A Flow Valve Position Sensor for an Electrosurgical Device

Abstract

An electrosurgical instrument 3 comprises: a handpiece 3a and a cutting accessory. The handpiece comprises: a housing; a suction lumen (50, fig 5) within the housing, extending from a distal end (54,

Description

Embodiments of the present invention described herein relate to a surgical device, and in particular to a flow valve position sensing circuit for a surgical device. 5 Background to the Invention and Prior Art Electrosurgical instruments provide advantages over traditional surgical instruments in that they can be used for coagulation and tissue sealing purposes. One such prior art arrangement is known from US 2018 / 0132850 Al, which describes a surgical instrument with interchangeable shaft assemblies. US 2018 / 0132850 Al describes io using a Hall Effect sensor and a magnet to determine whether a trigger for releasing a shaft assembly from the surgical instrument's housing is actuated or not. Arthroscopic shavers are used in keyhole surgery to remove tissue from the surgical field. The vast majority of shavers (see Figures 1-3 for examples) use a mechanical flow valve situated within the handpiece to adjust the flow rate of saline out of the is surgical field. The saline is sucked out through the handpiece due to a back pressure that is applied to a tube connection at the rear of the handpiece. Currently, the flow valves in arthroscopic shavers are purely a mechanical interface, and do not provide any information with respect to the positioning of the flow valve with respect to the operation of the shaver. DC electric motors are used within 20 arthroscopic shavers to actuate the mechanical prime mover (e.g., a mechanical shaver). Through normal operating procedures the motors produce latent heat and may require cooling. The saline flowing through the handpiece helps to remove some of the latent heat from the motor. If the motor is allowed to heat up excessively, the motor may become damaged or may heat the handpiece to an unacceptable 25 temperature, such that it is too hot for the surgeon to hold. Additionally, it may be the case that the motor reaches a temperature where a thermal cut-out is activated and the motor needs to be left to cool for a period of time, resulting in a potential delay to the procedure. In the instance where the motor requires cooling from the saline flow, the surgeon may not be aware of this and therefore may not have the 30 flow valve in the open position. Summary of the Invention Embodiments of the present invention aim to provide a solution to the above identified drawbacks of the prior art by providing an improved handpiece for a 05 11 24 surgical instrument having a sensing circuit to monitor the condition of the mechanical flow valve. This allows the condition of the valve to be electronically monitored at all times. The sensing circuit can then notify the user of the instrument if the valve is closed when ideally it should be open for any reason. For example, this reason could be to prevent extreme overheating of the motor, to cool the in-joint temperature, or to improve the RF function performance. In view of the above, from one aspect the present invention provides a surgical instrument, comprising: a handpiece for a surgical instrument, the handpiece comprising: a housing; a suction lumen within the housing extending from the distal end of the handpiece to a proximal end of the handpiece; a flow valve arranged to control the flow of fluid through the suction lumen; and a flow valve position sensing circuit arranged to detect a position of the flow valve; the surgical instrument further comprising: a cutting accessory comprising a shaft and an end effector, a proximal end of the shaft being coupled to the distal end of the handpiece, and a distal end of the shaft being coupled to the end effector; wherein: a) the suction lumen further extends through the shaft to the end effector; b) the surgical instrument is an electrosurgical instrument with an RF component; and c) the valve position sensing circuit is arranged to alert a user if the valve is closed when the RF component is in use. This aspect is advantageous as it is known that RF performance is enhanced when the valve is open. Another aspect of the present disclosure provides an electrosurgical system, comprising: an RF electrosurgical generator; a surgical instrument according to the aspect described above, wherein the surgical instrument is an electrosurgical instrument, the arrangement being such that in use the RF electrosurgical generator supplies an RF coagulation or ablation signal to the end effector; and a suction source, fluidly connected to the suction lumen. 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 an image of a Stryker Formula Shaver Handpiece, a prior art electrosurgical instrument which has a mechanical flow valve (circled) with no way of electronically monitoring the condition of the valve. Figure 2 is a diagram showing the Stryker Formula Shaver in more detail. 2 05 11 24 Figure 3 is an image of a Conmed Ergo Shaver Handpiece, a prior art electrosurgical instrument which also has a mechanical flow valve (circled) with no way of electronically monitoring the condition of the valve. Figure 4 is a schematic diagram of an electrosurgical system including an 5 electrosurgical instrument; Figure 5 is a diagram showing a flow valve in accordance with the present invention in an open position. Figure 6 is a diagram showing a flow valve in accordance with the present invention in a closed position. io Description of the Embodiments Referring to the drawings, Figure 1 shows a prior art arrangement, the Stryker Formula Shaver Handpiece. The mechanical valve, operated by a lever 100, does not have any way of electronically monitoring the condition of the valve. A suction tube 102 is connected to the proximal end of the handpiece, as is a power cord 104. is Figure 2 shows the Stryker Formula Shaver in more detail. The mechanical valve is operated by moving the lever 100 between two positions. Increasing the flow of fluid through the valve is achieved by opening the valve, and decreasing the flow of fluid through the valve is achieved by closing the valve. At the distal end, the handpiece connects to a shaft 106, which would be connected to an end effector. 