WO2003082132A1

WO2003082132A1 - Ultrasonic cutting tool with transversely ribbed blade and jaw means

Info

Publication number: WO2003082132A1
Application number: PCT/GB2003/001322
Authority: WO
Inventors: Michael John Radley Young
Original assignee: Sra Developments Limited
Priority date: 2002-03-28
Filing date: 2003-03-27
Publication date: 2003-10-09
Also published as: GB0207314D0; AU2003217036A1; GB2388029A; GB2388029B

Abstract

The cutting tool is powered by an ultrasonic vibration generator through an elongate waveguide. A blade (1) at a distal end of the waveguide has a face with a series of transversely directed ribs (4), separated by grooves (5). A jaw (3) having a correspondingly transverse ribbed face is controllably moveable into interlocking contact with the ribbed face of the blade.

Description

ULTRASONIC CUTTING TOOL WITH TRANSVERSELY RIBBED BLADE AND JAW MEANS

IMPROVED ULTRASONIC CUTTING TOOL

The present invention relates to an ultrasonic cutting tool. More particularly, but not exclusively, it relates to a surgical tool utilising longitudinal mode ultrasonic vibrations, of especial utility in a laparoscopic cutting system, particularly for haemostatic cutting.

It is known to cut tissue by means of ultrasonically vibrated knives or scalpels. A particularly effective form of ultrasonic cutting device, especially in confined spaces, e.g. during laparoscopic procedures, comprises an ultrasonically vibratable blade and a pivotable jaw which is used to clamp the tissue to be cut against the blade. Ultrasonic vibration of the blade then both coagulates and cuts the tissue. It is not necessary for the blade to be particularly sharp, and in many cases a generally cylindrical ultrasonic waveguide can be used as the blade, optionally with a relatively flattened tissue contact surface cooperating with a substantially flat jaw.

The majority of such tools employ longitudinal mode ultrasonic vibrations. A problem experienced with such tools is that the ultrasonic vibrations tend to propagate preferentially axially, much of the energy emerging from a distal tip of the tool rather than being transmitted into the tissue being cut. This energy can produce absorptive heating, cavitation and consequent tissue damage at sites remote from the tool, and so caution must be exercised when applying high intensities of ultrasound in this manner.

The transmission of energy from an ultrasonic blade to tissue clamped thereto occurs mainly by frictional forces, producing localised heating of the tissue, which is inherently safe. However, the power transmitted by a longitudinal mode system to tissue pressed against it in a direction normal to the axis of vibration is directly proportional to the frictional force, which is in turn dependent on the pressing force. The pressing force exertable by a conventional jaw mechanism is limited. The frictional force is also dependent on the coefficient of friction between the blade and the tissue, which for a polished metal blade will be significantly less than unity. As a result, in existing tools employing longitudinal ultrasonic waves, energy transmission into the selected tissue is inefficient and most of the energy generated is undesirably propagated out of the distal tip of the tool instead.

It is therefore an object of the present invention to provide an ultrasonic cutting/coagulation tool adapted to give improved transmission of longitudinal ultrasonic vibrational energy into the tissue to be treated.

According to the present invention, there is provided a cutting tool comprising a source of ultrasonic vibration, a waveguide connected thereto, elongate blade means at a distal end thereof and having a transversely ribbed face and jaw means having a correspondingly transverse ribbed face and being controllably moveable into interlocking contact with the ribbed face of the blade means. Each rib of the blade means may have a generally flat summit and each corresponding valley therebetween may have a generally flat floor.

The rib summits and valley floors may then be connected by a plurality of sloped zones.

Alternatively, the ribs and valleys of the blade means may together have a generally sinusoidal profile.

The height of each rib above adjacent valleys is preferably comparable with the thickness of the tissue to be treated.

Advantageously, said height is at least one tenth of a corresponding dimension of the blade means, and optionally at least one fifth thereof.

The jaw member is preferably pivotably mounted to the tool, and is operatively connected to manually operable control means disposed adjacent a proximal end of the tool.

The blade means is preferably linear.

Alternatively, the blade means may be curved.

