GB2582317A

GB2582317A - An end effector for a surgical instrument

Info

Publication number: GB2582317A
Application number: GB1903711.8A
Authority: GB
Inventors: Dickson James; Tissington Bryan
Original assignee: Gyrus Medical Ltd
Current assignee: Gyrus Medical Ltd
Priority date: 2019-03-19
Filing date: 2019-03-19
Publication date: 2020-09-23
Anticipated expiration: 2039-03-19
Also published as: GB201903711D0; GB2582317B

Abstract

The end effector comprises a pair of pivotally connected 104 jaw members (100, 102, fig 1) each having a flange 106, 108 with an elongate slot 110, 112 and a drive assembly having a drive pin 22 and a drive shaft 24. The drive pin is received in the slots such that movement of the drive shaft along the effector’s longitudinal axis causes the jaw members to move relative to each other. The drive pin is further moveable in a lateral direction A ensuring that the force is evenly distributed to both jaw members in the closed position. The effector may be controlled through one moveable jaw, but this has the same mechanical advantage of an end effector where both jaws are moveable. The drive shaft may have a slot 26 extending perpendicular to the longitudinal axis into which the drive pin is received, or the drive shaft may move in a perpendicular direction (Figs 5A & B), to allow the lateral movement of the drive pin.

Description

An End Effector for a Surgical Instrument

Technical Field

Embodiments of the present invention described herein relate to an end effector for a surgical instrument, and in particular an end effector comprising a pair of jaws wherein one of the pair of jaws is configured to move between an open and closed position.

Background to the Invention and Prior Art

It is known to provide a surgical instrument with a pair of opposing jaw members configured to grasp tissue therebetween. In some arrangements, both jaw members are configured to move so as to move between an open and closed position. The jaw members are moveable by means of a drive assembly comprising a drive shaft configured to move a drive pin along angled slots disposed on each of the jaw members, wherein both slots are at the same angle relative to the longitudinal axis of the drive shaft, but extending in opposite directions. GB 2546414 is one example of such an arrangement. This arrangement allows the force applied to the drive pin to be equally distributed between the two jaw members to provide the resultant force on the tissue being grasped.

It is also known to provide surgical instruments where only one of the pair of jaw members is configured to move so that the jaw members move between an open and closed position, as is the preference of some medical professionals. In some arrangements, a similar drive assembly is used to that described above, however, the slot on the fixed jaw is kept parallel to the longitudinal axis of the drive shaft, whilst the angle of the slot on the moveable jaw member is increased, approximately doubled, in order to provide the same resultant force on the target tissue as an instrument where both jaw members are configured to move. In such an arrangement, the force required to move the drive pin is also increased, and thus the medical professional is required to exert greater forces on the mechanism used to actuate the drive assembly. US 5,366,134 provides one example of such an arrangement where only one jaw member is configured to move.

Summary of the Invention

Embodiments of the present invention provide an improved end effector and drive assembly having advantages over the prior art. In particular, the present invention provides an end effector that is controlled through one moveable jaw, but that has the mechanical advantage in the fully closed position of an end effector where both jaws are moveable. To achieve this, the end effector is driven by a drive pin and slot arrangement, wherein both slots are angled so that the force exerted by the drive means used to move the drive pin along the slots is evenly distributed between the two jaw members once at the fully closed position. To ensure that the drive shaft remains horizontal during closing, while the jaw forces are partially imbalanced, the drive pin is moveable in both a longitudinal and lateral direction. During the closing phase, the flange extending from the end of the fixed jaw is restrained, for example, by the outer shaft, to prevent any pivotal rotation of the fixed jaw member and ensure that the jaw member stays horizontal. As the moveable jaw reaches the fully closed position, the reaction force from the fixed jaw to the restraining means, for example the outer shaft, will tend towards zero as the mechanism mechanical advantage increases. At the fully closed position, once both of the cam slot angles balance equally, the drive shaft force will be split equally between the upper and lower jaws, with little reaction force through the outer shaft.

