Switch for ultrasonic surgical tool

A switch unit (40) is mountable to a distal end of a handpiece of an electrically-activatable surgical tool, such as an ultrasonically-vibratable surgical tool. The switch unit (40) has a generally bullet-shaped outer form with an axial bore (42) through which a waveguide of the tool extends. A resiliently deformable band (1) extends around the switch unit (40) above a polygonal-section contact zone (2), such that fingertip pressure on the band (1) may locally depress the band (1) towards a flat area (12) of the contact zone (2). Switch contacts (11) are mounted to an inner surface of the band (1) opposite a plated circuit (10) located on each flat area (12) so as to form a plurality of switches. A switch to activate the tool is thus easily accessible to a user's fingertip in any orientation of the handpiece in the user's hand. The switch contacts (11) may each comprise a body having an electrical resistance dependent on a pressure exerted thereon. A magnitude of a response from the tool may thus be controlled by the pressure exerted by the user's fingertip.

This application claims priority to PCT International Application PCT/GB2008/001994 filed on Jun. 11, 2008 which was published on Dec. 18, 2008 as Publication No. WO 2008/152378 A2. The PCT application claims priority to a patent application filed on Jun. 11, 2007 in Great Britain and assigned Patent Application No. GB0711151.1. The entire content of these applications is incorporated herein by reference.

The present invention relates to a switching mechanism for activating a surgical tool, such as tools used for minimally invasive surgery (MIS). More particularly, but not exclusively, it relates to a switch system for use with a laparoscopic ultrasonic surgical tool.

Historically, ultrasonically-energised tools, and other electrically activated surgical devices that are activated during surgery to conduct a procedure, have had at least one common problem to address: the provision of activating means that may easily be contacted by a user's digits without compromising any aspect of the surgery. This is particularly useful in cases in which handling the tool may require twisting or angular movements of the hand-joints or fingers, in order to place and hold the tool in a desired position before activation. For example, while performing a small internal incision, it is of the highest importance to place an activatable distal end of the tool in the correct position so that the user may ensure that it acts on the desired target tissue. The user will often need simultaneously to manipulate a laparoscope positioned to show the target tissue and to manipulate the surgical tool, while viewing a monitor displaying the view captured by the laparoscope.

There is hence a need for a surgical tool that will provide maximum ease of manipulation to position the tool as desired, while permitting easy access to activating means of the tool in any alignment of the tool in the user's hand.

It is known to provide such a surgical tool with a pistol-like butt comprising a trigger switch operable to activate the tool once the cutting tip of the tool is positioned and held in the desired position. The problem with this arrangement is that the user may well be restricted in his hand movements. The butt may interfere with the user's hand movements, restricting rotational motions which may be required for delicate surgery, and the trigger switch may not be conveniently positioned for the user's fingers when the tool is correctly positioned.

Accordingly, while trying to position the tool, judging by the feedback being monitored from the laparoscope, the surgeon may have to make an uncomfortable twist or even use help from the hand holding the laparoscope in order to achieve the correct position. This may in turn affect the optimum view being captured by the laparoscope.

It is therefore an object of the present invention to provide manual activation arrangements for a laparoscopic surgical tool or the like allowing activation in a range of hand positions, particularly should complex hand movements be required to position the tool before activation to carry out a surgical procedure.

According to a first aspect of the present invention, there is provided a switch unit so mountable to a distal end of a handpiece of an activatable surgical tool as to be contactable by a finger of a hand manipulating the handpiece, wherein the switch unit is generally radially symmetrical and comprises a plurality of first digitally-operable switch means arranged around a circumference thereof, operation of any one of which is adapted to activate the tool.

Preferably, the switch unit is provided with an axially-extending bore adapted for passage of a shaft of the tool therethrough.

Said shaft may comprise a waveguide of an ultrasonically-vibratable surgical tool.

The switch unit may comprise a generally frustoconical body having said plurality of first switch means mounted thereto.

Preferably, the switch unit comprises at least one second digitally-operable switch means disposed between a distal end of the switch unit and the first switch means.

Said second switch means may be adapted to activate a different function of the tool to that activated by the first switch means.

In a preferred embodiment, each said switch means comprises resiliently flexible cover means spaced in an “off” configuration of the switch means from contact means thereof, said cover means being deflectable by digital pressure into contact with said contact means in an “on” configuration of the switch means.

