Surgical blade abstract
An ultrasonic surgical blade, and an instrument, having a gain
step. The blade body has, in any half wave length of the ultrasonic-surgical-blade
body, a first vibration antinode, a vibration node, a second vibration
antinode, and a gain step. The gain step is located between the
second vibration antinode and the first vibration antinode. The
gain step is spaced apart from the vibration node by a gain-step
distance greater than 5% of the distance between the second vibration
antinode and the first vibration antinode. The instrument includes
the blade, a handpiece having an ultrasonic transducer, and an ultrasonic
transmission rod whose proximal end is operatively connected to
the ultrasonic transducer and whose distal end activates the blade.
In one option, the first vibration antinode is the distal tip, and
the gain step is located between the vibration node and the distal
tip, resulting in an increased active length of the blade.
Surgical blade claims
What is claimed is:
1. An ultrasonic surgical blade comprising an ultrasonic-surgical-blade
body having a distal tip which is a most-distal vibration antinode,
having a most-distal vibration node, having a second-most-distal
vibration antinode, and having a gain step, wherein the gain step
is disposed between the second-most-distal vibration antinode and
the distal tip, and wherein the gain step is spaced apart from the
most-distal vibration node by a gain-step distance greater than
5% of the distance between the second-most-distal vibration antinode
and the distal tip.
2. The ultrasonic surgical blade of claim 1 wherein the gain-step
distance is between substantially 25% and substantially 45% of the
distance between the second-most-distal vibration antinode and the
distal tip.
3. The ultrasonic surgical blade of claim 1 wherein, between the
second-most-distal vibration antinode and the distal tip, the maximum
vibration amplitude of the ultrasonic-surgical-blade body proximal
the gain step is less than the maximum vibration amplitude of the
ultrasonic-surgical-blade body distal the gain step.
4. The ultrasonic surgical blade of claim 1 wherein, between the
second-most-distal vibration antinode and the distal tip, the maximum
vibration amplitude of the ultrasonic-surgical-blade body proximal
the gain step is greater than the maximum vibration amplitude of
the ultrasonic-surgical-blade body distal the gain step.
5. The ultrasonic surgical blade of claim 1 wherein the gain step
is disposed between the most-distal vibration node and the distal
tip.
6. The ultrasonic surgical blade of claim 1 wherein the gain step
is disposed between the most-distal vibration node and the second-most-distal
vibration antinode.
7. The ultrasonic surgical blade of claim 1 wherein the ultrasonic-surgical-blade
body has a longitudinal axis and consists essentially of a first
geometric solid having a substantially constant first transverse
cross-sectional area from the gain step to the distal tip and a
second geometric solid having a substantially constant second transverse
cross-sectional area from the gain step to the second-most-distal
vibration antinode, wherein the second transverse cross-sectional
area is different than the first transverse cross-sectional area.
8. The ultrasonic surgical blade of claim 7 wherein the shape
and size of the first external perimeter of the first transverse
cross-sectional area is substantially equal to the shape and size
of the second external perimeter of the second transverse cross-sectional
area.
9. The ultrasonic surgical blade of claim 8 wherein at least one
of the first and second transverse cross-sectional areas surrounds
a void.
10. The ultrasonic surgical blade of claim 9 wherein the void
includes a first longitudinal hole which is disposed in the first
geometric solid and which extends proximally from the distal tip.
11. The ultrasonic surgical blade of claim 10 wherein the void
includes a second longitudinal hole which is disposed in the second
geometric solid and which is in fluid communication with the first
longitudinal hole, and wherein the first and second longitudinal
holes are adapted for irrigation and/or suction.
12. The ultrasonic surgical blade of claim 10 also including a
membrane, which covers the first longitudinal hole, and which is
removably or permanently attached to the first geometric solid at
the distal tip.
