HK1223532B - Ultrasonic cutting blade with cooling liquid conduction - Google Patents

Description

Ultrasonic cutting blades with coolant conduction

Technical Field

The present invention relates to ultrasonic tools. More specifically, the present invention relates to ultrasonic cutting blades. The blades are particularly useful in surgical applications for cutting tissue, such as cartilage and bone. The present invention also relates, in part, to related surgical methods.

Background Art

In the field of plastic surgery, cutting live bone is a prerequisite for many procedures. Such procedures include the reconstruction of tissue structures damaged by accidents, the transplantation of healthy bone to areas damaged by disease, or the correction of congenital facial deformities like a receding jawline. For centuries, these procedures have been performed using a device called a bone saw.

Traditional bone saws fall into several basic categories. A manual saw or drill is simply a handheld device that requires the operator to move it in a manner similar to a woodworking tool. Powered by either electric or pneumatic power, they are either reciprocating or rotary types. Reciprocating devices use a flat, sword-like blade, with the back-and-forth motion provided by an electric motor instead of a hand. Rotary devices employ a rotary motor to spin the drill bit or blade, which has teeth arranged around its perimeter similar to a table saw blade. All of these traditional bone saws are currently used in medical procedures around the world.

While conventional saws are useful, they have a number of disadvantages. For example, neither band saws nor reciprocating saws are easy to start and guide the cut. The cut must be started from an edge, or a starter hole must be used. To create the starter hole, an operating drill bit or similar instrument is drilled into the bone. Next, a cutting blade is inserted into the drilled hole. The user can then make the cut. Alternatively, a rotary blade can be used. However, when using a rotary blade, the cut must be made along a relatively straight path to prevent the blade from binding in the cut. For all blades, the ability to make curved or mixed angle cuts is very limited by the blade selected. Relatively thick blades have a wide kerf, resulting in a significant thickness of living bone being lost during the cutting procedure. Physicians want this thickness to be as thin as possible in most reconstructive procedures.

In summary, the relatively slow linear or tangential speed of conventional bone saw blades, combined with the teeth required for cutting, results in high friction losses that manifest as heat. If the bone temperature reaches 47°C for more than a few seconds, the heat will cause tissue necrosis. When the tissue necroses, the bone appears to fall back after the operation because of overgrowth of necrotic bone. During this natural post-operative tissue development, the thickness of the cut in the bone is actually increased. The bone fallback procedure must be completed before healing can begin. In order to prevent the bone length from shortening, metal plates and screws are used to fix the bone fragments in place. All of these factors obviously lead to increased operating time, and more importantly, to a significant increase in healing time because the bone must be joined across a larger span. Some studies have shown that the strength of the bone is also adversely affected.

When cutting the upper or lower jaw during elective surgery, it's particularly important to mitigate the heat effects of traditional saws to prevent damage. If the bone is damaged or doesn't heal quickly, cutting between the teeth can lead to tooth loss. To prevent tooth loss, the teeth must be separated before surgery, often forcing patients to wear braces for up to six months before the procedure can begin. In these cases, costs and patient discomfort increase significantly.

To limit tissue temperature increases in an attempt to reduce necrosis, some conventional surgical saws deliver cooling fluid to the surgical site. See, for example, U.S. Patent 4,008,720 to Brinckmann et al. These devices typically introduce the coolant into the spaces between the segments on the cutting edge or rely on a spray method that covers the cutting site with fluid. Another technique used by clinicians is to make very light cuts and increase the time between tool switches. Combined with regional irrigation, this moderately reduces bone temperature increases. However, this technique increases operating time and clinician fatigue.

