Abstract:
A surgical jaw instrument having two jaw pieces mounted at the distal end section of a shaft for relative reciprocal displacement, whereby at each displaced jaw piece a sliding rod is fastened at an incline to the axis of the shaft, to which a displaceable sliding element can be connected parallel to the axis of the shaft in such a way that upon displacement of the sliding element, the jaw pieces are relatively reciprocally displaced wherein a second sliding element is mounted at the first sliding element, diametrically opposed relative to the sliding rod.

Description:
BACKGROUND OF THE INVENTION 
     I. Field of the Invention 
     The invention relates to a surgical jaw instrument. 
     II. Description of the Related Art 
     Jaw instruments of this type are known, for example, from U.S. Pat. No. 6,190,386 B1 and U.S. Pat. No. 4,819,633 A. In both designs, the sliding rods are located diverging in distal direction. The distal edge of a thrust tube that can be displaced in the axial direction of the shaft is the sliding element. 
     The advantage of this known solution lies in the special simplicity of the design, whereby in particular, the complicated joint between the jaw components is avoided, as it is used in most forceps designs and scissors designs. This also results in an additional important advantage, namely, the simpler electric isolation for forceps provided with electrodes that are used, for example, for vascular electrocoagulation. In particular, in the case of bipolar design, i.e. with different terminals at the two jaw components of a forceps or a scissors, enormous technical problems arise at the joints between the jaw components with respect to the electric isolation. These are completely avoided by using the design cited at the beginning. 
     SUMMARY 
     The known design that was cited at the beginning has, however, also a significant disadvantage. Such a forceps or scissors is customarily constructed in such a way that it closes the jaw pieces upon a displacement of the thrust tube. This can take place with a high degree of force. But the reverse motion, namely the opening motion of the jaw pieces cannot take place by an actuation of the thrust tube. In known designs, this displacement is generated by using a spring. In the known designs, the sliding rods are designed as flat springs for this purpose. But the resilient forces of this design must be small, as they must be continually overcome for closing with the thrust tube. It generates only small potential opening forces, which is very disruptive in some applications, for example, when widening or any kind of separating pressure motions are to be performed with such a forceps or scissors. If such tasks are to be performed with a sufficient level of force, a special jaw instrument must be used that can perform the opening motion with a high degree of force by using kinematic inversion. 
     The objective of the present invention consists of expanding the possibilities of application for a surgical jaw instrument of the type cited at the beginning. 
     According to embodiments of the invention, a sliding rod displacing a jaw piece does not only abut on a sliding element on one side, as is known from prior art, but also on a second sliding element on the opposite side of the sliding rod. The sliding elements are fastened to each other. If the sliding elements are displaced in one direction, the jaw instrument is closed, and if they are displaced in the other direction, the jaw instrument is opened. Both functions are possible by using the same high degree of force that can be exerted upon a sliding element. The required design changes compared with a known design in prior art are relatively small. Therefore, at low cost, the applicability of a forceps or a scissors can be increased significantly, as it can not only be operated with a high degree of closing force, but also with a high degree of opening force. Thus, with a jaw instrument, both operating modes are possible with a high degree of force. The customary variants of jaw instruments are possible; these are, for example, those with only one moving and one rigid jaw piece, or those with two displaced jaw pieces. The jaw instrument can, depending on the design of the jaw pieces, be provided as forceps or as scissors, and can be designed with a longer shaft, for example, for laparoscopic surgeries. 
     A sliding rod having the design according to the invention can, as is the case in the designs cited at the beginning, be mounted at a connecting rod located in the shaft tube. Advantageously, however, the sliding rod is mounted on the shaft tube. Thereby, this mounting is designed as a joint, in order to make the angular motion of the sliding rod possible while it is gliding. Thereby, it is advantageous that the joint is designed as bendable part of the sliding rod, which makes a particularly simple construction possible, in particular then, when the sliding rod is used as a conductor. 
     In this type of construction, all displaceable jaw parts are mounted at the end of the sliding rod that is located diametrically opposed to the joint, they are thus moved as one-armed levers. In the crowded cross section of a laparoscopic jaw instrument, this severely limits the angle of deflection and thus the angle of aperture of a forceps or scissors. Hereby, the sliding rod and jaw part are connected by a bearing part, which is mounted on the shaft. Sliding rod and jaw part thus form a two-armed lever that is mounted in the center, with which a larger angular deflection is possible in the limited space. 
