the
initial width of the slits in the row along the outside of the
curve produced by plastic deformation (226, 228).
[0101] In an exemplary embodiment of the invention, cannula 212 is
constructed so that the larger slits 230, 232 on the inside of the
curve resulting from plastic deformation tend to close during
deformation while smaller slits 226, 228 on the inside of the curve
resulting from plastic deformation tend to open or stay a same
width during deformation. This is described in greater detail in
FIG. 4C, below.
[0102] In an exemplary embodiment of the invention, total cement
leakage (or risk thereof) through the slits is less when cannula
212 is plastically deformed to a certain degree than when the
cannula is straight.
Optional Sleeve
[0103] FIG. 6 is a perspective view of a cannula 212 fitted with a
sleeve 238 to prevent leakage of cement injected through the
cannula. Sleeve 238 is deployed to cover the slits. While the
sleeve is depicted on the outside of the cannula, it may optionally
be provided as an inner coating. Alternatively or additionally, an
external coating may be applied to cannula 212 to reduce leakage.
In an exemplary embodiment of the invention, sleeve 238 adheres to
cannula 212 with sufficient force to prevent or reduce leakage of
bone cement being injected at pressures in the range of 100 to 300
(or 50 to 200) atmospheres. Optionally, sleeve 238 extends beyond
the portion of the cannula which is slit. In an exemplary
embodiment of the invention, sleeve 238 is non-compliant so that
during cement injection at high pressure, the sleeve diameter
remains the same. Optionally, sleeve 238 is made of a polymer with
sufficient wall thickness for stability under the relevant
injection pressure. Optionally, sleeve 238 is placed over cannula
212 during use (e.g., after insertion of the cannula, or prior
thereto). Optionally, cannula 212 is provided with sleeve 238 in
place.
[0104] In an exemplary embodiment of the invention, the slit
cannula provides mechanical support for the sleeve, which may be,
for example, coated on or adhered to the cannula.
[0105] In some cases, additional strengthening may be desired, for
example, by providing an additional sleeve over the sleeve, or by
providing compression rings which prevent flow out between the
sleeve and the cannula body, at the sleeve edge. Optionally, a
compression ring is provided for each set of or for more than one
set of slits.
[0106] In an exemplary embodiment of the invention, an inner
coating is provided to reduce friction between the cement and the
cannula. Alternatively or additionally, an outer coating is
provided to prevent adhesion of the cannula to hardening cement.
Such coatings may also serve to reduce leakage. An exemplary
thickness is 0.1 mm.
[0107] Optionally, one or more of chemical resistance (to cement),
friction reduction and/or sticking prevention are provided by a
cover. Exemplary cover materials include PTFE, ETFE, PFA, or
FEP--Teflon.RTM. or other materials with suitable properties.
Optionally, a heat-shrinking sleeve is used, which may be heat
shrunk while manufacturing or after bending (e.g., with a heat
gun).
Bending Location
[0108] In an exemplary embodiment of the invention, series of slits
224 deployed on cannula 212 designed so that they are located
substantially or wholly outside a patient body during use, for
example, at least 60%, at least 75% or more of the deformable area
is outside the patient. Optionally, plastic deformation of cannula
212 bends the cannula towards the surgeon so that attachment of a
cement reservoir is convenient. In an exemplary embodiment of the
invention, a marking (not shown in the Figure) on cannula 212
indicates preferred deformation orientation (e.g., toward larger
cuts 230, 232).
[0109] In an exemplary embodiment of the invention, the deforming
area is selected to reduce kinking of the cannula and/or reduce the
amount of bending at each point and thus the local straightening
force applied when injecting cement.
[0110] In an exemplary embodiment of the invention, the length of
the cannula between the deforming area and the distal tip is
between 100 mm and 150 mm. Optionally, 100 mm is used for the upper
spine and 150 for the lower back.
[0111] In an exemplary embodiment of the invention, the use of a
bending cannula allows the cement reservoir to be closer to the
bone. Reduction in distance may be useful, for example, for one or
more of reducing resistance to flow, reducing dead volume of cement
and/or for reducing temperature changes of the cement as it flows.
Optionally, the use of a bending cannula obviates the need for a
separate short flexible tube and its associated connectors and
possible need for manual manipulation. In an exemplary embodiment
of the invention, the total length of the cannula including the
bending region is for example, 150 mm, for example, 100 mm straight
and 50 mm bending. A longer straight and/or bending area may be
provided, for example, to give a cannula length of 200 mm.
