Abstract
A tool (30) for a microinvasive surgical instrument includes a body member (40). A proximal end (41) of the body member is mechanically connected to or is configured to be mechanically coupled to a distal end (16) of a shaft (14) of a microinvasive surgical instrument (10). A first jaw (50) has a mechanically articulated connection to the body member. A second jaw (60) has a mechanically articulated connection to the body member. The first jaw and the second jaw are configured to be pivoted independently from each other. The second jaw provides the shape of a U or O at least partially encircling a fenestration (61). The tool provides open configurations, each with an angular distance between the first jaw and the second jaw. The tool provides a closed configuration with the first jaw at least partially accommodated in or capping the fenestration of the second jaw.
Claims
1. A tool for a microinvasive surgical instrument, the tool comprising: a body member with a proximal end configured to be mechanically coupled to a distal end of a shaft of the microinvasive surgical instrument; a first jaw articulated to the body member; and a second jaw articulated to the body member, wherein: the first jaw and the second jaw are configured to be pivoted independently from each other; the second jaw provides the shape of a U or O at least partially encircling a fenestration; the tool provides open configurations with each of the open configurations providing an angular distance between the first jaw and the second jaw; and the tool provides a closed configuration with the first jaw at least partially accommodated in or capping the fenestration of the second jaw.
2. The tool according to claim 1, wherein the first jaw and the second jaw are grasping jaws, whereby tissue between the first jaw and the second jaw is grasped upon the tool being transformed from at least one of the open configurations towards the closed configuration.
3. The tool according to claim 1, wherein the first jaw and the second jaw are the only jaws of the tool.
4. The tool according to claim 1, wherein the first jaw provides a grasping surface area and a U-shaped or O-shaped edge of the grasping surface area.
5. The tool according to claim 1, wherein the second jaw provides a cutting edge exposed and averted from the first jaw in at least one configuration of the tool.
6. The tool according to claim 1, wherein in the closed configuration, the contour of the first and second jaws is essentially wedge-shaped.
7. The tool according to claim 1, wherein a cross section of the fenestration at least partially encircled by the second jaw is complementary to a cross section of the first jaw such that at least a portion of the first jaw is configured to pass through the fenestration from a first side of the second jaw to a second side of the second jaw averted from the first side of the second jaw.
8. The tool according to claim 7, wherein: the first jaw provides, at first jaw sides averted from each other, a first surface area with a U-shaped or O-shaped cutting edge and a second surface area with a U-shaped or O-shaped blunt edge; the second jaw provides, at second jaw sides averted from each other, a first U-shaped or O-shaped surface area with a U-shaped or O-shaped cutting edge and a second U-shaped or O-shaped surface area with a U-shaped or O-shaped blunt edge; in a cutting open configuration of the tool, the cutting edge at the second jaw faces the cutting edge at the first jaw; and in a grasping open configuration of the tool, the blunt edge at the second jaw faces the blunt edge at the first jaw.
9. The tool according to claim 8, wherein in a cutting action transforming the tool from the cutting open configuration towards the closed configuration, the cutting edge at the first jaw slides against or passes the cutting edge at the second jaw in a tissue cutting motion.
10. The tool according to claim 8, wherein in a grasping action transforming the tool from the grasping open configuration to the closed configuration, the blunt edge at the first jaw is moved towards the blunt edge at the second jaw.
11. The tool according to claim 1, wherein both the first jaw and the second jaw are pivotable about the same pivot axis.
12. The tool according to claim 1, wherein the tool provides at least two configurations of: an elevating closed configuration in which the first jaw is arranged at least partially inside the fenestration in the second jaw, wherein the second jaw, by abutting on or being located close to a cutting edge at the first jaw, prevents the cutting edge at the first jaw from cutting tissue, and the first jaw, by abutting on or being located close to a cutting edge at the second jaw, prevents the cutting edge at the second jaw from cutting tissue; a grasping open configuration in which, tissue being grasped between the first jaw and the second jaw upon the first and second jaws are moved towards each other from the grasping open configuration towards the closed configuration; a cutting open configuration in which tissue being cut between cutting edges at the first and second jaws sliding against or passing each other upon the first and second jaws are moved towards each other from the cutting open configuration towards the closed configuration; and a curettage configuration in which a cutting edge at the second jaw averted from the first jaw is exposed and configured to cut tissue when the tool is moved parallel to a surface of the tissue.
