U.S. patent application number 12/509356 was filed with the patent office on 2010-03-25 for systems and methods for cable-based tissue removal.
Invention is credited to Singfatt Chin, Robert May, Hiep Nguyen, John T. TO, Dan Zaretzka.
Application Number | 20100076476 12/509356 |
Document ID | / |
Family ID | 41570633 |
Filed Date | 2010-03-25 |
United States Patent
Application |
20100076476 |
Kind Code |
A1 |
TO; John T. ; et
al. |
March 25, 2010 |
SYSTEMS AND METHODS FOR CABLE-BASED TISSUE REMOVAL
Abstract
Systems and methods for treating disc herniation include
surgical and endoscopic access and removal of disc tissue. The
tissue removal devices that may be used include flexible elongate
members, such as a cable, that may be inserted into a vertebral
disc and rotated to pulverize the disc material and facilitate its
removal.
Inventors: |
TO; John T.; (Newark,
CA) ; Zaretzka; Dan; (Castro Valley, CA) ;
Nguyen; Hiep; (Milpitas, CA) ; Chin; Singfatt;
(Pleasanton, CA) ; May; Robert; (Hayward,
CA) |
Correspondence
Address: |
MORRISON & FOERSTER LLP
755 PAGE MILL RD
PALO ALTO
CA
94304-1018
US
|
Family ID: |
41570633 |
Appl. No.: |
12/509356 |
Filed: |
July 24, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61083857 |
Jul 25, 2008 |
|
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61106858 |
Oct 20, 2008 |
|
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61223343 |
Jul 6, 2009 |
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Current U.S.
Class: |
606/170 |
Current CPC
Class: |
A61B 2017/320775
20130101; A61B 2017/00685 20130101; A61B 17/1617 20130101; A61B
2017/003 20130101; A61B 2017/00734 20130101; A61B 2017/320733
20130101; A61B 17/320758 20130101; A61B 2090/064 20160201; A61B
17/320725 20130101; A61B 17/8805 20130101; A61B 17/32002 20130101;
A61B 2017/320064 20130101; A61B 2017/00261 20130101; A61B
2017/00398 20130101; A61B 17/1671 20130101 |
Class at
Publication: |
606/170 |
International
Class: |
A61B 17/32 20060101
A61B017/32 |
Claims
1. A system for tissue removal, comprising: a motor configured to
rotate at a speed of at least 1000 rpm; a rotatable shaft assembly
coupled to the motor, wherein the rotatable shaft assembly
comprises a distal coupling site and a proximal coupling site
comprising a proximal surface opening; and a flexible elongate
member, comprising a distal section coupled to the distal coupling
site of the rotatable shaft assembly and a proximal section
slidably positioned in the proximal surface opening, and a middle
section therebetween; wherein the flexible elongate member has a
retracted configuration and an extended configuration wherein a
perpendicular distance between the middle section of the flexible
elongate member and the rotatable shaft assembly is greater in the
extended configuration than in the retracted configuration.
2. The system of claim 1, wherein the flexible elongate member
comprises a flexible multi-filament elongate member.
3. The system of claim 2, where the flexible multi-filament
elongate member comprises no more than about ten filaments.
4. The system of claim 1, wherein the proximal surface opening and
the distal surface opening are longitudinally aligned.
5. The system of claim 1, wherein the proximal surface opening and
the distal surface opening are longitudinally offset.
6. The system of claim 1, wherein the rotatable shaft assembly
further comprises a groove between the proximal surface opening and
the distal surface opening.
7. The system of claim 6, wherein the groove is a helical
groove.
8. The system of claim 7, wherein the helical groove has variable
pitch.
9. The system of claim 1, wherein the rotatable shaft assembly
further comprises a narrow segment located between the proximal
surface opening and the distal surface opening.
10. The system of claim 1, wherein the perpendicular distance
between the middle section of the flexible elongate member and the
rotatable shaft assembly in the extended configuration is equal to
or greater than about the average diameter of the rotatable shaft
assembly.
11. The system of claim 10, wherein the perpendicular distance
between the middle section between the middle section of the
flexible elongate member and the rotatable shaft assembly in the
extended configuration is equal to greater than about twice the
average diameter of the rotatable shaft assembly.
12. The system of claim 1, wherein the rotatable shaft assembly
comprises a distal penetrating tip.
13. The system of claim 1, wherein the length of the flexible
elongate member outside of the rotatable shaft assembly is
different in the retracted configuration and the extended
configuration.
14. The system of claim 1, wherein the distance between the distal
coupling site and the proximal surface opening is unchanged in the
retracted configuration and the extended configuration.
15. The system of claim 1, wherein the flexible elongate member
comprises at least one rigid section and at least one flexible
section.
16. The system of claim 15, wherein the flexible elongate member
comprises at least two rigid sections.
17. The system of claim 15, wherein at least one rigid section is a
linear rigid section.
18. The system of claim 16, wherein the flexible elongate member
comprises a proximal rigid rod and a distal rigid rod
interconnected by a flexible cable.
19. The system of claim 18, wherein the proximal rigid rod is
located in the proximal surface opening.
20. The system of claim 19, wherein the proximal rigid rod is
located in the proximal surface opening when the flexible elongate
member is in the extended configuration.
21. The system of claim 1, wherein at least a portion of the
flexible elongate member comprises a grit surface with an average
grit number in the range of about 200 to about 500.
22. The system of claim 1, wherein the flexible elongate member has
a flexural modulus that is less than a flexural modulus of intact
bony tissue.
23. The system of claim 22, wherein the flexible elongate member
has a flexural modulus that is less than a flexural modulus of
intact annular fibrosis tissue.
24. The system of claim 1, wherein the flexible elongate member has
a generally uniform flexural modulus along its length.
25. The system of claim 1, wherein the rotatable shaft assembly is
coupled to the motor by a bendable driveshaft.
26. The system of claim 25, further comprising a steering assembly
configured to bend the driveshaft.
27. The system of claim 1, wherein a ratio of the perpendicular
distance between the middle section of the flexible elongate member
and the rotatable shaft assembly in the extended configuration to a
diameter of the rotatable shaft assembly is at least about 3:1.
28. The system of claim 1, wherein a ratio of the perpendicular
distance between the middle section of the flexible elongate member
and the rotatable shaft assembly in the extended configuration to a
diameter of the rotatable shaft assembly is at least about 5:1.
29. The system of claim 1, wherein the flexible elongate member
comprises a polymeric coating.
30. The system of claim 29, wherein the polymeric coating comprises
polyimide.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority under 35 U.S.C.
.sctn.119(e) to U.S. Provisional Application No. 61/083,857 filed
on Jul. 25, 2008, and U.S. Provisional Application No. 61/106,858
and was filed on Oct. 20, 2008, and Provisional Application No.
61/223,343 filed on Jul. 6, 2009, all of which are hereby
incorporated by reference in their entirety.
BACKGROUND
[0002] Vertebral disc herniation is a common disorder where a
portion of a vertebral disc, a cushion-like structure located
between the bones of the spine, bulges out or extrudes beyond the
usual margins of the disc and the spine. Disc herniation is
believed to be the result of a loss of elasticity of the tissue
comprising the disc, and is associated with increasing age. Disc
herniation and other degenerative disc disease are also associated
with spinal stenosis, a narrowing of the bony and ligamentous
structures of the spine. Although disc herniation can occur
anywhere along the perimeter of the disc, it occurs more frequently
in the posterior and posterior-lateral regions of the disc, where
the spinal cord and spinal nerve roots reside. Compression of these
neural structures can lead to pain, parasthesias, weakness, urine
and fecal incontinence and other neurological symptoms that can
substantially impact basic daily activities and quality of
life.
[0003] Temporary relief of the pain associated with disc herniation
is often sought through conservative therapy, which includes
positional therapy (e.g. sitting or bending forward to reduce
pressure on spine), physical therapy, and drug therapy to reduce
pain and inflammation. When conservative therapy fails to resolve a
patient's symptoms, surgery may be considered to treat the
structural source of the symptoms. Surgical treatments for disc
herniation traditionally involve open procedures that require
extensive dissection of muscle, connective tissue and bone along a
patient's back to achieve adequate surgical exposure. These
surgeries also expose the patient to a significant risk of
complications, due to the presence of critical neurovascular
structures near the surgical site. For example, a discectomy
procedure may be used to decompress the herniation by accessing the
affected disc and removing a portion of the disc and any loose disc
fragments. To achieve sufficient access to the affected disc, a
portion of the lamina or bony arch of the vertebrae may be removed,
thereby increasing the invasiveness of the procedure. When
discectomy fails to resolve a patient's symptoms, more drastic
measures may include disc replacement surgery or vertebral
fusion.
[0004] Fractures of the vertebrae bodies are another common
disorder of the spinal column. When a vertebra fractures, the usual
shape of the bone becomes compressed and distorted, which results
in pain. These vertebral compression fractures (VCF), which may
involve the collapse of one or more vertebrae in the spine, are a
common finding and result of osteoporosis. Osteoporosis is a
disorder that often becomes more severe with age and results in a
loss of normal bone density, mass and strength. Osteoporosis often
leads to a condition in which bones are increasingly porous or full
or small holes and vulnerable to breaking. In addition to
osteoporosis, vertebrae can also become weakened by cancer or
infection.
[0005] In some instances, fractures of the vertebral bodies may be
treated with surgical removal of the vertebral body and the
implantation of a vertebral body replacement device. Other
treatments may include vertebroplasty and kyphoplasty, which are
minimally invasive procedures for treating vertebral compression
fractures. In vertebroplasty, physicians use image guidance to
inject a cement mixture through a hollow needle into the fractured
bone. In kyphoplasty, a balloon is first inserted through the
needle into the fractured vertebral body to restore at least some
of the height and shape of the vertebral body, followed by removal
of the balloon cement injection into the cavity formed by the
balloon.
BRIEF SUMMARY OF THE INVENTION
[0006] Systems and methods for treating disc herniation include
surgical and endoscopic access and removal of disc tissue. The
tissue removal devices that may be used include flexible elongate
members, such as a cable, which may be inserted into a vertebral
disc and rotated to pulverize the disc material and to facilitate
its removal.
[0007] In one example, a tissue removal system is provided,
comprising a handheld housing with a power supply, an adjustment
assembly and a motor configured to rotate at a speed of at least
about 7000 rpm, an outer shaft attached to the handheld housing and
having a length of about 10 cm to about 30 cm and an average
diameter of less than about 2 mm, an inner shaft located within the
outer shaft and coupled to the motor, a tissue removal assembly
comprising a tubular core attached to the inner shaft and
comprising a distal side opening and a proximal side opening spaced
about 10 mm or less from the distal side opening, and a single
flexible multi-filament cable coupled to the adjustment assembly
and comprising a distal section coupled to the distal side opening
of the tubular core, a proximal section coupled to the proximal
side opening, and a middle section therebetween located outside of
the tubular core, wherein the single flexible multi-filament cable
has a retracted configuration and an extended configuration wherein
the perpendicular distance between the middle section of the single
flexible multi-filament cable and the tubular core is at least
about twice the average diameter of the tubular core. The average
diameter of the outer shaft may be less than about 1 mm and/or the
average diameter of the tubular core may be less than about 1 mm.
In some variations, at least a portion of the multi-filament cable
may be extended to a perpendicular distance of at least about 3 mm
or about 5 mm with respect to the tubular core. The single flexible
multi-filament cable may have a helical configuration, which may be
right-handed or left-handed helical configuration, as well as a
variable pitch configuration. The single flexible multi-filament
cable may interconnect a proximal and a distal linear rigid rod.
and the proximal linear rigid rod may be partially located in the
proximal side opening and the distal linear rigid rod may be
partially located in the distal side opening. In other variations,
the cable may be coated or fused with a rigid polymer coating
proximally and/or distally, or completely. The coating may be a
polyimide coating. In some further examples, the tissue removal
system may further comprise a steering assembly. The steering
assembly may comprise a steering wire distally coupled to a
flexible region of the outer shaft.