According to a first aspect, the present invention provides an end effector for a surgical instrument, comprising: a pair of opposing first and seconds jaw members, the first and second jaw members being pivotally connected, each of the jaw members comprising a flange extending from its proximal end, each flange having an elongate slot disposed at an angle relative to the longitudinal axis of the respective jaw member; and a drive assembly configured to move the first jaw member relative to the second jaw member from a first open position to a second closed position, the drive assembly comprising: a drive pin configured to be received by the elongate slots of the first and second jaw members, the drive pin being moveable between proximal and distal ends of the elongate slots; and a drive shaft configured to move in a first direction along its longitudinal axis so as to actuate the drive pin longitudinally towards a distal end of the elongate slots to thereby move the first jaw member to the first open position, and further configured to move in a second direction along its longitudinal axis so as to actuate the drive pin longitudinally towards a proximal end of the elongate slots to thereby move the first jaw member to the second closed position; characterised in that the drive pin is further moveable in a substantially lateral direction relative to the longitudinal axis of the drive shaft.

As such, the angled elongate slots on the jaw members ensure that the force exerted by the drive shaft to actuate the drive pin along the slots is evenly distributed between both jaw members, once in the fully closed position. To ensure that the longitudinal movement of the drive pin along the elongate slots is only translated to the first jaw member, the drive pin is able to move laterally relative to the longitudinal axis. The fixed jaw member is also rotationally restrained by some means, for example the outer shaft, in the location of the flange, in order to prevent rotation of the second jaw member during the clamping phase. At the fully clamped position, this reaction force between jaw flange and the outer shaft will tend towards zero. For example, when the drive pin is actuated towards the proximal end to close the first jaw member, the drive pin also translates downwards in the direction of the first jaw member.

This way, the first jaw member and its flange rotate about the point at which the two jaw members are connected, such that in the open position, the longitudinal axis of the first jaw member and its flange lies at an angle to the drive shaft, and in the closed position, the longitudinal axis of the first jaw member and its flange is substantially parallel with the drive shaft. In contrast, the flange of the second jaw member remains stationary, such that the longitudinal axis of the second jaw member and its flange stays substantially parallel with the drive shaft in both the open and closed positions.

The drive shaft may be configured to actuate the drive pin in a substantially lateral direction with respect to the longitudinal axis as the drive shaft moves in the first and second direction. As such, the drive shaft is configured to move the drive pin in both the longitudinal and lateral direction.

In some arrangements, the drive shaft may further comprise a drive slot extending in a direction substantially perpendicular to the longitudinal axis of the drive shaft, the drive pin being further received by the drive slot. That is to say, the drive shaft may be provided with a drive slot that extends laterally with respect to the longitudinal axis of the drive shaft. In such cases, the drive pin is moveable between a first end of the drive slot and a second end of the drive slot, the first end being in a first direction offset to the longitudinal axis, and the second end being in a second direction offset to longitudinal axis. That is to say, the drive slot enables the drive pin to move laterally.

In particular, the drive shaft may be configured to actuate the drive pin towards the first end of the drive slot when the drive shaft is moved in the second direction. That is to say, when the drive shaft is moved in the second direction so as to move the drive pin longitudinally towards the proximal end of the elongate slots, the drive pin can also move laterally downwards in the direction of the first jaw member, to thereby close only the first jaw member, whilst the second jaw member is further restrained from rotating by some means. At the fully clamped position, the restraining force between flange of the second jaw member and the restraining means will tend towards zero.

Conversely, the drive shaft may then be further configured to actuate the drive pin towards the second end of the drive slot when the drive shaft is moved in the first direction. That is to say, when the drive shaft is moved in the first direction so as to move the drive pin longitudinally towards the distal end of the elongate slots, the drive pin is also moved laterally upwards in the direction of the second jaw member, to thereby allow the drive shaft to remain in a horizontal position during the opening and closing of the jaw members.

In some arrangements, the drive slot may be angled towards the distal end of the drive shaft. Such an arrangement helps to bias the drive pin towards the proximal end of the elongate slots when the first jaw is in the closed position.

