DE20309774U1 - Surgical instrument couple has a form/fit union with the power transmission link - Google Patents

Abstract

A surgical instrument (10) has a shaft (12) defining a longitudinal shaft (12) whose distal end has a tool (14, 16) linked to a hand-operated lever at the proximal end. The link (22) is axially coupled to the tool (14, 16). In the engaged presentation, the couple (24) is a form/fit union with the link. The couple moves axially within the shaft.

Description

A 57 470 u Applicant: AESCULAP AG & Co. KG

June 20, 2003 At Aesculap Square

z-286 78532 Tuttlingen

Surgical instrument

The present invention relates to a surgical instrument with a shaft defining a longitudinal axis, with a tool movably mounted at a distal end of the shaft and with a force transmission member axially movably mounted in the shaft for transmitting tensile and/or thrust forces exerted at the proximal end of the instrument to the force transmission member for moving the tool.

Surgical instruments of the type described above are known in many different forms, for example in the form of endoscopic tubular shaft instruments. It is necessary to connect the force transmission element, which is movably mounted in the shaft and is often designed as a push and pull rod, to one or more movably mounted tools, for example jaws of forceps or scissors, in such a way that the jaws can be moved in the desired manner. Such a connection requires a great deal of design effort. In addition, assembling the instrument can be very complex.

It is therefore an object of the present invention to improve a surgical instrument of the type described above in such a way that the force transmission member can be connected to the at least one tool in a simple manner.

This object is achieved in a surgical instrument of the type described above in that a coupling device is provided for axially connecting the force transmission member with

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the at least one tool in a coupling position, that the coupling device in the coupling position is positively and/or non-positively connected to the force transmission member and that the coupling device is axially guided in the shaft.
5

Developing a surgical instrument of the type described above in this way has the advantage that no additional connection has to be made between the force transmission member and the coupling device when assembling the instrument. The positive and/or force-locking connection between the two parts makes an additional connection process, such as gluing or soldering, superfluous. The coupling device cannot come loose from the force transmission member because the coupling device itself is guided in the shaft and the shaft thus serves as a securing element which holds the coupling device and the force transmission member in the coupling position.

It is advantageous if the coupling device has at least one coupling element that at least partially surrounds a distal end section of the force transmission member. In this way, the coupling device can be designed to be particularly short in the direction of the longitudinal axis. By partially encompassing the force transmission member by the at least one coupling element, the required positive and/or non-positive connection is securely held after the coupling device has been introduced into the shaft with the force transmission member.

It is advantageous if two coupling elements are provided that are essentially half-shell-shaped. These allow for easy

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It is possible to completely enclose the distal end of the force transmission element so that it is securely connected to the coupling device in the coupling position. It is also conceivable to design both coupling elements identically, which further minimizes the design effort.
5

According to a preferred embodiment of the invention, an anti-twist device can be provided to prevent rotation of the coupling device about the longitudinal axis of the shaft. This design ensures that the at least one tool movably mounted at the distal end of the shaft can be guided unchanged relative to the shaft, even if the force transmission member is rotated about the longitudinal axis of the shaft. In other words, the movably mounted tool can be rotated together with the shaft about its longitudinal axis without the force transmission member being rotated.

A particularly simple construction of the instrument is achieved if the anti-twisting device comprises at least one recess extending in the longitudinal direction of the shaft and a corresponding projection, if the at least one recess is arranged on the coupling device or on the shaft and if the projection is arranged on the shaft or on the coupling device. By immersing the projection in the recess, rotation about the longitudinal axis of the shaft is prevented.

The construction of the instrument becomes even simpler if the recess includes a flattened area on the coupling device. This creates large contact surfaces on the coupling device and on the shaft, which

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are easy to manufacture and ensure optimal anti-twisting function.

It is advantageous if at least one coupling receptacle is provided on the force transmission member or on the at least one coupling element and if, in the coupling position, at least one coupling projection of the at least one coupling element or of the shaft extends into the coupling receptacle. By engaging the coupling receptacle and the coupling projection in the coupling position, a positive and/or non-positive connection between the at least one coupling element and the force transmission member is produced in a simple manner.

A particularly simple construction of the instrument is achieved if the coupling receptacle comprises a groove that is open transversely to the longitudinal direction and if the coupling projection comprises a projection that protrudes transversely to the longitudinal direction. By orienting the groove and the coupling projection transversely to the longitudinal direction, an axial securing of the at least one coupling element relative to the force transmission member can be achieved in a simple manner.