In this case, said longitudinal axis of the blade means may comprise a curved median line thereof. The source of ultrasonic vibration is preferably adapted to produce longitudinal mode vibration.

An embodiment of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: -

Figure 1 is a side elevation of a distal end of a tool embodying the invention; and Figure 2 is a plan view of a distal end of a waveguide of the tool of Figure 1.

Referring now to the drawings and to Figure 1 in particular, a blade 1 forms the distal end of a waveguide to which may be applied longitudinal mode ultrasonic vibrations to cause ultrasonic vibration as indicated by arrow 2. A non- vibrating jaw member 3 is moveable towards and away from the blade 1 by any one of a range of mechanisms. In the majority of these, the jaw member 3 is so pivotably mounted to the tool that a user of the tool may controllably pivot the jaw member 3 towards the blade 1, catching and clamping tissue to be treated therebetween.

A contact surface of the blade 1 facing the jaw member 3 is provided with a series of ribs 4 extending transversely to a longitudinal axis of the blade 1 (and hence to the direction of vibration 2 thereof). The ribs 4 are separated by grooves 5 of generally similar dimensions. In the embodiment shown, the ribs 4 each have a substantially level summit and the grooves 5 each have a substantially level floor, although a more sinusoidal cross-sectional profile is also envisaged. A contact surface of the jaw member 3 for the blade 1 has a corresponding profile of ribs 6 with grooves 7 therebetween, so that the contact surfaces of the blade 1 and jaw member 3 interlock as shown when brought together (the gap is shown exaggerated for purpose of clarity).

As a result, when the jaw member 3 is brought down to clamp a section of tissue against the blade 1, much of the tissue is held against angled transmission facets 8 of the blade 1. Longitudinal ultrasonic vibrations are therefore much more readily transmitted into those portions of the tissue. The tissue as a whole is much more firmly held than with conventional jaw profiles and so the frictional transmission of ultrasonic energy into the tissue is significantly more efficient. Overall, a much greater proportion of the ultrasonic energy input into the tool is transmitted into the selected tissue, and far less remains to be dissipated out of a distal end of the blade 1, potentially harming tissue remote from the site of treatment.

The blade 1 of the tool may be substantially straight (not shown), or curved as shown in Figure 2. A curved blade 9 is provided with a series of ribs 4 and grooves 5 therebetween. A jaw member (not shown) is provided, of corresponding curvature and with corresponding ribs and grooves, which may be pivoted towards the blade 9 to clamp tissue for treatment.

For optimum effectiveness, the height of the ribs 4 above the grooves 5 in each case should be comparable with the thickness of the tissue to be treated. Conveniently, this height should be at least a tenth of the corresponding dimension of the blade 1, as shown.

Claims

1. A cutting tool comprising a source of ultrasonic vibration, a waveguide connected thereto, elongate blade means at a distal end thereof and having a face provided with outstanding ribs extending transversely to the axis of the waveguide and jaw means having a correspondingly transversely ribbed face and being controllably moveable into interlocking contact with the ribbed face of the blade means.

2. A tool as claimed in claim 1, wherein each rib of the blade means has a generally flat summit and each corresponding valley therebetween has a generally flat floor.

3. A tool as claimed in claim 2, wherein the rib summits and valley floors are connected by a plurality of sloped zones.

4. A tool as claimed in claim 1, wherein the ribs and valleys therebetween of the blade means together have a generally sinusoidal profile.

5. A tool as claimed in any one of the preceding claims, wherein the height of each rib above adjacent valleys is determined according to the thickness of the tissue to be treated.

6. A tool as claimed in any one of the preceding claims, wherein the jaw member is pivotably mounted to the tool, and is operatively connected to manually operable control means disposed adjacent a proximal end of the tool.

7. A tool as claimed in any one of the preceding claims, wherein the blade means is linear.

8. A tool as claimed in any one of claims 1 to 6, wherein the blade means is curved.

9. A tool as claimed in claim 8, wherein a longitudinal axis of the blade means comprises a curved median line thereof.

10. A tool as claimed in any one of the preceding claims wherein the source of ultrasonic vibration is adapted to produce longitudinal mode vibration.