This helps to ensure that the drive shaft remains horizontal during opening and closing of the jaw members, which may be preferential for the specific drive shaft actuation mechanism being implemented.

In other arrangements, the drive shaft is configured to move in a direction substantially perpendicular to its longitudinal axis. That is to say, the drive shaft is able to move both longitudinally and laterally to thereby actuate the drive pin in the same way.

In particular, the drive shaft may be configured to move laterally in a direction of the first jaw member when the drive shaft is moved in the second direction.

As such, when the drive shaft is moved in the second direction so as to move the drive pin longitudinally towards the proximal end of the elongate slots, the drive shaft also moves the drive pin laterally downwards in the direction of the first jaw member. In such arrangement, a drive shaft actuation mechanism may be provided that allows for a small amount of drive shaft rotation between the open and closed positions of the jaw members.

Conversely, the drive shaft may then be further configured to move laterally in a direction of the second jaw member when the drive shaft is moved in the first direction. As such, when the drive shaft is moved in the first direction so as to move the drive pin longitudinally towards the distal end of the elongate slots, the drive shaft also moves the drive pin laterally upwards in the direction of the second jaw member, to thereby open the first jaw member.

In some arrangements, the elongate slots of each flange are disposed at equivalent angles relative to the longitudinal axis of the respective jaw member.

That is to say, both elongate slots form the same angle with the longitudinal axis of its respective jaw member. This helps to ensure that an equal amount of force is distributed between the two jaw members when the jaws are in the fully closed position.

In some arrangement, the end effector further comprises a restraining means for constraining the movement of the second jaw member. For example, the restraining means may be configured to constrain the movement of the flange of the second jaw member.

The end effector may further comprise an outer shaft extending from the first and second jaw members, wherein the first flange, the second flange and the drive assembly are located within the outer shaft. In some arrangements, the outer shaft is configured to constrain the movement of the second jaw member. That is to say, the outer shaft is the restraining means and is configured to prevent the fixed jaw member from pivotally rotating. For example, the outer shaft may be configured to prevent this rotation by constraining the movement of the flange of the second jaw member.

In some arrangements, the drive shaft may be further configured to rotate about its longitudinal axis. For example, the drive shaft may be configured to rotate so as to rotate the first and second jaw members to enable the operator to grasp tissue from different angles.

In some arrangements, a blade assembly may be located within the drive shaft, the blade assembly being moveable along a track within the drive shaft such that the blade assembly can be translated between the first and second jaw members to cut tissue grasped therebetween. The blade assembly may comprise a lockout arrangement configured to engage with the drive pin, such that the drive pin engages with the lockout arrangement when the jaw members are in the open position to prevent the blade from being actuated, and disengages with the lockout arrangement when the jaw members move to the closed position to allow the blade assembly to be translated along the drive shaft. In other arrangements, the drive shaft may comprise a locking surface that is arranged to engage with the lockout arrangement when the jaw members are in the open position, and disengages with the lockout arrangement when the jaw members move to the closed position to allow the blade assembly to be translated along the drive shaft.

According to a further aspect, the present invention provides a surgical instrument, comprising the end effector as described above. The surgical instrument may further comprise a hand piece, and an elongate shaft extending between the end effector and the hand piece.

In some cases, the surgical instrument may be an electrosurgical instrument, wherein each of the first and second jaw members includes an electrically conductive sealing surface for communicating electrosurgical energy through tissue held therebetween, and the shaft comprises RF electrical connections, drive componentry for the end effector portion, the end effector arrangement being operably connected to the drive componentry to drive the end effector to operate in use, and the electrically conductive sealing surface being connected to the RF electrical connections. The electrosurgical instrument may be part of an electrosurgical system, also comprising an RF electrosurgical generator.

