GB2510098B

GB2510098B - Surgical instrument

Info

Publication number: GB2510098B
Application number: GB1220089.5A
Authority: GB
Inventors: Maxwell Vhairi; Ridler Keir
Original assignee: Surgical Innovations Ltd
Current assignee: Surgical Innovations Ltd
Priority date: 2012-11-07
Filing date: 2012-11-07
Publication date: 2019-10-16
Anticipated expiration: 2032-11-07
Also published as: GB2510098A; GB201220089D0

Description

SURGICAL INSTRUMENT

The present invention relates to a surgical instrument for dispensing a fluid. Inparticular the invention may relate to a surgical instrument for dispensing a fluidto an operative site in the human or animal body.

Surgical instruments for dispensing a fluid to an operative site in the human oranimal body are known. WO2009/132331 discloses a minimally invasive (e.g.laparoscopic) applicator device which dispenses fluid and which may include aratcheted trigger system to overcome backflow. W002/064192 discloses alaparoscopic gel applicator. However, it has been recognised by the applicantthat the devices disclosed in these documents do not provide any means toreduce the likelihood of accidental operation of the device before the device isintended to be used.

The present invention seeks to reduce the likelihood of accidental dispensing offluid from a surgical instrument for dispensing a fluid. According to the presentinvention, there is provided a surgical instrument for dispensing a fluidcomprising: a housing; a dispensing shaft which is elongate and which has a proximal end and adistal end, wherein the proximal end of the dispensing shaft is received in thehousing and the distal end defines a dispensing opening for dispensing the fluidand the dispensing shaft includes a through bore which extends along thedispensing shaft from the proximal end to the dispensing opening at the distalend; a dispensing assembly connected to the housing with said dispensingassembly including a trigger mounted to the housing, said dispensing assemblyfurther including a dispensing chamber, having a plunger mounted therein, forholding the fluid before the fluid is dispensed, wherein the dispensing chamber is in fluid communication with the through bore of the dispensing shaft and thedispensing assembly being operable, by means of the plunger to move the fluidfrom the dispensing chamber along the through bore for dispensing the fluidfrom the dispensing opening; said fluid movement being effected by the trigger acting on the plungervia a pawl and ratchet mechanism, the trigger being movable between a firstposition and a second position, movement of the trigger from the first position tothe second position effecting movement of the plunger and movement of thetrigger from the second position to the first position not effecting movement ofthe trigger; and a priming assembly connected to the housing, said priming assemblybeing operable for moving an amount of fluid into the through bore of thedispensing shaft to prime the through bore with the fluid before the dispensingassembly is operated, said dispensing assembly then being operable repeatedlyto dispense a predetermined amount of fluid each time the trigger is operatedthe priming assembly and the dispensing assembly forming an interlock so thatthe dispensing assembly cannot be operated until the priming assembly hasbeen operated.

By providing a priming assembly, the likelihood of accidental dispensing of fluidby a user of the surgical instrument may be reduced because the fluid will not bepresent in the through bore until the priming assembly is operated to prime thethrough bore with the fluid. In this way operation of the dispensing assemblywill not dispense fluid from the dispensing opening until the priming assemblyhas been operated. Reducing the likelihood of accidental dispensing of fluid isadvantageous because fluid may be dispensed in an undesirable location. Forexample, if the fluid is an adhesive, accidentally dispensed adhesive may contactunintended tissue in the human or animal body which may be undesirable.Operation of the priming assembly may prepare the surgical instrument for use.

The housing may comprise a handle. The handle may allow the surgicalinstrument to be gripped in one hand to allow one-handed operation of the surgical instrument. The housing may comprise a body. The extension shaftmay extend from the body. The housing may have a 'pistol' configuration inwhich the handle extends from the body in a similar configuration to a pistolhandle extending from a pistol barrel.

The dispensing shaft may have a longitudinal axis. The longitudinal axis of thedispensing shaft may define a proximo-distal axis for the surgical instrument.The proximo-distal axis may be oriented so that the distal direction is generallytowards the distal end of the dispensing shaft and the proximal direction isgenerally away from the distal end.

The dispensing shaft may comprise an inner tube and an outer tube. The outertube may be made of metal. The inner tube may be made of a polymer. Thepolymer may be polytetrafluoroethylene (PTFE), fluorinated ethylene propylene(FEP) or silicone. The polymer may be a non-stick or low friction polymer. Thismay assist the movement of the fluid along the through bore by reducing shearstress. Foe example, when the fluid is an adhesive or has a significant viscosity,a non-stick or low friction polymer may assist the flow of fluid along the throughbore. The through bore may extend within the inner tube.