20 Figure 3 shows a similar prior art arrangement, the Conmed Ergo Shaver Handpiece. Again, the mechanical valve is operated by a lever 200, and there is no way of electronically monitoring the condition of the valve. A suction tube 202 is connected to the proximal end of the handpiece, as is a power cord 204. Figure 4 shows electrosurgical apparatus including an electrosurgical generator 1 25 having an output socket 2 providing a radio frequency (RF) output, via a connection cord 4, for an electrosurgical instrument 3. The instrument 3 may have irrigation and suction tubes 14 which are connected to an irrigation fluid and suction source 10. Activation of the generator 1 may be performed from the instrument 3 via a handswitch (not shown) on the instrument 3, or by means of a footswitch unit 5 30 connected separately to the rear of the generator 1 by a footswitch connection cord 6. In the illustrated embodiment, the footswitch unit 5 has two footswitches 5a and 5b for selecting a coagulation mode or a cutting or vaporisation (ablation) mode of the generator 1 respectively. The generator front panel has push buttons 7a and 7b for respectively setting ablation (cutting) or coagulation power levels, which are indicated in a display 8. Push buttons 9 are provided as an alternative means for selection between the ablation (cutting) and coagulation modes. 5 The instrument 3 includes a handpiece 3a, a hollow shaft 3b extending in a distal direction away from the handpiece, and a distal end effector assembly 3c at the distal end of the shaft. A power connection cord 4 connects the instrument to the RF generator 1. The instrument may further be provided with activation buttons (not shown), to allow the surgeon operator to activate either the mechanical cutting io function of the end effector, or the electrosurgical functions of the end effector, which typically comprise coagulation or ablation. Figures 5 and 6 show the handpiece 3a in more detail. A suction lumen 50 extends through the handpiece 3a from the proximal end of the handpiece 52 to the distal end 54. At the proximal end of the handpiece 52, the suction lumen 50 connects to is a further suction tube 14 (not shown in Figures 5 and 6) which is connected to the suction source 10 (not shown in Figures 5 and 6). At the distal end of the handpiece <N 54, the suction lumen 50 extends through the shaft 3b (not shown in Figures 5 and 'I— 6) to the end effector 3c (not shown in Figures 5 and 6). In a surgical procedure, irrigation fluid is introduced into the surgical site in order to serve as a transport LO 20 medium for removing debris from the site. The irrigation fluid containing the debris is then sucked up through the suction lumen 50. The suction force is provided by the suction source 10. A valve 56 is provided to control the flow of fluid through the suction lumen 50. Figures 5 and 6 show a motor 58 which is connected to the generator 1 by the power cord 4 (not shown in Figures 5 and 6) attached to the 25 proximal end of the handpiece 52. The motor 58 is used to provide power to a mechanical component in the end effector, for example, a mechanical shaver component. The motor 58 may be a DC electric motor. The motor 58 is operably connected to a clutch-type arrangement 59 which allows the motor 58 to actuate the mechanical component. The clutch-type arrangement 59 allows the mechanical 30 component to engage and disengage from the motor 58. Figures 5 and 6 illustrate one method of achieving the sensing circuit of the present invention, to have a magnet 60 connected to the flow valve lever 62 and a Hall Effect sensor 64 mounted in a static position on a circuit board 66 in the handpiece 3a. The circuit board 66 acts as a processor for the sensing circuit. The magnet 60 may be 35 any magnetic element, for example, a permanent magnet. Figure 5 illustrates the 10 15 20 25 30 35 system when the flow valve 56 is in the open position. Figure 6 illustrates the system when the flow valve 56 is in the closed position. The Hall Effect sensor 64 can detect any relative movement of the magnet 60 by detecting changes in a magnetic field surrounding the Hall Effect sensor 64, and consequently movement of the flow valve lever 62. This enables the position of the flow valve lever 62, and consequently the position of the flow valve 56 (i.e. whether the flow valve 56 is open or closed, or somewhere in between), to be monitored. In Figure 5, the magnet 60 (and the lever 62) is in a first position and the valve 56 is consequently open. In Figure 6, the magnet 60 (and the lever 62) has moved to a second position, and the valve 56 is consequently closed. The movement of the magnet 60 between these two positions is detectable by the Hall Effect sensor 64, which detects the relative movement of the magnet 60 via the change in magnetic field around the Hall Effect sensor 64. The Hall Effect sensor 64 sends a signal to the processor 66 to communicate the change in position. Based on this signal, the processor 66 can determine whether the valve 56 is open or closed. The condition of the valve 56 can then be communicated to a user of the instrument via a further signal on the handpiece 3a, or via the generator 1. For example, in the context of a RF shaver instrument, if the user is using the RF part of the instrument with the flow valve 56 closed, the handpiece 3b may provide tactile feedback to warn the user. Alternatively or additionally, the generator display 8 may display a warning to the user. This is desirable as it is known that the RF performance is enhanced when the flow valve 56 is open. The sensing circuit may also be used to alert the user to open the flow valve 56 in the event that the motor 58 in the handpiece 3b is overheating and the flow valve 56 is closed. The flow of saline through the instrument can help to remove latent heat from the motor 58. The sensing circuit may be used in conjunction with an in-joint temperature sensor to ensure that the saline temperature in the joint is not allowed to exceed a certain point. If the in-joint temperature is approaching unacceptable levels and the saline in the joint is not being exhausted because the flow valve 56 is closed, the user could be prompted to open the flow valve 56. The hot saline would then be removed from the surgical site, allowing cooling of the joint. In various embodiments, any number of magnetic sensing elements 60 may be used to monitor the condition of the flow valve 56. Technologies used for magnetic field sensing include search coil, fluxgate, optically pumped, nuclear precession, SQUID, Hall-effect, anisotropic magnetoresistance, giant magnetoresistance, magnetic tunnel junctions, giant magnetoimpedance, magnetostrictive / piezoelectric composites, magnetodiode, magnetotransistor, fiber optic, magnetooptic, and microelectromechanical systems-based magnetic sensors, among others. An example of an alternative to the magnet 60 and Hall Effect sensor 64 sensing 5 circuit would be to use an accelerometer to monitor the movement of the flow valve lever. The concepts of the present invention can be used on a wider suite of arthroscopic instruments as further embodiments, and they are not limited specifically to shaver instruments. In further embodiments the magnet may be included in the movable io part of the flow control of many arthroscopic instruments. Various modifications whether by way of addition, deletion, or substitution of features may be made to above described embodiment to provide further embodiments, any and all of which are intended to be encompassed by the appended claims. 05 11 24

