HK1223007B - Ultrasonic cutting blade with cooling liquid conduction - Google Patents

Description

Ultrasonic cutting blade with cooling liquid conduction

Technical Field

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

Background

In the field of orthopedic surgery, cutting of living bone is a prerequisite for many procedures. Such procedures include reconstruction of accidentally damaged tissue structures, transplantation of healthy bone into the site of damage due to disease, or correction of congenital facial deformities such as mandibular retrogradation. For centuries, these tasks have been performed by using a device called a bone saw.

Conventional bone saws fall into several basic types. A manual saw or drill is a hand held device that requires an operator to move the device in a manner similar to that used with a carpentry tool. Power equipment, whether electric or pneumatic, is reciprocating or rotating. Reciprocating devices use flat sword blades, in which the reciprocating motion is provided by a motor rather than manually. Rotary devices use a rotating motor to rotate a drill bit or blade having serrations disposed about its circumference similar to a table saw blade. Today, all of these conventional bone saws are used worldwide for medical procedures.

Despite its functionality, conventional bone saws have a number of disadvantages. For example, it is not easy to initiate and guide a cut with a band saw or reciprocating saw. The cutting must be started from the edge or a starter hole must be used. To form the starter hole, a drill or similar instrument is operated to drill a hole in the bone. Subsequently, a cutting blade is inserted into the drilled hole. The user is then able to perform the cut. Alternatively, a rotating blade may be used. However, when a rotating blade is used, the cut must be made along a relatively straight path to prevent the blade from becoming stuck in the cut. The ability of all blades to form a curved or compound angle cut is greatly limited by the blade selected. The relatively thick blades saw a wider kerf, so that the active bone loses much of its thickness during the cutting process. In most procedures where reconstruction is necessary, the physician will want the width to be as narrow as possible.

Most importantly, the linear or tangential velocity of conventional bone saw blades coupled with the teeth necessary to make the cut is relatively slow, resulting in high frictional wear, which manifests as heat. If the bone temperature reaches 47℃ for more than a few seconds, heat will cause tissue necrosis. When tissue is necrosed, bone may retract after surgery due to overgrowth of necrotic bone. During this natural post-operative tissue development, the thickness of the incision in the bone actually increases. The bone retraction process must be completed before healing can begin. To prevent the length of the bone from shortening, metal plates and screws are used to fix the bone fragments in place. All of these factors will obviously lead to increased procedure time and, more importantly, will lead to a significant increase in healing time, since the bone must be engaged across a larger span. Several studies have shown that the strength of bone is also adversely affected.

The thermal effects of conventional bone saws require more non-conventional intervention to prevent injury when the maxilla or mandible is to be cut in elective surgery. If the bone is damaged or does not heal very quickly, cutting the jaw between teeth will cause the teeth to fall out. To prevent tooth loss, the teeth must be separated prior to surgery; patients are sometimes required to have braces up to 6 months prior to surgery. In these cases, costs and patient discomfort increase significantly.

Some conventional surgical bone saws provide cooling fluid to the surgical site in order to limit tissue temperature rise in an attempt to reduce necrosis. See, for example, U.S. patent No.4,008,720 to Brinckmann et al. These devices typically introduce a coolant into the space between the segments on the cutting edge or rely on a spray method to irrigate the cutting site with fluid. Another technique used by clinicians is to make very shallow incisions and increase the time between tool passes. With the addition of irrigation to the area, the bone temperature rise is moderately reduced. Of course, this technique increases the operating time and the degree of fatigue of the clinician.

Some researchers have proposed the use of ultrasonic tools for bone separation. The use of ultrasonic surgical instruments to cut through a variety of tissues is well known. While these devices are superior to conventional bone saws in several respects, such as reducing kerf size, reducing noise, etc., and are capable of forming cuts of complex geometry, the temperature rise due to frictional heating at the blade/tissue interface remains a significant problem. This problem is exacerbated by the fact that the use of ultrasound involves rapid movement as compared to conventional reciprocating bone saws. Some designers have sought to reduce heat generation by making improvements to the cross-section of the cutting blade. U.S. Pat. No.5,188,102 to Idernoto, U.S. Pat. No.4,188,952 to Loschilov, and U.S. Pat. No.5,261,922 to Hood all show cutting designs that have been modified in cross-section to reduce frictional heating.

