HK1101768B - Ultrasonic surgical blade and instrument having a gain step - Google Patents

Description

Ultrasonic scalpel with gain step and instrument

Technical Field

The present invention relates generally to ultrasonic scalpels (blades) and ultrasonic surgical instruments including ultrasonic scalpels, and more particularly to ultrasonic scalpels and ultrasonic surgical instruments having gain steps.

Background

Known ultrasonic surgical instruments include ultrasonic surgical blades. The handpiece of known ultrasonic surgical instruments includes an ultrasonic transducer that is powered by an ultrasonic generator through a cable. The ultrasonic transmission rod of the instrument has a proximal end and a distal end, wherein the proximal end is operatively connected to an ultrasonic transducer. The ultrasonic surgical blade is actuated by the distal end of the ultrasonic transmission rod. Known knife shapes include straight knives and curved knives, and include knives that are symmetric and asymmetric about a longitudinal axis or about a center line of curvature of the knife.

The known ultrasonic surgical blade is a cylindrical blade having a distal tip, a most-distal vibration node (a vibration node is a point of substantially zero displacement), and a second most-distal vibration antinode (a vibration antinode is a point of maximum displacement relative to all other points in a half wave), where the most-distal vibration antinode is the distal tip. The longitudinal ultrasonic vibration of the blade generates motion and heat in the contacted tissue, wherein the heat primarily provides a means for the blade to cut and/or coagulate patient tissue. The cutter has a gain step located a distance from the most-distal vibration node that 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 amplitude gain. The known blade comprises a geometrically right circular cylinder of larger diameter from the second-most-distal vibration antinode to the most-distal vibration node. Known knives include a small diameter geometric right circular cylinder from the most-distal vibration node to the distal tip. The change in diameter provides a gain in amplitude for the smaller diameter section of the blade equal to the ratio of the cross-sectional areas of the larger diameter blade section to the smaller diameter blade section when the gain step is located at the node.

The effective length of an ultrasonic surgical blade is defined by applicant as the distance from the distal tip to where the amplitude (i.e., longitudinal amplitude) drops to 50% of the amplitude of the tip. The knife is considered useless beyond its effective length. The effective length of a straight cylindrical titanium rod at a resonant frequency of about 55.5kHz is about 15 mm.

It is known in ultrasonic welding of plastics to provide an ultrasonic electrode with a gain step, such as a discontinuity between the larger and smaller electrode diameters, located between the most-distal vibration node and the distal end of the welding head (welding horn) and spaced from the most-distal vibration node of the electrode by a distance that is less than 5% of the distance between the second-most-distal vibration antinode and the distal end of the electrode. It is also known in ultrasonic welding of plastics to provide an ultrasonic welding rod with a hole or slot to provide gain in longitudinal amplitude.

What is needed is an improved ultrasonic surgical blade and an improved ultrasonic surgical instrument including an ultrasonic surgical blade having a longer or shorter effective length.

Disclosure of Invention

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 that 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 from the most-distal vibration node by a gain step distance that is greater than 5% of the distance between the second-most-distal vibration antinode and the distal tip.

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 ultrasound transmission rod has a proximal end and a distal end, wherein the proximal end is operably connected to the ultrasound transducer. The ultrasonic surgical blade is actuated by the distal end and includes an ultrasonic-surgical-blade body. The ultrasonic-surgical-blade body has a distal tip that 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 from the most-distal vibration node by a gain step distance that is greater than 5% of the distance between the second-most-distal vibration antinode and the distal tip.

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 a first vibration antinode, a vibration node, a second vibration antinode, and a gain step, in any half wavelength of the ultrasonic-surgical-blade body. The gain step is located between the second vibration antinode and the first vibration antinode. The gain step is spaced from the vibration node by a gain step distance that is greater than 5% of the distance between the second vibration antinode and the first vibration antinode.

Several benefits and advantages are obtained from one or more of the expressions of an embodiment of the invention. Applicants have discovered that positioning a gain step having a gain greater than unity (i.e., an amplification step) farther from the most-distal vibration node toward the distal tip can further increase the effective length of the ultrasonic surgical blade than has been conventionally taught, even though the amplitude gain is less than when the gain step was conventionally positioned closer to the most-distal vibration node. Applicants determined that positioning the gain step farther away from the most-distal vibration node toward the second-most-distal vibration antinode would shorten the half-wavelength of the ultrasonic surgical blade as compared to that conventionally taught. Applicants have also determined that such changes in the effective and half wavelengths of the ultrasonic surgical blade also result from gain steps having gains less than unity (i.e., attenuation steps), but that if an attenuation step results in a decrease in effective length, an amplification step at the same location will result in an increase in effective length, and if an attenuation step results in an increase in effective length, an amplification step at the same location will result in a decrease in effective length. It will be appreciated by those skilled in the art that the ability to lengthen or shorten the effective length of an ultrasonic surgical blade provides advantages for particular surgical applications.