Self-Penetrating Cannula
[0112] FIG. 7 illustrates an exemplary embodiment of a cannula 712
with a radial injection aperture 710 and a penetration tip 720.
Penetration tip 720 optionally serves in place of stylet tip 218 as
described above. A separate stylet may be provided for ensuring
that cannula 712 does not bend during insertion. In some
embodiments, no stylet is used.
[0113] Optionally, multiple fill ports are provided, for example as
described below.
[0114] Multiple ports and/or a penetrating tip are optionally
provided with any of the cannula designs described herein.
Detailed Exemplary Slit Design
[0115] FIG. 4C shows a detail of an exemplary slit design, in
accordance with an exemplary embodiment of the invention. In the
detail shown, there are two slits, 228 (from the outer bend) and
232 (from the inner bend). Slit 228 includes a base cut 246 and a
beam cut 248. As shown in FIG. 5, a second base cut may be provided
on the other side of the cannula. Slit 232 includes a base cut 236
and a beam cut 244.
[0116] In an exemplary embodiment of the invention, the various
slits define a portion 240 in the general shape of a rectangle that
is defined by the base cuts (and the lines connecting them) which
is plastically deformed when the cannula is deformed. In some
cases, the deformation extends a short distance away from the
cuts/rectangular area, for example, from the base cuts. In an
exemplary embodiment of the invention, portion 240, even if
deformed is robust enough to maintain the deformed configuration of
the cannula. In an exemplary embodiment of the invention, portion
240 acts as a bending bar.
[0117] In an exemplary embodiment of the invention, base cut 246
serves to limit the deformation to portion 240 and/or guide the
deformation region. Optionally, the edges of base cut 246 and/or
base cut 236 are rounded to prevent tearing and/or reduce stress
concentrations.
[0118] In an exemplary embodiment of the invention, when bent
towards slit 232, beam cut 244 tends to close. Optionally, beam cut
244 is pre-formed to be open, so that it can close lip to lip.
[0119] In an exemplary embodiment of the invention, base cut 236
tends to close when the cannula is bent and includes a cut-out so
as to facilitate lip to lip matching. Optionally, the cuts are not
straight lines, but curved in anticipation of lip-to-lip meeting in
a deformed configuration.
[0120] In an exemplary embodiment of the invention, the bending of
the cannula envelope is at beam cut 248, so that there is less
strain in the cannula.
[0121] In an exemplary embodiment of the invention, at least some
of the cuts may be replaced by other weakening methods, for
example, etching, chemical treatment, thinning and/or heat
treatment. Alternatively or additionally, elongation properties of
plastically deforming areas may be enhanced to reduce and/or
prevent tearing.
[0122] In an exemplary embodiment of the invention, beam cut 248 is
provided as a weakened area. Optionally, some of portion 240 is
weakened. Optionally, the weakened area is selected so that
crumpling and possible kinking of the cannula lumen are
avoided.
[0123] While the figure shows a symmetric design with opening at
one side and closing at the other, this is not essential. For
example, the amount of resistance to bending at either side need
not be equal. In one example, slit 228 does not exist and part of
portion 240 is weakened to facilitate deformation thereof when slit
232 is closed by the deformation of the cannula. Optionally, one or
more wedge sections are removed from portion 240, instead of
weakenings, extending from base cut 236 towards base cut 246 (which
need not exist in this embodiment).
[0124] In another example, the slit design comprises only a wedge
shaped slit generally aligned with beam cut 244 and narrowing in
the direction of the outside of the bend. At the tip of the slit, a
strain relief cut-out is optionally provided. Optionally, a plain
slit on the outside bending side of the cannula is provided.
[0125] In an exemplary embodiment of the invention, the exact
shapes, dimensions and/or mechanical properties of the cuts and
nearby regions are determined using finite element software. For
example, by setting the thickness of the cannula and searching for
values for the dimensions of portion 240 and/or selecting amount
various shapes and/or other parameters until a best solution is
found. Optionally, a best solution is one with minimal working,
minimal chance of tearing, minimal leakage potential and/or minimal
narrowing of the lumen by buckling.
[0126] In an exemplary embodiment of the invention, the cannula is
made of metal (e.g., stainless steel 304 or 316), as this typically
allows a bigger inner diameter for a same outer diameter.