Some researchers have proposed using ultrasonic tools to perform bone separation. Ultrasonic surgical instruments are known to be used to cut a variety of tissues. Although these devices are superior to traditional saws in some respects, such as reduced incision size, reduced noise, and the superior ability to make complex geometric incisions, temperature rise in the bone remains a significant problem due to frictional heat at the blade/tissue interface. Compared to traditional reciprocating saws, the use of ultrasound exacerbates this problem because of the rapid motion involved. Some designers have attempted to reduce heat generation by modifying the cross-section of the cutting blade. U.S. Patent 5,188,102 to Idernoto, U.S. Patent 4,188,952 to Loschilov, and U.S. Patent 5,261,922 to Hood all show cutting designs with modified cross-sections to reduce frictional heat.

Some ultrasonic devices have been used to provide cooling to cutting blades, with varying degrees of success. U.S. Patent No. 4,823,790 to Alperovich et al. shows a design for cryogenically cooling a scalpel blade. However, this design may actually damage living tissue by freezing it. Furthermore, this design does not provide any coolant to surrounding tissue that is not in direct contact with the blade.

Idemoto's U.S. Patents 5,205,817, 5,188,102, and 4,832,683 all illustrate examples of ultrasonic instruments that provide fluid cooling. However, these instruments neither provide optimal coolant flow, which is required primarily in the cutting portion of the blade, nor, for some instruments, provide coolant at the tip, interrupting the coolant flow to the cutting edge with holes. The interrupted, uneven cutting edge hinders operation and makes it difficult to guide the blade onto the bone surface.

Ultrasonic atomization is a phenomenon associated with ultrasonic tools that is used to interfere with the beneficial effects of flushing the surgical site. When an ultrasonic vibration body is introduced into contact with a fluid, the fluid breaks into small droplets, the size of which is inversely proportional to the vibration frequency. In other words, the higher the frequency, the smaller and more mobile the droplets. The size of the droplets produced by ultrasonic vibrations can be very small, some of which are less than 1 micron in diameter. This phenomenon is well known in the art, and in fact, many devices designed to atomize liquids, such as room humidifiers, medical sprayers, and industrial nozzles, are based on this principle. However, in the operating room, atomized particles are not desired because these particles may contain viral or bacterial agents. In addition, some fluids are atomized before reaching the surgical site, reducing the cooling efficiency. An effective way is needed to ensure fluid transport.

U.S. Patent 6,379,31 discloses an ultrasonic surgical blade with a cooling function, which has a blade body having a smooth continuous cutting edge and a handle, the handle being connected to the blade body at one end and operably connected to an ultrasonic vibration source at the opposite end. The handle is provided with an axially extending hole to transport cooling liquid to the cutting edge, while the blade body is provided with an axially extending through groove connected to the hole at one end. The blade body is preferably provided with a recess connected to the hole at the end opposite to the handle to distribute the fluid from the narrow groove to the cutting edge. The recess may have a structure parallel to at least a portion of the cutting edge. Wherein the cutting edge is circular and the blade body has a flat surface between the fluid distribution guide surface and the cutting edge, for example, the recess has a fluid distribution surface that is inclined relative to the flat blade surface and extends along a circular arc.

Summary of the Invention

The object of the present invention is to provide an improved ultrasonic tool or probe with improved cooling capabilities. The ultrasonic tool or probe according to the present invention can be in the form of an ultrasonic cutting blade in particular, which makes the cutting incision thinner, does not require pre-drilled holes for cutting, allows complex geometric cutting, has a continuous cutting surface, and provides liquid irrigation mainly at the blade/tissue interface. More specifically, the present invention relates to an ultrasonic vibrating cutting blade that provides improved delivery of a cooling medium to reduce and limit thermal damage to living tissue. The present invention is particularly directed to the application of cutting living bone during surgery, although the device does not exclude this application.

The ultrasonic surgical instrument according to the present invention comprises a substantially planar blade body having a pair of opposing side surfaces and a cutting edge. A handle integral with the blade body at the distal end is provided with a connector at the proximal end for operatively connecting the blade to a source of ultrasonic mechanical vibrations. The blade body is provided with a shallow recess on at least one side surface, which extends approximately the same as the respective side surface. The blade body has a raised edge surrounding and defining the recess, the edge narrowing on three sides. On a fourth, proximal side of the recess, the proximal portion of the blade body, which is coupled to the handle, surrounds the recess.