Brief Description of the Drawings

Embodiments of the invention will now be further described by way of example only and with reference to the accompanying drawings, wherein like reference numerals refer to like parts, and wherein: Figure 1 is a schematic side view of an end effector according to an embodiment of the present invention, shown in an open configuration; Figure 2 is a schematic side view of the end effector of Figure 1, shown in a closed configuration; Figure 3A is a schematic side view further illustrating the drive assembly of the end effector in the open configuration shown in Figure 1; Figure 3B is a schematic side view further illustrating the drive assembly of the end effector in the closed configuration shown in Figure 2; Figure 4 is a schematic side view illustrating the drive assembly of an end effector according to a further embodiment of the present invention in the closed position; Figures 5A-B are schematic side views illustrating the drive assembly of an end effector according to a further embodiment of the present invention; Figure 6 is a schematic side view of a cutting mechanism for use with embodiments of the present invention; Figure 7 is a schematic side view of a further cutting mechanism for use with embodiments of the present invention; Figure 8 is a schematic side view illustrating a further a cutting mechanism for use with embodiments of the present invention; Figure 9 illustrates a surgical system including an instrument having an end effector according to embodiments of the present invention.

Detailed Description of the Embodiments

Figures 1 and 2 illustrate an end effector for a surgical instrument, shown generally at 10, comprising an upper jaw member 100 pivotably connected to a lower jaw member 102 about a pivot 104. The end effector 10 is configured so that the upper jaw member 100 remains in a fixed position, whilst the lower jaw member 102 is actuated between a first and second position so as to open and close the end effector 10, as will now be described.

A first flange 106 extends from the proximal end of the upper jaw member 100, and a second flange 108 extends from the proximal end of the lower jaw member 102. The first and second flanges 106, 108 each have angled slots 110 and 112 respectively, through which a drive pin 22 extends, the drive pin 22 forming part of a drive assembly shown generally at 20. A proximal and distal movement of the drive pin 22 by means of a drive shaft 24 causes the lower jaw member 102 to pivot between the open position shown in Figure 1 and the closed position shown in Figure 2. The drive shaft 24 may be actuated by any suitable mechanism, for example, a trigger located on a handle (not shown) at the proximal end of the instrument. In use, the first flange 106, the second flange 109, and the drive assembly 20 are enclosed within an elongate outer shaft 30 extending between the distal end effector 10 and the proximal handle.

During actuation of the drive pin 22 by the drive shaft 24, the outer shaft 30 acts to prevent any rotational movement of the first flange 106, to thereby keep the upper jaw member 100 in a fixed position. In some arrangements, the outer shaft 24 may comprise a small slot or recess through which the second flange 108 of the lower jaw member 102, or whichever jaw member 100, 102 is configured to move, extends out of when the jaw members 100, 102 are in the open position, whilst the flange 106 of the fixed jaw member 100 is held in place in both the open and closed position. In other arrangements, the outer shaft 30 may be configured to encompass both the first and second flanges 106, 108, the flange 108 of the moveable jaw member 102 being free to rotate, whilst the flange 106 of the fixed jaw member 100 is again held in a fixed position.

The slots 110, 112 are disposed on the first and second flanges 106, 108 such that they lie at an angle to the longitudinal axis of the respective jaw member 100, 102. In some preferred arrangement, both slots 110, 112 form the same angle with the longitudinal axis of its respective jaw member 100, 102 once the jaw members 100, 102 are closed. More specifically, when the jaw members 100, 102 are in the closed configuration shown in Figure 2, the slots 110, 112 are both disposed such that they lie at an approximately equal, but opposing, angle relative to the longitudinal axis X of the drive shaft 24, the slots 110, 112 thereby extending away from each other in the distal direction. That is to say, the angle that the slot 110 on the first flange 106 makes with the longitudinal axis X of the drive shaft 24 is substantially the same as the angle that the slot 112 on the second flange 108 makes with the longitudinal axis X of the drive shaft 24, albeit in the opposite direction. For example, both slots 110, 112 may form an angle of around 15°-20°, preferably about 17°, with the longitudinal axis of its respective jaw member 100, 102 such that the slots 110, 112 also form the same angle with the longitudinal axis X of the drive shaft 24 when the jaw members 100, 102 are in the closed configuration. By providing each jaw member 100, 102 with an angled slot 110, 112, the force exerted by the drive pin 22 is distributed between the two jaw members 100, 102, and the upper jaw member 102 is restrained by the outer shaft 30 during closing. Once the jaw members 100, 102 are fully closed, and the cam angles are balanced, the force required by the mechanism used to actuate the drive assembly 20 (e.g. a trigger on the handle) is minimised.