13. The ultrasonic surgical blade of claim 1 wherein the ultrasonic-surgical-blade
body has a longitudinal axis and consists essentially of a first
geometric solid and a second geometric solid, wherein the first
geometric solid has a first mass, extends from the gain step to
the distal tip, and has a non-constant first transverse cross-sectional
area, wherein the second geometric solid has a second mass, extends
from the gain step to the second-most-distal vibration antinode,
and has a non-constant second transverse cross-sectional area, and
wherein the second mass is different than the first mass.
14. The ultrasonic surgical blade of claim 13 wherein the shape
and size of the first external perimeter of the first transverse
cross-sectional area is substantially equal to the shape and size
of the second external perimeter of the second transverse cross-sectional
area.
15. The ultrasonic surgical blade of claim 14 wherein at least
one of the first and second transverse cross-sectional areas surrounds
a void.
16. The ultrasonic surgical blade of claim 15 wherein the void
includes a first longitudinal hole which is disposed in the first
geometric solid and which extends proximally from the distal tip.
17. The ultrasonic surgical blade of claim 16 wherein the void
includes a second longitudinal hole which is disposed in the second
geometric solid and which is in fluid communication with the first
longitudinal hole, and wherein the first and second longitudinal
holes are adapted for irrigation and/or suction.
18. The ultrasonic surgical blade of claim 16 also including a
membrane, which covers the first longitudinal hole, and which is
removably or permanently attached to the first geometric solid at
the distal tip.
19. The ultrasonic surgical blade of claim 1 wherein the ultrasonic
surgical blade body has a longitudinal axis and consists essentially
of a first geometric solid having a first mass and having a first
axial length extending from the gain step to the distal tip and
a second geometric solid having a second mass and having a second
axial length extending from the gain step to the second-most-distal
vibration antinode, wherein the second mass is different than the
first mass, wherein one of the first and second geometric solids
has a substantially constant transverse cross-sectional area along
its corresponding axial length, and wherein a different one of the
first and second geometric solids has a non-constant transverse
cross-sectional area along its corresponding axial length.
20. The ultrasonic surgical blade of claim 1 wherein the ultrasonic-surgical-blade
body has a longitudinal axis and is substantially symmetrical about
the longitudinal axis.
21. The ultrasonic surgical blade of claim 1 wherein the ultrasonic-surgical-blade
body has a longitudinal axis, has an active length, and is substantially
asymmetric about the longitudinal axis along at least a portion
of the active length.
22. The ultrasonic surgical blade of claim 21 wherein the ultrasonic-surgical-blade
body is curved.
23. The ultrasonic surgical blade of claim 1 wherein the ultrasonic-surgical-blade
body has at least one gain feature selected from the group consisting
of: a discrete change in outer diameter or perimeter, a taper, a
longitudinal hole, a discrete change in diameter of a longitudinal
hole, a transverse hole, a surface flat, and a surface slot.
24. The ultrasonic surgical blade of claim 1 wherein the ultrasonic-surgical-blade
body has an additional gain step which is spaced-apart from the
gain step, which is disposed between the second-most-distal vibration
antinode and the distal tip, and which is spaced apart from the
most-distal vibration node by a gain-step distance greater than
5% of the distance between the second-most-distal vibration antinode
and the distal tip, wherein the ultrasonic-surgical-blade body has
a longitudinal axis and a longitudinally hole, and wherein the longitudinal
hole has a shoulder defining the additional gain step.
25. An ultrasonic surgical instrument comprising: a) a handpiece
including an ultrasonic transducer; b) an ultrasonic transmission
rod having a proximal end and a distal end, wherein the proximal
end is operatively connected to the ultrasonic transducer; and c)
an ultrasonic surgical blade activated by the distal end and including
an ultrasonic-surgical-blade body having a distal tip which is a
most-distal vibration antinode, having a most-distal vibration node,
having a second-most-distal vibration antinode, and having a gain
step, wherein the gain step is disposed between the second-most-distal
vibration antinode and the distal tip, and wherein the gain step
is spaced apart from the most-distal vibration node by a gain-step
distance greater than 5% of the distance between the second-most-distal
vibration antinode and the distal tip.