13. The tool according to claim 12, wherein: in the elevating closed configuration, the first and second jaws are in any angular position within a first predetermined range of angular positions relative to the body member, with a first predetermined angular relation between the first jaw and the second jaw; in the grasping open configuration, each of the first jaw and the second jaw is in any angular position within a respective second predetermined range of angular positions relative to the body member, with a second predetermined angular relation between the first jaw and the second jaw; in the cutting open configuration, each of the first jaw and the second jaw is in any angular position within a respective third predetermined range of angular positions relative to the body member, with a third predetermined angular relation between the first jaw and the second jaw; in the curettage configuration, the first and second jaws are in any angular position within a fourth predetermined range of angular positions relative to the body member, with a fourth predetermined angular relation between the first jaw and the second jaw.
14. A microinvasive surgical instrument, comprising: a shaft with a proximal end and a distal end; a tool comprising a body member with a proximal end configured to be mechanically coupled to the distal end of the shaft of the microinvasive surgical instrument, a first jaw articulated to the body member, a second jaw articulated to the body member, wherein the first jaw and the second jaw are configured to be pivoted independently from each other, the second jaw provides the shape of a U or O at least partially encircling a fenestration, the tool provides open configurations with each of the open configurations providing an angular distance between the first jaw and the second jaw, and the tool provides a closed configuration with the first jaw at least partially accommodated in or capping the fenestration of the second jaw, wherein the proximal end of the body member of the tool is mechanically connected to the distal end of the shaft; and a handle assembly comprising a fixed handle mechanically connected to the proximal end of the shaft and controls manually movable relative to the fixed handle and mechanically coupled to the first and second jaws.
15. The microinvasive surgical instrument according to claim 14, wherein the handle assembly is configured to fix at least one of the first jaw and the second jaw in a manually adjustable position within a predetermined range of positions relative to the body member.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0069] In the drawings:
[0070] FIG. 1 is a schematic representation of a microinvasive surgical instrument;
[0071] FIG. 2 is another schematic representation of the instrument displayed in FIG. 1;
[0072] FIG. 3 is another schematic representation of the instrument displayed in FIGS. 1 and 2;
[0073] FIG. 4 is another schematic representation of the instrument displayed in FIGS. 1 through 3;
[0074] FIG. 5 is a schematic representation of a cross section of the tool of the instrument displayed in FIGS. 1 through 4;
[0075] FIG. 6 is another schematic representation of a cross section of the tool displayed in FIG. 5;
[0076] FIG. 7 is another schematic representation of a cross section of the tool displayed in FIGS. 5 and 6;
[0077] FIG. 8 is another schematic representation of the tool displayed in FIGS. 5 through 7;
[0078] FIG. 9 is a schematic representation of another microinvasive surgical instrument; and
[0079] FIG. 10 is a schematic representation of another microinvasive surgical instrument.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0080] Referring to the drawings, FIG. 1 shows a schematic representation of a microinvasive surgical instrument 10 with a proximal end 11 and a distal end 12. The microinvasive surgical instrument 10 comprises a shaft 14 with a proximal end 15 and a distal end 16. In the example displayed in FIG. 1, the shaft 14 is straight and rigid and has a longitudinal axis 18 parallel to the plane of projection of FIG. 1.
[0081] The proximal end 15 of the shaft 14 is permanently mechanically connected or detachably coupled to a handle assembly 20 forming the proximal end 11 of the instrument 10. The handle assembly 20 comprises a fixed handle 23 which is rigidly and permanently connected or rigidly but detachably coupled to the proximal end 15 of the shaft 14. Furthermore, the handle assembly 20 comprises controls (25, 26) manually movable relative to the fixed handle and mechanically coupled to the first and second jaws (50, 60). On of the controls is a moveable handle 25 which is pivotable relative to the fixed handle 23 about an axis orthogonal to the longitudinal axis 18 of the shaft 14 and orthogonal to the plane of projection of FIG. 1. Another of the controls is a rotatable wheel 26, which is rotatable about the longitudinal axis 18 of the shaft 14 and located between the proximal end 15 of the shaft 14 and the handle assembly 20.
[0082] The distal end 16 of the shaft 14 is permanently mechanically connected or detachably coupled to a tool 30. To be more specific, a proximal end 31 of the tool 30 is permanently connected or detachably coupled to the distal end 16 of the shaft 14. A distal end 32 of the tool 30 forms the distal end 12 of the instrument 10.
