Ultrasonic transducer assembly and ultrasonic surgical instrument comprising same

Abstract

An ultrasonic transducer assembly of an ultrasonic surgical instrument includes a piezoelectric stack, an ultrasonic horn secured to and extending distally from the piezoelectric stack and including a body and a nose extending distally from the body, an overmolded seal formed around the body of the ultrasonic horn, and a housing disposed around the piezoelectric stack, the body of the ultrasonic horn, and the overmolded seal. The housing defines a distal opening through which the nose of the ultrasonic horn extends. The overmolded seal establishes a hermetic seal with the housing to define a hermetically sealed interior that encloses the piezoelectric stack and the body of the ultrasonic horn therein.

Description

Technical Field

[0001] This disclosure relates to ultrasonic surgical instruments, and more particularly, to ultrasonic transducer assemblies and ultrasonic surgical instruments including said ultrasonic transducer assemblies. Background Technology

[0002] Ultrasonic surgical instruments utilize ultrasonic energy, or ultrasonic vibration, to treat tissues. More specifically, ultrasonic surgical instruments use mechanical vibration energy transmitted at ultrasonic frequencies to coagulate, burn, fuse, seal, cut, dry, and / or electrocauterize tissues to achieve hemostasis.

[0003] Ultrasonic surgical instruments typically employ transducers coupled to the instrument's handle and configured to generate ultrasonic energy to be transmitted along a waveguide to an end effector designed to treat tissue using that ultrasonic energy. The transducer may be driven by an ultrasound generator, which may be mounted on or within the handle of the instrument, or remotely positioned, for example, as a set-top box connected to the instrument via a surgical cable. The end effector of the ultrasonic surgical instrument may include: a blade that receives ultrasonic energy from the waveguide to apply to tissue; and a clamping member configured to hold tissue between the blade and the clamping member for treatment. Summary of the Invention

[0004] As used herein, the term "distal" refers to the portion described as being farther from the user, while the term "proximal" refers to the portion described as being closer to the user. Furthermore, to the extent consistent, any or all aspects described herein may be used in conjunction with any or all other aspects described herein.

[0005] According to various aspects of this disclosure, an ultrasonic transducer assembly for an ultrasonic surgical instrument is provided. The ultrasonic transducer assembly includes a piezoelectric stack, an ultrasonic amplitude transformer, an overmolded seal, and a housing. The ultrasonic amplitude transformer is attached to and extends distally from the piezoelectric stack. The ultrasonic amplitude transformer includes a body and a nose extending distally from the body. The overmolded seal is formed around the body of the ultrasonic amplitude transformer. The housing is disposed around the piezoelectric stack, the body of the ultrasonic amplitude transformer, and the overmolded seal. The housing defines a distal opening through which the nose of the ultrasonic amplitude transformer extends. The overmolded seal establishes an hermetically sealed seal with the housing to define a hermetically sealed interior that encloses the piezoelectric stack and the body of the ultrasonic amplitude transformer therein.

[0006] In one aspect of this disclosure, the body of the ultrasonic amplitude transformer is formed of first and second body portions joined to each other at a joint. The first and second body portions can be joined to each other at the joint by welding. Alternatively, the joint can be located near a node location along the ultrasonic amplitude transformer (within 10% of the node location). Furthermore, the first and second body portions can include complementary opposing surfaces to facilitate engagement.

[0007] In another aspect of this disclosure, the body of the ultrasonic amplitude transformer defines an annular groove, and an overmolded seal is disposed within and around the annular groove. In this respect, the annular groove of the ultrasonic amplitude transformer body may be discontinuous.

[0008] In another aspect of this disclosure, the overmolded seal includes at least one through-hole electrical connector extending therethrough. In this type of aspect, first and second electrode assemblies are disposed within a hermetically sealed interior and associated with and electrically connected to the first and second through-hole electrical connectors of the piezoelectric stack.

[0009] In another aspect of this disclosure, the housing includes a plurality of housing components that engage with each other at hermetically sealed joints.