The present invention is not limited and can be applied to robot-assisted surgery.

Drawings

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 present invention;

FIG. 2 is a longitudinal cross-sectional view of the most-distal half wavelength including the distal tip of the ultrasonic surgical blade of FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of the distal-most half wavelength including the distal tip of the second embodiment of the scalpel of FIG. 1; and

fig. 4 is a longitudinal cross-sectional view of the distal-most half wavelength including the distal tip of the third embodiment of the scalpel of fig. 1.

Detailed Description

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 embodiments 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 embodiments of the present invention for the convenience of the reader and are not for the purpose of limiting the invention.

It should be understood that one or more of the following expressions of an embodiment, examples, etc. may be combined with one or more other following expressions of an embodiment, examples, etc. For example, and without limitation, a reduced radius gain feature may be combined with the gain feature of the aperture.

Referring now to the drawings, FIGS. 1-2 illustrate a first embodiment of the present invention. A first expression of the first embodiment of fig. 1-2 is for an ultrasonic surgical blade 10 including an ultrasonic-surgical-blade body 12 having a distal tip 14 that is a most-distal vibration antinode (a vibration antinode is a point of maximum displacement relative to all other points in a half wave), having a most-distal vibration node 16 (a vibration node is 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 from the most-distal vibration node 16 by a gain step distance 22 that is greater than 5% of a distance 24 between the second-most-distal vibration antinode 18 and the distal tip 14.

In one implementation of the first expression of the first embodiment of FIGS. 1-2, the gain step distance 22 is between approximately 25% and approximately 45% of the distance 24 between the second-most-distal vibration antinode 18 and the distal tip 14. Using the teachings of the present invention for the location of the gain step 20, one of ordinary skill in the art can build analytical blade models and evaluate them using a computer program to optimize the design tradeoff between increasing or decreasing effective length of the ultrasonic surgical blade and increasing or decreasing amplitude of the longitudinal ultrasonic vibration for positioning 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.

In one example of the first expression of the first embodiment of FIGS. 1-2, the maximum amplitude of the ultrasonic-surgical-blade body 12 proximal the gain step 20 is less than the maximum amplitude of the ultrasonic-surgical-blade body 12 distal the gain step 20 between the second-most-distal vibration antinode 18 and the distal tip 14. In this example, the gain of the gain step 20 is greater than unity and results from the ultrasonic-surgical-blade body 12 having a smaller mass between the gain step 20 and the distal tip 14 than the ultrasonic-surgical-blade body 12 has between the gain step 20 and the second-most-distal vibration antinode 18.

In various embodiments, not shown, the maximum amplitude of the ultrasonic-surgical-blade body proximal the gain step is greater than the maximum amplitude of the ultrasonic-surgical-blade body distal the gain step between the second-most-distal vibration antinode and the distal tip. In this embodiment, the gain of the gain step is less than unity and results from the ultrasonic-surgical-blade body having a greater mass between the gain step and the distal tip than the ultrasonic-surgical-blade body between the gain step and the second-most-distal vibration antinode. In one embodiment, this embodiment can be readily envisioned by switching the position of the distal tip 14 and the second-most-distal vibration antinode 18 in FIG. 2.

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, thereby causing the effective length of the ultrasonic surgical blade 10 to increase. In a different embodiment, not shown, the gain step is disposed between the most-distal vibration node and the second-most-distal vibration antinode, thereby resulting in a reduction of the half-wavelength of the ultrasonic surgical blade. This embodiment can be easily envisioned by moving the gain step 20 between the most-distal vibration node 16 and the second-most-distal vibration antinode 18 in FIG. 2.