[0008] In another example, a system for tissue removal is provided,
comprising a motor configured to rotate at a speed of at least 1000
rpm, a rotatable shaft assembly coupled to the motor, wherein the
rotatable shaft assembly comprises a distal coupling site and a
proximal coupling site comprising a proximal surface opening, and a
flexible elongate member, comprising a distal section coupled to
the distal coupling site of the rotatable shaft assembly and a
proximal section slidably positioned in the proximal surface
opening, and a middle section therebetween, wherein the flexible
elongate member has a retracted configuration and an extended
configuration wherein a perpendicular distance between the middle
section of the flexible elongate member and the rotatable shaft
assembly is greater in the extended configuration than in the
retracted configuration. The flexible elongate member may comprise
a flexible multi-filament elongate member, and in some but not all
variations, the flexible multi-filament elongate member may
comprise no more than about ten filaments. The proximal surface
opening and the distal surface opening may be longitudinally
aligned along the shaft or may be longitudinally offset, and may
optionally further comprises a groove between the proximal surface
opening and the distal surface opening. The groove may be straight
or may be a helical groove, with a constant or a variable pitch.
The rotatable shaft assembly may also further comprise a narrow
segment located between the proximal surface opening and the distal
surface opening. In some variations, the perpendicular distance
between the middle section of the flexible elongate member and the
rotatable shaft assembly in the extended configuration may be equal
to or greater than about the average diameter of the rotatable
shaft assembly, and sometimes may be equal to greater than about
twice the average diameter of the rotatable shaft assembly. The
rotatable shaft assembly may also comprise a distal penetrating
tip. In some variations, the length of the flexible elongate member
outside of the rotatable shaft assembly may be different in the
retracted configuration and the extended configuration. The
distance between the distal coupling site and the proximal surface
opening may be unchanged in the retracted configuration and the
extended configuration. The flexible elongate member may also
comprise at least one rigid section and at least one flexible
section, and in some examples, may comprise at least two rigid
sections, which may be interconnected by a flexible cable. At least
one rigid section may be a linear rigid section. In some
variations, the proximal rigid rod may be located in the proximal
surface opening. The proximal rigid rod may also be located in the
proximal surface opening when the flexible elongate member is in
the extended configuration. In some examples, at least a portion of
the flexible elongate member may comprise a grit surface with an
average grit number in the range of about 200 to about 500. The
flexible elongate member may have a flexural modulus that is less
than a flexural modulus of intact bony tissue, and/or less than a
flexural modulus of intact annular fibrosis tissue. In some
variations, the flexible elongate member may have a generally
uniform flexural modulus along its length. In some systems, the
rotatable shaft assembly may be coupled to the motor by a bendable
driveshaft. The system may also further comprise a steering
assembly configured to bend the driveshaft. In some examples, the
ratio of the perpendicular distance between the middle section of
the flexible elongate member and the rotatable shaft assembly in
the extended configuration to a diameter of the rotatable shaft
assembly may be at least about 3:1 or at least about 5:1. The
flexible elongate member may comprise a polymeric coating, which
may or may not comprise polyimide.
[0009] In another embodiment, a method for treating a patient is
provided, comprising inserting a cable toward a vertebral tissue
region, wherein the cable is coupled to a rotatable shaft assembly,
extending the cable from an opening of the rotatable shaft
assembly, rotating the cable around a cable rotation axis of the
rotatable shaft assembly, and withdrawing the cable from the
patient. The method may further comprise retracting the cable into
the opening of the rotatable shaft assembly, pulverizing vertebral
tissue rotating the cable, removing the pulverized vertebral tissue
from the patient, and/or removing the pulverized vertebral tissue
comprises suctioning vertebral tissue. Rotating the cable may
comprise rotating the cable to a speed of at least about 1000 rpm
or about 5000 rpm or greater. The method may further comprise
providing access to the vertebral tissue region using a cannula
and/or using a surgical retractor. The vertebral tissue may
comprise vertebral bone tissue and/or vertebral disc tissue and may
further comprise penetrating vertebral disc tissue with a distal
tip of the rotatable shaft assembly or another instrument. The
vertebral disc tissue may be located within the annulus fibrosus of
a vertebral disc, or may include the annulus. In some examples,
penetrating the vertebral disc may comprise forming a self-sealing
passageway through the wall of the vertebral disc, which may be
less than about 2 mm or even less than about 1 mm in size. The may
further comprise positioning the cable within the vertebral disc,
and sometimes extending the cable may be performed while at least a
portion of the cable is in the vertebral disc. Extending the cable
may also be performed while at least a portion of the cable is in a
nucleus pulposus of the vertebral disc. Extending the cable may
also be performed while at least a portion of the cable is in a
bony structure adjacent to the vertebral disc. Pulverizing
vertebral tissue may comprise pulverizing nucleus pulposus tissue,
and may be performed without substantially damaging annulus
fibrosus tissue and/or bony endplate tissue of an adjacent
vertebral body. In some examples, the method may further comprise
bending the rotatable shaft assembly, and rotating the cable may be
performed while the rotatable shaft assembly is bent. The method
may also further comprise rotating a proximal segment of the
rotatable shaft assembly about a proximal rotation axis that is
different from the cable rotation axis of the rotatable shaft
assembly. Rotating the cable around the cable rotation axis of the
rotatable shaft assembly may occur while the rotatable shaft
assembly is rotating about the proximal rotation axis. Extending
the cable may comprise extending a portion of the cable to a
separation distance of at least about 3 mm from the rotatable shaft
assembly, or at least about 5 mm from the rotatable shaft assembly.
Pulverizing vertebral tissue about the cable may be performed in a
tissue zone that has a diameter with respect to the rotatable shaft
assembly that is at least about 5 times greater than a diameter of
the rotatable shaft assembly, or sometimes is at least about 7
times greater than a diameter of the rotatable shaft assembly.
[0010] In another embodiment, a method for treating disc herniation
is provided, comprising endoscopically visualizing a disc
herniation, inserting an tissue removal device into vertebral disc
tissue, wherein the tissue removal device comprises an elongate
shaft with a distal shaft segment coupled to an adjustable
pulverizing member, bending the elongate shaft of the tissue
removal device toward a target site within the vertebral disc
tissue, setting the adjustable pulverizing member to a first
distance from the distal shaft segment, mechanically pulverizing
the vertebral disc tissue located at about the first distance,
endoscopically visualizing the disc herniation after pulverizing
the vertebral disc tissue located at the first distance, adjusting
the adjustable pulverizing member to a second distance from the
distal shaft segment that is greater than the first distance,
mechanically pulverizing vertebral disc tissue located about the
second distance, and endoscopically visualizing the disc herniation
after pulverizing the vertebral disc tissue located at the second
distance. The may further comprise unbending the elongate shaft,
and withdrawing the elongate shaft from the vertebral disc
tissue.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a schematic perspective view of a portion of a
lumbar spine;
[0012] FIG. 2 is a schematic side elevational view of a portion of
the lumbar spine;
[0013] FIG. 3 is a schematic superior view of a portion of a lumbar
vertebra and disc;
[0014] FIGS. 4A and 4B are schematic superior views of a herniated
disc during and after treatment, respectively;
[0015] FIG. 5A is a side elevational view of an embodiment of a
tissue removal device; FIG. 5B is a detailed cutaway view of the
device in FIG. 5A.
[0016] FIGS. 6A and 6B are side elevational views of an embodiment
of tissue removal device with a rotatable elongate member in its
retracted and extended configurations, respectively.
[0017] FIG. 7 depicts another embodiment of a tissue removal device
with a recessed groove;
[0018] FIG. 8 depicts another embodiment of a tissue removal device
with a multi-filament elongate member;
[0019] FIG. 9 depicts another embodiment of a tissue removal
device;
[0020] FIG. 10 depicts one embodiment of a tissue removal device
with a plurality of rigid supports;
[0021] FIG. 11 depicts another embodiment of a tissue removal
device with rigid supports;
[0022] FIGS. 12A and 12B illustrate another embodiment of a tissue
removal device with a helically-oriented elongate member in the
retracted and extended states, respectively;
[0023] FIGS. 13A and 13B are side elevational and longitudinal
cross-sectional views of another embodiment of a tissue removal
device; FIG. 13C is a side elevational view of the tissue removal
device of FIG. 13A with a tissue-removing cable in an extended
state;
[0024] FIGS. 14A and 14B are side elevational views of another
embodiment of tissue removal device in the retracted and extended
configurations, respectively.
[0025] FIG. 15 is an embodiment of a tissue removal device with
tapered central region.
[0026] FIG. 16 is an embodiment of a tissue removal device with a
narrow corkscrew region.
[0027] FIG. 17 is a detailed view of one embodiment of an optional
tissue transport mechanism;
[0028] FIGS. 18A and 18B are perspective and side elevational views
of another embodiment of a tissue removal device; FIG. 18C is a
component view of the tissue removal device in FIGS. 18A and 18B;
and FIG. 18D is a cross-sectional view of the tissue removal device
in 18A and 18B with a portion of the housing removed;
[0029] FIG. 19A schematically depicts one embodiment of a flexible
tissue removal device; FIG. 19B is a schematic side elevational
view of the proximal end of the flexible tissue removal device of
FIG. 19A with a portion of the housing removed; FIG. 19C is a
detailed view of the distal end of the flexible tissue removal
device of FIG. 19A in a bent configuration; and
[0030] FIGS. 20A and 20B are schematic side and superior
cross-sectional views of a steerable tissue removal device inserted
into a vertebral disc, respectively.
[0031] FIG. 21A depicts the distal end of another embodiment of a
tissue removal device with a blunt tip and in an extended
configuration; FIGS. 21B to 21D depict various views of the tissue
removal device in FIG. 21A in the retracted configuration.
[0032] FIG. 22 illustrates the tissue removal device of FIG. 21A
with an optional viewing chamber.
[0033] FIG. 23 illustrates an embodiment of a cannula and obturator
device usable with various access systems.
[0034] FIGS. 24A to 24C depicts one embodiment for performing
vertebroplasty.
[0035] FIG. 25 schematically illustrates another embodiment of a
cutting mechanism.
DETAILED DESCRIPTION OF THE INVENTION
[0036] FIGS. 1 and 2 are schematic views of a lumbar region of a
spine 100. The vertebral canal 102 is formed by a plurality of
vertebrae 104, 106, and 108, which comprise vertebral bodies 110,
112 and 114 anteriorly and vertebral arches 116 and 118
posteriorly. The vertebral arch and adjacent connective tissue of
the superior vertebra 104 has been omitted in FIG. 1 to better
illustrate the spinal cord 122 within the vertebral canal 102.
Spinal nerves 124 branch from the spinal cord 122 bilaterally and
exit the vertebral canal 102 through intervertebral foramina 126
(seen best in FIGS. 2 and 3) that are formed by the adjacent
vertebra 104, 106 and 108. The intervertebral foramina 126 are
typically bordered by the inferior surface of the pedicles 120, a
portion of the vertebral bodies 104, 106 and 108, the inferior
articular processes 128, and the superior articular processes 130
of the adjacent vertebrae. Also projecting from the vertebral
arches 116 and 118 are the transverse processes 132 and the
posterior spinous processes 134 of the vertebrae 106 and 108.
Located between the vertebral bodies 110, 112 and 114 are the
vertebral discs 132.
[0037] Referring to FIG. 3, the spinal cord 122 is covered by a
thecal sac 136. The space between the thecal sac 136 and the
borders of the vertebral canal 102 is known as the epidural space
138. The epidural space 138 is bound anteriorly and posteriorly by
the longitudinal ligament 140 and the ligamentum flavum 142 of the
vertebral canal 102, respectively, and laterally by the pedicles
120 of the vertebral arches 116 and 118 and the intervertebral
foramina 126. The epidural space 138 is contiguous with the
paravertebral space 144 via the intervertebral foramina 126.
[0038] Referring to FIG. 4A, a vertebral disc 150 typically
comprises an outer, multi-layer, annular band of connective tissue,
known as the annulus fibrosus 152, which encases a gel-like
resilient material known as the nucleus pulposus 154. The nucleus
pulposus 154 acts as a shock-absorbing structure for the forces
acting on the spine. Both the annulus fibrosus 152 and the nucleus
pulposus 154 are elastic collagenous structures which, over time,
may decrease in elasticity and cause the nucleus pulposus to bulge
out at a weakened region of the annulus fibrosus 152, and even
extrude through the annulus fibrosus 152. FIG. 4A schematically
depicts an extrusion 156 of the nucleus pulposus 154, which has
penetrated through the wall of the annulus fibrosus 152 within an
intervertebral foramen 126 and compressed a nerve 124 exiting the
spine. Although the extrusion 156 remains in continuity with the
remaining nucleus pulposus 154, the extrusion 156 may sometimes
pinch off or separate, resulting in the sequestration of a portion
of the nucleus.