[0010] The ultrasonic surgical instruments provided according to various aspects of this disclosure include a handle assembly and an elongated assembly. The handle assembly includes a housing and an ultrasonic transducer assembly according to any of the aspects detailed above or other aspects herein. The elongated assembly extends distally from the handle assembly. The elongated assembly includes a waveguide configured to engage the nose of an ultrasonic amplitude transformer and define a blade at its distal end. Ultrasonic energy generated by a piezoelectric stack is transmitted along the ultrasonic amplitude transformer and the waveguide to the blade for treating tissue adjacent to the blade. Attached Figure Description

[0011] The above and other aspects and features of this disclosure will become more apparent when considered in conjunction with the accompanying drawings, which identify similar or identical elements, in the following detailed description.

[0012] Figure 1 This is a side perspective view of the ultrasonic surgical instruments provided in this disclosure;

[0013] Figure 2 yes Figure 1 An enlarged longitudinal cross-sectional view of the proximal portion of an ultrasonic surgical instrument;

[0014] Figure 3 yes Figure 1 An enlarged side view of the transducer assembly of an ultrasonic surgical instrument;

[0015] Figure 4 yes Figure 3Exploded side view of the ultrasonic amplitude transformer of the transducer assembly;

[0016] Figure 5 Is it like this? Figure 4 The image shown is an exploded perspective view of the ultrasonic amplitude transformer including the overmolded seal mounted thereon.

[0017] Figure 6 Is it like this? Figure 5 An exploded perspective view of the ultrasonic amplitude transformer, including the distal component of the outer housing mounted thereon; and

[0018] Figure 7 The outer casing was removed. Figure 3 A side view of the transducer assembly. Detailed Implementation

[0019] Reference Figure 1 and 2 The image shows an ultrasonic surgical instrument provided according to this disclosure, generally identified by reference numeral 10. The ultrasonic surgical instrument 10 includes a handle assembly 100 and an elongated assembly 200 extending distally from the handle assembly 100. The handle assembly 100 includes a housing 110 defining a body portion 112 and a retaining handle portion 114. The handle assembly 100 includes an activation button 120 and a clamping trigger 130.

[0020] The main body portion 112 of the housing 110 is configured to support an ultrasonic transducer and generator assembly (“TAG”) 300, which includes a generator assembly 310 and an ultrasonic transducer assembly 320. The TAG 300 may be permanently engaged with or removable from the main body portion 112 of the housing 110. The generator assembly 310 includes a housing 312 configured to house the internal electronics of the generator assembly 310 and a support 314 configured to rotatably support the ultrasonic transducer assembly 320. Alternatively, the generator assembly 310 may be remotely positioned and connected to the ultrasonic surgical instrument 10 via a surgical cable.

[0021] The fixed handle portion 114 of the housing 110 defines a compartment 116 configured to receive the battery assembly 400 and a door 118 configured to close the compartment 116. An electrical connection assembly 140 is disposed within the housing 110 of the handle assembly 100 and, when the TAG 300 is supported on or in the body portion 112 of the housing 110 and the battery assembly 400 is disposed within the compartment 116 of the fixed handle portion 114 of the housing 110, electrically connects the activation button 120, the generator assembly 310 of the TAG 300, and the battery assembly 400 to each other, thereby enabling the ultrasound surgical instrument 10 to be activated in response to pressing the activation button 120. In embodiments where the generator assembly 310 is located away from the ultrasound surgical instrument 10, the configuration of the battery assembly 400 and the fixed handle portion 114 for receiving the battery assembly 400 is not required, as the generator assembly 310 can be powered by a standard wall socket or other remote power source.

[0022] Still refer to Figure 1 and 2 The elongated assembly 200 of the ultrasonic surgical instrument 10 includes an outer drive sleeve 210, an inner support sleeve 220 disposed within the outer drive sleeve 210, a waveguide 230 extending through the inner support sleeve 220, a drive assembly 250, a knob 270, and an end effector 280 including a blade 282 and a clamp 284. The proximal portion of the outer drive sleeve 210 is operably coupled to a clamp trigger 130 of the handle assembly 100 via the drive assembly 250, while the distal portion of the outer drive sleeve 210 is operably coupled to the clamp 284. Thus, the clamp trigger 130 can be selectively actuated, causing the outer drive sleeve 210 to move about the inner support sleeve 220, causing the clamp 284 to pivot relative to the blade 282 of the end effector 280 from a spaced-apart position to an approaching position for clamping tissue between the clamp 284 and the blade 282. The drive assembly 250 provides a force limiting feature, thereby limiting the clamping pressure applied to the tissue to a specific clamping pressure or a specific clamping pressure range. The knob 270 can be rotated in either direction to allow the elongated assembly 200 to rotate relative to the handle assembly 100 in either direction.