The blade body is preferably provided with a through hole in the recess. The through hole extends between the side surfaces of the blade body and enables liquid to flow from the recess to the opposite surface of the blade body.

The stem is preferably provided with a hole or channel having an outlet communicating with the recess, thereby enabling liquid to flow into the recess from a source connected to the channel.

Through hole can extend to the proximal end of a recess or a plurality of recesses in the proximal direction.In that case, through hole is connected to each other at its outlet with hole or passage.

In a preferred embodiment of the invention, the recess is one of two recesses provided in each face of the side blade surface, each recess being defined by a peripheral edge.The through hole enables liquid to communicate between the recesses.

Each recess occupies a major portion of each side surface. Each recess is largely defined by a shallow wall formed by edges on three sides and a proximal portion of the blade body on the proximal side. When the handle is provided with a liquid delivery hole or channel, the hole or channel can communicate with each recess, either through a separate outlet hole or through a single outlet opening on both side blade surfaces.

According to another feature of the invention, the blade body and the recess are elongated and the through-hole is an elongated narrow opening, ie a slot.

The ultrasonic surgical tool according to the present invention comprises a substantially planar blade body having a pair of opposing major faces and a peripheral flange extending along three sides of the blade body. The flange defines a recess on at least one of the opposing major faces. The recess is substantially coextensive with the blade body, i.e., occupies substantially all of the major faces of the blade body. At least a portion of the flange has a cutting edge or surface. A handle integral with the blade body at a distal end is provided with a connector proximally for operatively connecting the blade to a source of ultrasonic mechanical vibrations.

Other features of the present invention are described above, namely, the provision of two recesses, one on each major surface of the blade body, a slot in the blade body, a liquid delivery hole or channel in one or more recesses, and a liquid outlet arrangement. When there are two recesses on opposite sides of the blade body, each recess is defined on three sides by a flange. In that case, the flange protrudes in opposite directions from the blade body, which is positioned perpendicular to it. The thickness of the proximal end of the blade body is equal to the thickness of the flange and defines one or more recesses on its proximal side.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an ultrasonic surgical tool according to the present invention.

FIG. 2 is a cross-sectional view along line II-II in FIG. 1 , showing a modified design of the ultrasonic surgical tool on a smaller scale.

FIG. 3 is a partial cross-sectional view taken along line III-III in FIG. 1 , and shows a modified design of FIG. 2 .

FIG4 is a cross-sectional view similar to FIG2 showing another modified design on a reduced scale.

FIG. 5 is a partial cross-sectional view similar to FIG. 3 , showing a modified design of FIG. 4 .

FIG. 6 is a perspective view of another ultrasonic surgical tool according to the present invention.

FIG. 7 is a top view of the ultrasonic surgical tool of FIG. 6 .

8 is a side view of the ultrasonic surgical tool of FIG. 6 and FIG. 7 .

DETAILED DESCRIPTION

As shown in Figures 1 to 3, the ultrasonic surgical tool 10 includes a substantially planar blade body 12 having a pair of opposing major faces (not separately shown) provided with recessed surfaces 14 and 16, and a flange 18. The opposing major faces are provided with recessed surfaces 14 and 16, and the flange 18 extends around the recessed surfaces 14 and 16 on three sides thereof to define a pair of relatively shallow recesses 20 and 22. The flange 18 extends outwardly away from the recessed surfaces 14 and 16, generally perpendicular to or perpendicular to the planes of those surfaces (not separately shown). The flange 18 serves as the edge or sidewall of each recess 20 and 22. The blade body 12 is separated on the proximal side by respective side walls 24, each of which continues the flange 18 and is formed by a proximal blade body portion 26 that combines with a tapered portion 28 of the handle 30 to form the recesses 20 and 22.