To ensure that the drive shaft 24 only actuates in a horizontal direction, and not vertically, the drive shaft 24 is further provided with a slot 26 in which the drive pin 22 also sits, shown in more detail in Figures 3A and 3B. This additional slot 26 is configured to allow the drive pin 22 to translate laterally in a direction Y perpendicular to the longitudinal axis X of the drive shaft 24 as the lower jaw member 102 is moved between the open and closed position. In Figure 3A, when the end effector 10 is in the open position, the drive pin 22 is located at the top of the slot 26 on the drive shaft 24 and at the distal end of the slots 110, 112 located on the first and second flanges 106, 108. As the drive shaft 24 is moved in the proximal direction so as to move the lower jaw member 102 to the closed position, the drive pin 22 moves to the proximal end of the slots 110, 112 located on the first and second flanges 106, 108, and translates downwards in the direction of the arrow labelled A to the bottom of the slot 26 on the drive shaft 24, as shown in Figure 3B. By enabling drive pin 22 to move laterally, the drive shaft 24 will only move in a horizontal direction along the longitudinal axis, whilst the first flange 108 and upper jaw member 100 remain in the same position.

To then move the lower jaw member 102 back to the open position, the drive shaft 24 is moved in the distal direction so as to move the drive pin 22 back to the proximal end of the slots 110, 112 located on the first and second flanges 106, 108, the drive pin 22 being translated upwards in the opposite direction to the arrow labelled A to the top of the slot 26 on the drive shaft 24.

As a result of the longitudinal and lateral movement of the drive pin 22, the lower jaw member 102 and its flange 108 rotate about the pivot 104. In contrast, the upper jaw member 100 remains stationary, movement of its flange 106 being restricted by the outer shaft 30, such that the longitudinal axis of the upper jaw member 100 and its flange 106 stays parallel with that of the drive shaft 24 in both the open and closed positions, as can be seen in Figures 1 and 2.

The slot 26 in the drive shaft 24 compensates for the angled slot 110 on the flange 106 of the fixed upper jaw member 100, ensuring that the movement of the drive shaft 24 is only in the horizontal direction. The upper jaw member 100 is restrained by the outer shaft 30 so that the upper jaw member 100 remains in a fixed position. By allowing the drive pin 22 to translate by a small amount laterally, that is, perpendicular to the proximal and distal movement of the drive shaft 24, it is possible to provide angled slots 110, 112 on both jaw members 100, 102, and thereby obtain a single moveable jaw 102 having the same mechanical advantage of an end effector having two moveable jaws, while allowing the drive shaft 24 to move only in a horizontal direction along the longitudinal axis.

Figure 4 shows an alternative construction in which the drive shaft 24 comprises a slot 46 that is angled towards the distal end of the instrument. As such, the slot 46 does not extend absolutely perpendicular to the longitudinal axis X of the drive shaft 24, as in the arrangement described with reference to Figures 1 to 3, but instead extends slightly away from the perpendicular axis Y. This angled slot 46 helps to bias the drive pin 22 towards the preferred position when then the jaw members 100, 102 are in the closed position, that is, to bias the drive pin 22 towards the proximal end of the slots 110, 112 located on the first and second flanges 106, 108. This arrangement works substantially in the same way as that shown in Figures 1-3, whereby the drive pin 22 is allowed to translate a small amount laterally in a direction that is substantially perpendicular to the proximal and distal movement of the drive shaft 24 so as to compensate for the angled slot 110 in the fixed upper jaw member 100. The angle of the slot 110 helps to overcome any frictional forces which may oppose the movement of the drive pin 22 to the preferred location at the closed position.