[0023] Waveguide 230 extends through inner support sleeve 220. Waveguide 230 defines body 232 and blade 282 extending from the distal end of body 232. Blade 282 serves as the blade of end effector 280. Waveguide 230 further includes a proximal threaded convex connector 236 configured for threaded engagement within a threaded concave receiver 325d of ultrasonic transducer assembly 324, such that ultrasonic vibrations generated by ultrasonic transducer assembly 320 are transmitted along waveguide 230 to blade 282 for treating tissue clamped between blade 282 and clamp 284 or positioned adjacent to blade 282.

[0024] Reference Figure 2 and 3 The ultrasonic transducer assembly 320 includes a piezoelectric stack 322, an ultrasonic amplitude transformer 324, an overmolded seal 326, and bolts 328. Figure 7 ), proximal nut 329, first and second electrode assemblies 330, contact assembly 332, and outer housing 340. Bolt 328 ( Figure 7 The piezoelectric stack 322 is secured between the ultrasonic amplitude transformer 324 and the proximal nut 329. First and second electrode assemblies 330 are positioned between the piezoelectric elements 323 of the piezoelectric stack 322 and connected to the contact assembly 332. The contact assembly 332 enables the transmission of drive and / or data signals through the outer housing 340, for example, between the piezoelectric stack 322 and / or the ultrasonic amplitude transformer 324 and the generator assembly 310.

[0025] An outer housing 340 defines a body 341 formed of one or more proximal body parts 342 and distal body parts 344, which are joined to each other by welding or any other suitable means of providing a hermetically sealed weld. The distal body part 344 defines a through-hole 334 to allow the nose 325b of the ultrasonic amplitude transformer 324 to pass through. As detailed below, an overmolded seal 326 is formed around the body 325a of the ultrasonic amplitude transformer 324 toward its distal end and is disposed within the outer housing 340 in a hermetically sealed relationship with the inner annular surface and / or the inner proximal-facing surface of the distal body part 344 of the body 340, defining a hermetically sealed closure 345 that encloses the internal volume 349 defined by the body 341, the overmolded seal 326, and the ultrasonic amplitude transformer 324. The enclosure 345 is airtightly sealed within the internal volume 349 to the piezoelectric stack 322, the proximal portion of the ultrasonic amplitude rod 324, the bolt 328, the proximal nut 329, and the first and second electrode assemblies 330.

[0026] Knob 350 ( Figure 1 It can be defined, mounted, or coupled to the proximal end portion of the outer housing 340. For example... Figure 1 As shown, the knob 350 can be accessed from the outside of the handle assembly 100 and is configured to be manually rotated to rotate the ultrasonic transducer assembly 320 relative to the generator assembly 310 and the housing 110.

[0027] Continue to refer to Figure 2 and 3The generator assembly 310 includes a contact assembly 364 (comprising multiple contacts) arranged to make slidable contact with a contact assembly 332 (comprising multiple contacts) of the ultrasonic transducer assembly 320. Therefore, the contacts of the contact assembly 364 and the contacts of the ultrasonic transducer assembly 320 define a slidable contact assembly, such as a slip ring contact assembly, which enables drive and / or data signals to be transmitted between the generator assembly 310 and the piezoelectric stack 322 (or other components) of the ultrasonic transducer assembly 320, regardless of the rotational orientation of the ultrasonic transducer assembly 320 relative to the generator assembly 310.

[0028] More specifically, regarding the transmission of the drive signal, the first electrode assembly 330 includes at least one positive electrode disposed between the piezoelectric elements 323 of the piezoelectric stack 322 and an electrode connector connecting the at least one positive electrode to a contact of a contact assembly 332, the contact of which is in turn electrically connected to a contact of a contact assembly 364 of the generator assembly 310. The second electrode assembly 330 includes at least one negative electrode disposed between the piezoelectric elements 323 of the piezoelectric stack 322 and an electrode connector connecting the at least one negative electrode to another contact of a contact assembly 332, the other contact of which is in turn electrically connected to another contact of a contact assembly 364 of the generator assembly 310. Thus, a drive signal voltage can be applied from the generator assembly 310 across the piezoelectric elements 323 of the piezoelectric stack 322 via the positive and negative electrodes. The piezoelectric stack 322 then converts the applied voltage into mechanical energy in the form of ultrasonic vibration, which is transmitted to the ultrasonic amplitude transformer 324.