Fluid is held in the dispensing chamber before it is moved into the dispensingshaft to be dispensed. The plunger is positioned to advance or retract within thedispensing chamber. When the plunger is advanced within the dispensingchamber, fluid is urged out of the dispensing chamber and into the dispensingshaft. The plunger advances within the dispensing chamber in a distal direction.Fluid urged out of the dispensing chamber enters the through bore of thedispensing shaft at the proximal end of the dispensing shaft.

The plunger may engage the internal surface of the dispensing chamber to forma seal. Alternatively the plunger may abut against a sealing disc which engagesthe internal surface of the dispensing chamber to form a seal. Advancement of the plunger advances the sealing disc within the chamber. The chamber mayinclude a proximal end and a distal end. The distal end of the plunger may abutthe sealing disc.

Preferably the plunger abuts against a sealing disc which is slidably mountedwithin the dispensing chamber, wherein operation of the dispensing assemblycauses the plunger to advance the sealing disc within the dispensing chamber tourge the fluid out of the dispensing chamber and along the through bore in thedispensing shaft.

The plunger may be connected to a plunger drive assembly. The plunger driveassembly may be a rack and pinion. The pinion gear wheel may be mountedwithin the housing. Turning the pinion gear wheel may engage the rack toadvance or retract the plunger along the dispensing chamber.

The trigger may be reciprocable. The trigger may be mounted on the housing.The trigger may be mounted on the handle or the body of the housing. Thetrigger may be operable by a user's finger from a first trigger position to asecond trigger position. The trigger may be biased by a spring to return to thefirst trigger position when the user's finger is released at the second triggerposition. The spring may be attached to the housing at a first end and attachedto the trigger at a second end.

The pawl and ratchet may be connected to the trigger and a trigger gear wheel.The pawl may be connected to one of the trigger and the trigger gear wheel andthe ratchet may be connected to the other of the trigger and the trigger gearwheel. The pawl may be moulded into the trigger. When the trigger is movedfrom the first trigger position to the second trigger position the pawl may engagethe ratchet to turn the trigger gear wheel. When the trigger is moved from thesecond trigger position to the first trigger position the pawl and ratchet maydisengage so that the trigger gear wheel does not turn.

Turning the trigger gear wheel may turn the pinion gear wheel to advance theplunger. An intermediate gear wheel may be connected between the triggergear wheel and the pinion gear wheel. The relative sizes of the trigger gearwheel and pinion gear wheel may be chosen to provide a suitable gear reduction.This may provide a mechanical advantage to the operation of the trigger fromthe first trigger position to the second trigger position. The intermediate gearwheel may contribute to the gear reduction. The overall gear ratio between thetrigger gear wheel and the pinion gear wheel may be 4 to 1. Therefore a 10°rotation of the trigger may result in a 2.5°rotation of the pinion gear wheel. Thesize of the pinion gear wheel may be chosen to advance the rack by apredetermined amount when the trigger is operated from the first triggerposition to the second trigger position. This will cause the plunger to advance bya predetermined amount to dispense a predetermined volume of the fluid.

An indexing wheel may be attached to the trigger gear wheel. The indexingwheel may enable the movement of the trigger between the first trigger positionand the second trigger position to be indexed. The indexing wheel may includeindentations on its circumference which engage an indexing formation on thehousing to provide the indexing. The engagement of the indentations wth theindexing formation may also provide an additional frictional force on the ratchetto assist the trigger to move from the second trigger position to the first triggerposition without moving the ratchet

The priming assembly may comprise a priming actuator. The priming actuatormay be operable to drive the priming assembly. The priming actuator may bemounted to a proximal end of the housing. The priming actuator may berotatably mounted to the housing. The priming actuator may be operable from afirst priming position to a second priming position. The priming actuator may berotatable from the first priming position to the second priming position.

The priming assembly may include a safety element which is moveable from anengaged position to a disengaged position. The safety element may prevent thepriming assembly from being operated when it is in the engaged position. Thesafety element may be in the form of a pull tab connected to the primingactuator. In its engaged position, the pull tab may engage a recess on thehousing to prevent the priming actuator from being operated from the firstpriming position to the second priming position. The pull tab may be separablefrom the priming actuator and disengaged from the recess so that the primingoperation can be operated.

Preferably the priming assembly includes a safety element which is moveablefrom an engaged position to a disengaged position, wherein when the safetyelement is in the engaged position it prevents the priming assembly from beingoperated and when the safety element is in the disengaged position the primaryassembly is operable.