It would be conceivable to provide several coupling elements and to secure them to the force transmission element only via positive and/or non-positive connections. However, it is advantageous if several coupling elements are provided and if the coupling elements are connected to each other positively and/or non-positively in the coupling position. This additional connection ensures particularly good guidance of the coupling elements in the

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shaft and a particularly good connection of the coupling elements with the power transmission member is achieved.

A particularly simple possibility of connecting several coupling elements to one another is realized according to a preferred embodiment of the invention in that each of the coupling elements has a toothing corresponding to a toothing of another coupling element and that the toothings of different coupling elements engage one another in a form-fitting manner in the coupling position.

In principle, the teeth could be designed to point in the direction of the longitudinal axis of the shaft. In order to achieve a particularly compact overall structure of the instrument, however, it is advantageous if the teeth include projections that protrude in the circumferential direction of the shaft.

Instead of or in addition to a toothing, it can be advantageous if each of the coupling elements has recesses corresponding to the toothing of another coupling element.

It is advantageous if the force transmission member can be rotated about the longitudinal axis of the shaft in the coupling position on the coupling device. This allows the coupling device and thus also the at least one tool to be rotated relative to the force transmission member. If the coupling device is secured against rotation relative to the shaft, the shaft with a tool movably mounted on it can then be rotated relative to the force transmission member.

• *

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It is advantageous if a guide device is provided for transforming an axial movement of the force transmission member into a movement of the tool in the coupling position. A desired movement of the at least one tool can be specified using the guide device.

The construction of the instrument is particularly simple if at least one tool is pivotably mounted about a pivot axis running transversely to the longitudinal axis of the shaft.

According to a preferred embodiment of the invention, it can be provided that the guide device comprises a guide recess and a guide projection, that the at least one tool or the coupling device has the guide recess and that the coupling device or the at least one tool has the guide projection which is guided in the coupling position in the guide recess during an axial movement of the force transmission member. This design allows the at least one tool to be positively guided as a result of a movement of the coupling device, so that it can be moved in the desired manner.

In order to ensure safe guidance in every position of the at least one tool, it can be advantageous if each of the coupling elements has a guide projection or a guide recess.

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To prevent a relative movement of the force transmission member and the coupling device towards each other, it may be advantageous if the coupling device has a proximal stop for the distal end of the force transmission member.

According to a preferred embodiment of the invention, it can further be provided that the coupling device has a proximal stop for the distal end of the force transmission member for preventing a relative movement of the force transmission member and the coupling device away from each other.

Alternatively or additionally, in order to prevent a relative movement of the force transmission member and the coupling device away from one another and/or towards one another, it can be provided that the coupling device comprises at least one retaining element engaging a retaining member of the force transmission member. By engaging the retaining element on the retaining member in the coupling position, an axial relative movement between the force transmission member and the coupling device can be prevented.

In order to be able to use the instrument as a bipolar instrument, it can be advantageous if at least one coupling element is made of an electrically non-conductive material, in particular of a ceramic. In this way, parts of the instrument can be electrically separated from one another. The at least one coupling element thus serves two purposes, on the one hand

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the connection with the power transmission element, on the other hand the electrical insulation between two current-carrying parts.

The following description of a preferred embodiment of the invention serves to explain it in more detail in conjunction with the drawing. They show:

Figure 1: a longitudinal sectional view of a pair of scissors according to the invention;
Figure 2: an enlarged view of detail A in Figure 1;
Figure 3: a sectional view taken along line 3-3 in Figure 2;

Figure 4: a partially broken plan view of the scissors in the direction of arrow B in Figure 2;

Figure 5: a longitudinal sectional view of the enlarged detail area A similar to Figure 2; and

Figure 6: a perspective view of a coupling element.

Figure 1 shows a longitudinal sectional view of a pair of bipolar scissors, designated overall by the reference numeral 10, designed as an endoscopic tubular shaft instrument.

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The bipolar scissors 10 comprise an elongated, tubular shaft 12, at the distal end of which two scissor blades 14 and 16 which can be pivoted relative to one another are mounted on a bearing pin 18 which penetrates the shaft 12 on both sides and transversely to a longitudinal axis 20 of the shaft 12.