[0029] Regarding data signal transmission, contact component 332 may include a data chip (not explicitly shown) (or an electrical connector, wherein the data chip is housed within generator component 310) disposed to communicate with ultrasonic amplifier 324 (and / or other portions of ultrasonic transducer assembly 320). The data chip, more specifically, may be a microprocessor chip or other suitable chip with a sensing circuitry system to detect various conditions, parameters, characteristics, etc., of the piezoelectric stack 322, ultrasonic amplifier 324, and / or other portions of ultrasonic transducer assembly 320. The data chip may be configured to, for example, sense the frequency, amplitude, impedance, and / or temperature of ultrasonic amplifier 324 (or other portions of ultrasonic transducer assembly 320); the number of times ultrasonic transducer assembly 320 has been activated; the activation duration of ultrasonic transducer assembly 320; etc. The data chip may additionally or alternatively include a memory storing information related to ultrasonic transducer assembly 320, such as model number, serial number, manufacturing date, calibration and / or testing information, manufacturer settings, etc. In embodiments where the data chip includes sensor circuitry, the memory may also store the sensed data.

[0030] The data chip (or electrical connector) within the ultrasonic transducer assembly 320 is connected to another contact of the contact assembly 332, which is in turn electrically connected to another contact of the contact assembly 364 of the generator assembly 310, thereby enabling the transmission of data signals between the ultrasonic transducer assembly 320 and the ultrasonic generator assembly 310.

[0031] Turning Figure 3-7 And first refer to Figure 4 As mentioned above, the ultrasonic amplitude transformer 324 includes a body 325a and a nose-like structure 325b extending distally from the body 325a. The body 325a includes a proximal body portion 372 and a distal body portion 374. The distal body portion 374 and the nose-like structure 325b of the body 325a may be integrally formed from a single piece of material, while the proximal body portion 372 is formed separately and subsequently attached to the distal body portion 374, for example, by welding at a joint, to form the ultrasonic amplitude transformer 324, although other configurations are also considered.

[0032] The proximal body portion 372 defines a flared proximal end 373a, which defines a proximal side 373b including a hole 373c defined therethrough. The distal side 373d of the proximal body portion 372 and the proximal side 375a of the distal body portion 374 may define complementary features, such as complementary protrusions(one or more) and recesses(one or more) to facilitate alignment for attachment, such as welding. The joint where the distal side 373d of the proximal body portion 372 and the proximal side 375a of the distal body portion 374 meet may be located at an anti-note point, such that no internal stress is applied to it.

[0033] The distal body portion 374 of the body 325a defines an annular groove 375b toward but spaced apart from its distal end. The annular groove 375b may be continuous, for example, extending continuously around the circumference of the distal body portion 374, or may be defined by one or more discontinuous groove segments extending around the circumference of the distal body portion 374 (as shown).

[0034] The nose-like feature 325b extends distally from the distal body portion 374 of the body 325a, and gradually decreases in diameter from the larger diameter of the distal body 374 to the smaller diameter of the extension 325c, which extends distally from the nose-like feature 325b to a threaded concave receiver 325d. The nose-like feature 325b extends through a hole 334 in the distal body portion 344 of the outer housing 340 (see [link to other document]). Figure 2 This allows the main body 325a to be housed within the outer casing 340. Figure 2The extension 325c and the threaded concave receiver 325d are disposed on the outside of the outer housing 340. Figure 2 ).

[0035] For further reference Figure 5 The overmolded seal 326 is formed of any suitable polymeric material and is overmolded around (and within) the annular groove 375b of the distal body portion 374 of the body 325a of the ultrasonic amplitude transformer 324 to define a donut-shaped seal extending radially outward from the distal body portion 374 toward its distal end. The overmolding of the overmolded seal 326 around the annular groove 375b of the distal body portion 374 forms an airtight seal between the overmolded seal 326 and the distal body portion 374.