26. An ultrasonic surgical blade comprising an ultrasonic-surgical-blade
body having, in any half wave length of the ultrasonic-surgical-blade
body, a first vibration antinode, a vibration node, a second vibration
antinode, and a gain step, wherein the gain step is disposed between
the second vibration antinode and the first vibration antinode,
and wherein the gain step is spaced apart from the vibration node
by a gain-step distance greater than 5% of the distance between
the second vibration antinode and the first vibration antinode.
Surgical blade description
FIELD OF THE INVENTION
[0001] The present invention relates generally to ultrasonic surgical
blades and ultrasonic surgical instruments which include ultrasonic
surgical blades, and more particularly to those having a gain step.
BACKGROUND OF THE INVENTION
[0002] Ultrasonic surgical instruments are known which include
ultrasonic surgical blades. A handpiece of a known ultrasonic surgical
instrument includes an ultrasonic transducer which is powered by
an ultrasonic generator through a cable. An ultrasonic transmission
rod of the instrument has a proximal end and a distal end, wherein
the proximal end is operatively connected to the ultrasonic transducer.
An ultrasonic surgical blade is activated by the distal end of the
ultrasonic transmission rod. Known blade shapes include straight
blades and curved blades and include blades that are symmetric and
blades that are asymmetric about a longitudinal axis or about a
curved centerline of the blade.
[0003] A known ultrasonic surgical blade is a cylindrical blade
which has a distal tip, a most-distal vibration node (a vibration
node being a point of substantially zero displacement), and a second
most-distal vibration antinode (a vibration antinode being a point
of maximum displacement relative to all other points in a half wave),
wherein the most-distal vibration antinode is the distal tip. Longitudinal
ultrasonic vibration of the blade generates motion and heat in the
contacted tissue, wherein the heat primarily provides the means
for the blade to cut and/or coagulate patient tissue. The blade
has a gain step located a distance from the most-distal vibration
node which is less than 5% of the distance between the distal tip
and the second-most-distal vibration antinode because locating the
gain step close to the most-distal vibration node maximizes the
vibration amplitude gain. The known blade consists of a larger-diameter
right-circular geometrically-solid cylinder from the second most-distal
vibration antinode to the most-distal vibration node. The known
blade consists of a smaller-diameter right-circular geometrically-solid
cylinder from the most-distal vibration node to the distal tip.
The change in diameter provides a gain in vibration amplitude for
the smaller-diameter section of the blade equal to the ratio of
the transverse cross-sectional areas of the larger diameter blade
section to the smaller diameter blade section when the gain step
is located at the node.
[0004] The active length of an ultrasonic surgical blade is defined
by applicants as the distance from the distal tip to where the vibration
amplitude (i.e., the longitudinal vibration amplitude) has fallen
to 50% of the tip amplitude. The blade is not considered useful
beyond its active length. The active length is about 15 mm for a
straight cylindrical titanium rod at a resonant frequency of about
55.5 kHz.
[0005] It is known in ultrasonic welding of plastics to provide
an ultrasonic welding rod having a gain step, such as a discontinuity
between a larger and a smaller rod diameter, which is located between
the most-distal vibration node and the distal end of the welding
horn and which is spaced apart from the most-distal vibration node
of the welding rod by a distance less than 5% of the distance between
the second-most-distal vibration antinode and the distal end of
the welding rod. It is also known in ultrasonic welding of plastics
to provide an ultrasonic welding rod with a hole or a slot to provide
a gain in longitudinal vibration amplitude.
[0006] What is needed is an improved ultrasonic surgical blade,
and an improved ultrasonic surgical instrument which includes an
ultrasonic surgical blade, having a longer or shorter active length.
SUMMARY OF THE INVENTION
[0007] A first expression of an embodiment of the invention is
for an ultrasonic surgical blade including an ultrasonic-surgical-blade
body. The ultrasonic-surgical-blade body has a distal tip which
is a most-distal vibration antinode, has a most-distal vibration
node, has a second-most-distal vibration antinode, and has a gain
step. The gain step is located between the second-most-distal vibration
antinode and the distal tip, and the gain step is spaced apart from
the most-distal vibration node by a gain-step distance greater than
5% of the distance between the second-most-distal vibration antinode
and the distal tip.