Figures 5A and 5B show an alternative construction of the drive assembly shown generally at 50, wherein the drive shaft 54 itself is further configured to translate in the direction perpendicular to its longitudinal axis to thereby provide a corresponding translation of the drive pin 52. As such, instead of a slot, the drive shaft 54 is provided with a hole 56 that the pin 52 sits firmly within, and the drive shaft 54 is instead configured to move laterally, as well as in the proximal and distal directions.

It will also be appreciated that the drive shaft in all of the above examples may be further arranged to rotate within the outer shaft 30, for example, to allow the operator to rotate the end effector 10.

As can be seen from Figures 5A and 5B, the proximal ends of the upper jaw member 100 and the lower jaw member 102 fit snuggly within the distal end 32 of the outer shaft 30 such that they abut the inner wall 34 thereof. As such, no part of the end effector 10 is able to move laterally or in the direction parallel to the longitudinal axis of the outer shaft 30. Instead, the end effector 10 only has one degree of freedom, that being a rotational movement about the pivot 104. This is also the case in the arrangements shown with reference to Figures 1-4, but is particularly important in this arrangement to ensure that the lateral movement of the drive shaft 54 has the effect of translating its simultaneous movement in the proximal and distal direction to the lower jaw member 102, and ensuring that the upper jaw member 100 remains in a fixed position. As described previously, the outer shaft 30 acts to provide a reaction force to the flange 106 of the fixed jaw member 100 during closing, wherein this reaction force will tend towards zero at the closed position.

Figure 5A illustrates the arrangement when the lower jaw member 102 is in the open position, wherein the drive pin 52 is at the distal end of the slots 110, 112 located on the first and second flanges 106, 108. Here the drive shaft 54 is shown in a first position within the outer shaft 30, wherein an outer edge 58 of the drive shaft 54 is a distance B from a second position within the outer shaft 30, denoted by the line labelled C. As the drive shaft 54 is moved in the proximal direction so as to move the lower jaw member 102 to the closed position, the drive shaft 54 also moves laterally in the direction of the arrow labelled D. Figure 5B illustrates the arrangement when the lower jaw member 102 is in the closed position, wherein the drive pin 52 has moved to the proximal end of the slots 110, 112, and the drive shaft 54 has moved the second position within the outer shaft 30 such that the outer edge 58 is now aligned with the line C. As the first and second flanges 106, 108 are not able to move laterally with the lateral movement of the drive shaft 54, this has the effect that only the second flange 108, and thus the lower jaw member 102, are actuated by the proximal movement of the drive shaft 54. The upper jaw member 100 is also fixed to the drive shaft 24 to prevent rotation during closing. As can be seen from Figures 5A and 5B, the first flange 106 remains in the same position, whilst the second flange 108 is rotated about the pivot 104.

To then move the lower jaw member 102 back to the open position, the drive shaft 54 is moved in the distal direction so as to move the drive pin 52 back to the proximal end of the slots 110, 112, the drive shaft 54 also translating upwards in the opposite direction to the arrow labelled D back to its first position within the outer shaft 30.

Therefore, in this arrangement, the lateral movement of the drive shaft 56 itself compensates for the angled slot 110 on the flange 106 of the fixed upper jaw member 100, ensuring that the movement of the drive shaft 24 is only translated to the lower jaw member 102.

Whilst the arrangements described herein all show an end effector in which the upper jaw member 100 is fixed and the lower jaw member 102 is configured to move between the open and closed positions, it will be appreciated by a person skilled in the art that the drive assembly 20 may be easily modified so that the lower jaw member 102 is fixed and the upper jaw member 100 is moved relative to the lower jaw member 102.

In the arrangements described herein, the outer shaft 30 is used to constrain the movement of the fixed jaw member 100, however, it will be appreciated that the drive assembly may be comprise some other suitable restraining means configured to hold the fixed jaw member 100 in place and prevent it from rotating about the pivot 104. For example, the restraining means may be in the form of some internal moulding within the outer shaft, such as a collar moulding or some other internal component suitable for restricting the movement of the flange of the fixed jaw member 100.