[0039] As mentioned previously, treatments of disc herniation may
involve internal access to the affected disc with removal or volume
reduction of the disc material. This may relieve the pressure
causing the bulging or extrusion to at least partially restore the
profile of the disc. In FIG. 4A, for example, a tissue removal
device 200 has been inserted into the extrusion 156 extending out
of the herniated disc 150. The tissue removal device 200 is then
actuated to break up and remove the extruded material. In some
embodiments, the tissue removal device 200 may be further inserted
distally into the disc 150. Additional tissue with the disc 150 may
then be removed. As shown in FIG. 4B, after removing a volume of
the nucleus pulposus 154 and relieving some of the pressure causing
the extrusion 156, the extrusion 156 was able to retract back into
the disc 150, thereby reducing the extrusion pathway 160 and
relieving compression of the spinal nerve 124. Although
contralateral access of the herniated disc is depicted in FIG. 4A,
ipsilateral access may also be used. Furthermore, direct tissue
removal of the extruded herniated disc may also be performed.
[0040] Devices used to remove disc tissue for discectomy or
nucleotomy may include lasers, discectomes, trephines, burrs,
rongeurs, rasps, curettes and cutting forceps. Many of these
devices have a substantial cross-sectional size, and when inserted
into a disc, create an insertion channel which substantially
compromises the integrity of the annulus fibrosus at the insertion
site. Thus, any remaining nucleus pulposus material may extrude or
herniate through the insertion site without taking measures to
suture or otherwise close the insertion site, thereby adding
complexity to the discectomy or nucleotomy procedure.
[0041] In contrast, a tissue removal device may be configured for
minimally invasive insertion toward or into a vertebral disc
without requiring suturing, gluing or other procedures to seal or
close the access pathway into the disc. The tissue removal device
may be used for any of a variety of procedures, including but not
limited to discectomy, nucleotomy, lysis of adhesions, and other
tissue removal procedures in the spine and throughout other regions
of the body. FIG. 5A depicts one embodiment of a tissue removal
device 2, comprising an outer tube 4 coupled to a housing 6. The
static outer tube 4 covers a rotating drive shaft (not shown) that
is attached to a tissue removal assembly 8. In other embodiments,
the tissue removal device 2 may lack an outer tube and the drive
shaft of the tissue removal device may be inserted into a lumen of
a cannula or other access device. The housing 6 contains one or
more components configured to control the tissue removal assembly 8
and other optional features of the tissue removal device 2. The
tissue removal assembly 8, examples of which are described in
greater detail below, may be configured to cut, chop, grind, burr,
pulverize, debride, debulk, emulsify, disrupt or otherwise remove
tissue when rotated at various speeds. Emulsification includes, for
example, forming a suspension of tissue particles in a medium,
which may be the existing liquid at the target site, liquid added
through the tissue removal device, and/or liquid generated by the
debulking of the tissue. Optional components may include, but are
not limited to, a motor configured to rotate or move the tissue
removal assembly, a power source or power interface, a motor
controller, a tissue transport assembly, an energy delivery or
cryotherapy assembly, a therapeutic agent delivery assembly, a
light source, and one or more fluid seals. The optional tissue
transport assembly may comprise a suction assembly and/or a
mechanical aspiration assembly. One or more of these components may
act through the outer tube 4 to manipulate the tissue removal
assembly and/or other components located distal to the housing 6,
or from the housing 6 directly. For example, the tissue removal
device 2 further comprises an optional port 20 that may be attached
to an aspiration or suction source to facilitate transport of
tissue or fluid out of the target site or patient. The suction
source may be a powered vacuum pump, a wall suction outlet, or a
syringe, for example.
[0042] The housing 6 may further comprise a control interface 10
that may be used to control the power state of the tissue removal
device 2, including but not limited to on and off states. In this
particular embodiment, the control interface 10 comprises a lever
or pivot member, but in other embodiments, control interface 10 may
comprise a push button, a slide, a dial or knob. In some
embodiments, the control interface 10 may also change the motor
speed and/or movement direction of the tissue removal assembly 8. A
bi-directional tissue removal device may be provided, for example,
as a potential safety feature should the tissue removal assembly 8
get lodged in a body tissue or structure. The web-like connective
tissue that may be found in the epidural space may get wound onto
or caught up on the burr device or other tissue removal device.
This connective tissue may be dislodged with a bi-directional
tissue removal device by reversing the direction of rotation to
unwind the tissue. The control interface 10 may be analog or
digital, and may comprise one or more detent positions to
facilitate selection of one or more pre-selected settings. In other
embodiments, a separate motor control interface may be provided for
one or more features of the motor. In still other embodiments,
control interfaces for other features of the tissue removal device
may be provided.
[0043] Referring to FIGS. 6A and 6B, the tissue removal assembly
200 may comprise at least one elongate member 202 having a proximal
section 204 and distal section 206, with each section coupled to a
rotatable shaft 208. The elongate member 202 has a retracted
configuration, shown in FIG. 5A, and an extended configuration,
shown in FIG. 5B. In the extended configuration, at least a portion
210 of the elongate member 202 is displaced farther away from the
rotatable shaft 208 than the same portion 210 in the retracted
configuration. To adjust the configuration of the elongate member
202, the proximal section 204 of the elongate member 202 may be
slid in or out of a proximal opening 212 of the rotatable shaft 208
to alter the exposed length of the elongate member 208 between the
proximal opening 212 and a distal opening 214 (or distal attachment
of the distal section 206) of the elongate member 202. The
percentage change in the length of the elongate member 202 from its
retracted configuration to its extended configuration may be in the
range of about 10% to about 60% or more, sometimes about 20% to
about 40%, and other times about 15% to about 20%. In some
embodiments, transformation of the elongate member 202 between
configurations may include sliding its distal section 206 in or out
of the distal opening 214, in addition to or in lieu of movement
between the proximal section 204 and the proximal opening 212.
[0044] The tissue removal device 200 may further comprise a distal
head 216 with a conical configuration, as depicted in FIGS. 6A and
6B. Other head configurations are also contemplated, including but
not limited to an ovoid configuration, a dome configuration, a
concave configuration, a cube configuration, etc. The head 216 may
be configured to penetrate or dissect body tissue, such as the
annular wall of a vertebral disc, and may be used while the
rotatable shaft 208 is being rotated, or when the rotatable shaft
208 is not rotated. In other embodiments, the head may comprise
multiple points or edges that may be used to cut, chop, grind,
burr, pulverize, debride, debulk, emulsify, disrupt or otherwise
remove tissue or body structures. In still other embodiments, the
head may comprise surfaces with a grit that may be used as a burr
mechanism. The grit number may range from about 60 to about 1200 or
more, sometimes about 100 to about 600, and other times about 200
to about 500.
[0045] The head may optionally comprise a port or aperture which
may be used to perform suction or aspiration at the target site
and/or to perfuse saline or other biocompatible fluids or materials
to the target site. Use of saline or other cooling materials or
liquids, for example, may be used to limit any thermal effect that
may occur from frictional or other forces applied to the target
site during removal procedures. The saline or other materials may
or may not be chilled. In other embodiments, one or more
therapeutic agents may be provided in the saline or fluid for any
of a variety of therapeutic effects. These effects may include
anti-inflammatory effects, anti-infective effects, anti-neoplastic
effects, anti-proliferative effects, hemostatic effects, etc.
[0046] In some embodiments, the rotatable shaft may optionally
comprise one or more recesses or grooves on its outer surface to
receive the elongate member 202. For example, FIG. 7 depicts a
single groove 218 between the proximal and distal openings 212 and
214 of the rotatable shaft 208. The depth and cross-sectional shape
of the groove 218 may be configured to partially or fully receive
the elongate member 202.
[0047] The elongate member 202 may comprise any of a variety of
materials and structures. For example, the elongate member 202 may
comprise titanium, a nickel-titanium alloy, stainless steel, a
cobalt-chromium alloy, a polymer (e.g. nylon, polyester and
polypropylene) or a combination thereof. The elongate member 202
may also have a monofilament or multi-filament structure. FIG. 8,
for example depicts a tissue removal device 300 with an elongate
member comprising a multi-filament cable 302. In some embodiments,
a multi-filament elongate member may provide greater flexibility
and/or stress tolerance than a monofilament elongate member. A
multi-filament elongate member may comprise any number of
filaments, from about 2 filaments to about 50 filaments or more,
sometimes about 3 filaments to about 10 filaments, and other times
about 5 filaments to about 7 filaments. In some embodiments, the
elongate member has a flexural modulus that is less than the
flexural modulus of bony tissue, such as the endplates of the
vertebral bodies adjacent to a vertebral disc. In some instances,
by providing a flexural modulus that is lower than certain body
structures, damage to those body structures may be reduced or
substantially eliminated. Thus, in some discectomy or nucleotomy
procedures, a tissue removal device with an elongate member that
has a flexural modulus that is less than the flexural modulus of
both the bony tissue of the vertebral endplates and the flexural
modulus of the annular fibrosus walls of the disc may be able to
pulverize the inner tissue of a disc without damaging the adjacent
walls of the disc or the vertebral bone. In some examples, the
flexural modulus of the elongate member may be less than about half
of the flexural modulus of intact bone or the annular fibrosis
tissue, while in other embodiments, the flexural modulus of the
elongate member is at least about 5 times lower, or even at least
about 10 times or 20 times lower. In some embodiments, the flexural
modulus of the elongate member is generally uniform along its
exposed length or between its coupling sites on the rotatable
shaft. For example, in some embodiments, the flexural modulus may
not vary by more than about a 10.times. range along the length of
the elongate member, while in other embodiments, the variation may
be no greater than a range of about 5.times. or about 2.times..
[0048] In some variations, the elongate member (e.g., multifilament
or monofilament) of any of the variations described herein may be
coated or sheathed with one or more materials. For example, the
elongate member may be coated with polyimide, parylene, silicone,
or urethane, or other polymer, or with an adhesive. The material
may or may not penetrate into or between the filaments of a
multi-filament elongate member. The coating may be applied by spray
coating or dip coating, or other coating method, for example. In
other examples, the material may be provided between the filaments
but not on the exposed outer surfaces of the filaments, e.g. the
material may be at least partially wiped or removed by air blowing
from the outer surface of elongate member after spraying or
dipping. In other variations, the coating material may comprise a
sheath or tube that is glued or heat shrunk to the elongate member
202. In some variations, the sleeve or coating has an average
thickness in the range of about 0.001 to about 0.01 inches, about
0.002 to about 0.008 inches, or about 0.003 to about 0.005 inches.
The coating, sheath or tube may further comprise one or more
support structures, such as a helical L304 stainless steel wire
that is partially or completely embedded into the coating, sheath
or tube, or adhered to the inner and/or outer surface of the
coating, sheath or tube. The coating or sleeve may or may not cover
the entire length of exposed or exposable elongate member or cable,
and may also cover the unexposed portions of the elongate member or
cable. In some variations, the coating or sleeve may be cover a
portion of the proximal, middle, or distal portion of the elongate
member and may be characterized as a percentage of coverage
relative to the overall exposed or exposable length of the elongate
member or cable, e.g. about 10%, about 20%, about 30%, about 40%,
about 50%, about 60%, about 70%, about 80%, about 90%, or about
100%.
[0049] Although the elongate member 202 may have a retracted
configuration and an extended configuration, the elongate member
202 may also have a native or base configuration in which the
stress acting on the elongate member 202 is reduced compared to
other configurations. This native configuration, if any, may be the
retracted configuration, the extended configuration, or a
configuration between the retracted configuration and the extended
configuration. Thus, the stress exerted on the elongate member 202
in the native configuration may be lower in either the retracted
configuration or the extended configuration, or a third
configuration that is different from the retracted configuration or
the extended configuration. In some embodiments, a native
configuration that is similar to the extended configuration may be
beneficial because a lower baseline stress acting on the elongate
member 202 while in its extended configuration may provide greater
stress tolerance from impacting tissues or bone before stressing
the elongate member 202 beyond its fracture point. Although
adjusting the elongate member 202 to its retracted configuration
may result in greater stress acting on the elongate member 202, the
stress may occur only during insertion and removal of tissue
removal device 2, and without the impact stressed that act on the
elongate member 202 during use. To produce the elongate member 202
with a particular native configuration, the manufacturing steps may
vary depending upon the particular material or composition used. In
embodiments where the elongate member 202 comprises stainless steel
(e.g. 304L or 316L stainless steel) or nickel-titanium alloys, for
example, a series of deformation steps and heat annealing steps may
be used to form the elongate member 202 in a native, expanded
configuration.