Several ultrasonic devices have provided cooling to the cutting blade with varying degrees of success. U.S. patent No.4,823,790 to Alperovich et al shows a design of a scalpel blade that is cooled at low temperatures. However, this design may actually damage viable tissue due to freezing. Furthermore, the design does not provide any coolant to surrounding tissue that is not in direct contact with the blade.

U.S. Pat. Nos. 5,205,817, 5,188,102, and 4,832,683 to Idernoto all show examples of ultrasonic instruments that provide fluid cooling. However, these instruments either fail to provide an optimal coolant where needed (mainly at the cutting portion of the blade) or for instruments providing a coolant at the tip, the holes for the coolant block the cutting edge. The interrupted, uneven cutting edge hinders the operation and makes it difficult to guide the blade over the bone surface.

One phenomenon associated with the operation of ultrasonic tools whose action hinders the beneficial effects of irrigating the surgical site is ultrasonic atomization. When the ultrasonic vibrator is brought into contact with the fluid, the fluid is broken down 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 droplet. The size of the droplets formed by ultrasonic vibration can be very small, some being less than 1 micron in diameter. This phenomenon is well known in the art. In fact, many devices for nebulizing liquids, such as room humidifiers, medical nebulizers and industrial nozzles, are based on this principle. In the operating room, however, the presence of spray particles is undesirable because these particles may contain viral or bacterial agents. In addition, some of the fluid may be atomized before reaching the surgical site, reducing the cooling efficiency. There is a need for an efficient way of ensuring liquid transport.

U.S. patent No.6,379,371 discloses an ultrasonic surgical blade with cooling having a blade body with a smooth continuous cutting edge and a handle connected at one end to the blade body and at an opposite end operatively connectable to a source of ultrasonic vibrations. The shank portion is provided with an axially extending bore for delivering cooling fluid to the cutting edge, while the blade body is provided with an axially extending through slot having one end communicating with the bore. The blade body is preferably provided at an end opposite the shank with a recess communicating with the aperture for dispensing fluid from the through slot to the cutting edge. The groove may have a configuration parallel to at least a portion of the cutting edge. For example, where the cutting edge is circular and the blade body has a planar surface between the fluid distribution guide surface and the cutting edge, the groove has a fluid distribution surface that is inclined relative to the planar blade surface and extends along an arc of a circle.

Disclosure of Invention

It is an object of the present invention to provide an improved ultrasonic tool or probe having improved cooling capabilities. The ultrasonic tool or probe according to the present invention may particularly take the form of an ultrasonic cutting blade that allows for narrow kerf cuts, does not require pre-drilling of holes for cutting, allows for complex geometry cuts, has a continuous cutting surface, and provides fluid irrigation primarily at the blade/tissue interface. More particularly, the present invention relates to an ultrasonically-vibrating cutting blade having improved delivery of a cooling medium for reducing and limiting thermal damage to living tissue. The invention is particularly relevant to the application of active bone cutting during surgery, however the device is not limited to this application.

An ultrasonic surgical tool according to the present invention includes a probe body having an operative surface or edge contactable with organ tissue for performing a surgical procedure on the tissue. The tool further includes a handle connected to the proximal end of the probe body and provided with a connector at an end opposite the blade body for operatively attaching the tool to a source of ultrasonic mechanical vibratory energy. The handle and a portion of the probe body form a channel for delivering fluid to the probe body. At least a portion of the probe body located between the channel and the operative surface or edge has a microporous structure that enables fluid to permeate from the channel to the operative surface or edge.