Thus, the blade body 12 has a pair of opposing side surfaces 32 and 34 that are planar outer surfaces proximate the blade body portion 26 and the flange 18. The recessed surfaces 14 and 16 are parallel to the side surfaces 32 and 34 and spaced inwardly therefrom.

The recesses 20 and 22 occupy substantially all of the blade body 12 along its opposing major faces. The flange or edge 18 is a narrow strip surrounding the recesses 20 and 22. An outwardly facing surface 36 of the flange 18 includes a cutting edge or surface, at least at a distal tip 38 of the blade body 12 and optionally along one or both of the sides 40 and 42 of the blade body 12.

The handle 30 is integrally connected to the blade body 12 at the distal end and is provided with an externally threaded connector 44 at the proximal end for operatively connecting the blade to an ultrasonic mechanical vibration source (not shown). Typically, the connector 44 is screwed into a socket on the handle, which houses a piezoelectric crystal stack that generates ultrasonic vibration energy in response to an electrical waveform input at an ultrasonic frequency.

The blade body 12 is provided with a through-hole 46 extending between the recessed surfaces 14 and 16 and providing a fluid communication path between the recesses 20 and 22 .

The handle 28 is provided with a hole or channel 48, which in one embodiment of the ultrasonic surgical tool 10 has a single outlet 50 that communicates directly with one recess 20. The hole or channel 48 can be connected to a source of irrigation or cooling fluid and introduce the fluid into the recess 20 through the outlet 50. The irrigation or cooling fluid enters the other recess 22 through the through hole 46.

2 and 3 , the bore or passage 48 may include a central axial upstream portion 52 and a pair of branching downstream portions 54 and 56 terminating in respective outlets 58 and 60. The outlets 58 and 60 are located in the proximal sidewall 24 of the recesses 20 and 22. Thus, the recesses 20 and 22, respectively, receive flushing or cooling fluid from the bore or passage 48 through the respective outlets 58 and 60. The through-hole 48 may be eliminated, but is preferably retained to maintain pressure balance and thereby enhance fluid flow.

4 and 5 , the holes or passages 48 may extend distally to outlet openings 62 in the sidewalls 24 of the recesses 20 and 22. The recessed surfaces 14 and 16 define a web or septum (not separately indicated) that bifurcates the outlet openings 62 to form a pair of D-shaped output ports 64 and 66.

Recesses 20 and 22 allow for improved irrigation delivery at the tissue contacting surface of the blade, both along side surfaces 32 and 34 and cutting edge 38, as well as along the side surface of flange or sidewall edge 18. The side surfaces may serve as additional cutting edges for blade body 12.

As shown in Figures 6 to 8, the ultrasonic surgical tool 110 includes a substantially planar blade body 112 having a pair of opposing major faces (not separately listed) provided with recessed surfaces 114 and 116, and a flange or shoulder 118. The opposing major faces are provided with recessed surfaces 114 and 116, and the flange or shoulder 118 extends on three sides around the recessed surfaces 114 and 116 to define a pair of opposing shallow recesses (not separately shown). The flange 118 extends outwardly away from the recessed surfaces 114 and 116, generally perpendicular to or perpendicular to the planes of those surfaces. The flange 118 serves as an edge or sidewall together with the recessed surfaces 114 and 116 that define the recess. The blade body 112 is separated on the proximal side by a corresponding sidewall 124, which continues the flange 118 and passes through a tapered portion 128 of the handle 130 to form the recess.

Thus, the blade body 112 has a pair of opposed side surfaces 132 and 134 ( FIG. 8 ) that are planar outer surfaces of the flange 118 and that connect to respective ramped outer surfaces (not shown) of the tapered shank portion 128. The recessed surfaces 114 and 116 are parallel to the side surfaces 132 and 134 and are spaced inwardly therefrom.