[0050] The elongate member 202 may have any of a variety of
cross-sectional shapes, including but not limited to square,
rectangular, trapezoidal, circular, elliptical, polygonal, and
triangular shapes, for example. The cross-sectional shape and/or
size may be uniform along its length, or may vary along one or more
sections. In one example, the elongate member may have a tapered
configuration, with a cross-sectional area that decreases from its
proximal section to its distal section, or from its distal section
to its proximal section. In some embodiments, the elongate member
202 may comprise a metallic wire or other elongate structure with a
diameter or maximum cross-sectional dimension in the range of about
0.2 mm to about 1.5 mm or more, sometimes about 0.3 mm to about 1
mm, and other times about 0.3 mm to about 0.5 mm.
[0051] In some embodiments, the elongate member may be
micropolished. Micropolishing may or may not reduce the risk of
chipping or fragment formation when used to debride harder or
denser body structures or tissues. In other embodiments, the
elongate member may comprise a grit surface or a cutting edge along
one or more portions of its length. For example, the elongate
member may comprise a cutting edge with an edge angle in the range
of about 90 degrees to about 10 degrees, sometimes about 75 degrees
to about 15 degrees, and other times about 60 degrees to about 30
degrees, and still other times about 45 degrees to about 40
degrees. The configuration of the elongate member surface may be
the same or different on opposing sides of the elongate member. For
example, having different configuration on the leading surface
compared to the trailing surface of the elongate member, may permit
changes in the cutting, chopping, debriding, or emulsifying
characteristics of the elongate member 202, depending upon its
direction of rotation. In other embodiments, the leading and
trailing surfaces may generally have the same features and may have
similar performance in either rotation direction, but may also
permit users to switch from one surface to the other if one surface
has worn out. In still other embodiments, the rotation direction
may be user-selected, depending upon the relative location of the
tissue to be removed and any critical anatomical structures. For
example, the rotation direction may be selected such that if the
cutting edge 58 or 60 catches on the tissue or structure, tissue
disrupting element 8 will be rotated away from the critical
anatomical structure(s), if any.
[0052] As depicted in FIG. 6B, the elongate members 202 may have
proximal and distal sections 204 and 206 with generally similar
lengths and generally straight configurations, and a curved or
angled middle portion 210 between them. FIG. 9, however, depicts
another embodiment of a tissue removal device 310, comprising an
elongate member 312 with proximal and distal sections 314 and 316
with concave configurations and a middle section 318 with a convex
configuration. Other configurations are also contemplated,
comprising any of a variety of linear, curved, or angled sections,
and comprising symmetrical or asymmetrical configurations. In the
embodiment depicted in FIG. 9, the longitudinal distance 320
between the proximal and distal openings 322 and 324 of the
rotatable shaft 326 may be in the range of about 4 mm to about 30
mm or more, sometimes about 6 mm to about 15 mm, and other times
about 9 mm to about 12 mm. The longitudinal distances 328 and 330
from the proximal and distal openings 322 and 324 to the peak
displacement distance 332 of the elongate member 302, respectively,
may be similar or different. In some embodiments, the distances 328
and 330 may be in the range of about 2 mm to about 20 mm or more,
sometimes about 3 mm to about 10 mm, and other times about 4 mm to
about 6 mm. The peak displacement distance 332 between the middle
section 318 and the rotatable shaft 326 can vary, depending upon
the particular configuration of the elongate member. The minimum
displacement distance (not shown) of the middle section need not be
zero, as in embodiments where the elongate member does not fully
retract along its entire length against the rotatable shaft. In
some embodiments, the displacement distance 318 may be in the range
of about 2 mm to about 10 mm or more, sometimes about 3 mm to about
8 mm, and other times about 4 mm to about 6 mm. In some
embodiments, the peak displacement distance 322 may be
characterized relative to the longitudinal distance 320 or the
proximal or distal distances 328 and 330 to the peak distance. For
example, the ratio of the peak displacement distance to the
longitudinal distance may be in the range of about 0.2 to about 1
or more, sometimes about 0.3 to about 0.8, and other times about
0.4 to about 0.5. The distance 334 between the distal opening 324
of the rotatable shaft and the distal head 336 may be in the range
of about 0.5 mm to about 5 mm or more, sometimes about 1 mm to
about 4 mm, and other times about 2 mm to about 3 mm. The length
338 of the head 336 may be in the range of about 2 mm to about 15
mm or more, sometimes about 3 mm to about 10 mm, and other times
about 4 mm to about 5 mm. In embodiments comprising a conical or
tapered head, the angle 340 of the head configuration may be in the
range of about 10 degrees to about 90 degrees or more, sometimes
about 20 degrees to about 60 degrees, and other times about 30
degrees to about 45 degrees.
[0053] The diameter 342 (or maximum transverse axial dimension) of
the rotatable shaft 326 and/or head 336 may be in the range of
about 0.5 mm to about 5 mm or more, sometimes about 1 mm to about 3
mm, and other times about 1 mm to about 2 mm. The diameter of the
shaft 326 and the head 336 may be similar or different. The maximum
cross-sectional dimension of the proximal and distal openings may
be the same or different, and may be in the range of about 0.1 mm
to about 1.5 mm or more, sometimes about 0.2 mm to about 1 mm, and
other times about 0.4 mm to about 0.8 mm.
[0054] The width of the groove 344 of the rotatable shaft 326, if
any, may be in the range of about 0.2 mm to about 1.5 mm or more,
sometimes about 0.3 mm to about 1 mm, and other times about 0.4 mm
to about 0.7 mm. The width of the groove 344 may also be
characterized as a percentage of the diameter or width of the
elongate member, which may be in the range of about 80% to about
400% or more, sometimes about 105% to about 300%, and other times
about 150% to about 200%. As mentioned previously the depth of the
groove 344 may be less than, similar to, or greater than the
maximum transverse dimension of the elongate member 312. In some
embodiments, the groove depth or average groove depth may be in the
range of about 0.2 mm to about 2 mm or more, sometimes about 0.4 mm
to about 1 mm, and other times about 0.6 mm to about 0.8 mm. In
other embodiments, the depth of the groove may be a percentage of
the depth of the elongate member, in the range of about 20% to
about 200% or more, sometimes about 50% to about 125%, and other
times about 40% to about 100%.
[0055] Although a single elongate member 202 is provided in the
tissue removal device 200 depicted in FIG. 6A, other embodiments
may comprise two or more elongate members. In some embodiments,
however, a single elongate member may permit higher rotational
speeds, due the reduced surface drag compared to tissue removal
devices with multiple elongate members. In embodiments with
multiple elongate members, the elongate members may be distributed
uniformly or non-uniformly around the perimeter of the rotatable
shaft. In some embodiments, each elongate member may have its own
proximal and distal openings, but in other embodiments, two or more
elongate members may share a proximal and/or distal opening. The
proximal and/or distal openings may be located at the same or
different longitudinal position on rotatable shaft, and each
elongate member may have the same or different length or
configuration. The elongate members may be independently adjustable
or adjustable in groups.
[0056] Referring to FIG. 10, in some embodiments, the elongate
member 350 of the tissue removal device 352 may comprise other
structures 354, 356 and 358 attached or coupled to the flexible
elongate member 350. These structures may comprise any of a variety
of structures, including tubes, rods, bars, cutting discs or other
cutting members, beads or other structures. In the specific example
depicted in FIG. 10, the elongate member 352 comprises rigid
sections 354, 356 and 358 alternating between flexible segments
360, 362, 364 and 366. One or more flexible segments may also be
substituted with a mechanical joint, such as a pin joint or a hinge
joint. In some embodiments, the flexible elongate segments 360,
362, 364 and 366 are part of a single contiguous flexible elongate
member that passes through a lumen of each rigid section 354, 356
and 358 or are otherwise coupled to each rigid section 354, 356 and
358. In other embodiments, one or more of the flexible segments
360, 362, 364 and 366 are separate and interconnect only two rigid
sections 354, 356 and 358 or a rigid section and the rotatable
shaft 368 or a structure therein. The particular number, shape,
flexibility/rigidity, lengths and locations of the rigid segments
and flexible segments may vary and need not be uniform or
symmetrical. In some embodiments, the percentage of rigid section
to flexible section along the length of the fully extended elongate
member may in the range of about 0 to about 99%, sometimes about
50% to about 95%, and other times about 75 to about 90%. In some
embodiments, the length of the flexible segment may be less than
about 75% of the length of the adjacent rigid segments, sometimes
less than about 50%, and other times less than about 20% or about
10%.
[0057] In the example shown in FIG. 10, the tissue removal device
352 comprises one rigid section 354 that is larger than the other
rigid sections 356 and 358. The section located at the peak
displacement distance of the elongate member 350 may be a flexible
segment 362 as shown in FIG. 10, or a rigid section in other
embodiments. The rigid sections 354, 356 and 358 are generally
linear in shape, but may also be curved or angled or any
combinations thereof. The elongate member 350 in FIG. 10 is also
generally configured to lie in a single plane in both the retracted
and extended configurations, but in other embodiments, one or more
rigid or flexible sections may be oriented out of plane in the
retracted and/or extended configurations. As further illustrated in
FIG. 10, the shaft 368 may comprise a groove 369, or a region of
the shaft with a narrow diameter or axial transverse dimension,
which may reduce the overall cross-sectional area of the tissue
removal device 352 by permitting the elongate member 352 to
protrude less when in the retracted configuration.
[0058] As shown in FIG. 10, the elongate member 350 in the extended
state may have flexible sections 366 and 360 located about its
proximal and distal openings 370 and 372. In other embodiments,
however, the elongate member may have a rigid section or other
structure about the proximal or distal openings in the extended
state. In FIG. 11, for example, the tissue removal device 380
comprises a generally symmetrical elongate member 382 with proximal
and distal rigid members 384 and 386 interconnected by a flexible
cable 388. In the extended configuration, the rigid members 384 and
386 are partially located or recessed within the proximal and
distal openings 390 and 392 of the rotatable shaft 394. In some
further embodiments, having rigid members 384 and 386 at the
proximal and distal openings 390 and 392 may reduce the tilting or
bending of the elongate member 382 with respect to the shaft 394.
The degree with which the elongate member 382 is restricted may
depend, for example, on the widths of the openings 390 and 392 and
the rigid member 384 and 386, the lengths 396 and 398 of the rigid
member 384 and 386 outside and inside the shaft 394, the lengths
400 of the flexible segment(s), and the overall diameter of the
shaft 394, and the degree of rigidity of the rigid members 384 and
386. As further shown in FIG. 11, the shaft 394 may further
comprise a groove 400 or other configuration with a reduced
diameter or transverse axial dimension. At least a portion of the
groove 400 or configuration is located between the proximal and
distal openings 390 and 392, but the groove 400 or configuration
may also be located proximal or distal to the openings 390 and 392,
respectively.
[0059] As shown in FIGS. 12A and 12B, in some embodiments, the
tissue removal device 420 may have proximal and distal openings 422
and 424 which are located at different circumferential locations
along the longitudinal length of the rotatable shaft 426, and/or
where the elongate member 428 comprises at least one section having
a helical, twisted or skewed configuration with respect to the
rotatable shaft 426. FIG. 12A depicts the tissue removal device 420
in a retracted or collapsed configuration, while FIG. 12B depicts
the tissue removal device 400 in an extended or expanded
configurations. By extending the elongate member 408 through the
proximal opening 422 of the shaft 426, the elongate member 426 may
become axially compressed and expand radially outward from the
shaft 426.
[0060] The configuration of the elongate member may vary in the
direction of turning. For example, the elongate member may have a
right or left-handed spiral orientation (i.e. a clockwise or
counter-clockwise orientation). In FIGS. 12A and 12B, for example,
the elongate member 428 has a left-handed or counter-clockwise
spiral orientation (as viewed from the proximal end of the tissue
removal device 420). The spiral orientation of the elongate member
428 may be in the same as the rotation direction of the shaft 426,
or be the opposite of the rotation direction. The spiral
configuration of the elongate member 428 may be characterized in
any of a variety of ways. For example, the absolute number of turns
may be the elongate member may be anywhere in the range from about
zero (e.g. a linear elongate member) to about 4 turns or more,
sometimes about a 1/4 turn to about 11/2 turns, and other times
about 1/2 turn to about one turn. In other embodiments, the spiral
configuration may be characterized by its rate of turning, which
may be calculated as the number of turns per millimeter or
centimeter. In some embodiments, the rate of turning may be in the
range of about 0.3 turns/cm to about 2 turns/cm or more, sometimes
about 0.7 turn/cm to about 1.5 turns/cm, and other times about 0.9
turns/cm to about 1 turn/cm. The elongate member 428 may also be
characterized by its pitch angle, which may be in the range of
about 0 degrees to about 90 degrees, sometimes about 5 degrees to
about 90 degrees, and other times about 45 degrees to about 85
degrees. The spiral configuration of the elongate member may be
generally curved along its length, but may also comprise multiple
linear segments with angled or curved bends in between. The
configuration of the spiral elongate member in the retracted and
extended configuration may vary, depending upon the flexibility of
the elongate member, the manner and angle with which one or more
ends of the elongate member are attached or fixed to the rotatable
shaft, and the native configuration of the elongate member.