[0036] In an embodiment, the overmolded seal 326 may be formed to include a plurality of through electrical contacts 327 (e.g., pins, rings, or other suitable contacts) extending longitudinally through it, for example, from its distal side to its proximal side, forming an hermetically sealed relationship, thereby enabling the transmission of electrical signals across the overmolded seal 326 without compromising the hermetically sealed seal. In this way, as... Figure 2 As shown, the electrode assembly 330, housed within the internal volume 349 of the hermetically sealed enclosure 345, can be electrically connected to an externally mounted contact assembly 332 via a direct-connection contact 327 (see [reference]). Figure 2 Data and other signals may be transmitted, either additionally or alternatively, between the internal volume 349 of the hermetically sealed enclosure 345 and the outside via a direct-through electrical contact 327 (see [link]). Figure 2 As an alternative to or in addition to the through contact 327, the overmolded seal 326 may include a conductive shell (not shown) to enable electrical communication therethrough and / or to otherwise transmit communication through the outer housing 340.

[0037] Go to Figure 6 , combined Figure 5 The overmolded seal 326 defines a radial dimension such that its outer annular surface is configured to provide an airtight seal against the inner annular surface of the distal body member 344 of the body 341 of the outer housing 340. Alternatively, the distal side of the overmolded seal 326 is configured to provide an airtight seal against the inner surface of the distal body member 344 of the body 341 of the outer housing 340. Therefore, the overmolded seal 326 defines the distal end of the closure 345. Figure 2 As detailed below, the outer housing 340 defines the proximal end and radial boundary of the closure 345. Figure 2 ).

[0038] Reference Figure 5and 7 Once an overmolded seal 326 is formed around the distal body portion 374 of the ultrasonic amplitude transformer 324 (or in any other suitable order during manufacturing), the distal body portion 374 and the proximal body portion 372 can be attached to each other, for example, by welding at a joint. The joint can be located near a node, for example, at the node or within 10% of the node location. Thereafter, piezoelectric elements 323 of the piezoelectric stack 322 can be stacked, with the first and second electrode assemblies 330 disposed between them and positioned adjacent to the proximal side 373b of the flared proximal end 373a of the proximal body portion 372 of the ultrasonic amplitude transformer 324. The proximal nut 329 can then be positioned adjacent to the piezoelectric stack 322 and the bolt 328 for securing these components to each other under suitable compression, for example, by extending through a hole 373c in the proximal end 373a of the flared proximal body portion 372 of the ultrasonic amplitude transformer 324, passing through the proximal nut 329 and the piezoelectric stack 322. The electrode assembly 330 can then be coupled to the through electrical contact 327 of the overmolded seal 326, either after or before this.

[0039] refer to Figure 3 and 5 -7. To complete the assembly of the ultrasonic transducer assembly 320, a housing 340 is installed. More specifically, the distal body part 344 of the main body 341 of the outer housing 340 slides over the threaded concave receiver 325d, the extension 325c, and the nose 325b of the ultrasonic amplitude transformer 324, and slides to seal and engage around and / or abut against the overmolded seal 326. Simultaneously, before or after this, a through-hole electrical contact 327 is electrically connected to the contact assembly 332. To complete the assembly of the housing 340, one or more proximal body components 342 slide proximally and are joined to each other and / or to the distal body component 344, for example by welding, such that the overmolded seal 326, the housing 340, and the ultrasonic amplitude transformer 324 cooperate to form an airtight seal 345, which encloses within an internal volume 349 containing the piezoelectric stack 322, the proximal portion of the ultrasonic amplitude transformer 324, bolts 328, proximal nuts 329, and the first and second electrode assemblies 330 (see [link to documentation]). Figure 2 ).

[0040] In embodiments, in addition to or as an alternative to overmolded seal 326, overmolded seal 335 ( Figure 2 A nose-shaped seal 325b can be formed around the hole 334 of the distal body component 344 to provide an airtight seal against the nose-shaped seal 325b of the ultrasonic amplitude transformer 324 when the nose-shaped seal 325b is inserted through it during assembly. Furthermore, an overmolded seal 335 (which is formed around the hole 334 of the distal body component 344) is also included. Figure 2As an alternative, the entire distal body component 344 can be formed of an overmolded material that overmoldes to the farthest side of the proximal body component 342 to similarly establish a seal around the ultrasonic amplitude transformer 324. Therefore, various components of the housing 340 can be formed of conductive materials and / or overmolded materials that are welded or otherwise joined; polymeric materials for the housing 340 are also considered.

[0041] In embodiments, two or more of the manufacturing steps detailed above may be performed together. For example, in an embodiment, the distal body portion 374 of the ultrasonic amplitude transformer 324, the through contact 327, and the distal body component 344 of the outer housing 340 (and, in an embodiment, the contact assembly 332) are inserted into a mold (not shown), and an overmolding material is injected into the mold in and / or around these components to form an overmolded seal 326, sealing these components as a single integrated unit to each other.