[0008] A second expression of an embodiment of the invention is
for an ultrasonic surgical instrument including a handpiece, an
ultrasonic transmission rod, and an ultrasonic surgical blade. The
handpiece includes an ultrasonic transducer. The ultrasonic transmission
rod has a proximal end and a distal end, wherein the proximal end
is operatively connected to the ultrasonic transducer. The ultrasonic
surgical blade is activated by the distal end and includes an ultrasonic-surgical-blade
body. The ultrasonic-surgical-blade body has a distal tip which
is a most-distal vibration antinode, has a most-distal vibration
node, has a second-most-distal vibration antinode, and has a gain
step. The gain step is located between the second-most-distal vibration
antinode and the distal tip, and the gain step is spaced apart from
the most-distal vibration node by a gain-step distance greater than
5% of the distance between the second-most-distal vibration antinode
and the distal tip.
[0009] A third expression of an embodiment of the invention is
for an ultrasonic surgical blade including an ultrasonic-surgical-blade
body. The ultrasonic-surgical-blade body has, in any half wave length
of the ultrasonic-surgical-blade body, a first vibration antinode,
a vibration node, a second vibration antinode, and a gain step.
The gain step is located between the second vibration antinode and
the first vibration antinode. The gain step is spaced apart from
the vibration node by a gain-step distance greater than 5% of the
distance between the second vibration antinode and the first vibration
antinode.
[0010] Several benefits and advantages are obtained from one or
more of the expressions of the embodiment of the invention. Applicants
found that locating a gain step having a gain greater than unity
(i.e., an amplification step) further than conventionally taught
from the most-distal vibration node toward the distal tip further
increased the active length of the ultrasonic surgical blade even
though the vibration amplitude gain was less than when conventionally
locating the gain step closer to the most-distal vibration node.
Applicants determined that locating the gain step further than conventionally
taught from the most-distal vibration node toward the second-most-distal
vibration antinode should shorten the half wave length of the ultrasonic
surgical blade. Applicants also determined that such changes in
active and half wave lengths of the ultrasonic surgical blade would
also result from gain steps having gains less than unity (i.e.,
a deamplification step) but with a deamplification step causing
a decrease in active length where an identically located amplification
step would cause an increase in active length and with a deamplification
step causing an increase in active length where an identically located
amplification step would cause a decrease in active length. Being
able to lengthen or shorten the active length of an ultrasonic surgical
blade offers advantages for particular surgical applications, as
can be appreciated by those skilled in the art.
[0011] The present invention has, without limitation, application
in robotic-assisted surgery.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] FIG. 1 is a schematic view of a first embodiment of an ultrasonic
surgical instrument including a first embodiment of an ultrasonic
surgical blade of the invention;
[0013] FIG. 2 is a longitudinal cross-sectional view of the most-distal
one-half wavelength, including the distal tip, of the ultrasonic
surgical blade of FIG. 1;
[0014] FIG. 3 is a longitudinal cross-sectional view of the most-distal
one-half wavelength, including the distal tip, of a second embodiment
of the surgical blade of FIG. 1; and
[0015] FIG. 4 is a longitudinal cross-sectional view of the most-distal
one-half wavelength, including the distal tip, of a third embodiment
of the surgical blade of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Before explaining the present invention in detail, it should
be noted that the invention is not limited in its application or
use to the details of construction and arrangement of parts illustrated
in the accompanying drawings and description. The illustrative embodiment
of the invention may be implemented or incorporated in other embodiments,
variations and modifications, and may be practiced or carried out
in various ways. Furthermore, unless otherwise indicated, the terms
and expressions employed herein have been chosen for the purpose
of describing the illustrative embodiment of the present invention
for the convenience of the reader and are not for the purpose of
limiting the invention.