     It is thereby advantageous that the bearing position is designed as groove mounting that can not only absorb extremely high forces, but also makes a better electric isolation possible of gliding rod and jaw piece. 
     Preferably, at least one of the jaw pieces has an electrode. With it, the jaw instrument can be used, for example, for coagulation, whereby preferably, of course, both jaw pieces are connected bipolar, the connection of one jaw piece takes place via the shaft, and the connection of the other jaw piece is established by a connecting rod that drives the sliding elements. Thus, design elements that are already present anyway, which extend over the length of the shaft and consist of electrically conductive metal are used as terminal leads, which significantly simplifies the design. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawing illustrates embodiments of the invention schematically and by way of example. Shown are: 
         FIG. 1  shows an axial section through the distal end section of a jaw instrument according to the invention with two sliding members; 
         FIG. 2  shows a sliding member according to  FIG. 1  in a design variant; 
         FIG. 3  shows a sliding member according to  FIG. 1  in an additional design variant; and 
         FIG. 4  shows an illustration according to  FIG. 1  of a jaw instrument in a design variant. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       FIG. 1  shows a surgical jaw instrument  1  with a shaft  2  that consists of a metal tube  3  with an isolating covering  4 . 
     Two jaw pieces  5 ,  6  are located projecting over the distal end of shaft  2 , that are mounted at the distal ends of two sliding rods  7 ,  8  that are converging slanted in distal direction. The proximal ends of the sliding rods are fastened articulated with joints  9  at end pieces  10 , which are mounted at metal tube  3 . 
     Joints  9  allow a deviating motion of sliding rods  7 ,  8 . Joints  9  can, for example, be designed as hinged joints with bearing pin, in the preferred embodiment shown in  FIG. 1 , however, they are designed as bendable spring elements that make an integral connection between jaw pieces  5 ,  6  and end pieces  10  possible. 
     Sliding members  11 ,  12  engage with sliding rods  7 ,  8 , of which sliding member  11  is shown in cross section in  FIG. 1 . Both sliding members  11 ,  12  can be designed identically. As can be seen on sliding element  11 , it has two sliding elements  11   a ,  11   b  that are designed as blade edges in this exemplary embodiment, having a gap in between, in which sliding rod  7  is retained slideable. With its two sliding elements  11   a ,  11   b , sliding member  11  engages at the two sides that lie against sliding rod  7  in the plane of projection, and it can be displaced extending along sliding rod  7 . Sliding member  12  is designed exactly alike and mounted on sliding rod  8 . 
     Both sliding members  11 ,  12  are mounted via cross pieces  13  and  14  at a connecting rod  15 . If the connecting rod is pulled back in proximal direction in shaft  2 , then as a result of the sliding adjustment of the sliding members  11 ,  12  on sliding rods  7 ,  8 , sliding rods  7 ,  8  are deviated toward each other and with them jaw pieces  5 ,  6 , as it is shown by the arrows indicating the closing motion. 
     To bring about the closing motion that was described, sliding members  11 ,  12  are displaced in proximal direction and end up—with their outer sliding elements  11   b —against the outer sides of sliding rods  7 ,  8 . 
     Upon a motion in the opposite direction, connecting rod  15  is displaced in distal direction. Now, sliding members  11 ,  12  come to abut with their inner sliding elements  11   a  at the inner sides of sliding rods  7 ,  8  and press these apart within the meaning of an opening motion of jaw pieces  5 ,  6 . 
     It can be seen that both motions of the jaw pieces are brought about with the same force. 
     Preferably, the shown jaw instrument  1  is designed as bipolar forceps. Both jaw pieces  5 ,  6  are equipped with electrodes that are to be connected to different terminals of a power source. 
     In addition,  FIG. 1  shows that jaw pieces  5 ,  6  are connected electrically via the electrically conductive sliding rods  7 ,  8 . 
     In the case of jaw piece  5 , the electric connection extends over sliding rod  7 , joint  9 , and end piece  10 , all of which are electrically conductive metal parts. End piece  10  is, as shown in  FIG. 1 , fastened directly to metal tube  3 , for example, via welding or soldering that is not shown. At the proximal end of shaft  2 —not shown—the metal tube can be connected by a line  16  to a terminal of a power source that is not shown. 