In one example 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 and a second geometric solid 30, the first geometric solid 28 having a first substantially constant cross-sectional area from the gain step 20 to the distal tip 14, the second geometric solid 30 having a second substantially constant cross-sectional area from the gain step 20 to the second-most-distal vibration antinode 18. The second cross-sectional area is different from the first cross-sectional area. In one variation, the shape and size of the first outer perimeter of the first cross-sectional area is substantially equal to the shape and size of the second outer perimeter of the second cross-sectional area. In one variation, at least one of the first and second cross-sectional areas surrounds an interior cavity 32. In one configuration, the lumen 32 includes a first longitudinal bore 34 disposed in the first geometric solid 28 and extending proximally from the distal tip 14. Applicants have found that positioning the gain step 20 at a position where the gain is equal to the square root of the ratio of the cross-sectional areas of the second geometric solid 30 to the first geometric solid 28 optimizes the increase in the effective length of the blade. In one arrangement, the lumen 32 comprises a second longitudinal hole 36 arranged in the second geometrical entity 30 and in fluid communication with the first longitudinal hole 34, the first and second longitudinal holes 34 and 36 being adapted for irrigation and/or aspiration. In another arrangement, the ultrasonic surgical blade 10 further includes a membrane 38 having a composition substantially the same as the composition of the ultrasonic-surgical-blade body 12, covering the first longitudinal hole 34 and removably or permanently attached to the first geometric solid 28 at the distal tip 14. It should be noted that when irrigation and/or suction is required, the membrane 38 will be removed from the first geometrical entity 28 in fig. 2. Alternatively, the membrane 38 may be made of a permeable fabric (e.g., a wire mesh or screen), or a sintered mesh made of titanium or other suitable material to facilitate irrigation and/or suction.

In various embodiments 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 that extends from the gain step to the distal tip and has a first cross-sectional area that is not constant. The second geometric solid has a second mass extending from the gain step to the second-most-distal vibration antinode and having a second cross-sectional area that is not constant. The second mass is different from the first mass. In one example, this embodiment is readily envisioned by considering in FIG. 2 that the second longitudinal bore 36 has a diameter that decreases from the second-most-distal vibration antinode 18 to the gain step 20, and that the first longitudinal bore 34 has a diameter that increases from the gain step 20 to the distal tip 14. Variations, modifications, etc. of the preceding paragraphs are equally applicable to this embodiment.

In another 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 a second-most-distal vibration antinode. The second mass is different from the first mass. One of the first and second geometric entities has a substantially constant cross-sectional area along its respective axial length and the other of the first and second geometric entities has a non-constant cross-sectional area along its respective axial length. In one example, this embodiment is readily envisioned by considering in fig. 2 that the first longitudinal bore 34 has a diameter that increases from the gain step 20 to the distal tip 14. The modifications, improvements, and the like of the second preceding paragraph are equally applicable to this embodiment.

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 symmetric about the longitudinal axis 26. In another design, not shown, the ultrasonic-surgical-blade body has a longitudinal axis, has an effective length, and is substantially asymmetric about the longitudinal axis along at least a portion of the effective length. In one variation, the ultrasonic-surgical-blade body is curved. In one example, this variation is readily envisioned by bending the distal portion of the ultrasonic-surgical-blade body 12 upward from the longitudinal axis 26 in fig. 2.

In one employment 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: discontinuous changes in outer diameter or perimeter, conicity, longitudinal bore, discontinuous changes in longitudinal bore diameter, transverse bore, surface flatness, and surface slots. It should be noted that in this application, the gain step 20 is the location of the portion of the gain feature 40 that is closest to the most-distal vibration node 16. It should also be noted that the term "hole" includes through holes and non-through holes. Other gain characteristics may be envisaged by the skilled person.

Fig. 3 shows a second embodiment of the ultrasonic surgical blade 110 of the present invention. In this embodiment, ultrasonic-surgical-blade body 112 has an additional gain step 142 spaced from gain step 120, which is disposed between second-most-distal vibration antinode 118 and distal tip 114, and is spaced from most-distal vibration node 116 by a gain-step distance 122 that is greater than 5% of distance 124 between second-most-distal vibration antinode 118 and distal tip 114. The ultrasonic-surgical-blade body 112 has a longitudinal axis 126 and a longitudinal bore 134 with a shoulder 144 defining an additional gain step 142.

A third embodiment of the ultrasonic-surgical blade 210 is shown in fig. 4, wherein the ultrasonic-surgical-blade body 212 consists essentially of a first geometrically right 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 second right geometric cylinder 230 from the gain step 220 to the second-most-distal vibration antinode 218. The diameter of the first geometric cylinder 288 is less than the diameter of the second geometric cylinder 230. It should be 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 the mass and creates the first geometric cylinder 288. The gain step 220 is disposed between the second-most-distal vibration antinode 218 and the distal tip 214, and is spaced from the most-distal vibration node 216 by a gain step distance 222, the gain step distance 222 being greater than 5% of the distance 224 between the second-most-distal vibration antinode 218 and the distal tip 214.