To move the scissor blades 14 and 16, a drive body 24 is arranged at a distal end of a push and pull rod 22 which is longitudinally displaceable in the direction of the longitudinal axis 20 in the shaft 12. The drive body 24 is provided with two guide slots 26 into which bearing pins 28 projecting transversely to the longitudinal axis 20 from the scissor blades 14 and 16 are inserted and are positively guided as a result of an axial displacement of the drive body 24, whereby the scissor blades 14 and 16 are opened or closed.

At its proximal end 30, the shaft 12 is received in a longitudinal bore 32 of a fixed handle part 34, from which a fixed branch 36 with a finger opening 38 extends away from the longitudinal axis 20 essentially transversely. On the handle part 34, a second branch 40 is pivotally mounted in a recess 42 open in the proximal direction about a bearing pin 44 passing through the recess 42 transversely to the longitudinal axis 20 and has a further finger opening 46 at its free end.

A proximal end of the push and pull rod 22 is provided with a short cylindrical head 48, which positively engages and is held in a single-stage widening bearing groove 50 of a bearing cylinder 52. The push and pull rod 22 protrudes from the bearing groove 50 and is covered with an electrical insulating layer 54. A longitudinal axis of the bearing cylinder

- 10-A
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52 extends transversely to the longitudinal axis 20. The bearing cylinder 52 is held on the branch 40 near the bearing pin 44 in a bearing bore 56 which extends transversely to the longitudinal axis 20 and includes a slot 58 widening from the center of the bearing bore 56 in the distal direction.
5

Like the push and pull rod 22, the shaft 12 is also surrounded by an electrically insulating layer 60. Both the shaft 12 and the push and pull rod 22 are connected in a manner not shown in detail to a bipolar connection 62, via which the bipolar scissors 10 can be connected to an electrical power supply unit by means of cables. An electrical connection is made to one of the two scissor blades 14 and 16, which are insulated relative to one another, via both the push and pull rod 22 and the shaft 12. This makes it possible, for example, to conduct a high-frequency current over the scissor blades 14 and 16 to coagulate tissue and to sever the coagulated tissue following the coagulation process.

Furthermore, a rotary knob 64 is provided which is rotationally fixed relative to the shaft 12, but which can be rotated relative to the handle part, so that the distal end of the bipolar scissors 10 with the two scissor blades 14 and 16 can be rotated about the longitudinal axis 20 relative to the two branches 36 and 40.

Figure 2 shows an enlargement of section A in Figure 1. The drive body 24, which is composed of two half-shells 66 and 68, is used to move the two scissor blades 14 and 16. The two half-shells 66 and 68 are constructed identically and are essentially designed in the form of half a cylinder that is cut in the longitudinal direction. To assemble

- 11 A
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Both half shells 66 and 68 each have two pairs of connecting pins 72 projecting in the circumferential direction, as well as two pairs of recesses 74 receiving them. The recesses 74 and the connecting pins 72 are formed alternately along the edge of the half shells 66 and 68 running parallel to the longitudinal axis 20. In the assembled state, i.e. in a coupling position in which the two half shells 66 and 68 are connected to one another and connect the push and pull rod 22 to the two scissor blades 14 and 16, the two half shells 66 and 68 form a rod receptacle 70 in the form of a bore on the proximal side. This tapers in one step over a short section and then widens again in diameter in one step, so that an annular projection 76 is formed between the rod receptacle 70 and an annular groove 78.

A distal end of the push and pull rod 22 has an annular groove 80 corresponding to the annular projection 76 and an adjoining cylindrical head 82 which is formed corresponding to the annular groove 78.

On the distal side, both half shells 66 and 68 are provided with essentially V-shaped recesses 84 and 86 that are open in the distal direction, with one of the two guide slots 26 being incorporated in each recess in the direction of the shaft 12. The two guide slots 26 form a groove that is open transversely to the longitudinal axis 20 and toward it, into which the bearing pins 28 of the scissor blades 14 and 16 each penetrate transversely to the longitudinal axis 20 and pointing away from it. The guide slots 26 are slightly curved.

- 12-A
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To assemble the front end of the bipolar scissors 10, first the two scissor blades 14 and 16 are inserted with their bearing pins 28 into the respective guide slots 26 and the push and pull rod 22 is inserted with its head 82 into the annular groove 78. Furthermore, a contact foil or a contact sheet (not shown in the figures) is inserted between the two scissor blades 14 and 16, which rests against the head 82 of the push and pull rod 22. One of the two scissor blades 14 and 16 is electrically insulated relative to the bearing pin 18, for example by a bearing bush made of a non-conductive material, such as a ceramic, which surrounds the bearing pin 18. In this way, one scissor blade is also insulated from the other scissor blade, so that an electrical connection of the contact foil is only made to one scissor blade. It is thus possible to conduct an electrical current from the bipolar connection 62 via the push and pull rod 22 and the contact foil to one of the two scissor blades 14 and 16 and via the other of the two scissor blades 14 and 16, the bearing pin 18 and the shaft 12 back to the bipolar connection 62.