     Jaw piece  6  is likewise electrically connected by its sliding rod  8 , not, however to the metal tube  3 , with which end piece  10  of sliding rod  8  is connected isolating by an adhesive connection  17 . Rather, in this case, the electric connection takes place via the sliding contact with sliding member  12 , which is connected by the electrically conductive connecting rod  15  and a sliding contact  18  to an electric line  19  that extends to the second terminal of a power source that is not shown. To avoid a short circuit between the two terminals, cross piece  13  is connected with sliding member  11  by an isolator  20 . 
       FIGS. 2 and 3  show embodiment variants of sliding bodies  11 ,  12  of  FIG. 1 . Sliding member  21  of  FIG. 2  differs from sliding member  11  of  FIG. 1  thereby, that the two diametrically opposed sliding elements  21   a  and  21   b  that are designated for sliding contact with sliding rod  7 , are not designed as sharp cutting blades according to  FIG. 1 , but as rounded surfaces. 
     Sliding member  31  of  FIG. 3  has much broader, flat contact surfaces  32  with which attachment is possible in a large area at sliding rod  7 . As a result, the forces that are to be transmitted can be introduced in a large area and a safe electric contact can also be achieved. 
       FIG. 4  shows an embodiment variant of the design shown in  FIG. 1 , which is shown highly simplified. To the extent possible, the same reference numbers as those in  FIG. 1  are used. 
     In jaw instrument  41  that is shown here, the jaw parts  5 ,  6  are connected with their pertaining sliding rods  7 ,  8  by curved pieces  42 ,  43 . Curved pieces  42 ,  43  are respectively mounted in a groove that is delimited by concentric surfaces. Between curved pieces  42  and  43 , the groove is delimited by the outer surface of a pin  44 . The outer groove surfaces are formed by retaining pieces  45  and  46 . Pin  44  and retaining pieces  45  and  46  are fastened at the shaft, which is shown only with metal tube  3  in  FIG. 4 . 
     The pivoting operation of sliding rods  7 ,  8  takes place with sliding members  11  and  12  in the design in  FIG. 1 , which are correspondingly connected with connecting rod  15 . 
     Jaw piece  5  and sliding rod  7  form a two-armed lever that is connected by curved piece  42 , just like jaw piece  6  is connected with sliding rod  8  by curved piece  43 . These two two-armed levers can be deviated around the axis of deviation extending in the center of pin  44  perpendicular to the plane of projection, whereby the curved pieces  42  and  43  run against the outer surface of pin  44  with their inner surface, and the outer sides of curved pieces  42  and  43  are retained against pin  44  by the abutting concentric surfaces of retaining pieces  45  and  46 . 
     Thereby, a pivoting bearing of jaw pieces  5 ,  6  results with pivoting drive via sliding rods  7 ,  8  that operates, in the final analysis, just like in the embodiment in  FIG. 1 . Only the direction of motion is the reverse. As the arrows in  FIG. 4  show, jaw  5 ,  6  is closed when connecting rod  15  is displaced in distal direction. Even in this design, a high degree of force can be applied in the direction of opening as well as in the direction of closing. 
     Even the design of  FIG. 4  can be equipped with electric load of jaw pieces  5 ,  6 , whereby here, particularly simple design relationships result. The details of the electric connection are not shown in  FIG. 4 . For such, many possibilities exist. 
     Thus, for example, one of the jaw pieces  5 ,  6  can be connected by one of retention pieces  45 ,  46  in sliding contact. The other jaw piece can then, for example, be connected by pin  44  or by the other retention piece. 
     One or both jaw pieces can also be connected via sliding elements  11  or  12  and connecting rod  15 . 
     The goal of the previously described types of the electric contact of jaw pieces  5  and  6  with the aid of  FIGS. 1 and 4  is, to use, if possible, the available mechanical structures as electric conductors extending over the length of shaft  2 , i.e. metal tube  3 , for example, and connecting rod  15 . However, simpler types of contact are also possible, whereby, for example, in the design of  FIG. 1 , both end pieces  10  are connected isolating with an adhesive connection  17 , and are contacted with isolated electric cables—not shown—that run through tube  3  and are connected to lines  16  and  19 . 
     Jaw pieces  5 ,  6  that are shown in  FIGS. 1 and 4  can, as illustrated, be the jaw pieces of a forceps, but in a somewhat different execution of the design, also be the cutting blades of a scissors. Even when designed as scissors, a bipolar electric connection would be advantageous.