[0127] FIG. 5 is a plan view of a bendable cannula. As can be
appreciated, the final geometry of the cannula typically depends
not on a single slit area as shown in FIG. 4C, but on a plurality
of such slit areas. In an exemplary embodiment of the invention,
the series of slits is selected to achieve a desired final
geometry. It is noted that the deformation need not match this
geometry, for example, by providing more or less deformation.
However, in an exemplary embodiment of the invention, the design is
optimized for one or more deformation configurations.
[0128] In an exemplary embodiment of the invention, the deformation
is that of a simple bending. Such deformation is optionally
facilitated by providing multiple slit sections to act as joints
(bending areas). These sections are optionally provided as
equal-design joints, each of which bends about a same amount, for
example 10 degrees, in the same direction (e.g., same bending
direction. The distance between the joints can be used to set the
bending radius. For example, a length of deformable area of 30 mm
can provide a 19 mm bending radius for a 90 degree bend. In an
exemplary embodiment of the invention, the cannula is designed for
a 130 degree bend, which will allow resting of the cement reservoir
on the patient's back. Optionally, a bend of about 90 degrees is
provided, for example, to move the cement reservoir out of a line
of sight of an x-ray imager. Optionally, the degree of bending
varies among the joints, for example, increased bending per joint
being provided at one or the other end of the deformable area
and/or at a center thereof.
[0129] In an exemplary embodiment of the invention, the deformation
is not a plain curve. For example, an S-shaped curve can be
provided if a first series of joints face one way and a second
series of joints face another way. A non-planar (3D) deformation
can be facilitated if the base cuts do not all lie on a line
parallel to the cannula axis, for example lying on a spiral or
lying on two or more such parallel or non-parallel lines.
[0130] Optionally, the cannula is pre-bent and then cut, so the
joints define a deformation on a curved element, rather than on a
straight element. Optionally, such joints define a straightened (or
straighter) configuration of the cannula.
[0131] FIG. 5 also illustrates that each slit (e.g. 232) comprises
a beam cut 244 and two base cuts, 234 and 236. Optionally, these
base slits improve stress distribution along the length of cannula
212. Optionally, greater stress distribution reduces unwanted
crimping of walls of the cannula.
[0132] While specific numbers, shapes and
distributions/arrangements of slits are depicted in the figures and
text, it is stressed that the scope of the invention any number
and/or arrangement and/or shape and/or dimensions and/or spacing of
slits employed to facilitate plastic deformation of a bone cement
cannula. In an exemplary embodiment of the invention, the slits are
distributed along the entire length of cannula 212, rather than the
proximal part only. Optionally, an offset of at least 5 mm, at
least 10 mm or more is provided between the last joint and the
connector. Optionally, this area is used to anchor the above
described optional flexible sleeve.
[0133] In an exemplary embodiment of the invention, the
configuration of cannula 212 after bending is such that the cement
(or other viscous material) flows in a non-straight path (e.g.,
curved path or piecewise linear) for a substantial distance. A
potential advantage over a pivoting design, where a single joint
provides a large angular change between parts of the cannula is
that at each point in the non-straight path, the straightening
forces may be small. Alternatively or additionally, flow of
non-fluids may be facilitated by gradual direction changes.
Alternatively or additionally, the mechanism for pivoting (e.g.,
with an alignment of the flow path with the pivot center) may be
complicated. Alternatively or additionally, leakage at integral
metal joints with small angles may be relatively small (and in some
cases ignored). Alternatively or additionally, deformation of metal
at small angles is possible, potentially allowing complicated (to
make) joints to be dispensed with and formed directed out of the
cannula body.
Supported Deformation
[0134] Cannula 212 is an example of a cannula where the cannula
body itself provides support for the deformed configuration of the
cannula. In alternative embodiments, this is not the case.
[0135] FIGS. 8A and 8B show a cannula 812 including a deformable
section 820, a rigid section 826 ending at a tip 710, and a
connector 828, for providing cement into the cannula. FIG. 8A shows
cannula 812 in a straight configuration and FIG. 8B shows cannula
812 in a bent configuration.
[0136] In an exemplary embodiment of the invention, deformable
section 820 comprises a flexible tube 824 and a construct which
sets a bending state of the tube.