[0061] As shown in FIGS. 13A to 13C, a tissue removal device 450
with a spiral elongate member 452 may also comprise one or more
grooves 454 on the rotatable shaft 456. The groove 454 may
facilitate seating and/or securing of the elongate member 452 in
its retracted configuration. As can be seen in FIG. 13C, the spiral
configuration of the elongate member 452 and the groove 454 may not
be uniform along the length of the rotatable shaft 456. The distal
groove 458 adjacent to the distal opening 460 comprises
approximately a 1/2 turn along a longitudinal distance that is
about 50% shorter than the 1/2 turn of the middle groove 462, while
the proximal groove 464 between the middle groove 462 and the
proximal opening 466 is generally linear. In some embodiments, the
change in turn rate may be in the range of about zero to about 4
turns/cm or more, other times about zero to about 1 turn/cm, and
other times about zero to about 0.5 turns/cm. In the particular
embodiment depicted in FIGS. 13A to 13C, the distal portion 468 of
the elongate member 452 remains generally wrapped around the shaft
456 in the distal groove 458 in the extended configuration, while
the proximal portion 470 of the elongate member 452 bows radially
outward. As can be seen in FIG. 13C, in this particular
configuration, the peak displacement distance 472 of the elongate
member 452 is located closer to the proximal opening 466 of the
shaft 456 than the distal opening 460. The proximal and distal
openings 466 and 460 may be oriented perpendicular to the outer
surface of the shaft 456, or may be oriented at an angle or tangent
with respect to the outer surface of the shaft 456, which may
reduce stresses exerted onto the elongate member 452 at the
openings 460 and 466. The edges of the groove 454 may also rounded
along its length or at least about the openings 460 and 466. The
elongate member, however, may be configured with a peak
displacement distance located anywhere between the proximal and
distal openings, or even extending distal to the distal opening
and/or proximal to the proximal opening. In other embodiments, the
elongate member may even comprise multiple peak displacement
distances (e.g. a multi-angle, undulating or sinusoidal elongate
member in the extended configuration). In some embodiments, the
peak displacement distance 472 is in the range of about 0.5 to
about 10 times greater than the diameter or transverse axial
dimension of the shaft 456, sometimes about 1 to about 5 times
greater, and other times about 2 times to about 3 times greater.
The longitudinal location of the peak distance may be characterized
as a relative position from the proximal to distal openings, which
may be about -20% or less, about -10%, about 0%, +10%, about +20%,
about +30%, about +40%, about +50%, about +60%, about +70%, about
+80%, about +90%, about +100%, about +110% or about +120% or
more.
[0062] Referring now to FIGS. 14A and 14B, in some embodiments, the
tissue removal device 480 may comprise a shaft 482 with a narrowed
region 484. At least a portion of the narrowed portion 484 may be
located between the proximal and distal attachments or openings 486
and 488 from which the elongate member 490 protrude, but in other
embodiments, at least a portion of the narrowed portion 484 may be
proximal or distal to the openings 486 and 488, respectively. As
depicted in FIG. 14A, the narrowed portion 484 of the shaft 482 may
facilitate a low profile retracted configuration, but may also
provide additional space for snagged tissue or adhered biological
material to occupy. This may occur, for example, when the elongate
member 490 in FIG. 14B is retracted into its retracted
configuration in FIG. 14A, or during a prolonged procedure. This
additional space may be beneficial when withdrawing tissue removal
device from an endoscopy instrument or cannula. As further
illustrated in FIGS. 14A and 14B, the attachments or openings 486
and 488 may have a transverse axial orientation, rather than the
surface orientation of the openings 422 and 424 of the tissue
removal device 420 depicted in FIGS. 12A and 12B.
[0063] Although the narrowed portion 484 in FIGS. 14A and 14B has a
uniform diameter and configuration, in other embodiments, such as
the tissue removal device 492 in FIG. 15, the narrowed portion 494
may have a tapered configuration with a variable diameter or
configuration. Referring back to FIGS. 14A and 14B, the
longitudinal axis of the narrowed portion 494 may be co-axial with
the axis of the rest of the shaft 482, but in some embodiments, the
longitudinal axis may be different, e.g. eccentric or variable. In
FIG. 16, for example, the tissue removal device 496 comprises a
narrowed portion 498 with a non-linear longitudinal axis comprising
a helical or corkscrew configuration. Also, although this example
of the tissue removal device 496 has narrowed portion 498 and an
elongate member 399 with the same helical orientation, in other
example, the helical orientations may be different or opposite.
[0064] Referring now to FIG. 5B, the tissue removal device 2 in
FIG. 5A is illustrated with a portion of the housing 6 removed to
show various internal components. In this embodiment, the tissue
removal device 2 further comprises a battery 12 to provide power to
the motor 14 which drives the tissue removal assembly 8. In other
embodiments, a connector to an external power source may be
provided in addition to, or in lieu of, the battery 12. The type of
battery and power provided may differ depending upon the particular
power needs of the motor and/or other components of the tissue
removal device 2.
[0065] In some embodiments, the motor 14 of the tissue removal
device 2 is a DC motor, but in other embodiments, the motor 14 may
have any of a variety of configurations, including but not limited
to an AC or a universal motor. The motor 14 may be a torque,
brushed, brushless or coreless type of motor. In some embodiments,
the motor 14 may be configured to provide a rotational speed of
about 500 rpm to about 200,000 rpm or more, sometimes about 1,000
rpm to about 40,000 rpm, and at other times about 5,000 rpm to
about 20,000 rpm. The motor 14 may act on the tissue removal
assembly 8 via the outer tube 4, or a by drive member located
within the outer tube 4. In some further embodiments, a fluid seal
16 may be used to protect the motor 14 and/or other components of
the housing 6 from any fluids or other materials that may be
transported through the outer tube 4, or through the housing
aperture 18. In some embodiments, a connector or seal may be
provided about the housing aperture 18 to permit coupling of the
housing 6 to a trocar, an introducer, a cannula or other tubular
member into which the tissue removal assembly 8 and the outer tube
4 are inserted. In some embodiments, the tissue removal device may
be used with an introducer or cannula having an outer diameter of
about 0.01 cm to about 1.5 cm or more, sometimes about 0.1 cm to
about 1 cm, and other times about 2 mm to about 6 mm.
[0066] As shown in FIGS. 5A and 5B, the tissue removal device 2 may
further comprise a conduit 24 which may be used to connect the
tissue removal device 2 and an aspiration or suction source. An
aspiration or suction source may be used, for example, to transport
fluid or material through a lumen or conduit of the outer tube 4 or
through a tubular member in which the outer tube 4 is inserted. In
one particular embodiment, the conduit 24 comprises a port 20 which
communicates with the fluid seal 16 via a length of tubing 22. The
fluid seal 16 is configured to permit flow of fluid or material
between the outer tube 4 and the tubing 22, while permitting
movement of the outer tube 4 or a drive member therein coupled to
the motor 14. In other embodiments, the conduit 24 may further
comprise additional components, including but not limited to a
fluid or material trap, which may be located within or attached to
the housing 6, or attached to the port 20 or the tubing 22, or
located anywhere else along the pathway from the tissue removal
assembly 8 to the suction source. In some embodiments, a separate
port may be provided for infusing or injecting substances into
target site using the tissue removal device 2. In other
embodiments, the conduit 24 may be used for both withdrawal and
infusion of materials and/or fluids, or for infusion only.
Depending upon the configuration of the tissue removal device,
withdrawal and/or infusion may occur at the distal end of the outer
tube 4, and/or through one or more openings of the tissue removal
assembly 8. In other embodiments, a port may be used to insert a
coagulation catheter, an ablation catheter or other energy delivery
device to the target site.
[0067] In some embodiments, the outer tube comprises an outer
tubular member with at least one lumen, and an elongate drive
member configured to mechanically couple the motor to the tissue
removal assembly. In other embodiments, the outer tube may contain
additional members, for example, to adjust or control the
configuration of the tissue removal assembly. In some embodiments,
the outer tube 4 may comprise one or more lumens containing control
wires, which may be used to manipulate the deflections of the
distal end of the outer tube. The outer tube and optional drive
members may be rigid or flexible. The outer tube may be pre-shaped
with a linear or a non-linear configuration. In some embodiments,
the outer tube and the components is configured to be
user-deformable, which may facilitate access to particular target
sites, or may be user-steerable using a steering mechanism
comprising one or more pull wires or tension elements. In some
embodiments, a stiffening wire or element may be inserted into the
outer tube to provide additional stiffness to the tissue removal
device. The length of the outer tube between the tissue removal
element and the motor or housing may vary from about 0 cm to about
30 cm or more in some embodiments, sometimes about 4 cm to about 20
cm, and other times about 10 cm to about 14 cm.
[0068] In other embodiments, the tissue removal device may comprise
a tissue removal assembly that may be detachably attachable to the
shaft of a motor or coupled to a motor. In still other embodiments,
the tissue removal device may comprise a tissue removal assembly
coupled to a shaft, wherein the shaft may be detachably attachable
to a motor or a shaft coupled to a motor.
[0069] In some embodiments, the housing 6 is configured with a size
and/or shape that permits handheld use of the tissue removal device
2. In other embodiments, the tissue removal device 2 may comprise a
grip or structure located about the outer tube 4 to facilitate
handling by the user, while the proximal end of the outer tube 4 is
attached to a benchtop or cart-based machine, for example, or a
mounted or fixed machine. In these embodiments, the grip may or may
not contain any other components of the tissue removal device, such
as a motor, while the machinery at the proximal end of the outer
tube 4 may contain one or more other components, such as a suction
system or various radiofrequency ablation components, for example.
In some embodiments, the housing 6 may have a length of about 1 cm
to about 12 cm or more, sometimes about 2 cm to about 8 cm, and
other times about 3 cm to about 5 cm. The average diameter of the
housing (or other transverse dimension to the longitudinal axis of
the housing) may be about 1 cm to about 6 cm or more, sometimes
about 2 cm to about 3 cm, and other times about 1.5 cm to about 2.5
cm. The housing 6 may further comprise one or more ridges, recesses
or sections of textured or frictional surfaces, including but not
limited to styrenic block copolymers or other polymer surfaces.
[0070] As illustrated in FIG. 17, a tissue removal device may
optionally comprise a tissue transport assembly 68, which may be
used to facilitate transport or removal of tissue within or along
the outer tube 4. In the particular embodiment depicted, the tissue
transport assembly 68 comprises a helical member 70 mounted on a
drive member 78 that may be rotated. Actuation of the drive member
78 may mechanically facilitate proximal movement of tissue or other
materials within the channel or the lumen 72 of the outer tube 4 by
rotating the helical member 70. The actuated drive member 78 will
also rotate the distal burr element or other tissue removal
assembly 8. In some embodiments, use of the tissue transport
assembly 68 may be performed at lower rotational speeds when tissue
debulking is not concomitantly performed. When rotated in the
opposite direction, the helical member 70 may be used expel or
distally transport tissue, fluid or other materials or agents from
the outer tube 4 or supplied to an infusion port of the housing
6.
[0071] In some embodiments, the helical member 70 may have a
longitudinal dimension of about 2 mm to about 10 cm or more,
sometimes about 3 mm to about 6 cm, and other times about 4 mm to
about 1 cm. In other embodiments, the longitudinal dimension of the
helical member 70 may be characterized as a percentage of the
longitudinal dimension of the outer tube 4, and may range from
about 5% to about 100% of the longitudinal dimension of outer tube
4, sometimes about 10% to about 50%, and other times about 15% to
about 25%, and still other times is about 5% to about 15%. Although
the helical member 70 depicted in FIG. 17 rotates at the same rate
as the tissue removal assembly, due to their mounting or coupling
onto common structure, drive member 78, in other embodiments, the
helical member may also be configured to rotate separately from
drive member. For example, a helical member may comprise a helical
coil located along at least a proximal portion of the lumen of the
outer tube but is not mounted on the drive member. In this
particular example, the helical member may rotate independently of
the drive member. In still other embodiments, the helical member 70
may be mounted on the surface of the lumen 72 and can be used to
transport tissue or substances along the lumen 72 by rotation of
the outer tube 4, independent of the drive member 78 or a tissue
removal assembly.