The channel may comprise a main section extending longitudinally along said probe body and at least one branch section extending at least partially transversely from the main section towards the operative surface or edge. The branch section of the passage extends only partway from the main section to the operative surface or edge and has a free end opposite the main section and spaced from the operative surface or edge.

Preferably, at least the part of the probe body between the channel and the operative surface or edge is made of a sintered material. The probe body may be made entirely of a sintered material.

The liquid feed channel may comprise a plurality of branch segments, each branch segment extending at least partially transversely from the main segment of the channel to the operative surface or edge of the probe body, each branch segment extending only partway from the main segment to the operative surface or edge, and each branch segment having a respective free end opposite the main segment and spaced from the operative surface or edge. The portion of the probe body between the end of each branch segment and the outer surface or edge of the probe body is preferably made of a sintered material.

The probe body may take the form of a flat or planar cutting blade having a pair of opposed major surfaces defined by a pair of opposed longitudinal edges of the blade and a terminal edge, the operative surface or edge extending partially along one of the longitudinal edges and partially along the terminal edge. The insert is partially or entirely made of sintered material to enable liquid to be conducted from the feed channel to the outer surface and/or edge of the insert.

The microporous structure of an ultrasonic tool or probe according to the present invention defines or enables a plurality of microporous pathways extending from a liquid feed channel to an operative surface or edge, the probe body being free of other pathways for liquid to flow from the channel to the operative surface or edge.

A surgical method according to the present invention includes providing an ultrasonic surgical tool having a probe body and a handle connected to a proximal end thereof, the probe body having an operative surface or edge, the handle and probe body forming a channel, at least a portion of the probe body extending between the channel and the operative surface or edge having a microporous structure. The method further includes operably connecting the proximal end of the handle to a source of ultrasonic mechanical vibrations, operably coupling the channel to the source of liquid, moving the probe body to a surgical site of the patient, and contacting the operative surface or edge with organ tissue at the surgical site. Ultrasonic mechanical vibrations are generated in the probe body when the operative surface or edge is in contact with the organ tissue, thereby ultrasonically vibrating the operative surface or edge. Pressurized liquid is supplied to the passage from a liquid source and from the passage to the operative surface or edge through a plurality of microporous pathways in the probe body while the operative surface or edge is in contact with the organ tissue and during generation of ultrasonic mechanical vibrations in the probe body.

As above, the probe body has no other path for liquid to flow from the channel to the operative surface or edge. Thus, supplying pressurized liquid from the liquid source to the operative surface or edge of the probe body includes moving the liquid only along the path of the pores between the channel and the operative surface or edge.

The probe body may take the form of a flat or planar cutting blade having a pair of opposed major surfaces defined by a pair of opposed longitudinal edges and a terminal edge, the operative surface or edge extending partially along one of the longitudinal edges and partially along the terminal edge. The method then further includes cutting into the organ tissue by generating ultrasonic mechanical vibrations in the probe body and generating ultrasonic vibrations in the operative surface or edge.

Drawings

FIG. 1 is a schematic side view of an ultrasonic surgical tool, blade or probe according to the present invention.

FIG. 2 is a top plan view of the ultrasonic surgical tool, blade or probe of FIG. 1 showing one configuration of the fluid delivery channels of the tool, blade or probe.

FIG. 3 is a top plan view similar to FIG. 2 showing another configuration of the fluid delivery passageway of the tool, blade or probe.

Fig. 4 is a top plan view similar to fig. 2 and 3 showing a further configuration of the fluid delivery passageway of the tool, blade or probe.

Fig. 5 is an enlarged view of the distal portion of the ultrasonic tool, blade or probe of fig. 1 and 2, corresponding to the region marked V in fig. 1.