[0017] It is understood that any one or more of the following-described
expressions of an embodiment, examples, etc. can be combined with
any one or more of the other following-described expressions of
an embodiment, examples, etc. For example, and without limitation,
a gain feature of a reduced diameter can be combined with a gain
feature of a hole.
[0018] Referring now to the drawings, FIGS. 1-2 illustrate a first
embodiment of the invention. A first expression of the first embodiment
of FIGS. 1-2 is for an ultrasonic surgical blade 10 including an
ultrasonic-surgical-blade body 12 having a distal tip 14 which is
a most-distal vibration antinode (a vibration antinode being a point
of maximum displacement relative to all other points in a half wave),
having a most-distal vibration node 16 (a vibration node being a
point of substantially zero displacement), having a second-most-distal
vibration antinode 18 and having a gain step 20. The gain step
20 is disposed between the second-most-distal vibration antinode
18 and the distal tip 14 and is spaced apart from the most-distal
vibration node 16 by a gain-step distance 22 greater than 5% of
the distance 24 between the second-most-distal vibration antinode
18 and the distal tip 14.
[0019] In one implementation of the first expression of the first
embodiment of FIGS. 1-2 the gain step distance 22 is between substantially
25% and substantially 45% of the distance 24 between the second-most-distal
vibration antinode 18 and the distal tip 14. Those of ordinary skill
in the art, employing the teachings of the invention for the location
of the gain step 20 can create analytical blade models and evaluate
them using a computer program to optimize design trade-offs between
increased or decreased active length of the ultrasonic surgical
blade and increased or decreased amplitude of the longitudinal ultrasonic
vibrations for locating the gain step 20 substantially away from
the most-distal vibration node 16 in the direction of the distal
tip 14 or in the direction of the second-most-distal vibration antinode
18.
[0020] In one example of the first expression of the first embodiment
of FIGS. 1-2 between the second-most-distal vibration antinode
18 and the distal tip 14 the maximum vibration amplitude of the
ultrasonic-surgical-blade body 12 proximal the gain step 20 is less
than the maximum vibration amplitude of the ultrasonic-surgical-blade
body 12 distal the gain step 20. In this example, the gain of the
gain step 20 is greater than unity and results from a reduction
in mass of the ultrasonic-surgical-blade body 12 between the gain
step 20 and the distal tip 14 compared to the mass of the ultrasonic-surgical-blade
body 12 between the gain step 20 and the second-most-distal vibration
antinode 18.
[0021] In a different embodiment, not shown, between the second-most-distal
vibration antinode and the distal tip, the maximum vibration amplitude
of the ultrasonic-surgical-blade body proximal the gain step is
greater than the maximum vibration amplitude of the ultrasonic-surgical-blade
body distal the gain step. In this embodiment, the gain of the gain
step is less than unity and results from an increase in mass of
the ultrasonic-surgical-blade body between the gain step and the
distal tip compared to the mass of the ultrasonic-surgical-blade
body between the gain step and the second-most-distal vibration
antinode. This embodiment can be easily visualized, in one example,
by switching the locations of the distal tip 14 and the second-most-distal
vibration antinode 18 in FIG. 2.
[0022] In one enablement of the first expression of the first embodiment
of FIGS. 1-2 the gain step 20 is disposed between the most-distal
vibration node 16 and the distal tip 14 resulting in an increased
active length of the ultrasonic surgical blade 10. In a different
embodiment, not shown, the gain step is disposed between the most-distal
vibration node and the second-most-distal vibration antinode resulting
in a decreased half wave length of the ultrasonic surgical blade.
This embodiment can be easily visualized by moving the gain step
20 between the most-distal vibration node 16 and the second-most-distal
vibration antinode 18 in FIG. 2.