[0072] Although the helical member 70 is depicted as a continuous
structure, in some embodiments, the helical member 70 may be
interrupted at one or more locations. Also, the degree or angle of
tightness of the helical member 70 may vary, from about 0.5
turns/mm to about 2 turns/mm, sometimes about 0.75 turns/mm to
about 1.5 turns/mm, and other times about 1 turn/mm to about 1.3
turns/mm. The cross-sectional shape of the helical member 70 may be
generally rounded as depicted in FIG. 17, but in other embodiments,
may have one or more edges. The general cross-sectional shape of
the helical member 70 may be circular, elliptical, triangular,
trapezoidal, squared, rectangular or any other shape. The turn
tightness and cross-sectional shape or area of the helical member
70 may be uniform or may vary along its length. In some
embodiments, multiple the helical members 70 may be provided in
parallel or serially within the outer tube 4.
[0073] In some embodiments, the drive member 78 may be configured
to extend distally and retract from the outer tube 4 by a length of
about 0.01 cm to about 2 cm or more, sometimes about 0.02 cm to
about 1.5 cm and other times about 0.05 to about 1 cm. In some
embodiments, the helical member 70 is located proximal to the
tissue removal assembly at a distance of about 0.01 cm to about 2
cm or more, sometimes about 0.02 cm to about 1.5 cm and other times
about 0.05 to about 1 cm. In some embodiments, when drive member 78
is maximally extended from outer tube 4, helical member 70 may
protrude from outer tube 4 by a longitudinal dimension of about
0.01 cm to about 2 cm or more, sometimes about 0.1 cm to about 1
cm, and other times about 0.25 cm to about 0.5 cm. In some
embodiments, the degree of extension of the drive member 78 and/or
the helical member 70 may affect the degree of tissue transport by
the tissue transport assembly.
[0074] Referring to FIGS. 18A and 18B, in another embodiment, a
tissue removal device 500 comprises a housing 502 and an outer
shaft 504. The housing 502 may include an adjustment mechanism with
a thumbwheel 506 configured to adjust the retraction and extension
of extendable tissue removal assembly (not shown). The thumbwheel
506 may provide a continuous range of change to extendable tissue
removal assembly, but in other embodiments, the turning of
thumbwheel 506 may be configured with clicks or detents that
provide one or more preset positions. As mentioned previously, any
of a variety of other control mechanisms and interfaces may be
used. The adjustment mechanism may comprise one or more blocking
elements or other adjustment limiting configurations to resist or
prevent overextension of extendable tissue removal assembly. For
example, limit structures may be provided in housing 502 to resist
overextension of extendable tissue removal assembly (not shown). In
this particular embodiment, tissue removal device 500 is configured
to rotate the tissue removal assembly at a fixed rotational speed,
controllable by a rocker-type power switch 508. As mentioned
previously, however, any of a variety of power and/or speed control
mechanisms may be used.
[0075] Referring to FIGS. 18C and 18D, FIG. 18C is a component view
of the internal components within housing 502, while FIG. 18D is a
schematic cross-sectional view of the internal components with a
portion of housing 502 removed. As shown in FIG. 18C, a drive
member 510 rotatably resides within the outer shaft 504 of the
tissue removal device 500. The distal end (not shown) of the drive
member 510 is coupled to the tissue removal assembly (not shown),
while the proximal end 512 of the drive member 510 is coupled to
the distal end 514 of a driveshaft 516. The proximal end 518 of the
driveshaft 516 may be coupled to a motor 520, either directly or
through a coupler 522. The coupler 522 may be configured to permit
some axial movement of driveshaft 526. The proximal end 524 of an
adjustment member 526 protrudes from the proximal end 510 of drive
member 512 and is attached to a drive key 528. The drive key 528
may comprise a flange 530 that is slidably located between the
proximal and distal ends 518 and 514 of the driveshaft 516. The
thumbwheel 506 may be movably coupled to a thrust member 532 so
that the rotation of the thumbwheel 506 results in the axial
movement of thrust member 532. In some embodiments, the thrust
member 532 may be configured with helical threads that are
complementary to a threaded lumen of the thumbwheel 506. In other
embodiments, however, the thrust member may comprise a slide
member, a pivot member or other coupling structure. The thrust
member 532 may be configured to axially slide the drive key 528
through a retaining structure 534 which movably couples the thrust
member 532 to the drive key 528. The retaining structure 534
permits the rotation of the driveshaft 516 by the motor 520 while
also coupling the axial movements of the thrust member 532 to the
drive key 528, thereby permitting adjustment of the tissue removal
assembly located at the distal end of the shaft 504 while
maintaining the ability of the drive member 510 to rotate. The
thrust member 532 may comprise a flange 536 to facilitate retention
of the thrust member 532 within the retaining structure 534. The
flange 536 may comprise one or more bearings to facilitate
rotational movement of the drive key 528 against the non-rotating
flange 536. The retaining structure 534 may also contain one or
more retaining bearings 538 to facilitate the rotation of the
driveshaft 516 against the drive key 528 while transmitting any
axial forces to the drive key 528. The retaining structure 534 is
optionally provided with one or more limiters 540, which may be
used to restrict overextension or retraction of the tissue removal
assembly. A seal 542 may be provided around the outer shaft 504 to
protect the contents of the housing 502.
[0076] As illustrated in FIG. 18D, the tissue removal device 500
may be powered using a battery 544 that is coupled to the motor 520
using a battery connector 546. As depicted in FIG. 18C, battery 544
may be a standardized battery, such as a 9-volt battery, but may
also be a customized battery. Other examples of drive shafts
couplings and adjustment mechanisms that may be used are disclosed
in U.S. Pat. No. 5,030,201, which is hereby incorporated by
reference in its entirety.
[0077] In the various examples described herein, the outer tube and
the driveshaft of the tissue removal device may comprise a rigid
structure and material, but may also optionally comprise at least
one flexible region which may bend while still permitting rotation
of the driveshaft. Examples of flexible driveshafts that may be
used are disclosed in U.S. Pat. Nos. 5,669,926 and 6,053,907, which
are hereby incorporated by reference in their entirety. In some
examples, the flexible region(s) may comprise a substantial portion
or all of the length of the driveshaft and outer tube. A tissue
removal device with a flexible region may facilitate access to
certain regions of the body, such as the central spinal canal
through an intervertebral foramen. In some examples, the flexible
tissue removal device may comprise a steering assembly that uses
one or more steering wires that are attached distal to the flexible
region and manipulated by a steering member in the proximal
housing. Other steering mechanisms used with catheters and other
elongate instruments may also be used. In other examples, an active
steering mechanism is not provided on the flexible tissue removal
device, but the flexible tissue removal device may be steered by an
endoscopic instrument into which the tissue removal device has been
inserted. Some examples of steerable endoscopic instruments are
disclosed in Application No. 61/045,919, which is hereby
incorporated by reference in its entirety.
[0078] FIGS. 19A to 19C depict one embodiment of a tissue removal
device 600 with a flexible region 602 and a steering assembly 604
located in the housing 606 of the tissue removal device 600. In
addition, the housing 606 includes a power switch 608 which
actuates the motor 610 that rotates the driveshaft (not shown)
located in the outer tube 612, and an irrigation tube 614 which may
be used infuse fluid or provide suction about the distal end of the
device 600. As shown in FIG. 19B, the steering assembly 604
comprises a pivoting lever 616 with two arms 618 and 620 protruding
from the housing 606. In other embodiments, the steering assembly
604 may comprise a single arm lever, a slider, knob or other type
of actuator. The steering assembly 604 may optionally comprise one
or more springs or bias structures, which may facilitate springback
of the lever 616 once released. The steering assembly 604 may also
optionally comprise a releasable locking mechanism to maintain the
steering assembly in a particular configuration. The locking
mechanism may be a frictional interfit or an interlocking
mechanism, for example.
[0079] Coupled to the lever 616 are two steering elements or wires
622 and 624, which are slidably movable within the outer tube 614
and are distally coupled to a distal site of the flexible region
602. The steering wires 622 and 624 may be separate wires, or two
segments of the same wire looped through the lever 616. When a
steering wire 622 or 624 is tensioned by actuating one of the lever
arms 618 and 620, the flexible region 602 will curve or bend. The
flexible region may comprise any of a variety of flexible materials
and/or flexible structures, including any of a variety of polymeric
or metallic structures. In the depicted embodiment, the flexible
region 602 comprise a plurality of optional slots 626, which may
augment the bending characteristics, but in other embodiments, an
accordion-like configuration or other type of bending configuration
may be provided. The ends 628 of the slots 626 depicted in FIG. 19C
have optional enlarged arcuate configurations, which may
redistribute at least some of the bending forces that may act of
the flexible region 602 and may resist tearing or reduce any
resulting damage to the flexible region. The length of the flexible
region may be in the range of about 1 mm to about 200 mm or more,
sometimes about 5 mm to about 50 mm, and other times about 8 mm to
about 20 mm. The width of the ends 628 of the slots 626, as
measured in the unbent configuration along the longitudinal axis of
the tissue removal device, may be in the range of about 0.5 mm to
about 4 mm or more, sometimes about 1 mm to about 3 mm, and other
times about 1 mm to about 2 mm. In still other embodiments, the
flexible region may lack a particular configuration but comprises a
flexible material that has a lower durometer than the other
portions of the outer tube. The maximum degree of bending may vary
from about 5 degrees up to about 10 degrees or more, sometimes
about 15 degrees up to 25 degrees or more, and other times about 45
degrees to about 75 degrees or more, and even about 90 degrees to
about 105 degrees or more in certain embodiments. In embodiments of
the tissue removal device having bi-direction steering from its
neutral axis, the maximum degree of bending in each direction may
be the same or may be different.
[0080] As illustrated in FIG. 19C, a flexible elongate member 630
is coupled to a rotatable shaft assembly 632 comprising a reduced
diameter core 634 located between a proximal and distal sections
636 and 638. A piercing element 640 may be attached to the distal
end of the rotatable shaft assembly 632. The proximal and distal
sections 636 and 638 each comprise optional taper regions 642 and
644. In some embodiments, the taper regions 642 and 644 may reduce
or eliminate the potential snagging of the elongate member 630
during retraction, or snagging of the rotatable shaft assembly 632
during its insertion or withdrawal with respect to the vertebral
disc, the epidural space, or the cannula or endoscopic device in
which it was placed. In the retracted configuration illustrated in
FIG. 19C, the elongate member 630 has a helical orientation about
the reduced diameter core 634, but may or may not be contacting the
core 634.
[0081] As depicted in FIG. 19C, the exposed proximal and distal
ends 646 and 648 of the flexible elongate member 630 may be coupled
to the rotatable shaft assembly 632 through either openings or
attachment sites located on the circumferential surfaces of the
proximal and distal ends 646 and 648. Other sites where one or both
ends of the flexible elongate member 630 may be coupled include but
are not limited to the taper regions 642 and 644, if any, or any
other transversely surface have at least some degree of transverse
orientation with respect to the longitudinal axis of the rotatable
shaft assembly 632. Still other coupling sites may include the
reduce diameter core 634 and the piercing element 640.
[0082] A steerable tissue removal device may be used during some
procedures to increase the region or amount of tissue removed,
compared to a rigid tissue removal device, for example. In some
instances, anatomical restrictions or increased risks of injury may
limit the range with which a rigid tissue removal device may be
manipulated. FIGS. 20A and 20B, for example, schematically depict
some of the movement axes and the potential tissue removal zones
that may be achieved with a steerable tissue removal device 650.
Here, a steerable tissue removal device 650 with an extendable
cable 652 may be inserted into a vertebral disc 653. While the
steerable tissue removal device 650 and a rigid linear tissue
removal device may translate and rotate with respect to its
longitudinal axis 654, the pivoting range 656 of the rigid portion
of the outer tube 658 of the tissue removal device 650 (and the
corresponding structure on a rigid tissue removal device) may be
substantially limited because even small angular movements of the
outer tube 658 may be require substantial absolute displacement of
the more proximal portions of the outer tube 658. This
displacement, however, will be limited by the amount, the location
and/or the compliance of the body tissues and structures between
the proximal end (not shown) and the distal end 660 of the rigid
portion of the outer tube 658. In contrast, a tissue removal device
650 with a flexible segment 662 located distally permits a range of
angulation or bending 664 from the longitudinal axis 654 of the
tissue removal device 650 without requiring substantial
displacement or leveraging of the rigid portion of the outer tube
658. Thus, the flexible segment 662 may be able to reach tissue
that is spaced apart from the longitudinal axis 654 with less
physical effort, and may be even be able to reach tissue that
cannot be reached by pivoting a rigid portion of the outer tube
658.