[0137] In an exemplary embodiment of the invention, as pictured,
this construct comprises one or more bars 870 and 880, coupled to
either side of tube 824. In the example shown a first block 860 is
provided at one side of the tube and is pivotally attached to bars
870, 880, for example, using one or more pins 822. A second block
850 is provided at a second end of the tube and is attached to bars
870, 880, using a sliding attachment, for example, with one or more
sliding pins 830. Optionally, each side of the tube has one sliding
and one pivoting pin. In an exemplary embodiment of the invention,
the friction of the sliding connection and/or the pivoting
connection are set to resist straightening forces, while allowing
manual deformation.
[0138] In an exemplary embodiment of the invention, bars 870 and
880 serve to resist twisting forces associated with inserting
and/or removing the cannula from the body.
[0139] An alternative construct is that of a goose-neck covering
for tube 824 (goose-neck not shown). Another alternative construct
is a tube of plastically deformable material. Another alternative
construct is a providing one or more metal wires which are
malleable. Such wires may be provided, for example, outside of tube
824 or embedded therein.
Flexible Connector
[0140] FIG. 9A is a cross-sectional side view of a cannula 912
including a flexible section 900. Optionally, the flexible section
is thicker than the rest of the cannula, but being outside the
body, this may be acceptable. Optionally, a tissue stop 902 is
provided, for example, as a rigid ring or as a movable ring, which
prevents penetration of section 900 into the body. Section 900 can
be, for example, a deformable section as described above.
[0141] FIG. 9B shows cannula 912 in a bent configuration, without
optional tissue stop 902.
Method of Manufacture
[0142] FIG. 11 is a flowchart of an exemplary method 1100 of
manufacture of a deformable cannula in accordance with exemplary
embodiments of the invention.
[0143] At 1110, a work piece is provided, for example, a flat metal
sheet, a metal tube, a tube with an end formed thereon and/or a
tube with a handle fitted thereon. Optionally, a long tube suitable
for multiple cannulae is provided. In some embodiments, the cannula
is formed of a polymer, rather than a metal tube.
[0144] At 1120, the work piece is engaged by a cutting device
including control circuitry, for example, a computer.
[0145] At 1130, the cutting device is programmed for cutting a
desired pattern, for example, by etching, laser cutting, water
cutting, e-beam cutting, machining, abrasion and/or other metal
working methods known in the art. Optionally, the device is
preprogrammed.
[0146] At 1140 the program is executed to form the slits and/or
other weakenings. Optionally, the program also forms cement inlet
and/or outlets.
[0147] Optionally, laser heating and/or electron-beam heating are
used to anneal portions 240, and thereby improve their ductability.
This may be done on a same device or on a different device.
[0148] At 1150, the deformable cannula is removed from the cutting
device. Optionally, a handle is attached. Optionally, if the work
piece was provided as a sheet, it is now welded or otherwise formed
into a tube.
Distal Aperture
[0149] FIG. 12 is a schematic side cross-sectional view of a
sealed-tip cannula 1200, with an axial aperture 1202 for a stylet
1204, in accordance with an exemplary embodiment of the invention.
A second, side exit port 1206, is shown for exit of cement.
[0150] In an exemplary embodiment of the invention, aperture 1202
is smaller than a grain size of the cement used and/or is small
relative to a viscosity of the cement used, so there is little
leakage there through once stylet 1204 is removed. In an exemplary
embodiment of the invention, the ratio of cement flow through the
axial aperture and the side port(s) is better than 3:1, better than
4:1, better than 6:1, better than 10:1 or intermediate values.
[0151] In an exemplary embodiment of the invention, the area ratio
between the aperture and the port is at least 1:5, 1:8, 1:10, 1:15,
1:20 or intermediate or greater values. Such ratios may reduce the
leakage.
[0152] Alternatively or additionally, a closing mechanism is
provided. In one example, a plug (not shown) is pushed along the
stylet and plugs aperture 1202. Optionally, the plug is provided as
a forward part of the cement delivery system. Optionally, such a
plug travels along a bent cannula and is too wide to exit through
side exit port 1206.
[0153] In another example, a trap-door mechanism 1208 is provided
which closes, either on its own or due to cement pressure, once
stylet 1204 is removed.
[0154] In another example, a plug 1210, for example, a ball, is
attached to the inside of the cannula and plugs aperture 1202 when
cement flows thereto.
Multiple Loading Ports
[0155] In an exemplary embodiment of the invention, a cannula is
provided with multiple loading ports. This may be useful for a
non-deforming cannula, where an axial loading port is used for
entry of a stylet and a side loading port is provided for injecting
cement without a cement delivery system blocking a line of sight of
a doctor and/or imaging system and/or without applying torque to
the patient. Typically, cement is injected after the stylet
removed.