Operation of the priming actuator may cause the plunger to advance into thedispensing chamber. The plunger may advance in a distal direction.

If the priming actuator is rotatably mounted to the housing, rotation of thepriming actuator may rotate a priming cap with an internal screw thread. Thepriming cap may be linearly moveable with respect to the priming actuator bythe engagement of a spline feature on one of the priming cap and thd thepriming actuator with a groove on the other of the priming cap and the thepriming actuator. The internal screw thread on the priming cap may engage acomplementary screw thread on the plunger drive assembly. Since the plunger isconnected to the priming cap, the plunger will advance distally with respect tothe plunger drive assembly. The advancement of the plunger may prime thethrough bore of the dispensing shaft with fluid by advancing the sealing disc inthe dispensing chamber and urging the fluid out of the dispensing chamber.

The interlock may be moveable from a locked configuration in which it preventsthe dispensing assembly from being operated to a released configuration inwhich the dispensing assembly is operable. The interlock may only be moveableto the released configuration once the priming actuator is in the second primingconfiguration. An advantage of the interlock may be that accidental operation ofthe dispensing assembly is not possible until the priming assembly has beenoperated and the priming actuator is in the second priming position.

The interlock may include a locking member. The locking member may beelongate and may be moveably mounted in the housing to contact a lockingformation on the dispensing assembly and to contact the priming actuator.When the priming actuator is in the first priming position and the interlock is inthe locked configuration, the locking member may be unable to move and maylock the trigger in the second trigger position by contact with the lockingformation.

The priming actuator may include an interlock recess positioned so that whenthe priming actuator is in the second priming position, the interlock recess isaligned with the locking member to allow the locking member to move into theinterlock recess. The spring bias on the trigger may then cause the lockingformation to move the locking member into the interlock recess and thisreleased configuration allows the trigger to move from the second triggerposition to the first trigger position. Once the trigger is in the first triggerposition, it is operable by the user.

Preferably the priming assembly includes a priming actuator which is operablefrom a first priming position to a second priming position and which includes aninterlock recess; and the interlock includes a locking member which is able toenter the interlock recess when the priming actuator is in the second primingposition to release the interlock and allow the dispensing assembly to beoperated.

The fluid may be a medical fluid. The fluid may be a liquid or a gel. The fluid may aid inthe recovery or the comfort of the patient. The fluid may have a viscosity similar to waterat room temperature. The fluid may have a higher viscosity than water at roomtemperature. The fluid may be a pharmaceutical agent, hemostatic solution, wound-healing agent, analgesic, anti-adhesive, adhesive, irrigation fluid or cooling fluid. Thefluid may include an anesthetic, an antibiotic in fluid form, a growth factor, suspendedstem cells, chondrocytes, other biologically active substances such as extra-cellular matrix,including proteoglycans, glycosaminoglycan (GAG), chondroitin sulfate, or anantihemorragic.

The fluid may be a bone cement.

The fluid may be an adhesive. The adhesive may be a collagen-based adhesive, ahydrogel, an albumin-based compound, a cyanoacrylate or a fibrin.

The fluid may be a cyanoacrylate adhesive. The cyanoacrylate adhesive may have aviscosity similar to water at room temperature.

In another embodiment, the fluid may be a fibrin adhesive. The fibrin adhesive may be abinary mixture in which two inactive precursor fluids are mixed to form the active fibrinadhesive. The dispensing assembly may comprise a first dispensing chamber for the firstprecursor fluid and a second dispensing chamber for the second precursor fluid. Thedispensing assembly may include a first plunger for the first dispensing chamber and asecond plunger for the second dispensing chamber. The first and second plungers may beadvanced by a common plunger drive assembly. A mixing chamber may be locatedbetween the first and second dispensing chambers and the dispensing shaft. The first andsecond precursor fluids may mix in the mixing chamber to form the active fibrin adhesivebefore moving into the dispensing shaft.

To ensure sterility and prolong shelf-life, a medical fluid may be stored in a sealed glasscontainer. The container may be a glass ampoule. If the fluid to be used in the surgicalinstrument of the present invention is stored in a sealed glass container, the surgical instrument may include a transfer assembly as described herein. The transfer assemblymay enable the transfer of the fluid from the sealed glass container to the dispensingchamber. The fluid may be a cyanoacrylate adhesive which is stored in a sealed glasscontainer. The cyanoacrylate adhesive may be stored in a sealed glass container to preventcontact with moisture which may cause the cyanoacrylate adhesive to polymerise.