[0083] In addition to the bending of the flexible segment 662, the
steerable tissue removal device 650 may also access tissues located
away from the longitudinal axis 654 by increasing the extension of
the extendable cable 652 along its extension range 665. The
extension range 665 may be characterized as a dimension that is
perpendicular to the longitudinal orientation of the core section
668 to which the extendable cable 652 is coupled. For example, a
tissue removal device with a 1 mm diameter core and configured with
an extendable cable that may be adjusted to a perpendicular
distance of 3 mm away from the core can remove tissue in a zone
that is 7 mm in at its maximum diameter (i.e. 1 mm shaft plus 2
times 3 mm of the rotated elongate member). In embodiments where
the extendable cable is extended to a greater degree, even greater
volumes or zones of tissue removal may be achieved. Thus, by
manipulating the degree of cable extension, the volume or range of
tissue removal that may be performed may be adjusted without
requiring repositioning the tissue removal device, either by
torqueing its shaft or using its steering mechanism (if any).
[0084] Because the particular tissue removal device 650 in FIGS.
20A and 20B permits the actuation of the extendable cable 652 while
the flexible segment 662 is bent by providing a flexible or
bendable driveshaft (not shown), the tissue removal zone 670 may be
displaced away from the longitudinal axis 654. Furthermore, because
each of the movement described above may be synergistically
combined with one or more other movements, even greater larger
tissue removal zones may be achieved. For example, rotation 672 of
the bent tissue removal device 650 around the longitudinal axis 654
by torqueing the rigid portion of the outer tube 658, may achieve
an even larger tissue removal zone 674. The rotation 672 of the
bent tissue removal device 650 may occur while the extendable cable
652 is being rotated, or when the cable 652 is not rotating. The
amount of rotation 672 may be anywhere in the range of about 1
degree to about 360 degrees or more. Any of a variety of
combinations of cable extension, flexible zone bending, and outer
tube rotation and translation may be used to achieve the desired
tissue removal.
[0085] While various flexible, steerable and rigid embodiments of
the tissue removal device may be used to remove larger volumes of
tissue as described above, in other embodiments, a tissue removal
device may be used to perform focal debulking of tissue. For
example, by utilizing the small profile and/or the steerable
features of certain embodiments of the tissue removal device, the
tissue removal device may be more accurately positioned or
navigated to a specific target site in a body structure. In some
instances, the removal of lower volumes of tissue at a specific
target location may be used to achieve a desired result, in
comparison to the removal of a larger volume of tissue from a
general target location. Furthermore, by adjusting the cable or
tissue removal element relative the shaft of the tissue removal
device, the volume of mechanical tissue removal may be adjusted
relative to the shaft without requiring repositioning of the shaft.
By removing less disc tissue to reduce a herniation, for example, a
larger amount of non-pathologic disc tissue and structural
integrity of the disc may be preserved. In some instance,
relatively greater preservation of the disc tissue which may slow
the rate of further disc degeneration and reherniation compared to
lesser degrees of tissue preservation.
[0086] In one example, a herniated disc may be accessed and
visualized endoscopically. A steerable tissue removal device may be
inserted into the disc and steered toward the region of herniation,
rather than to the center of the disc, for example. The extendable
cable or other adjustable tissue removal element is actuated to
pulverize an initial amount of tissue at the region of herniation
and removed by the auger. In some embodiments, to facilitate
controlled volume tissue pulverization, the distance between the
couplings of the extendable cable to its rotatable shaft may be
less than about 10 mm, sometimes less than about 7 mm, and other
times less than about 5 mm. To facilitate precise removal of the
pulverized tissue, the distal suction opening of the tissue removal
device may be located less than about 10 mm from the proximal
coupling of the extendable cable, sometimes less than about 7 mm,
and other times less than about 5 mm or about 3 mm. After the
initial actuation of the extendable cable, the herniation is
reevaluated endoscopically and the degree of cable extension may be
adjusted higher in a stepwise manner and reevaluated until the
desired reduction in the herniation is achieved.
[0087] In some uses of the tissue removal device, in both steerable
and non-steerable configurations, the tissue removal zones may
positioned whereby structures such as the annulus fibrosus and the
vertebral body endplates may be unintentionally damaged or
contacted. In embodiments where the tissue removal device has been
configured as described previously to limit or avoid significant
damage to these structures, greater tissue removal may be safely
achieved even when the distal tip of the tissue removal device
cannot be directly visualized, e.g. when the endoscope is located
in the epidural space while the tissue removal device is located
inside the vertebral disc.
[0088] In some instances, embodiments of the tissue removal device
may be characterized by the ratio of the maximum diameter or
cross-sectional area of tissue removal of a rotating extended
elongate member, and the diameter or cross-sectional area of the
outer tube of the tissue removal device or the tissue pathway
formed by the tissue removal device. In the example described
above, the diameter of the elongate member in its rotating deployed
configuration to the diameter of the outer tube is a ratio of about
7:1. In some embodiments, this ratio is at least about 3:1 or
higher, but in other embodiments, the ratio is at least about 5:1
or higher, or even about 10:1 or about 20:1 or higher in certain
embodiments. In other examples, the tissue removal device may be
characterized by the maximum perpendicular distance that the
elongate member may be extended, or by the ratio of this distance
to the diameter (or an axial transverse dimension) of the outer
tube. In some examples, this ratio is at least about 3:1 or more,
sometimes about 5:1 or more, or even about 7:1 or about 10:1 or
more.
[0089] Examples of procedures that may be used to access the spine
are disclosed in U.S. Pat. No. 7,108,705, U.S. Pat. No. 4,573,448,
U.S. Pat. No. 6,217,5009, and U.S. Pat. No. 7,273,468, which are
hereby incorporated by reference in their entirety. The various
embodiments of the tissue removal device disclosed herein may be
used to perform a discectomy or nucleotomy, but may also be used to
perform any of a variety of tissue removal procedures in the spine
and outside of the spine. The tissue removal device may be used in
minimally invasive procedures as well as open surgical procedures
or limited access procedures. These procedures may include but are
not limited to interlaminar, translaminar and intralaminar access
procedures. In one particular embodiment, a patient may be placed
into a prone position with a pillow or other structure below the
abdomen to limit lumbar lordosis. The patient is prepped and draped
in the usual sterile fashion and anesthesia is achieved using
general, regional or local anesthesia. Under fluoroscopic guidance,
a sharp tipped guidewire, or a needle with a guidewire may be
inserted into the paravertebral space or epidural space from a
posterior or postero-lateral location of the patient's back at a
location in the range of about 5 cm to about 15 cm lateral to the
midline. In some instances, guidewire insertion may be facilitated
by inserting a needle into the tissue first. In alternate
embodiments, an anterior procedure through the abdominal cavity or
anterior neck region may be performed. Once access to the target
location is confirmed, a dilator may be used with the guidewire to
enlarge the insertion pathway. Then, an introducer or cannula may
be inserted over the guidewire, followed by subsequent guidewire
removal and insertion of an endoscope into the introducer or
cannula. Alternatively, an endoscope may be inserted over the
guidewire. The endoscope may be manipulated or steered to directly
visualize and identify the relevant structures such as the disc,
the nerve or other adjacent structures and site(s) of tissue
removal. In some embodiments where the patient is under local or
regional anesthesia, the suspected nerve impingement may be
confirmed by contacting or manipulating the suspected nerve with
the endoscope, or other device inserted through the endoscope, and
assessing the patient's response or symptoms. One embodiment of an
endoscope that may be used is described in U.S. Application No.
61/045,919, which has been hereby incorporated by reference in its
entirety. Once the target region has been evaluated, a tissue
removal device may be inserted through the spinal access device or
endoscope and to pierce through the annular wall of a herniated
disc. Once inserted, the tissue removal device is manipulated the
elongate member to its extended or deployed configuration and
actuated to emulsify or pulverize the tissue of the nucleus
fibrosus. In some embodiments, the tissue removal device may be
actuated for a duration in the range of about 5 seconds to about 90
seconds or more, sometimes about 15 seconds to about 60 seconds,
and other times about 30 seconds to about 60 seconds. The
pulverized material may then be suctioned through the device and
then the effect of the tissue removal may be re-evaluated by the
endoscope or other visualization mechanisms. In some embodiments, a
liquid or lubricant may be injected or infused into the treatment
site. In some examples, the liquid or lubricant may be useful to
facilitate removal of the pulverized material, including but not
limited to vertebral discs that may be desiccated. In other
examples, the liquid or lubricant may be injected or infused before
or during the actuation of the tissue removal device. In some
examples, the liquid or lubricant may comprise a contrast agent
that may facilitate viewing of the tissue site on fluoroscopy,
x-ray, CT, MRI, ultrasound or other imaging modalities. The
contrast agent may be used at any time or at multiple times during
the procedure, including but not limited to confirmation of
guidewire or tissue removal device placement, and also to verify
the volume and/or location of tissue removal. In some specific
embodiments, actuation of the tissue removal device may be stopped
to verify that annulus of the vertebral disc or the cortical bone
of the vertebral body has not been compromised. Also, in some
examples, the contrast agent may be injected and imaged after
device to assess proper operation of the device, including but not
limited to tissue pulverization and aspiration mechanisms.
[0090] During actuation, the tissue removal device may be held in
place or may be moved around the treatment site. The movement may
include moving the device back and forth along its insertion
access, side to side, up and down, or with an orbital motion
(clockwise or counterclockwise), or any combination thereof. The
range of cable displacement from the rotatable shaft may also be
cyclically varied during device actuation. The cycling movements
may be performed based upon tactile feedback or rotational
resistance of the device, or may be done in repeating motion with
an average frequency in the range of about one complete motion
about every 0.5 sec to about 4 seconds, about 1 second to about 2
seconds, or about 0.5 seconds to about 1.5 seconds, for example.
The duration of each cycling period may be in the range of about 1
second to about 30 seconds or more, about 3 seconds to about 20
seconds, about 5 seconds to about 10 seconds, for example. Suction
or aspiration may be applied during these motions to assess the
amount of tissue pulverized and removed.
[0091] The actuation of the tissue removal device may be repeated
as desired to remove disc material. In some embodiments, the tissue
removal device may be withdrawn from the disc and reinserted
directly into or against the extruded disc material and actuated.
Once the tissue removal is completed, the tissue removal device may
be withdrawn. The puncture site in the annular wall may have a
cross-sectional area of less than about 2 mm.sup.2 or less,
sometimes about 1 mm.sup.2 or less, and other times about 0.9
mm.sup.2 or less, and thus may self-seal without requiring
treatment of the puncture location with an adhesive, a suture or
coagulation probe. The body location may be rechecked with the
endoscope or spinal access device to verify that no bleeding or
comprise of the integrity of the disc or spinal nerves has
occurred, and then the endoscope or spinal access device is removed
from the body and the skin access site is bandaged.
[0092] While the embodiments described above may be used to remove
soft tissue without substantially removing calcified or bony
tissue, in other embodiments, the tissue removal device may be
configured to remove bone. In some examples, this may include
configuring the tissue removal device various bone-removing
coatings and/or a higher rotational speed. The coatings may
comprise coarser grit structures made from materials including, but
not limited to titanium nitride, chrome alloy coating, tungsten
carbide, diamond grits, silicon carbide grits, ceramics, or other
suitable materials. The spiral cable may be spun at high speed
(e.g. about 10,000 rpm to about 30,000 rpm or more) to grind the
bone to smaller pieces that can be aspirated by the auger. Saline
irrigation may be used to clean and/or cool the spiral cable and/or
the surround tissue. In some further configurations, the tissue
removal device may be further configured to differentially removing
cancellous bone while generally preserving compact bone. Such a
tissue removal device may be used, for example, to form a
passageway or cavity within a vertebral body or a long bone without
disrupting the integrity of the outer surface of the bony
structure.
[0093] In one example, a hollow needle or trocar may be passed
through the spinal muscles until its tip is precisely positioned
within the fractured vertebra. This may be performed under external
imaging guidance (e.g. fluoroscopy, CT or ultrasound) or using an
endoscopy system. In other examples, intraosseous venography may be
performed in conjunction with other visualization modalities. In
some instances, intraosseous venography may be used to visualize
the basivertebral venous plexus or a paravertebral vein and to
possibly avoid inadvertent entry into these structures.