[0156] An alternative reason for providing multiple ports is that
it may be desirable to provide a plurality of materials into the
patient (e.g., bone cements of varying viscosities), without
detaching a high-pressure (or other) delivery system. An
alternative reason for providing multiple ports is for pressure
relief at the cannula.
[0157] FIG. 10A shows a cannula 1002 including an axial port 740
and a side port 730. FIG. 10B shows that after use of the axial
port, it may be closed using a cap 1010, for example, a threaded
cap. A similar cap may be used for side port 730.
[0158] FIG. 10C (axial open) and FIG. 10B (axial closed), show a
trap-door valve 1020 which selectively closes an axial port 740 of
a cannula 1004. A potential advantage of a trap-door valve is that
backpressure closes it and/or may assist in sealing it. Thus, for
example, entry of cement through port 730 will tend to close door
1020 and thus seal port 740. Application of a greater pressure at
port 740, will reopen the port.
[0159] In an exemplary embodiment of the invention, the trap-door
does not lie flush with the cannula inner surface. Rather a space
(not shown) is provided between the door and the surface, for
example, a wedge shape space, to ensure that flow of cement from
port 730 will close the door, rather than force it to remain open.
Alternatively or additionally, an elastic closing hinge is
used.
[0160] FIG. 10E (axially open) and FIG. 10F (axially closed) show a
cannula 1006, in which a rotating valve, such as a stopcock valve,
selectively makes one of the ports patent.
Other Tissue and General Comments
[0161] While the above application has focused on the spine, other
tissue can be treated as well, for example, compacted tibia plate
and other bones with compression fractures and for tightening
implants, for example, hip implants or other bone implants that
loosened, or during implantation. Optionally, for tightening an
existing implant, a small hole is drilled to a location where there
is a void in the bone and material is extruded into the void.
[0162] It should be noted that while the use in bones of the above
methods and devices provide particular advantages for bone and
vertebras in particular, optionally, non-bone tissue is treated,
for example, cartilage or soft tissue in need of treatment.
Optionally, the delivered material includes an encapsulated
pharmaceutical and is used as a matrix to slowly release the
pharmaceutical over time. Optionally, this is used as a means to
provide anti-arthritis drugs to a joint, but forming a void and
implanting an eluting material near the joint. In an exemplary
embodiment of the invention, the eluting material is of a high
viscosity and or is a soft non-flowing material.
[0163] In another embodiment, the injected material is a nucleus
for a disc.
[0164] It will be appreciated that the above described apparatus
and methods of implanting and treating may be varied in many ways,
including, changing the order of steps, which steps are performed
more often and which less often, the arrangement of elements, the
type and magnitude of forces applied and/or the particular shapes
used. In particular, various tradeoffs may be desirable, for
example, between applied forces, degree of resistance and forces
that can be withstood. Further, the location of various elements
may be switched, without exceeding the spirit of the disclosure,
for example, the location of the cement outlet. In addition, a
multiplicity of various features, both of method and of devices
have been described. It should be appreciated that different
features may be combined in different ways. In particular, not all
the features shown above in a particular embodiment are necessary
in every similar exemplary embodiment of the invention. Further,
combinations of the above features are also considered to be within
the scope of some exemplary embodiments of the invention. In
addition, some of the features of the invention described herein
may be adapted for use with prior art devices, in accordance with
other exemplary embodiments of the invention. The particular
geometric forms used to illustrate the invention should not be
considered limiting the invention in its broadest aspect to only
those forms, for example, where a cylindrical tube is shown, in
other embodiments a rectangular tube may be used. Although some
limitations are described only as method or apparatus limitations,
the scope of the invention also includes apparatus programmed
and/or designed to carry out the methods.
[0165] Also within the scope of the invention are surgical kits
which include sets of medical devices suitable for delivering
cement or other viscous materials and suitable material. Section
headers are provided only to assist in navigating the application
and should not be construed as necessarily limiting the contents
described in a certain section, to that section. Measurements are
provided to serve only as exemplary measurements for particular
cases, the exact measurements applied will vary depending on the
application. When used in the following claims, the terms
"comprises", "comprising", "includes", "including" or the like
means "including but not limited to".
[0166] It will be appreciated by a person skilled in the art that
the present invention is not limited by what has thus far been
described. Rather, the scope of the present invention is limited
only by the following claims.
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