In some arrangements, the drive shaft may be arranged to enclose a cutting blade. In use, once the jaw members 100, 102 are in the closed position so as to grasp a portion of tissue, the blade may be translated between the jaw members 100, 102 so as to cut the tissue clasped therebetween. To prevent the cutting blade from being actuated when the jaw members 100, 102 are in the open position, a lockout mechanism may be provided.

Figure 6 provides a first example of a blade assembly 60 that may be used in conjunction with embodiments of the present invention. As can be seen, the blade assembly 60 is enclosed within the drive shaft 24. The blade assembly 60 is provided with a lockout mechanism in the form of a locking slot 62 configured to receive the drive pin 22. When the jaw members 100, 102 are in the open position, the drive pin 22 sits within the locking slot 62 to prevent the longitudinal translation of the blade assembly 60. When the drive shaft 24 is moved longitudinally in the proximal direction so as to close the jaw members 100, 102, the drive pin 22 thereby being moved longitudinally and laterally, as described with reference to Figure 1-4 above, the drive pin 22 disengages with the locking slot 62 such that the blade assembly 60 is released to enable a distal cutting edge 64 to be driven through the jaw members 100, 102 to cut the tissue.

Figure 7 shows a further example of a blade assembly 70 that may be used in conjunction with embodiments of the present invention. As with Figure 6, blade assembly 70 is provided with a locking slot 72 that is configured to engage with the drive pin 22. As before, when the drive pin 22 is moved longitudinally and laterally by the drive shaft 24, the drive pin 22 is disengaged with the locking slot 72 to release the blade assembly 70. In this example, the drive pin 22 is received by a longitudinal slot 76 in the blade assembly 70 that allows the blade assembly 70 to move longitudinally to thereby enable the distal cutting edge 74 to be driven through the jaw members 100, 102 to cut the tissue. In this respect, it will be appreciated that the longitudinal slot 76 will be long enough to enable a full range of movement by the blade assembly 70 whilst the jaw members 100, 102 are in the closed position.

Figure 8 illustrates an example of blade assembly 80, similar to that of Figure 7, which may be used in conjunction with the embodiment described with reference to Figures 5A-B. As before, the blade assembly 80 is provided with a locking slot 82. In this example, the drive shaft 54 is further provided with a locking surface 88 or the like that engages with the locking slot 82 whilst the jaw members 100, 102 are in the open position to prevent the blade assembly 80 from being actuated at this time. When the drive shaft 54 is actuated so as to open the jaw members 100, 102, the locking surface 88 disengages with the locking slot 82 as the drive shaft 54 moves laterally downwards, as previously described with reference to Figure 5B, thereby also releasing the blade assembly 80. In this example, the locking surface 88 is received by a longitudinal slot 86 within the blade 80 that allows the blade assembly 80 to move longitudinally, thereby enabling the distal cutting edge 84 of the blade assembly 80 to be translated between the closed jaw members 100, 102.

It will be appreciated that other locking mechanisms may be used to engage and disengage the blade assembly. For example, in the embodiment described with reference to Figures 5A-B, the drive shaft 54 may be provided with a locking surface that is configured to engage with a locking slot such as that shown in Figure 6, wherein the locking surface is arranged to disengage from the locking slot by the lateral movement of the drive shaft 54, or alternatively, the locking surface may be disengaged by rotating the drive shaft 54 about a small angle.

Referring now to Figure 9, the end effector described herein may be used as part of an instrument 900, which may in use be intended for connection to an electrosurgical generator 902 having a controllable radiofrequency (RF) source therein (not shown) that in use produces an RF coagulation signal that coagulates or seals tissue when applied thereto via electrodes located within the end effector of the instrument 900. Electrosurgical generator 902 includes control input switches 902 and 904, to respectively allow the generator to be turned on and off, and to allow the power of the RF coagulation signal fed to the instrument 900 to be controlled. In these respects, the electrosurgical generator 902 is conventional.