[0042] Generally refer to Figure 2-7 The housing 340 described above, which surrounds the ultrasonic amplitude transformer 324, is sealed with an airtight enclosure 345 to ensure that the transducer assembly 320 can withstand multiple rounds of sterilization, such as autoclaving, without leakage or damage.

[0043] While several embodiments of this disclosure have been described in detail above and illustrated in the drawings, it is not intended that this disclosure be limited thereto, as it is intended that this disclosure be interpreted as broadly as the scope would be permitted in the art and in the same manner. Therefore, the foregoing description and drawings should not be construed as limiting, but merely as illustrative of particular embodiments. Those skilled in the art will contemplate other modifications within the scope and spirit of the appended claims.

Claims

1. An ultrasonic transducer assembly (320) of an ultrasonic surgical instrument, comprising: Piezoelectric stack (322); An ultrasonic amplitude transformer (324) is fixed to the piezoelectric stack (322) and extends distally from the piezoelectric stack. The ultrasonic amplitude transformer includes a body (325a) and a nose-like structure (325b) extending distally from the body. The body (325a) includes a proximal body portion (372) and a distal body portion (374). A housing (340) is disposed around the body (325a) of the piezoelectric stack (322) and the ultrasonic amplitude transformer (324), the housing defining a distal opening through which the nose (325b) of the ultrasonic amplitude transformer extends; Its features are, The ultrasonic transducer assembly further includes an overmolded seal (326) formed of a polymeric material surrounding a distal body portion (374) of the body (325a) of the ultrasonic amplitude transformer (324), a housing (340) arranged around the overmolded seal, and the overmolded seal establishing an hermetically sealed interior with the housing to define an hermetically sealed interior that encloses the piezoelectric stack (322) and the body of the ultrasonic amplitude transformer therein, wherein the overmolded seal (326) includes at least one through-hole electrical connector (327) extending through the overmolded seal.

2. The ultrasonic transducer assembly according to claim 1, wherein the proximal body portion (372) and the distal body portion (374) of the body (325a) of the ultrasonic amplitude transformer are joined to each other at a seam.

3. The ultrasonic transducer assembly according to claim 2, wherein the proximal body portion (372) and the distal body portion (374) are joined to each other at the joint by welding.

4. The ultrasonic transducer assembly of claim 2, wherein the seam is located near a node position along the ultrasonic amplitude transformer (324).

5. The ultrasonic transducer assembly of claim 2, wherein the proximal body portion (372) and the distal body portion (374) include complementary opposing surfaces (373d, 375a) for engagement.

6. The ultrasonic transducer assembly according to any one of claims 1-5, wherein the distal body portion (374) of the body (325a) of the ultrasonic amplitude transformer (324) defines an annular groove (375b), and wherein the overmolded seal (326) is disposed within and around the annular groove.

7. The ultrasonic transducer assembly according to claim 6, wherein the annular groove (375b) of the body (325a) of the ultrasonic amplitude transformer (324) is discontinuous.

8. The ultrasonic transducer assembly according to any one of claims 1-5, further comprising: a first electrode assembly and a second electrode assembly (330), the first electrode assembly and the second electrode assembly being disposed within the hermetically sealed interior and associated with the piezoelectric stack (322), the first electrode assembly and the second electrode assembly being electrically connected to a first direct-connector and a second direct-connector of the at least one direct-connector (327).

9. The ultrasonic transducer assembly according to any one of claims 1-5, wherein the housing (340) comprises a plurality of housing components (342, 344) joined to each other at an airtight joint.

10. An ultrasonic surgical instrument (10), comprising: Handle assembly (100), the handle assembly comprising: Outer shell (110); The ultrasonic transducer assembly (320) supported by the housing (110) according to any one of claims 1-9; and An elongated component (200) extending distally from the handle assembly includes a waveguide (230) configured to engage the nose (325b) of the ultrasonic amplitude transformer (324), the waveguide defining a blade (282) at its distal end. The ultrasonic energy generated by the piezoelectric stack (322) is transmitted along the ultrasonic amplitude transformer (324) and the waveguide (230) to the blade (282) for treating tissue adjacent to the blade.

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