Retractable electrosurgical electrode

[0001] This application claims priority of U.S. Provisional Patent Application Ser. No. 60/710,522 filed Aug. 23, 2005, and U.S. Provisional Patent Application Ser. No. 60/763,693 filed Jan. 31, 2006, both of which are incorporated herein by reference.

[0002] This invention relates to an electrode or probe for use with electrosurgery apparatus such as electrocutting or electrocoagulating systems and more particularly to an electrode which is normally covered by a housing and may be extended from the housing to allow a surgeon to perform an electrosurgical process and automatically retracts at the end of the process.

[0003] In electrosurgery a radiofrequency generator is adapted to be connected to a handheld or robotically held probe or electrode which the surgeon brings into contact with tissue. Depending upon the frequency of the generated current, the electrode may either cauterize the tissue or, at a higher frequency, cut the tissue.

[0004] When the electrode tip is accidentally brought into contact with body tissue on the patient or the surgeon, the tissue may be punctured or otherwise damaged in a potentially serious manner.

[0005] It has been proposed to provide an electrosurgical electrode with an insulating housing that allows the tip to be retracted within the housing to prevent accidental damage by contact with the tip. For example, in U.S. Pat. No. 6,569,161, springs within the device apparently urge the tip into an extended position with respect to the housing. After use the electrode is retracted back into the housing by pressing the tip of the electrode against a surface to cause a needle to retract back into the housing. It is apparently locked into this retracted position until released by a switch 24. Accordingly, the normal position, or default position, of the device is with the electrode extended and it may be retracted into the housing by forcing the extending spring into a retracted position. This design appears to be inherently unsafe in that the failure of the trigger mechanism will allow the electrode to be extended into its potentially dangerous position.

[0006] The present invention is therefore directed toward an electrosurgical electrode or probe which is normally surrounded by an insulated housing so as to avoid accidental injury to the patient and surgeon. When the surgeon desires to utilize the probe, he depresses a trigger which either extends the electrode from the housing, to an operative position, or allows a section of the housing to retract, exposing the electrode tip, and simultaneously connects the electrode to a conductor connected to the generator so as to provide cutting or coagulating currents to the electrode.

[0007] When the trigger is released the electrode is automatically drawn back into its retracted position or the cover section extends over the tip. Thus, in the absence of a depressing force on one of the triggers of the device, the probe will be safely disposed in its retracted position.

[0008] While retractable electrodes formed in accordance with tie present invention could be designed to either cut or coagulate, a preferred embodiment of the invention is operative to alternatively cut or coagulate. The unit is equipped with a pair of triggers which may be depressed by the surgeon. By depressing one of the triggers, the electrode is extended and simultaneously connected to a conductor providing coagulating currents. Upon release of the trigger, the electrode automatically retracts within the housing. By depressing the other trigger, the electrode is extended from the housing and connected to a conductor which provides cutting currents from the radiofrequency generator. Again, when the cutting trigger is released the electrode automatically retracts within the housing.

[0009] In the preferred embodiment of the invention the proximal end of the electrode is connected to one end of an extension spring having its other end connected to the housing. Depression of either one of the triggers exerts a force on a cam connected to the needle, forcing the electrode out of the housing and extending the spring so that it imposes a retracting bias on the electrode. When the trigger is released the spring automatically returns the electrode to within the housing. In the preferred embodiment the electrode is retained in a pencil type housing so that the surgeon may hold it in one hand and conveniently depress either the cutting or the coagulating triggers with one motion.

[0010] In an alternative embodiment of my invention, the electrode is fixed in a proximal end of the housing and a telescoping distal end is biased by a spring to surround the electrode tip. When a trigger is depressed the distal end is retracted against the spring bias, exposing the electrode end for use.

[0016] Referring to the drawings, the preferred embodiment of the present invention employs an elongated cylindrical electrode 10 having a tip 12 and a cylindrical body. It is normally disposed within an insulating elongated cylindrical housing 14 having a smaller diameter distal section 16 surrounding the electrode and having an opening 20 at its distal end from which the tip 12 may project. A spiral extension spring 21 has its proximal end fixed to a disc 22 formed at an end of the housing 14 and its forward end connected to the electrode 10 through a pin 24. The electrode further has a pair of inclined trigger surfaces or cams 26 and 28 connected midway along its length.

[0017] A pair of triggers 30 and 32 are each pivotably supported at the proximal ends of openings 34 and 36 which are formed in diametrically opposed sides of the needle body 14, midway along its length. A forward surface of each of the triggers 30 and 32 lies over a respective one of the cam surfaces 26 and 28. When one of the triggers is depressed downwardly toward the needle, its trigger surface forces against the surface 26 or 28 to force the electrode tip 12 forward, out of the opening 20. This extends the spring 21.

[0018] The electrodes 30 and 32 are respectively connected to conductors 38 and 40 which extend along the housing body. The conductor 38 connects to the RF generator 50 to provide a cutting current while the conductor 40 connects to the RF generator to provide a coagulating current. Alternatively, a single RF generator capable of emitting either electrocautery or electrocutting currents could be provided along with appropriate switches to provide one current or the other when the appropriate trigger is depressed. The generator is preferably grounded and the patient is grounded so that current is applied to the area contacted by the electrode 12. Other conventional arrangements may be employed to complete the electrosurgical circuit. When the trigger is released, the spring 21 retracts the electrode to within the housing and disconnects it from the associated RF generator.

[0019] The device of the present invention thus automatically disconnects electrical currents from the electrode 10 when manual pressure is removed from the associated trigger and the spring 21 moves the electrode into its retracted position within the insulated housing 14. Additionally, the same manual pressure which extends the electrode into operating position connects the electrode to the appropriate generator for either cutting currents or coagulating currents.

[0020] In a second embodiment of my invention, illustrated in FIGS. 3 and 4, an electrode 60 has its proximal end fixed to the proximal end 62 of a housing, which acts as a handle device. A cylindrical shield 64 is slidably supported relative to the handle section and is normally extended to cover and shield the electrode 60 by a spring 66, as shown in FIG. 3.

[0021] When either the cauterizing trigger 68 or the cutting trigger 70 is manually depressed as shown in FIG. 4, it connects the electrode to the appropriate terminal of the power supply 50 and forces the shield section 64 to retract, exposing the tip of the electrode 60 and compressing the spring 66. When the trigger is released, the electrode is disconnected from the power supply and the shield 64 is extended by the spring to cover the tip.

[0022] Other variations of the invention, employing other mechanisms, could be constructed within the scope of the appended claims.