The instrument 900 may be connected in use to the generator 902 by a control and power line 906, which contains separate electrical lines to allow an RF signal to be fed to the end effector of the instrument 900 via internal wiring, and also to allow a control signal to be received from a switch (not shown) on the instrument 900, to command the electrosurgical generator 902 to output an RF coagulation signal to the instrument 900. In use, the surgeon activates the generator via on-off switch 904, and selects the coagulation or sealing signal strength to be generated by the internal RF source using buttons 902. During a surgical procedure with the instrument 900 when a sealing or coagulation RF signal is required at the end effector, the surgeon controls the generator 902 to produce such a signal by pressing the switch on the instrument 900, the generated RF signal then being passed via the electrical lines 906 to the end effector. That is, pressing of the switch in use causes an RF coagulation or sealing signal to be supplied to the appropriate electrodes contained within the end effector.

Various further modifications to the above described embodiments, whether by way of addition, deletion or substitution, will be apparent to the skilled person to provide additional embodiments, any and all of which are intended to be encompassed by the appended claims.

Claims

CLAIMS1. An end effector for a surgical instrument, comprising: a pair of opposing first and seconds jaw members, the first and second jaw members being pivotally connected, each of the jaw members comprising a flange extending from its proximal end, each flange having an elongate slot disposed at an angle relative to the longitudinal axis of the respective jaw member; and a drive assembly configured to move the first jaw member relative to the second jaw member from a first open position to a second closed position, the drive assembly comprising: a drive pin configured to be received by the elongate slots of the first and second jaw members, the drive pin being moveable between proximal and distal ends of the elongate slots; and a drive shaft configured to move in a first direction along its longitudinal axis so as to actuate the drive pin longitudinally towards a distal end of the elongate slots to thereby move the first jaw member to the first open position, and further configured to move in a second direction along its longitudinal axis so as to actuate the drive pin longitudinally towards a proximal end of the elongate slots to thereby move the first jaw member to the second closed position; characterised in that the drive pin is further moveable in a substantially lateral direction relative to the longitudinal axis of the drive shaft.
2. An end effector according to claim 1, wherein the drive shaft is configured to actuate the drive pin in the substantially lateral direction as the drive shaft moves in the first and second direction.
3. An end effector according to claims 1 or 2, wherein the drive shaft further comprises a drive slot extending in a direction substantially perpendicular to the longitudinal axis of the drive shaft, the drive pin being further received by the drive slot.
4. An end effector according to claim 3, wherein the drive pin is moveable between a first end of the drive slot and a second end of the drive slot, the first end being in a direction of the first jaw member, and the second end being in a direction of the second jaw member.
5. An end effector according to claim 4, wherein the drive shaft is further configured to actuate the drive pin towards the first end of the drive slot when the drive shaft is moved in the second direction.
6. An end effector according to claims 4 or 5, wherein the drive shaft is further configured to actuate the drive pin towards the second end of the drive slot when the drive shaft is moved in the first direction.
7. An end effector according to any of claims 3 to 6, wherein the drive slot is angled towards the distal end of the drive shaft.
8. An end effector according to claims 1 or 2, wherein the drive shaft is further configured to move in a direction substantially perpendicular to its longitudinal axis.
9. An end effector according to claim 8, wherein the drive shaft is further configured to move laterally in a direction of the first jaw member when the drive shaft is moved in the second direction.
10. An end effector according to claims 8 or 9, wherein the drive shaft is further configured to move laterally in a direction of the second jaw member when the drive shaft is moved in the first direction.
11. An end effector according to any preceding claim, wherein the elongate slots of each flange are disposed at equivalent angles relative to the longitudinal axis of the respective jaw member.
12. An end effector according to any preceding claim, further comprising a restraining means for constraining the movement of the second jaw member.
13. An end effector according to claim 12, wherein the restraining means is configured to constrain the movement of the flange of the second jaw member.
14. An end effector according to any preceding claim, further comprising an outer shaft extending from the first and second jaw members, wherein the first flange, the second flange and the drive assembly are located within the outer shaft.
15. An end effector according to claim 14, wherein the outer shaft is configured to constrain the movement of the second jaw member.
16. An end effector according to any proceeding claim, wherein the drive shaft is further configured to rotate about its longitudinal axis. 15
17. A surgical instrument, comprising the end effector according to any of claims 1 to 16.