[0083] The tool 30 comprises a body member 40. The proximal end 41 of the body member 40 forms the proximal end 31 of the tool 30. Close to the distal end 42 of the body member 40, an axle 44 is provided. The axle 44 defines an axis 48 orthogonal to the plane of projection of FIG. 1 and connects the body member 40 to a first jaw 50 and to a second jaw 60 in an articulated manner. In other words, the axle 44 forms a hinge between the distal end of the body member 40 and proximal ends of the first jaw 50 and the second jaw 60.
[0084] Both jaws 50, 60 can be moved (pivoted about the axis 48) independent from each other. The jaws 50, 60 are mechanically coupled to the moveable handle 25 and the control 26 of the handle assembly 20. For instance, the first jaw 50 is coupled to the moveable handle 25, and the second jaw 60 is coupled to the control 26 of the handle assembly 20. A surgeon can pivot the second jaw 60 by manually rotating the control 26 about the axis 18 of the shaft 14 and pivot the first jaw 50 by manually moving the moveable handle 25 relative to the fixed handle 23 of the handle assembly 20. As an alternative, the control 26 of the handle assembly 20 can be mechanically coupled to both the first jaw 50 and the second jaw 60 such that any motion of the control 26 of the handle assembly 20 causes both first and second jaws 50, 60 to pivot in the same direction, while the movable handle 25 causes the first jaw 50 to pivot without moving the second jaw 60. This alternative configuration allows the second jaw to be fixed in place while it is used for curettage.
[0085] The first jaw 50 provides, at two sides averted from each other, a first surface area 52 and a second surface area 55 averted from the first surface area 52. In the configuration displayed in FIG. 1, the first surface area 52 of the first jaw 50 is oriented towards, or faces the second jaw 60.
[0086] The second jaw 60 provides the shape of a U the ends of which are mechanically connected to the body member 40 by means of the axle 44 in an articulated manner. The second jaw 60 (to be more specific: together with the axle 44) encircles a fenestration 61. Two arms of the U-shaped second jaw 60 are parallel or essentially parallel to the plane of projection of FIG. 1. A third section of the U-shaped second jaw 60 is orthogonal or essentially orthogonal to the plane of projection of FIG. 1, and the hidden part of the contour of its cross section is indicated by a dashed line in FIG. 1.
[0087] The second jaw 60 provides, at two sides averted from each other, a first U-shaped surface area 62 and a second U-shaped surface area 65. In the configuration displayed in FIG. 1, the first surface area 62 of the second jaw 60 is oriented towards, or faces the first jaw 50.
[0088] An edge 53 at the first jaw 50 forms a lateral boundary of the first surface area 52 of the first jaw 50. An edge 63 at the second jaw 60 forms a lateral boundary between the first surface 62 of the second jaw 60 and the fenestration 61 encircled by the first jaw 60. Both the edge 53 of the first surface area 52 at the first jaw 50 and the edge 53 at the second surface area 62 at the second jaw 60 are configured as cutting edges.
[0089] Another edge 56 at the first jaw 50 is blunt and forms a lateral boundary of the second surface area 55 of the first jaw 50. In the example displayed in FIG. 1, the second surface area 65 of the second jaw 60 provides another cutting edge 66. In the configuration displayed in FIG. 1, the cutting edge 66, together with the second surface area 65, is averted from the first jaw 50.
[0090] When the tool 30together with the entire instrument 10is moved parallel to a surface of tissue in a proximal direction (in FIG. 1: to the right), the cutting edge 66 at the second jaw can cut tissue like a conventional loop curette. If, while using the instrument like a loop curette, the fenestration 61 becomes filled with excised tissue, obscuring the users vision or the instrument's functionality, the first jaw 50 may be closed in order to eject the collected tissue from the fenestration 61.
[0091] In the example displayed in FIG. 1, the cross section (in a plane comprising the axis 48 defined by the axle 44) of the fenestration 61 in the second jaw 60 corresponds to the cross section of the first jaw 50 such that the first jaw 50 can be passed through the fenestration 61 in the second jaw 60. Clearance between the first jaw 50 and the second jaw 60 is such that tissue between the first jaw 50 and the second jaw 60 is cut between the cutting edge 53 at the first surface area 52 of the first jaw 50 and the cutting edge 63 at the first surface area 62 of the second jaw 60 when the first jaw 50 is moved into the fenestration 61 in the second jaw 60.