The two half-shells 66 and 68 are then pushed together transversely to the longitudinal axis 22 so that each connecting pin 72 of the half-shells 66 is inserted into a recess 74 of the half-shell 68 and vice versa. The half-shells 66 and 68 are not glued to one another or otherwise permanently connected to one another.

After the parts have been assembled as described, the push and pull rod 22 is inserted into the shaft 12 from the distal end until the shaft 12 surrounds the half shells 66 and 68. As soon as the half shells 66 and

- 13A
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68 are inserted into the shaft 12, the push and pull rod 22 and the scissor blades 14 are inseparably connected to one another in the axial direction, because the shaft 12 secures the half-shells 66 and 68 against loosening from the push and pull rod 22. Finally, the bearing pin 18 is inserted through holes 88 in the shaft 12 running transversely to the longitudinal axis, whereby the scissor blades 14 and 16 are fixed to the shaft 12, whereby due to a movement of the push and pull rod in the axial direction and by guiding the bearing pins 28 in the guide slots 26 only a pivoting movement of the scissor blades 14 and 16 towards or away from one another is possible.

Figure 3 shows a cross-sectional view showing the positive engagement of the connecting pins 72 of the half-shell 66 in a recess 74 of the half-shell 68 and vice versa. It can also be seen that the two half-shells 66 and 68 practically completely fill the interior of the shaft 12 and completely enclose the distal end of the push and pull rod 22. It is not possible to release the connection between the two half-shells 66 and 68 forming the drive body 24 from the push and pull rod 22 in the coupling position shown in Figures 2 to 5. To do this, the drive body 24 would have to be pushed out of the distal end of the shaft.

In the plan view shown in Figure 4, it can be seen how the connecting pins 72 form a type of toothing which engages in the corresponding recesses 74 of the other coupling element, which is designed in the form of a half-shell 66 or 68.

- 14A
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In Figures 5 and 6 it can be seen particularly well that a distal side wall of the annular groove 78 forms a stop 90 which limits a movement of the push and pull rod 22 in the distal direction. In principle the same way a movement of the push and pull rod in the proximal direction is limited by an annular edge 92 which runs parallel to the stop 90 and forms a proximal side wall of the annular groove 78.

Figure 6 shows an example of a half-shell 66 which is identical to the half-shell 68. The half-shells 66 and 68 can be made either from a metal or from a ceramic.

Claims (22)