Detailed Description

As depicted in fig. 1 and 2, the ultrasonic surgical tool 10 includes a probe body 12 having an operative surface or edge 14 contactable with organ tissue OT for performing a surgical procedure on the tissue. The tool 10 further includes a handle 16 connected to the proximal end of the probe body 12 and provided with a connector 18 at an end opposite the probe body for operatively attaching the tool to a source 20 of ultrasonic mechanical vibratory energy, such as a piezoelectric transducer or a magnetostrictive transducer, in a handpiece 22. The handle 16 and a portion of the probe body 12 form a channel 24 for delivering fluid to the probe body. At least a portion 26 of the probe body located between the channel 24 and the operative surface or edge 14 has a microporous structure 28 (fig. 5) to enable fluid to permeate from the channel to the operative surface or edge.

In the embodiment of fig. 1 and 2, the passage 24 takes the form of a linear bore extending centrally through the handle 16 and probe body 12. However, as shown in fig. 3, the channel 24' of the blade or probe body 12' may alternatively include a main longitudinal segment 30 extending longitudinally along the probe body 12 and one or more secondary or branch segments 32 extending transversely or perpendicularly from the main segment 30 to longitudinally oriented operative surfaces or edges 34 and 36 of the probe body 12 '. The branch section 32 of the channel 24' extends only partway from the main section 30 to the operative surfaces or edges 34 and 36 and has a respective free end 38 opposite the main section 30 and spaced from the operative surfaces or edges 34, 36. In fig. 3, the blade or probe body 12 'has a microporous structure (28 in fig. 5), preferably throughout but at least in the region between the end 38 of the branch section 32 and the blade edges 34 and 36, to enable fluid to penetrate from the channel 24' to the operative surface or edge.

Figure 4 shows another form of channel 24. As shown in fig. 4, the channel 24 "may alternatively include a main longitudinal section 40 extending longitudinally along the blade or probe body 12" and one or more angled or angled branch sections 42 extending transversely and longitudinally in part from the main section 40 to longitudinal operative surfaces or edges 44 and 46 of the probe body 12 ". The branch section 42 of the channel 24 "extends only partway from the main section 40 to the operative surfaces or edges 44 and 46 and has a respective free end 48 opposite the main section 40 and spaced from the operative surfaces or edges 44, 46.

In fig. 4, the blade or probe body 12 "has a microporous structure (28 in fig. 5), preferably throughout but at least in the region between the end 48 of the branch section 42 and the blade edges 44 and 46, to enable fluid to penetrate from the channel 24" to the operative surface or edge.

Those portions of the blade or probe body 12, 12', 12 "having a microporous structure may be made of a sintered material. The blade or probe body 12, 12', 12 "may be made entirely of sintered material.

The probe body 12, 12', 12 "may be a bone cutting blade having a flat or planar geometry with a pair of opposing major surfaces 50 and 52 (fig. 1) defined in part by opposing longitudinal edges (e.g., edges 34, 36, 44, 46) and a distal edge (14, fig. 1 and 2) of the blade. The blade or probe body 12, 12' has an operative surface or edge extending partially along the longitudinal edge (34, 36; 44, 46) and partially along the distal edge 14. As mentioned above, the blade or probe body 12, 12', 12 "is partially or entirely made of a sintered material to enable liquid to be conducted from the feed channel 24, 24', 24" to the outer surface and/or edge of the blade.

As shown in fig. 5, the microporous structure 28 of the ultrasonic tool or probe 10 defines or implements a plurality of microporous pathways 54 extending from the liquid feed channels 24, 24', 24 "to the operative surfaces or edges 14, 34, 36, 44, 46, the probe body having only microporous pathways for liquid flow from the channels 24, 24', 24" to the operative surfaces or edges 14, 34, 36, 44, 46.