[0023] In one illustration of the first expression of the first
embodiment of FIGS. 1-2 the ultrasonic-surgical-blade body 12 has
a longitudinal axis 26 and consists essentially of a first geometric
solid 28 having a substantially constant first transverse cross-sectional
area from the gain step 20 to the distal tip 14 and a second geometric
solid 30 having a substantially constant second transverse cross-sectional
area from the gain step 20 to the second-most-distal vibration antinode
18. The second transverse cross-sectional area is different than
the first transverse cross-sectional area. In one variation, the
shape and size of the first external perimeter of the first transverse
cross-sectional area is substantially equal to the shape and size
of the second external perimeter of the second transverse cross-sectional
area. In one modification, at least one of the first and second
transverse cross-sectional areas surrounds a void 32. In one construction,
the void 32 includes a first longitudinal hole 34 which is disposed
in the first geometric solid 28 and which extends proximally from
the distal tip 14. Applicants found that locating the gain step
20 at the point where the gain equaled the square root of the ratio
of the transverse cross-sectional areas of the second geometric
solid 30 to the first geometric solid 28 optimized the increase
in the active length of the blade. In one arrangement, the void
32 includes a second longitudinal hole 36 which is disposed in the
second geometric solid 30 and which is in fluid communication with
the first longitudinal hole 34 and the first and second longitudinal
holes 34 and 36 are adapted for irrigation and/or suction. In another
arrangement, the ultrasonic surgical blade 10 also includes a membrane
38 which has a composition substantially the same as the composition
of the ultrasonic-surgical-blade body 12 which covers the first
longitudinal hole 34 and which is removably or permanently attached
to the first geometric solid 28 at the distal tip 14. It is noted
that the membrane 38 would be removed from the first geometric solid
28 in FIG. 2 when irrigation and/or suction is desired. Alternatively,
membrane 38 may be made from a permeable fabric, such as a wire
mesh or screen, or sintered mesh made from titanium or other appropriate
material to facilitate irrigation and/or suction.
[0024] In a different embodiment, not shown, the ultrasonic-surgical-blade
body has a longitudinal axis and consists essentially of a first
geometric solid and a second geometric solid. The first geometric
solid has a first mass, extends from the gain step to the distal
tip, and has a non-constant first transverse cross-sectional area.
The second geometric solid has a second mass, extends from the gain
step to the second-most-distal vibration antinode, and has a non-constant
second transverse cross-sectional area. The second mass is different
than the first mass. This embodiment is easily visualized, in one
example, by considering the second longitudinal hole 36 to have
a diameter which decreases from the second-most-distal vibration
antinode 18 to the gain step 20 and the first longitudinal hole
34 to have a diameter which increases from the gain step 20 to the
distal tip 14 in FIG. 2. The variations, modifications, etc. of
the preceding paragraph are equally applicable to this embodiment.
[0025] In a further embodiment, not shown, the ultrasonic surgical
blade body has a longitudinal axis and consists essentially of a
first geometric solid having a first mass and having a first axial
length extending from the gain step to the distal tip and a second
geometric solid having a second mass and having a second axial length
extending from the gain step to the second-most-distal vibration
antinode. The second mass is different than the first mass. One
of the first and second geometric solids has a substantially constant
transverse cross-sectional area along its corresponding axial length,
and a different one of the first and second geometric solids has
a non-constant transverse cross-sectional area along its corresponding
axial length. This embodiment is easily visualized, in one example,
by considering the first longitudinal hole 34 to have a diameter
which increases from the gain step 20 to the distal tip 14 in FIG.
2. The variations, modifications, etc. of the second preceding paragraph
are equally applicable to this embodiment.
[0026] In one design of the first expression of the first embodiment
of FIGS. 1-2 the ultrasonic-surgical-blade body 12 has a longitudinal
axis 26 and is substantially symmetrical about the longitudinal
axis 26. In another design, not shown, the ultrasonic-surgical-blade
body has a longitudinal axis, has an active length, and is substantially
asymmetric about the longitudinal axis along at least a portion
of the active length. In one variation, the ultrasonic-surgical-blade
body is curved. This variation is easily visualized, in one example,
by curving the distal portion of the ultrasonic-surgical-blade body
12 upward from the longitudinal axis 26 in FIG. 2.