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, the blade body may be constructed substantially of aluminum, ceramic, sapphire, or any other material that transmits ultrasonic waves in an efficient manner. Mathematical analysis of various titanium blade designs using the principles described herein, which require positioning the gain step 20 substantially away from the most-distal vibration node 16 in the direction of the distal tip 14, yields an increase in the effective length of the ultrasonic surgical blade 10 of up to 40%. Applicants have theoretically found an increase of up to 60%. As previously mentioned, the effective length of the ultrasonic surgical blade 10 is defined as the distance from the distal tip 14 to where the amplitude of the vibration (i.e., the longitudinal amplitude) drops to 50% of the amplitude of the tip. The knife is considered useless beyond its effective length. Without applying the principles of the present invention, the effective length of a straight cylindrical titanium rod is about 15mm at a resonant frequency of about 55.5 kHz. Using the principles of the present invention, an increase in effective length of up to about 5mm is expected when the gain step 20 is disposed between the most-distal vibration node 16 and the distal tip 14.

In one arrangement, the ultrasonic surgical blade 10 is used alone as an 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 shearing end effector of an ultrasonic surgical instrument for cutting and/or coagulating patient tissue.

A second expression of the first embodiment of figures 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 ultrasound transmission rod 50 has a proximal end and a distal end, wherein the proximal end is operatively connected to an ultrasound transducer 52. The ultrasonic-surgical-blade 10 is distally actuated and includes an ultrasonic-surgical-blade body 12. The ultrasonic-surgical-blade body 12 has a distal tip 14 that 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 from the most-distal vibration node 16 by a gain step distance 22, the gain step distance 22 being greater than 5% of a distance 24 between the second-most-distal vibration antinode 18 and the distal tip 14.

In one enablement of the second expression of the first embodiment of FIGS. 1-2, further includes an ultrasonic generator 54 actuated 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 configuration, the ultrasonic surgical blade 10 is an integral part of the ultrasonic transmission rod 50. In another configuration, the ultrasonic surgical blade is a separate piece and is connected to the ultrasonic transmission rod. It should be noted that the foregoing ultrasonic-surgical-blade embodiments, implementations, examples, illustrations, etc. are equally applicable to ultrasonic surgical instruments.

A third expression of the first embodiment of fig. 1-2 is for an ultrasonic surgical blade including an ultrasonic-surgical-blade body having, in any half-wavelength 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 from the vibration node by a gain-step distance that is greater than 5% of a distance between the second vibration antinode and the first vibration antinode. It should be noted that the third expression does not limit the location of the half wave to the last half wavelength of the blade body as in the second expression set forth above, and that the embodiments, implementations, examples, illustrations, etc. of the foregoing second expression are equally applicable to the third expression, except for the location of the second expression of the half wave.

Several benefits and advantages are obtained from one or more of the expressions of an embodiment of the invention. Applicants have found that positioning the gain step (i.e., amplification step) having a gain greater than unity further away from the most-distal vibration node toward the distal tip further increases the effective length of the ultrasonic surgical blade than has been conventionally taught, even though the amplitude gain is less than when the gain step was conventionally positioned closer to the most-distal vibration node. Applicants determined that positioning the gain step farther away from the most-distal vibration node toward the second-most-distal vibration antinode would shorten the half-wavelength of the ultrasonic surgical blade as compared to that conventionally taught. Applicants have also determined that such changes in the effective and half wavelengths of the ultrasonic surgical blade will also result from gain steps having a gain less than unity (i.e., attenuation steps), but that if an attenuation step results in a decrease in effective length, an amplification step at the same location will result in an increase in effective length, and if an attenuation step results in an increase in effective length, an amplification step at the same location will result in a decrease in effective length. It will be appreciated by those skilled in the art that the ability to lengthen or shorten the effective length of an ultrasonic surgical blade provides advantages for particular surgical applications.

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 form disclosed, and obviously many modifications and variations are possible in light of the above teaching. For example, it will be apparent to those skilled in the art that the ultrasonic surgical blade and ultrasonic surgical instrument disclosed herein are equally applicable in robotic-assisted surgery in view of the obvious variations of such systems, components and methods that are compatible with robotic systems.

Claims (26)

1. An ultrasonic surgical blade comprising an ultrasonic-surgical-blade body having a distal tip that is a most-distal vibration antinode, a most-distal vibration node, a second-most-distal vibration antinode, and a gain step, wherein the gain step is disposed between the second-most-distal vibration antinode and the distal tip, and the gain step is spaced from the most-distal vibration node by a gain-step distance that is 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 25% and 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, a maximum amplitude of the ultrasonic-surgical-blade body proximal the gain step is less than a maximum 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, a maximum amplitude of the ultrasonic-surgical-blade body proximal the gain step is greater than a maximum 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 a most-distal vibration node and a second-most-distal vibration antinode.