In using the ultrasonic microporous surgical tool 10 in a surgical procedure, the handle 16 is connected to the source of ultrasonic mechanical vibrations 20 via the connection 18, the liquid feed channel 24, 24', 24 "is operatively coupled to the liquid source 56 (fig. 1), and the blade or probe body 12, 12', 12" is moved to the surgical site OT of the patient. The operative surface or edge 14, 34, 36, 44, 46 of the blade or probe body 12, 12', 12 "is then brought into contact with the organ tissue OT at the surgical site. The vibration source or transducer 20 operates to generate ultrasonic mechanical vibrations (typically standing waves of a predetermined wavelength or frequency) in the blade or probe body 12, 12', 12 "when the operative surface or edge 14, 34, 36, 44, 46 is in contact with the organ tissue OT, thereby ultrasonically vibrating the operative surface or edge 14, 34, 36, 44, 46 at the predetermined frequency. Upon contact of the operative surface or edge 14, 34, 36, 44, 46 with the organ tissue OT, and during generation of ultrasonic mechanical vibrations in the blade or probe body 12, 12', 12", pressurized liquid is supplied from a liquid source 56 to the liquid feed channel 24, 24', 24" and from the channel to the operative surface or edge 14, 34, 36, 44, 46 through a plurality of microporous pathways 54 of the blade or probe body 12, 12', 12", as indicated by arrows 58 in fig. 5.

In the case where the blade or probe body is a flat or planar cutting blade, the method may cut into the organ tissue OT by generating ultrasonic mechanical vibrations in the blade or probe body 12, 12', 12 "and ultrasonically vibrating the operative surface or edge 14, 34, 36, 44, 46.

Although the invention has been described with respect to specific embodiments and applications, one of ordinary skill in the art, in light of the teachings, can generate additional embodiments or modifications without departing from the spirit of the invention or exceeding the scope of the claimed invention. For example, while the invention has particular application in bone cutting blades, it is essentially directed to ultrasonic instruments in which a cooling liquid or a liquid with entrained debris must be delivered through the tool body to a surface in contact with the organ tissue or other target material. Accordingly, it is to be understood that the drawings and descriptions herein are proffered by way of example to facilitate comprehension of the invention and should not be construed to limit the scope thereof.

Claims (9)

1. An ultrasonic surgical tool comprising a probe body having an operative surface or edge contactable with organ tissue for performing a surgical procedure on said tissue; and a handle connected to the proximal end of the probe body, the handle being provided with a connection at the proximal end opposite the probe body for operatively attaching the tool to a source of ultrasonic mechanical vibratory energy, and the handle and a portion of the probe body forming a channel for conveying a fluid to the probe body, at least a portion of the probe body extending between the channel and the operative surface or edge having a plurality of pores or pore pathways extending from the channel to the operative surface or edge and enabling fluid to permeate from the channel to the operative surface or edge, the probe body being free of other pathways for liquid to flow from the channel to the operative surface or edge.

2. The surgical tool of claim 1, wherein the channel includes a main section extending longitudinally along the probe body, the channel further including at least one branch section extending at least partially transversely from the main section toward the operative surface or edge, the at least one branch section extending only partway from the main section toward the operative surface or edge, the at least one branch section having a free end opposite the main section and spaced from the operative surface or edge.

3. The surgical tool of claim 2, wherein a portion of the probe body is made of a sintered material.

4. The surgical tool of claim 3, wherein the probe body is made entirely of the sintered material.

5. The surgical tool of claim 2, wherein the channel comprises a plurality of branch segments, each branch segment extending at least partially transversely from the main segment to the operative surface or edge, each branch segment extending only partway from the main segment to the operative surface or edge, and each branch segment having a respective free end opposite the main segment and spaced from the operative surface or edge.

6. The surgical tool of claim 1, wherein a portion of the probe body is made of a sintered material.

7. The surgical tool of claim 6, wherein the probe body is made entirely of the sintered material.

8. The surgical tool of claim 2 wherein the probe body is a flat or planar cutting blade having a pair of opposed major surfaces defined by a pair of opposed longitudinal edges and a distal edge of the blade, the operative surface or edge extending partially along one of the longitudinal edges and partially along the distal edge.

9. The surgical tool of claim 8, wherein the blade is made of a sintered material.