[0094] Upon reaching the outer surface of the vertebral body, the
distal tip of the tissue removal device (e.g. the distal head 336
of the tissue removal device 300 in FIG. 8) may be used to
penetrate the compact bone of the vertebral body to provide access
to its interior. In other embodiments, a bone penetration device,
such as a trephine or a burr, may be used to form a channel or
passageway into the vertebral body. The bone penetration device is
then removed and the cable-based tissue removal device may be
inserted into the passageway and into the vertebral body. In other
embodiments, the tissue removal device may be provided with a
distal burr or drill head rather than a conical head. In some
examples, the spiral cable is displaced radially outward before the
rotating is initiated, while in other examples, rotation is
initiated first before the spiral cable it let out. In some
examples of vertebroplasty, the spiral cable may have a maximum
radial displacement of about 4 mm, about 5 mm, about 6 mm, about 7
mm, or about 10 mm or more. In some examples, the volume of space
formed by the tissue removal device may be further augmented
similar to the range of tissue removal disclosed for removal of
annular tissue depicted in FIGS. 20A and 20B. As mentioned
previously, the spiral cable may be rotated in the directional
sense as the spiral configuration, but may also be rotated in the
opposite direction.
[0095] The spiral cable may be as a single filament or a
multi-filament cable. Each filament may comprise the same or a
different material or configuration. In some examples, each
filament comprises stainless steel (e.g. 304, 316 or 17-4 stainless
steel) which is wound into a cable. The stiffness of the cable may
be altered by the changing the tightness of the winding, the number
of filaments, and/or the thickness of the filaments. One or more of
these characteristics, in combination with an optional grit surface
may be used to adjust the preferential grinding features of the
tissue removal device. In some procedures, by preferentially
cutting the cancellous bone while preserving the compact bone, the
compact bone shell or structure of the vertebrae or other bone may
protect the soft tissue structures located outside the shell or
surface. The compact bone shell or structure may also restrict flow
of any bone cement injected into the target site. In some examples,
contrast dye or other visualization agents may be injected into the
target site to assess the integrity of the target site prior to
cement injection or other treatments.
[0096] In another example, depicted in FIGS. 21A to 21D and FIG.
22, the tissue removal system 700 may comprise an extendable spiral
cable 702 with a blunt distal tip 704. In some instances, a blunt
distal tip 704 may be used when a passageway or channel has been
previously formed, or when blunt dissection is sufficient. For
example, during a discectomy or a vertebroplasty procedure, a
cannula 706 containing a removable obturator with sharp distal end
708, as shown in FIG. 23, may be used to form a passageway or
channel through the tissue surrounding the spine and/or through the
surface of a vertebra. The obturator may be removed from the
cannula 706 to insert the tissue removal system 700. In other
examples, a trocar with a sharp distal end may be used to form a
passageway and then removed to permit insertion of the tissue
removal system 700. Alternatively, a trephine or bone burr, which
may be either motorized or manually activated, may be used with the
cannula 706, in addition to or in lieu of the obturator. The
cannula 706 may comprise an optional proximal connector 709, such
as Luer lock, to releasably couple the obturator and/or the tissue
removal system 700.
[0097] Referring to FIG. 21A, which depicts the spiral cable 702 in
an extended position, and to FIGS. 21B to 21D, which depicts the
spiral cable 702 in a retracted position, the cable 702 is attached
distally to the blunt distal tip 704 and proximally to a base 710.
The cable 702 may be partially recessed in channels 712 and 714 of
the tip 704 and base 710. Between the tip 704 and base 710 is a
cable shaft 716 with a cross-sectional size that is smaller than
the tip 704 and/or base 710. In other embodiments, the cable shaft
may have a cross-sectional size that is similar to or greater then
the tip 704 or base 710. The cable shaft may also comprise an
optional groove or recess to at least partially retain the cable
704 when in a retracted position.
[0098] FIGS. 21A to 21D further depict an optional feature of the
tissue removal system 700 comprising an outer tubular shaft 718
with a cutting edge 720. In this particular example, the cutting
edge 720 is a beveled edge, which may or may not be at least
partially sharpened. In other examples, the cutting edge may be
sharpened but not beveled. As further depicted in FIGS. 21A to 21D,
the inner shaft 722 located in the outer tubular shaft 718 may
comprise at least one optional thread structure 724 which is
configured to draw fluids and/or other materials into the outer
tubular shaft 718 for removal from the target site. A beveled or
sharpened edge may further shear or break-up materials pulled into
the outer tubular shaft 718 by the thread structure 724. In some
examples, the rotational sense of the thread structure 724 may be
the same as the spiral cable 702, but in other examples, the thread
structure 724 and the spiral cable 702 may be opposite rotational
senses.
[0099] The thread structure 724 may be made from the same or a
different material as the inner shaft 722 and/or the outer tubular
shaft 718. In some examples, use of a different material between
the thread structure 724 and the outer tubular shaft 718 may reduce
or eliminate galling effects from the relative rotation between the
two structures. In some instances, galling may generate dark or
black materials that may pigment the pulverized material. This
pigmentation may interfere with various analyses of the pulverized
material, and/or the ability of the user to assess heat-related
effects of the tissue removal device on the pulverized tissue. In
one specific example, the outer tubular shaft 718 may comprise 304
stainless steel while the thread structure 724 may comprise 17-4
stainless steel. The thread structure 724 may be integrally formed
with the inner shaft 722, e.g. grounded or formed from a base
hypotube structure, but in other examples the thread structure 724
may be attached to the inner shaft 722 by welding, adhesives or
other attachment processes. For example, the thread structure 724
may comprise a coiled stainless steel or Parylene wire that may be
attached using epoxy along its entire length to the inner shaft 722
or may be attached at certain locations, e.g. the proximal end and
the distal end of the thread structure 724. In some instances,
partial attachment of the thread structure 724 to the shaft 722 may
permit greater flexion or other deformation of that section of the
tissue removal system 700 by permitting greater tensile or
compressive strain in the thread structure 724 compared to the
inner shaft 722. This greater flexion may also reduce heat
generation between the thread structure 724 and inner shaft
722.
[0100] FIG. 25 schematically depicts another example of a cutting
mechanism where instead of a cutting edge 720 located at the distal
opening of the outer tubular shaft 718 as depicted in FIGS. 21A to
21D, the tissue removal system may comprise an internal cutting or
grinding mechanism 750. This mechanism comprises an outer tubular
shaft 752 with an inner cutting or grinding structure 754 that
protrudes into the inner lumen 756 of the outer tubular shaft 752
and cooperates with a circumferential groove or recess 758 on the
inner tubular shaft 760 to morcellize, cut or otherwise breakdown
any larger tissue fragments that may enter the outer tubular shaft
752. The inner cutting structure 754 may have any of a variety of
configurations, including different rake angles and/or surface
configurations. The configuration of the recess 758 on the inner
tubular shaft 760 may vary in width and cross-sectional shape.
Although only a single internal mechanism 750 is depicted, in other
examples, multiple mechanisms may be provided along the shafts 752
and 760. In some further examples, an internal mechanism 750 may be
used with the tip-based mechanism illustrated in FIGS. 21A to
21D.
[0101] FIG. 22 further depicts another optional feature of a tissue
removal system 700, comprising an optically transparent chamber
726. Although the optically transparent chamber section 726 in FIG.
22 is located distally at the attachment of the outer tubular shaft
718, in other examples, the optically transparent housing chamber
726 may be located at a more proximal location. The optically
transparent housing section 726 comprises an optically clear
passageway or cavity in communication with the lumen of the outer
tubular shaft 718 so that any fluid and/or materials either
injected distally or removed proximally may be viewed by the user.
In some instances, the passageway or cavity may have a volume of at
least about 0.5 cc, sometimes about 1 cc, and other times about 2
cc or more. The optically transparent housing chamber 726 may also
comprise markings to identify the volume of material that has
aspirated or prepared for infusion or irrigation, for example. The
optically transparent chamber 726 may also features a removable cap
to empty the contents for of the chamber 726, to reduce clogging or
to collect a diagnostic tissue sample. In some examples, the tissue
removal system may have one or more infusion lumens with one or
more openings at the base, cable shaft, and/or distal tip of the
tissue removal system, which may be used in addition to or in lieu
distal end of the outer tubular shaft 718. In other examples, the
tissue removal system may be removed from the vertebral body and a
separate infusion instrument may be used to deliver therapeutic
agents or materials.
[0102] In use, the tissue removal system 700 depicted in FIGS. 21A
to 22 may be used for any of a variety of tissue removal
procedures, including discectomy and vertebroplasty, depending upon
the particular configuration. Referring to FIGS. 24A and to 24C, a
vertebral body 730 may be accessed by any of a variety of access
procedures described herein. A tissue removal system 700 (with a
shaft 718--not drawn to scale) may be inserted into the interior of
the vertebral body (FIG. 24A) and then rotated with the cable 702
extended to form a cavity 732 in the vertebral body 730 (FIG. 24B).
The tissue removal system 700 may be further manipulated until
adequate removal of cancellous bone is achieved. As shown in FIG.
24C, the tissue removal system 700 may be loaded with a bone cement
734 which is then delivered to the cavity 732. In some examples,
the bone cement 734 may comprise a material such as polymethyl
methacrylate hydroxyapatite, or any of a variety of other bone
cements or other hardenable or curable substances can be injected
through the trocar to fill the cavity created by the by the tissue
removal system 700. The cable 702 of the tissue removal system 700
may be retracted or extended during delivery of therapeutic agents.
In some instances, the extended cable 702 may redistribute the
therapeutic agents against the cavity walls, which may reduce the
risk of leakage out of the cavity.
[0103] In some of the procedures described above, the cavity in the
vertebral body is formed before the delivery of therapeutic agents,
but in other procedures, the delivery of therapeutic agents may
occur simultaneously. In procedure where the cavity is first
formed, filling of the empty cavity may reduce initial filling
pressures. In some instances, lower filling pressures may reduce
the risk of leakage. In some examples, the tissue removal system
may comprise a pressure sensor which may be used by the user or may
be configured automatically to shut off delivery or pressurization
of the therapeutic agents upon reaching a particular pressure
limit.
[0104] Although some of the examples described herein are directed
to treatment of vertebral disc fractures, in other examples, the
tissue removal systems may be used to treat or diagnose bone
lesions located in the vertebrae or other bones of the body.
Diagnosis of bone lesions may include biopsy of bone. These bone
lesions may include but are not limited to potentially cancerous
bone lesions, including osteomas, osteosarcomas and metastatic
lesions, as well as potentially infectious bone lesions, including
tuberculosis. Bone cement, with or without other therapeutic agents
such as anti-neoplastic and anti-infective agents, may or may not
be injected into the
[0105] It is to be understood that this invention is not limited to
particular exemplary embodiments described, as such may, of course,
vary. It is also to be understood that the terminology used herein
is for the purpose of describing particular embodiments only, and
is not intended to be limiting, since the scope of the present
invention will be limited only by the appended claims.
[0106] Where a range of values is provided, it is understood that
each intervening value, to the tenth of the unit of the lower limit
unless the context clearly dictates otherwise, between the upper
and lower limits of that range is also specifically disclosed. Each
smaller range between any stated value or intervening value in a
stated range and any other stated or intervening value in that
stated range is encompassed within the invention. The upper and
lower limits of these smaller ranges may independently be included
or excluded in the range, and each range where either, neither or
both limits are included in the smaller ranges is also encompassed
within the invention, subject to any specifically excluded limit in
the stated range. Where the stated range includes one or both of
the limits, ranges excluding either or both of those included
limits are also included in the invention.
[0107] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice or testing of the present
invention, some potential and preferred methods and materials are
now described. All publications mentioned herein are incorporated
herein by reference to disclose and describe the methods and/or
materials in connection with which the publications are cited. It
is understood that the present disclosure supersedes any disclosure
of an incorporated publication to the extent there is a
contradiction.
[0108] It must be noted that as used herein and in the appended
claims, the singular forms "a", "an", and the include plural
referents unless the context clearly dictates otherwise. Thus, for
example, reference to "a blade" includes a plurality of such blades
and reference to "the energy source" includes reference to one or
more sources of energy and equivalents thereof known to those
skilled in the art, and so forth.
[0109] The publications discussed herein are provided solely for
their disclosure. Nothing herein is to be construed as an admission
that the present invention is not entitled to antedate such
publication by virtue of prior invention. Further, the dates of
publication provided, if any, may be different from the actual
publication dates which may need to be independently confirmed.
* * * * *