[0092] FIG. 2 shows a schematic representation of the instrument 10 described above with reference to FIG. 1 in a second, closed configuration. The configuration of the instrument 10 displayed in FIG. 2 differs from the configuration displayed in FIG. 1 in that the first jaw 50 is located inside a fenestration 61 encircled by the second jaw 60. The first jaw 50 essentially or entirely fills the fenestration 61 in the second jaw 60.
[0093] In the closed configuration displayed in FIG. 2, the first and second jaws 50, 60 together form a tool for blunt dissection, in particular for elevation or separation of tissue layers. For this purpose, the first and second jaws 50, 60 are wedge-shaped, viz. their heights (measured in the plane of projection of FIGS. 1 and 2 in a direction orthogonal to the jaws' 50, 60 longitudinal extension) decrease from the body member 40 to the distal end 32 of the tool 30. As the first jaw 50 is located within the fenestration 61 of the second jaw 60, the total height of the closed jaws is small compared to a conventional jawed instrument. When in the configuration shown in FIG. 2, the cutting edges 66, 52, 53, 63 are all shielded from damaging contact with tissue by the other jaw.
[0094] When, in the open configuration of the tool 30 displayed in FIG. 1, tissue is located between the first jaw 50 and the second jaw 60 and thereafter the first and second jaws 50, 60 approach each other, the tool 30 is transformed towards the closed configuration displayed in FIG. 2, and the tissue is cut between the cutting edge 53 at the first jaw 50 and the cutting edge 63 at the second jaw 60.
[0095] FIG. 3 shows another schematic representation of the instrument 10 described above with reference to FIGS. 1 and 2 in a further configuration.
[0096] The configuration displayed in FIG. 3 is similar to the closed configuration displayed in FIG. 2 in that the first jaw 50 is positioned in the fenestration 61 of the second jaw 60. Thus, the configuration of the tool 30 displayed in FIG. 3 is a closed configuration like the configuration displayed in FIG. 2.
[0097] The configuration in FIG. 3 differs from the configuration displayed in FIG. 2 in that the angular position of both first and second jaws 50, 60 relative to the body member 40 and, thus, relative to the shaft 14 and the longitudinal axis 18 of the shaft 14 is different. While in the closed configuration displayed in FIG. 2, both first and second jaws 50, 60 are positioned as a straight or linear distal extension of the shaft 14, in the configuration displayed in FIG. 3, the first and second jaws 50, 60 form an angled or bent distal extension of the shaft 14.
[0098] Thus, the tool 30 facilitates blunt dissection of tissue at a range of different angular positions of the first and second jaws 50, 60 relative to the shaft 14. If tissue needs to be elevated at different angles, the surgeon does not need to exchange the instrument but can simply adjust the tool by altering the angular position of the first and second jaws 50, 60 relative to the shaft 14.
[0099] Similar to the closed configurations displayed in FIGS. 2 and 3 with different angular positions of the first and second jaws 50, 60 relative to the body member 40 and the shaft 14, an open configuration as displayed in FIG. 1 can be provided with a range of different angular positions of the first and second jaws 50, 60 relative to the body member 40 and the shaft 14. The adjustability of the angular positions of both first and second jaws 50, 60 provides a flexibility superseding many changes of instruments during a microinvasive surgical operation and considerably reduces the risk of trauma to the patient and the time required for the operation.
[0100] FIG. 4 shows another schematic representation of the instrument described above with reference to FIGS. 1 through 3 in a further configuration. The configuration displayed in FIG. 4 is an open configuration similar to the open configuration displayed in FIG. 1 but differs from the configuration displayed in FIG. 1 in that the first jaw 50 is located at the opposite side of the second jaw 60. Therefore, the second surface area 55 of the first jaw 50 faces the second surface area 65 of the second jaw 60. The first surface area 52 of the first jaw 50 and the first surface area 62 of the second jaw 60 are averted from each other. If the characteristics of the second surface areas 55, 65 of the jaws 50, 60 are different from the characteristics of the first surface areas 52, 62 of the first and second jaws 50, 60, the open configuration displayed in FIG. 4 can provide a functionality different from the functionality of the open configuration displayed in FIG. 1.