Claims

1. A surgical instrument, comprising:a handpiece for a surgical instrument, the handpiece comprising: a5 housing; a suction lumen within the housing extending from the distal end of the handpiece to a proximal end of the handpiece; a flow valve arranged to control the flow of fluid through the suction lumen; and a flow valve position sensing circuit arranged to detect a position of the flow valve;the surgical instrument further comprising: a cutting accessory comprising10 a shaft and an end effector, a proximal end of the shaft being coupled to the distal end of the handpiece, and a distal end of the shaft being coupled to the end effector;wherein:a) the suction lumen further extends through the shaft to the end effector;is b) the surgical instrument is an electrosurgical instrument with an RFcomponent; andc) the valve position sensing circuit is arranged to alert a user if the valve is CM closed when the RF component is in use.V— 20 2. A surgical instrument according to claim 1, wherein the flow valve positionLO sensing circuit detects whether the valve is in any one of: a first position, a secondposition, or an intermediate position between the first and second positions.

3. A surgical instrument according to claim 2, wherein the first position is an 25 open position and / or the second position is a closed position.

4. A surgical instrument according to any of claims 1 to 3, wherein the flow valve is arranged to adjust a flow rate of saline out of a surgical site.30 5. A surgical instrument according to any of claims 1 to 4, wherein the detectedposition of the valve is arranged to be communicated to a user of the electrosurgical instrument via a signal on the handpiece.

6. A surgical instrument according to any of claims 1 to 5, wherein the valve 35 position sensing circuit comprises a Hall Effect sensor.05 11 247. A surgical instrument according to claim 6, wherein the Hall Effect sensor is arranged to be in a static position relative to the handpiece.

8. A surgical instrument according to any of claims 6 or 7, wherein the valve 5 position sensing circuit further comprises a magnet.

9. A surgical instrument according to claim 8, wherein the magnet is arranged to move in conjunction with a lever arranged to operate the valve, such that the Hall Effect sensor can detect movement of the magnet.io10. A surgical instrument according to any of claims 1 to 9, further comprising a motor within the housing arranged to actuate the cutting accessory in use; anda temperature sensor arranged to monitor a temperature of the motor;wherein the valve position sensing circuit is arranged to alert a user if the is valve is closed when the temperature of the motor is over a threshold.

11. A surgical instrument according to any of claims 1 to 10, further comprising: an in-joint temperature sensor arranged to monitor a temperature of saline in a patient's joint;20 wherein the valve position sensing circuit is arranged to alert a user if thevalve is closed when the temperature of saline in a patient's joint is over a threshold.

12. An electrosurgicaI system, comprising:an RF electrosurgical generator;25 a surgical instrument according to any of the preceding claims, thearrangement being such that in use the RF electrosurgical generator supplies an RF coagulation or ablation signal to the end effector; anda suction source, fluidly connected to the suction lumen.

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