[0027] In one deployment of the first expression of the first embodiment
of FIGS. 1-2 the ultrasonic-surgical-blade body 12 has at least
one gain feature 40 selected from the group consisting of: a discrete
change in outer diameter or perimeter, a taper, a longitudinal hole,
a discrete change in diameter of a longitudinal hole, a transverse
hole, a surface flat, and a surface slot. It is noted that, in this
deployment, the gain step 20 is the location of the portion of the
gain feature 40 which is closest to the most-distal vibration node
16. It is also noted that the term "hole" includes a through
hole and a non-through hole. Other gain features are left to the
artisan.
[0028] FIG. 3 illustrates a second embodiment of the ultrasonic
surgical blade 110 of the invention. In this embodiment, the ultrasonic-surgical-blade
body 112 has an additional gain step 142 which is spaced-apart from
the gain step 120 which is disposed between the second-most-distal
vibration antinode 118 and the distal tip 114 and which is spaced
apart from the most-distal vibration node 116 by a gain-step distance
122 greater than 5% of the distance 124 between the second-most-distal
vibration antinode 118 and the distal tip 114. The ultrasonic-surgical-blade
body 112 has a longitudinal axis 126 and a longitudinally hole 134
wherein the longitudinal hole has a shoulder 144 defining the additional
gain step 142.
[0029] A third embodiment of an ultrasonic surgical blade 210 is
shown in FIG. 4 wherein the ultrasonic-surgical-blade body 212
consists essentially of a right-circular first geometrically-solid
cylinder 288 from the gain step 220 to the distal tip 214. In this
embodiment, the ultrasonic-surgical-blade body 212 consists essentially
of a right-circular second geometrically-solid cylinder 230 from
the gain step 220 to the second-most-distal vibration antinode 218.
The diameter of the first geometrically-solid cylinder 288 is less
than the diameter of the second geometrically-solid cylinder 230.
It is noted that in this embodiment, the gain feature 240 is a reduced
diameter from the distal tip 214 to the gain step 220 which reduces
mass and which creates the first geometrically-solid cylinder 288.
The gain step 220 is disposed between the second-most-distal vibration
antinode 218 and the distal tip 214 and is spaced apart from the
most-distal vibration node 216 by a gain-step distance 222 greater
than 5% of the distance 224 between the second-most-distal vibration
antinode 218 and the distal tip 214.
[0030] In one construction of the first expression of the first
embodiment of FIGS. 1-2 the ultrasonic-surgical-blade body 12 consists
essentially of titanium. In other constructions, blade bodies consist
essentially of aluminum, a ceramic, sapphire, or any other material
that transmits ultrasound in an efficient manner. Mathematical analysis
of various titanium blade designs using the described principles
of the invention calling for locating the gain step 20 substantially
away from the most-distal vibration node 16 in the direction of
the distal tip 14 achieved increases in the active length of the
ultrasonic surgical blade 10 up to 40%. Applicants have seen increases
up to 60% in theory. As previously mentioned, the active length
of an ultrasonic surgical blade 10 is defined as the distance from
the distal tip 14 to where the vibration amplitude (i.e., the longitudinal
vibration amplitude) has fallen to 50% of the tip amplitude. The
blade is not considered useful beyond its active length. The active
length is about 15 mm for a straight cylindrical titanium rod at
a resonant frequency of about 55.5 kHz without applying the principles
of the invention. An increase in active length up to about 5 mm
can be expected using the described principles of the invention
when the gain step 20 is disposed between the most-distal vibration
node 16 and the distal tip 14.
[0031] In one arrangement, the ultrasonic surgical blade 10 is
used alone as the end effector of an ultrasonic surgical instrument.
In another arrangement, the ultrasonic surgical blade 10 is used
with a clamp arm (not shown) to create a shears end effector of
an ultrasonic surgical instrument for cutting and/or coagulating
patient tissue.