7. The ultrasonic surgical blade of claim 1, wherein the ultrasonic-surgical-blade body has a longitudinal axis and is comprised of a first geometric solid having a constant first cross-sectional area from the gain step to the distal tip and a second geometric solid having a constant second cross-sectional area from the gain step to the second-most-distal vibration antinode, wherein the second cross-sectional area is different than the first cross-sectional area.

8. The ultrasonic surgical blade of claim 7, wherein a shape and size of a first outer perimeter of the first cross-sectional area is equal to a shape and size of a second outer perimeter of the second cross-sectional area.

9. The ultrasonic surgical blade of claim 8, wherein at least one of the first and second cross-sectional areas surrounds an inner lumen.

10. The ultrasonic surgical blade of claim 9, wherein the lumen comprises a first longitudinal hole disposed in the first geometric solid and extending proximally from the distal tip.

11. The ultrasonic surgical blade of claim 10, wherein the lumen comprises a second longitudinal bore disposed in the second geometric solid and in fluid communication with the first longitudinal bore, and the first and second longitudinal bores are adapted for irrigation and/or aspiration.

12. The ultrasonic surgical blade of claim 10, further comprising a membrane covering the first longitudinal bore and removably or permanently affixed 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 is comprised of a first geometric solid having a first mass extending from the gain step to the distal tip and having a first cross-sectional area that is not constant and a second geometric solid having a second mass extending from the gain step to the second-most-distal vibration antinode and having a second cross-sectional area that is not constant, 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 outer perimeter of the first cross-sectional area is equal to the shape and size of the second outer perimeter of the second cross-sectional area.

15. The ultrasonic surgical blade of claim 14, wherein at least one of the first and second cross-sectional areas surrounds an inner lumen.

16. The ultrasonic surgical blade of claim 15, wherein the lumen comprises a first longitudinal hole disposed in the first geometric solid and extending proximally from the distal tip.

17. The ultrasonic surgical blade of claim 16, wherein the lumen comprises a second longitudinal bore disposed in the second geometric solid and in fluid communication with the first longitudinal bore, and the first and second longitudinal bores are adapted for irrigation and/or aspiration.

18. The ultrasonic surgical blade of claim 16, further comprising a membrane covering the first longitudinal bore and removably or permanently affixed 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 is comprised 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, one of the first and second geometric solids has a constant cross-sectional area along its respective axial length, and the other of the first and second geometric solids has a non-constant cross-sectional area along its respective axial length.

20. The ultrasonic surgical blade of claim 1, wherein the ultrasonic-surgical-blade body has a longitudinal axis and is symmetrical about the longitudinal axis.

21. The ultrasonic surgical blade of claim 1, wherein the ultrasonic-surgical-blade body has a longitudinal axis, an effective length, and is asymmetric about the longitudinal axis along at least a portion of the effective 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: discontinuous changes in outer diameter or perimeter, conicity, longitudinal bore, discontinuous changes in longitudinal bore diameter, transverse bore, surface flatness, and surface slots.

24. The ultrasonic surgical blade of claim 1, wherein the ultrasonic-surgical-blade body has an additional gain step spaced from the gain step, the additional gain step being disposed between the second-most-distal vibration antinode and the distal tip and being spaced from the most-distal vibration node by a gain-step distance that is greater than 5% of the distance between the second-most-distal vibration antinode and the distal tip, the ultrasonic-surgical-blade body having a longitudinal axis and a longitudinal bore, wherein the longitudinal bore has a shoulder defining the additional gain step.

25. An ultrasonic surgical instrument, comprising:

a) a handpiece including an ultrasound transducer;

b) an ultrasound transmission rod having a proximal end and a distal end, wherein the proximal end is operably connected to the ultrasound transducer; and

c) an ultrasonic surgical blade actuated by the distal end and comprising an ultrasonic-surgical-blade body having a distal tip that is a most-distal vibration antinode, a most-distal vibration node, a second-most-distal vibration antinode, and a gain step, the gain step being disposed between the second-most-distal vibration antinode and the distal tip, and the gain step being spaced from the most-distal vibration node by a gain-step distance that is greater than 5% of a 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 wavelength of the ultrasonic-surgical-blade body, a first vibration antinode, a vibration node, a second vibration antinode, and a gain step, the gain step being disposed between the second vibration antinode and the first vibration antinode, and the gain step being spaced from the vibration node by a gain-step distance that is greater than 5% of the distance between the second vibration antinode and the first vibration antinode.