14 and 142 of the blade body 112. The recessed surfaces 114 and 116 and their corresponding associated recesses occupy nearly all of the blade body 112 along its opposing major faces, with the exception of the beveled cutting edge 126 that arcs around the distal tip 138 of the blade body 112 and partially along the distal end of the sides 140 and 142 of the blade body 112. Along the distal end section of the blade body 112, the flange or edge 118 is a narrow strip 118' sandwiched between the recessed surfaces 114 and 116 and the beveled cutting edge 126. On the proximal side of the blade body 112, the flange or edge 118 is a wider strip 118" that extends along the sides 140 and 142 of the blade body 112.

The handle 130 is integrally connected to the blade body 112 at the distal end and is provided with an externally threaded connector 144 at the proximal end for operatively connecting the blade to an ultrasonic mechanical vibration source (not shown). Typically, the connector 144 screws into a socket on the handle, which houses a piezoelectric crystal stack that generates ultrasonic vibration energy in response to an electrical waveform input at an ultrasonic frequency.

The blade body 112 is provided with an elongated through-hole or slot 146 extending between the recessed surfaces 114 and 116 and providing a fluid communication path between the recesses on the opposing major faces of the blade body 112 .

The shank 128 is provided with a hole or passage 148 having a single outlet 150 that is directly connected to the elongated through hole or slot 146 and the opposing recess on the opposing major face of the blade body 112. The through hole or slot 146 extends proximally to the sidewall 124 and connects with the hole or passage 148 at the outlet 150. The hole or passage 148 can be connected to a source of irrigation or cooling fluid and direct the fluid through the outlet 150 into the through hole or slot 146 and the opposing shallow recess.

The recessed surfaces 114 and 116 provide for improved delivery of irrigation fluid at the tissue contacting surface of the blade, with irrigation fluid being delivered along the side surfaces 132 and 134 and the cutting blade 126. The blade body 112 may be formed with a bevel or ramp extension 152 at the distal end of the slot 146 that facilitates movement of irrigation fluid from the slot 146 toward the portion of the cutting blade 126 at the distal tip 138 to distribute the irrigation fluid along the distal tip.

A bevel cutting blade 126 may be provided in the embodiment of Figures 1 to 3 and extend along nearly the entire sides 40 and 42.

Claims (6)

1. An ultrasonic surgical tool comprising: a substantially planar blade body having a pair of opposing side surfaces; and a handle which is integral with the blade body at the distal end and is provided with a connector at the proximal end for operatively connecting the blade to a source of ultrasonic mechanical vibrations, The blade body is provided with a shallow recess on at least one of the side surfaces, the recess extending as far as one of the side surfaces. said at least one side surface being formed with a raised edge surrounding and defining said recess, The edge is provided on the distal end side of the blade body and narrows along two side surfaces of the blade body. The blade is provided with a through hole in the recess, the through hole enabling liquid to flow from the recess to the opposite surface of the blade body, The handle is provided with a hole or channel having an outlet communicating with the recess and enabling liquid to flow from a source connected to the channel to the recess, The outlet is disposed at a proximal end of the recess and is spaced a certain distance from the through hole. 2 . The surgical tool according to claim 1 , wherein the recess is one of two recesses each defined by a peripheral edge provided in one of the side surfaces, the through hole enabling liquid to communicate between the recesses. 3. The surgical tool according to claim 2, wherein each of the recesses occupies a major portion of the corresponding main surface of the blade body, and the edge of each of the recesses defines a shallow side wall that extends parallel to the distal side and the side surface of the blade body. 4. The surgical tool of claim 1, wherein the blade body and the recess are elongated, and the through-hole is a slot. The surgical tool according to claim 2 , wherein each of the recesses occupies a major portion of a corresponding side surface of the blade body. 6. The surgical tool of claim 1, wherein the edge is in the form of a peripheral flange extending along three sides of the blade body and defining the recess, at least a portion of the flange having a cutting edge or surface.