[0032] A second expression of the first embodiment of FIGS. 1-2
is for an ultrasonic surgical instrument 46 including a handpiece
48 an ultrasonic transmission rod 50 and an ultrasonic surgical
blade 10. The handpiece 48 includes an ultrasonic transducer 52.
The ultrasonic transmission rod 50 has a proximal end and a distal
end, wherein the proximal end is operatively connected to the ultrasonic
transducer 52. The ultrasonic surgical blade 10 is activated by
the distal end and includes an ultrasonic-surgical-blade body 12.
The ultrasonic-surgical-blade body 12 has a distal tip 14 which
is a most-distal vibration antinode, has a most-distal vibration
node 16 has a second-most-distal vibration antinode 18 and has
a gain step 20. The gain step 20 is disposed between the second-most-distal
vibration antinode 18 and the distal tip 14 and is spaced apart
from the most-distal vibration node 16 by a gain-step distance 22
greater than 5% of the distance 24 between the second-most-distal
vibration antinode 18 and the distal tip 14.
[0033] In one enablement of the second expression of the first
embodiment of FIGS. 1-2 there is also included an ultrasonic generator
54 activated by a foot pedal 56 and a cable 58 operatively connecting
the ultrasonic generator 54 and the ultrasonic transducer 52 of
the handpiece 48. In one construction, the ultrasonic surgical blade
10 is a monolithic portion of the ultrasonic transmission rod 50.
In another construction, the ultrasonic surgical blade is a separate
piece and is attached to the ultrasonic transmission rod. It is
noted that the embodiments, implementations, examples, illustrations,
etc. previously described for the ultrasonic surgical blade are
equally applicable to the ultrasonic surgical instrument.
[0034] A third expression of the first embodiment of FIGS. 1-2
is for an ultrasonic surgical blade including an ultrasonic-surgical-blade
body having, in any half wave length of the ultrasonic-surgical-blade
body, a first vibration antinode, a vibration node, a second vibration
antinode, and a gain step, wherein the gain step is disposed between
the second vibration antinode and the first vibration antinode,
and wherein the gain step is spaced apart from the vibration node
by a gain-step distance greater than 5% of the distance between
the second vibration antinode and the first vibration antinode.
It is noted that the third expression does not limit the location
of the half wave to the last half wave length of the blade body
as with the previously presented second expression, and that apart
from the second expression's location of the half wave, the embodiments,
implementations, examples, illustrations, etc. previously described
for the second expression are equally applicable to the third expression.
[0035] Several benefits and advantages are obtained from one or
more of the expressions of the embodiment of the invention. Applicants
found that locating a gain step having a gain greater than unity
(i.e., an amplification step) further than conventionally taught
from the most-distal vibration node toward the distal tip further
increased the active length of the ultrasonic surgical blade even
though the vibration amplitude gain was less than when conventionally
locating the gain step closer to the most-distal vibration node.
Applicants determined that locating the gain step further than conventionally
taught from the most-distal vibration node toward the second-most-distal
vibration antinode should shorten the half wave length of the ultrasonic
surgical blade. Applicants also determined that such changes in
active and half wave lengths of the ultrasonic surgical blade would
also result from gain steps having gains less than unity (i.e.,
a deamplification step) but with a deamplification step causing
a decrease in active length where an identically located amplification
step would cause an increase in active length and with a deamplification
step causing an increase in active length where an identically located
amplification step would cause a decrease in active length. Being
able to lengthen or shorten the active length of an ultrasonic surgical
blade offers advantages for particular surgical applications, as
can be appreciated by those skilled in the art.
[0036] The foregoing description of several expressions and embodiments
of the invention has been presented for purposes of illustration.
It is not intended to be exhaustive or to limit the invention to
the precise forms disclosed, and obviously many modifications and
variations are possible in light of the above teaching. For example,
as would be apparent to those skilled in the art, the disclosures
herein of the ultrasonic surgical blade and ultrasonic surgical
instrument have equal application in robotic assisted surgery taking
into account the obvious modifications of such systems, components
and methods to be compatible with such a robotic system.
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