1. Surgical instrument ( 10 ) with a shaft ( 12 ) defining a longitudinal axis ( 20 ), with at least one tool ( 14 , 16 ) movably mounted at a distal end of the shaft ( 12 ) and with a force transmission member ( 22 ) axially movably mounted in the shaft ( 12 ) for transmitting tensile and/or shear forces exerted at the proximal end of the instrument ( 10 ) to the force transmission member ( 22 ) for moving the tool ( 14 , 16 ), characterized in that a coupling device ( 24 ) is provided for axially connecting the force transmission member ( 22 ) to the at least one tool ( 14 , 16 ) in a coupling position, that the coupling device ( 24 ) in the coupling position is positively and/or non-positively connected to the Power transmission member ( 22 ) and that the coupling device ( 24 ) is axially guided in the shaft ( 12 ). 2. Instrument according to claim 1, characterized in that the coupling device ( 24 ) has at least one coupling element ( 66 , 68 ) at least partially surrounding a distal end portion ( 80 , 82 ) of the force transmission member ( 22 ). 3. Instrument according to claim 2, characterized in that two essentially half-shell-shaped coupling elements ( 66 , 68 ) are provided. 4. Instrument according to one of the preceding claims, characterized in that an anti-twisting device is provided to prevent rotation of the coupling device ( 24 ) about the longitudinal axis ( 20 ) of the shaft ( 12 ). 5. Instrument according to claim 4, characterized in that the anti-twisting device comprises at least one recess extending in the longitudinal direction ( 20 ) of the shaft ( 12 ) and a corresponding projection, that the at least one recess is arranged on the coupling device ( 24 ) or on the shaft ( 12 ) and that the projection is arranged on the shaft ( 12 ) or on the coupling device ( 24 ). 6. Instrument according to claim 4 or 5, characterized in that the recess comprises a flattened portion on the coupling device ( 24 ). 7. Instrument according to one of the preceding claims, characterized in that at least one coupling receptacle ( 80 ; 78 ) is provided on the force transmission member ( 22 ) or on the at least one coupling element ( 66 , 68 ) and that in the coupling position at least one coupling projection ( 76 ; 82 ) of the at least one coupling element ( 66 , 68 ) or of the force transmission member ( 22 ) dips into the coupling receptacle ( 80 ; 78 ). 8. Instrument according to claim 7, characterized in that the coupling receptacle ( 80 ; 78 ) comprises a groove open transversely to the longitudinal direction ( 20 ) and that the coupling projection ( 76 ; 82 ) comprises a projection projecting transversely to the longitudinal direction ( 20 ). 9. Instrument according to one of the preceding claims, characterized in that several coupling elements ( 66 , 68 ) are provided and that the coupling elements ( 66 , 68 ) are positively and/or non-positively connected to one another in the coupling position. 10. Instrument according to claim 9, characterized in that each of the coupling elements ( 66 , 68 ) has a toothing ( 72 , 74 ) corresponding to a toothing (72, 74) of another coupling element ( 66 , 68 ) and that the toothings (72 , 74 ) of different coupling elements ( 66 , 68 ) engage one another in a form-fitting manner in the coupling position. 11. Instrument according to claim 10, characterized in that the toothing ( 72 , 74 ) comprises projections ( 72 ) projecting in the circumferential direction of the shaft ( 12 ). 12. Instrument according to one of claims 10 or 11, characterized in that each of the coupling elements ( 66 , 68 ) has recesses ( 74 ) corresponding to the toothing ( 72 , 74 ) of another coupling element ( 66 , 68 ). 13. Instrument according to one of the preceding claims, characterized in that the force transmission member ( 22 ) is rotatable about the longitudinal axis ( 20 ) of the shaft ( 12 ) in the coupling position on the coupling device ( 24 ). 14. Instrument according to one of the preceding claims, characterized in that a guide device ( 26 , 28 ) is provided for transforming an axial movement of the force transmission member ( 22 ) into a movement of the tool ( 14 , 16 ) in the coupling position. 15. Instrument according to one of the preceding claims, characterized in that the at least one tool ( 14 , 16 ) is pivotally mounted about a pivot axis extending transversely to the longitudinal axis ( 20 ) of the shaft ( 12 ). 16. Instrument according to one of claims 14 or 15, characterized in that the guide device ( 26 , 28 ) comprises a guide recess ( 26 ) and a guide projection ( 28 ), that the at least one tool ( 14 , 16 ) or the coupling device ( 24 ) has the guide recess ( 26 ) and that the coupling device ( 24 ) or the at least one tool ( 14 , 16 ) has the guide projection ( 28 ) which is guided in the coupling position in the guide recess ( 22 ) during an axial movement of the force transmission member ( 22 ). 17. Instrument according to claim 16, characterized in that the guide projection ( 28 ) projects substantially parallel to the pivot axis. 18. Instrument according to one of claims 3 to 17, characterized in that each of the coupling elements ( 14 , 16 ) has a guide projection ( 28 ) or a guide recess ( 26 ). 19. Instrument according to one of the preceding claims, characterized in that the coupling device ( 24 ) has a proximal stop ( 90 ) for the distal end of the force transmission member ( 22 ) for preventing a relative movement of the force transmission member ( 22 ) and the coupling device ( 24 ) towards each other. 20. Instrument according to one of the preceding claims, characterized in that the coupling device ( 24 ) has a proximal stop ( 90 ) for the distal end of the force transmission member ( 22 ) for preventing a relative movement of the force transmission member ( 22 ) and the coupling device ( 24 ) away from each other. 21. Instrument according to one of the preceding claims, characterized in that the coupling device ( 24 ) comprises at least one retaining element ( 76 ) engaging a retaining member ( 80 ) of the force transmission member ( 22 ) for preventing a relative movement of the force transmission member ( 22 ) and the coupling device ( 24 ) away from one another and/or towards one another. 22. Instrument according to one of the preceding claims, characterized in that at least one coupling element ( 66 , 68 ) is formed from an electrically non-conductive material, in particular from a ceramic.