Bipolar medical instrument

Details Bipolar medical instrument Bipolar medical instrument

2002-02-26

2003-12-30

Peffley, Michael (Department: 3739)

Surgery

Instruments

Electrical application

C606S206000, C606S048000

Reexamination Certificate

active

06669696

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a bipolar medical instrument comprising a tubular shaft with at least two jaw parts, which are arranged movably, one relative to the other, at the distal end of the tubular shaft and which are coupled via a joint, and each of which forms a work electrode of different polarity, with a separate current conductor being associated to each jaw part, one of such current conductors being constituted by an axially movable force transmission element that is arranged in the tubular shaft and is force-lockingly coupled to at least one of the jaw parts.
An instrument of this kind is known from DE 196 08 716 C1.
In minimally invasive surgery, an instrument of the before-mentioned kind is used for performing endoscopic operations in human or animal bodies.
The two jaw parts at the distal end of the tubular shaft are connected one with the other via a joint so that they can be opened and closed by actuation of a handle provided on the proximal end of the tubular shaft. Depending on the surgical application of such an instrument, the jaw parts are configured as cutting tools with cutting edges for cutting off tissue in the body, or as grasping tools and then with flatly abutting surfaces for grasping any cut-off tissue with the jaw parts in order to remove it from the body, or for holding an organ or a vessel so as to move it out of the operation field. Moreover, the jaw parts may have a combination of functions, namely a cutting and a grasping function.
At least one of the two jaw parts is connected with the tubular shaft in articulated fashion, while the other jaw part is connected with the tubular shaft either rigidly, or likewise in articulated fashion.
The before-mentioned kind of a medical instrument further provides that the two jaw parts each form a work electrode of different polarity that can be supplied with high-frequency (HF) current. Accordingly, each of the two jaw parts can be separately connected to one pole of a HF voltage source. By supplying the two jaw parts with a bipolar HF current it is possible, on the one hand, to increase the cutting effect by the thermal effect of the HF current in the tissue, if the tools are configured as cutting tools, while on the other hand, if they are configured as grasping tools, any tissue grasped between the jaw parts can be coagulated, and haemorrhages can be stopped, by the heat developed.
It is always a problem with such bipolar instruments to achieve a sufficient electric insulation effect between the two jaw parts in the region of the joint where the two jaw parts are in contact one with the other also in the open condition. When supplying the jaw parts with HF current, they must be electrically isolated as the two jaw parts are connected to different potentials. The problem of isolating the two jaw parts electrically is the greater the smaller such an instrument is configured in the region of the jaw parts and, thus, in the region of the joint. Small overall widths of the instrument in the area of the jaw parts are, however, especially important in minimally invasive surgery.
In the case of the instrument known from the before-mentioned DE 196 08 716 C1, the two jaw parts consist completely of metal and are, therefore, electrically conductive over their entire body. A force transmission element in the form of a push-and-pull rod is coupled with the two movable jaw parts via an articulated lever arrangement. The push-and-pull rod serves additionally as current conductor connecting one of the two jaw parts to the one pole of a HF voltage source.
In the case of this known instrument, the electric isolation of the two jaw parts is accomplished by ceramic elements which are inserted into the otherwise metallic joint of the two jaw parts and which, therefore, are themselves part of the joint. This way of electrically isolating the two jaw parts one from the other in the area of the joint provides, however, the disadvantage that when miniaturizing that instrument the size of the ceramic elements must be reduced as well. Since usually the HF frequency supplied to the jaw parts is in the range of 2.5 kV, this means that a voltage puncture may occur through the ceramic element in case that the size of the ceramic elements is reduced. Another disadvantage of the ceramic elements lies in the fact that the installed ceramic elements are subjected to frictional forces due to the movement of the jaw parts so that they may be crushed in the course of time. Further, it is a disadvantage of the configuration of the known instrument that the number of parts of the forceps in the region of the jaw parts and, thus, the constructional input and the cost of production of that known instrument, are undesirably increased.
From DE 43 12 284 A1 there has been further known a bipolar medical instrument where the jaw parts are completely made from a plastic material and stripped sections of current conductors are embedded in such plastic material. The jaw parts are configured as cutting members, consisting of plastic material, and work electrodes are embedded in the plastic material of the jaw parts. It is a disadvantage of that configuration that the current supply to the jaw parts is realized through separate electric conductors that are run through the push-and-pull rod in insulated fashion. The push-and-pull rod as such, therefore, does not serve as a current conductor in the case of these forceps. Consequently, this instrument is also connected with the disadvantage that the number of parts required is increased by the additional current conductors. An additional disadvantage lies in the fact that the end portions of the current conductors, that extend into the plastic material of the jaw parts, are subjected to bending stresses every time the jaw parts are opened or closed, so that the end portions may break in the course of time whereby the current flow to the electrodes would be interrupted.
An instrument similar to the instrument described above is known from WO 99/40861. This known medical bipolar instrument comprises, at the distal end of the shaft, two jaw parts that are movable one relative to the other, with one jaw part being movable, while the other jaw part is immovable. The movable jaw part is biased by means of a spring into a position in which it is pivoted away from the immovable jaw part, i.e. in which it occupies its open position. The actuating mechanism for the movable jaw part consists of a tubular shaft enclosing the shaft, which can be displaced in axial direction and which, when displaced in the distal direction, comes to slide onto the outer surface of the movable jaw part, whereby the latter is pressed against the immovable jaw part. The movable jaw part is coupled in articulated fashion with the immovable jaw part via a pin joint. The two jaw parts are again completely made from a plastic material, with metallic electrodes fastened to the plastic material. The current supply to the electrodes is again realized by individual conductors connected to the electrodes. Accordingly, this instrument is again connected with the disadvantage that the number of parts required is increased as a result of the additional current conductors and that the current supply lines, implemented as wires, are subjected to bending stresses during opening and closing of the jaw parts.
It is, therefore, the object of the present invention to improve a bipolar medical instrument of the before-mentioned type so that safe insulation of the jaw parts in the region of their joint is achieved without an increase in the number of parts and with lower constructional input.
SUMMARY OF THE INVENTION
According to the invention, this object is achieved with a bipolar instrument, comprising
a tubular shaft having a proximal end and a distal end;
at least two jaw parts arranged movably, one relative to the other, at said distal end of said tubular shaft and coupled one to the other via a joint, each of said at least two jaw parts forming a work electrode of different polarity;
a separate current line for each

Affiliated with

Also associated with

Rating

Bipolar medical instrument does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Bipolar medical instrument, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Bipolar medical instrument will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3146878