[0101] In particular, the lateral edge 56 of the second surface area 55 of the first jaw 50 is blunt rather than cutting. In this case, tissue between the first and second jaws 50, 60 is not cut but merely grasped when the first and second jaws 50, 60 are, starting from the open configuration displayed in FIG. 4, moved towards each other. For this purpose, the cutting edge 66 at the second surface area 65 at the second jaw 60 can be positioned distant from the fenestration 61. As an alternative, the cutting edge 66 can be replaced by a blunt edge or omitted.
[0102] FIG. 5 shows a schematic representation of a cross section of the first and second jaws 50, 60 of the tool 30 of the instrument 10 described above with reference to FIGS. 1 through 4. The sectional plane of FIG. 5 is essentially orthogonal to the longitudinal axes of the first and second jaws 50, 60.
[0103] FIG. 5 displays the open configuration described above with reference to FIG. 1. The cutting edges 53, 63 at the first surface areas 52, 62 of the first and second jaws 50, 60 are facing each other. When the first and second jaws 50, 60 are moved towards each other, tissue 99 between the first and second jaws 50, 60 is cut between the cutting edges 53, 63 sliding against each other or passing each other with a sufficiently small distance or clearance. Therefore, the open configuration displayed in FIGS. 1 and 5 is called a cutting open configuration.
[0104] FIG. 6 shows a further schematic representation of a cross section of the first and second jaws 50, 60 of the tool 30 of the instrument 10 described above with reference to FIGS. 1 through 5. Again, the sectional plane of FIG. 6 is essentially orthogonal to the longitudinal axes of the first and second jaws 50, 60.
[0105] FIG. 6 displays a cross section in the open configuration described above with reference to FIG. 4. Since the edge of the second surface area 55 of the first jaw 50 is blunt and the edge 66 at the second surface area 65 of the second jaw 60 is distant from the fenestration 61, tissue 99 between the first and second jaws 50, 60 is grasped rather than cut when the first and second jaws 50, 60 are moved towards each other. Therefore, the open configuration displayed in FIGS. 4 and 6 is called a grasping open configuration.
[0106] FIG. 7 shows a further schematic representation of a cross section through the first and second jaws 50, 60 of the tool 30 of the instrument 10 described above with reference to FIGS. 1 through 6. Again, the sectional plane of FIG. 7 is essentially orthogonal to the longitudinal axes of the first and second jaws 50, 60.
[0107] In FIG. 7, a closed configuration as described above with reference to FIGS. 2 and 3 is displayed. The first jaw 50 is accommodated inside the fenestration 61 encircled by the second jaw 60. Cutting edges 53, 63, 66 at the first and second jaws 50, 60 are less exposed than in the open configurations described above with reference to FIGS. 1, 4, 5 and 6. The proximity of the second jaw 60 to the cutting edge 53 at the first surface area 52 at the first jaw 50 and the proximity of the first jaw 50 to the cutting edge 63 at the first surface area 62 at the second jaw 60 prevent these cutting edges 53, 63 from cutting tissue.
[0108] FIG. 8 shows a schematic representation of a further cross section through the tool 30 of the instrument described above with reference to FIGS. 1 through 7. The sectional plane of FIG. 8 is orthogonal to the plane of projection of FIGS. 1 through 4 and comprises the longitudinal axes 18 of the shaft 14 (which itself is not displayed in FIG. 8).
[0109] In FIG. 8, the U-shape of the second jaw 60, the fenestration 61 encircled by the second jaw 60 and the first jaw 50 located in the fenestration 61 are visible.
[0110] In the example displayed in FIGS. 1 through 8, the axis 48 defined by the axle 44 and the longitudinal axis 18 of the shaft are within the same plane which is the sectional plane of FIG. 8. Pins 75, 85 at connection rods 70, 80 coupling the first and second jaws 50, 60 to respective transmission members in the shaft 14 (not shown in FIG. 8) and holes in the first and second jaws 50, 60 corresponding to the pins 75, 85 are out of the sectional plane of FIG. 8 and, thus, are indicated in dashed lines only.
[0111] FIG. 9 shows a schematic representation of another microinvasive surgical instrument 10. Many features, characteristics and functionalities of the instrument displayed in FIG. 9 are similar to those of the instrument described above with reference to FIGS. 1 through 8.
[0112] The instrument displayed in FIG. 9 differs from the instrument described above with reference to FIGS. 1 through 8 in particular in the shape of the first and second jaws 50, 60. The second jaw 60 provides the shape of an O entirely encircling a fenestration 61. The proximal and distal ends of the fenestration 61 are indicated by dashed lines.