A single common cover means may provided for all said first switch means.

The switch unit may be provided with a plurality of recess means, one said switch means being disposed within each said recess means.

A plurality of said first recess means may be arranged contiguously around a circumference of the switch unit, each first recess means containing a respective first contact means.

Each contact means preferably comprises a body of a material having an electrical resistance dependent on a pressure exerted thereon.

The switch means may then be adapted to provide an activation signal dependent on a digital pressure exerted thereon.

According to a second aspect of the present invention, there is provided a handpiece for an electrically activatable surgical tool comprising a switch unit as described in the first aspect above, operatively mounted to a distal end of said handpiece.

Referring to now to the Figures, and toFIGS. 1 and 2in particular, a switch head40has a generally bullet-shaped radially-symmetrical form, and is detachably mountable to a distal end of a handpiece of an ultrasonically-vibratable surgical tool (not shown). The switch head40is provided with an axial bore42, through which an elongate waveguide of the tool extends (not shown for clarity).

The switch head40comprises a resiliently-deformable band1of an elastomeric material extending circumferentially around a waist portion of the switch head40. A regularly-spaced array of six main switches is arranged circumferentially around the switch head40beneath this band1. A contact zone2of the switch head40beneath the band1has a hexagonal outer profile and a circular inner profile, arranged such that it contacts the band1supportingly at apical, thicker portions3. The band1may thus be depressed by a user's finger towards and into contact with any of the flat outer faces12of the contact zone2, while the band1as a whole maintains its shape. A first switch contact11is mounted to the inner face of the contact zone2beneath each flat outer face12thereof.FIG. 6shows the flat faces12with the band1removed.

A side-lobe of the deformable band1extends distally from its circumferential portion, covering a recess4in the switch head40(see alsoFIG. 6), mounted beneath an inner face of which is a second switch contact24.

Referring now toFIGS. 3 and 4, a generally radially-symmetrical rigid plastics mounting body5is located coaxially within the switch head40. A cylindrical outer surface8of the mounting body5adjacent the contact zone2of the switch head40is provided with a plurality of plated circuits10, each of which opposes a respective switch contact11. A similar arrangement of plated circuits (not shown inFIGS. 3 and 4) is provided adjacent the recess4and second switch contact24. The circuits10are preferably gold-plated and of a pin-in-socket configuration (seeFIGS. 7 to 9).

Thus, when a portion of the band1above a flat face12of the contact zone2is depressed by a finger of a user of the handpiece, it will deform into contact with the flat face12. The finger pressure will bow the flat face12slightly inwardly, such that the respective switch contact11meets its corresponding plated circuit10. This makes the circuit10. Each of the circuits10is operatively linked, through a metal-plated elongate interconnect element14extending proximally from the mounting body5, to the handpiece. The signal produced when any of the circuits10is made will activate the surgical tool, for example activating the ultrasound generator of an ultrasonically-vibratable laparoscopic implement. Release of the band1allows the respective flat face12to revert to being flat, displacing the contact switch11out of contact and inactivating the tool once more.

Thus, whatever the angular position of the tool in the user's hand, the user will be able to press on a portion of the band1convenient to his finger in order to activate the tool, without needing to adjust the position of the tool in his hand. More or less than six faces12are possible, but six is effective and convenient. The operation of the second switch4,24may be analogous or may be of a more conventional form. The second switch may be linked to a activation of a different function of the tool, or may be used as an additional on-off switch.

In a preferred embodiment, the switch contacts11,24each comprise a pellet of a material whose electrical resistance depends on the pressure exerted thereon. Conductive carbon “pills” or QTC (quantum tunnelling composite) elements are examples of these. When such a switch contact11,24is employed, not only is there a make/break contact to activate or inactivate the tool, but the digital pressure exerted by the user on the band1will affect the resistance of the switch contact11,24and hence the magnitude of the resultant signal passed on to the handpiece. This can be used to control the magnitude of the activation of the tool—e.g. the amplitude of the ultrasonic energy emitted by the generator in the handpiece of an ultrasonically-vibratable tool.

The switch head40may be detachable from the handpiece for cleaning. Alternatively, it would be a disposable item, replaced for each surgical procedure.