[0113] In the configuration displayed in FIG. 9, the first jaw 50 is partially accommodated in the fenestration 61. The first jaw 50 cannot be entirely passed through the fenestration 61 and, therefore, always remains on the same side of the second jaw 60.
[0114] In all the embodiments and variations described with reference to FIGS. 1 through 10, each of the first and second surface areas 52, 55, 62, 65 of the first and second jaws 50, 60 can be corrugated for an increased retention or holding force and a reduced risk that tissue to be grasped or cut by the tool slips away. For instance, transverse grooves or notches (parallel to the respective surface area but orthogonal to the longitudinal axis of the respective jaw 50, 60) can be provided. As far as cutting edges 53, 63 confine the surface areas 52, 62, a small distance between the corrugation and the cutting edge 53, 63 can be provided allowing uncorrugated cutting edges 53, 63. A centrally located raised grip feature may be included on the surface area 52 so that when the jaws 50, 60 are closed together they will come into contact with and grasp tissue before the opposing cutting edges 53, 63 close together and cut the tissue. The grip feature would not directly abut the cutting edges 53, 63.
[0115] FIG. 10 shows a schematic representation of another microinvasive surgical instrument 10. Many features, characteristics and functionalities of the instrument displayed in FIG. 10 are similar to those of the instrument described above with reference to FIGS. 1 through 9.
[0116] In the instrument displayed in FIG. 10, a first coupling member 71 is located inside the shaft 14. Since the coupling member 71 is not visible from outside, contours of the coupling member 71 are represented in dashed lines.
[0117] A proximal end 72 of the first coupling member 71 is mechanically coupled to the movable handle 25 of the handle assembly 20. In the example shown in FIG. 10, the first coupling member 71 is a rod. A first proximal connecting rod 77 couples the proximal end 72 of the first coupling member 71 to the movable handle 25, such that pivoting the movable handle 25 causes a translational movement of the first coupling member 71 parallel to the longitudinal axis 18 of the shaft. As an alternative, the proximal end of the first coupling member 71 is formed like a rack with a periodic arrangement of teeth, and a pinion at the movable handle 25 engages the teeth of the rack at the proximal end 72 of the first coupling member 71. As a further alternative, a region at the proximal end 72 of the first coupling member 71 can be bendable, and the proximal end 72 of the first coupling member 71 can be directly coupled to the movable handle 25 by a hinge, thereby integrating the function of a connecting rod into the first coupling member 71.
[0118] The distal end 74 of the first coupling member 71 is coupled to the first jaw 50 by a pair of connecting rods 70 as described above with reference to FIG. 8. As an alternative, the distal end 74 of the first coupling member 71 is formed like a rack with a periodic arrangement of teeth, and a pinion at the first jaw 50 engages the teeth of the rack at the distal end of the first coupling member 71. As a further alternative, a region at the distal end 74 of the first coupling member 71 can be bendable, and the distal end 74 of the first coupling member 71 can be directly coupled to the first jaw 50 by a hinge, thereby integrating the function of a connecting rod into the first coupling member 71.
[0119] In the instrument displayed in FIG. 10, a second coupling member 81 is located inside the shaft 14. Since the second coupling member 81 is not visible from outside, contours of the second coupling member 81 are represented in dashed lines.
[0120] In the example shown in FIG. 10, the second coupling member 81 is rod-like (rod shaped). A thread 28 at an inner surface of the rotatable wheel 26 engages one or more teeth 83 or one of more notches at a proximal end of the second coupling member 81.
[0121] The distal end 84 of the second coupling member 81 is coupled to the second jaw 60 by a pair of connecting rods 80 as described above with reference to FIG. 8. As an alternative, the distal end 84 of the second coupling member 81 is formed like a rack with a periodic arrangement of teeth, and a pinion at the second jaw 60 engages the teeth of the rack at the distal end of the second coupling member 81. As a further alternative, a region at the distal end 84 of the second coupling member 81 can be bendable, and the distal end 84 of the second coupling member 81 can be directly coupled to the second jaw 60 by a hinge, thereby integrating the function of a connecting rod into the second coupling member 81.
[0122] As an alternative, each of the coupling members 71, 81 can be or can comprise a Bowden cable or a cable pull.
[0123] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