In another embodiment, the fluid may be stored initially in the dispensing chamber. In thisembodiment, a transfer assembly may not be required.

The surgical instrument may include a container in which the fluid is stored before thesurgical instrument is used. The container may be a glass ampoule. The fluid may betransferred to the dispensing chamber by a transfer assembly. The transfer assembly mayinclude a container holder which holds the container. The container holder may include afilter. The apertures of the filter may be sized to allow the fluid to pass but to retain anyfragments of the container which are produced when the container is opened.

To release the fluid, the container may be opened. If the container is a sealed glasscontainer this may result in glass fragments being produced. The transfer assembly maycomprise a filter to retain any glass fragments produced in opening the sealed glasscontainer. An advantage of this configuration is that it ensures that fluid which istransferred to the dispensing chamber is free of glass fragments.

The dispensing chamber may be attached to the transfer assembly.

The transfer assembly may be operable to open the container and transfer the fluid fromthe opened container to the dispensing chamber before the priming assembly is operated.

The transfer assembly may be moveably mounted to the housing. The transfer assemblymay pivot with respect to the housing. The transfer assembly may be moveable between afirst transfer position, a second transfer position and a third transfer position.

Movement of the transfer assembly from the first transfer position to the second transferposition may cause the container to be opened to release the fluid. The container may beopened by a projection on the transfer assembly being pushed into the container. When thecontainer is a glass ampoule, this will break open the ampoule. Any container fragmentscreated by the opening of the container will be retained by the filter.

The container may be made of a frangible material. An example of a frangible material isglass. The container may be a frangible container.

The container may be made of a material which during deformation tends to break up intofragments, rather than deforming plastically and remaining in one piece. A polymer sleeve may at least partially surround the container. The polymer sleeve maybe a PTFE sleeve. When the container is opened, the polymer sleeve may prevent the fluidfrom spilling out of the container holder.

The projection may be pushed into the container by relative movement of the containerholder with respect to the projection. The transfer assembly may include a breaker sectionwhich is moveable with regard to a holder section. The projection may be located on thebreaker section and the container holder may attached to the holder section. When thetransfer assembly is moved from the first transfer position to the second transfer position,the holder section may move relative to the breaker section. For example, the breakersection may be moveably retained on the housing so that it cannot move as far as theholder section. In this way, moving the holder section to its maximum extent will movethe holder section relative to the breaker section.

Once the fluid is released from the container, it may be directed to the dispensing chamber.A valve may be positioned between the container and the dispensing chamber. The valvemay comprise an outer valve body and an inner valve member. The valve may be a plugvalve. The valve member may be a cylinder with a cylindrical surface and axial ends. Thevalve body may be annular and encircle the valve member. The valve member may beattached to the housing at its axial ends and the valve body may be attached to the transfer assembly. In this way the valve member may act as a pivot around which the valve bodyand transfer assembly rotates when the transfer assembly moves between the first transferposition, second transfer position and third transfer position. This use of the valve memberas a pivot for the transfer assembly may advantageously reduce the number of componentsrequired in the surgical instrument. A transfer channel may be defined by the valve member. When the valve member is acylinder, the transfer channel may be a channel on its cylindrical surface. The valve bodymay define a container holder opening which is in fluid communication with the containerholder. The valve body may define a dispensing chamber opening which is in fluidcommunication with the dispensing chamber.

The valve member may further define a dispensing channel. The dispensing channel maybe a diametrical channel through the valve member.

When the transfer assembly is in the first transfer position, the transfer channel may not bealigned with the container holder opening and the dispensing chamber opening. When thetransfer assembly is in the second transfer position, the transfer channel may be alignedwith the container holder opening and the dispensing chamber opening to provide a fluidpath between the container holder opening and the dispensing chamber opening. In thisway, fluid released from the container may flow from the container holder to thedispensing chamber when the transfer assembly is in the second transfer position.

Before the surgical instrument is used, the sealing disc may be located at a distal end of thedispensing chamber. To draw the released fluid through the transfer channel from thecontainer holder when the transfer assembly is in the second transfer position, the sealingdisc may be retracted proximally in the dispensing chamber. A pull member may beattached to the sealing disc to allow the user to retract the sealing disc. When the transferassembly is in the first transfer position, the pull member may be restrained frommovement by the housing. When the transfer assembly is moved from the first transferposition to the second transfer position, the pull member may move above the housing sothat it is no longer restrained.

Once all the fluid has been drawn into the dispensing chamber and the sealing disc is fullyretracted, the pull member may disengage from the sealing disc. The pull member maycomprise two fingers which engage a recess on the sealing disc so that the sealing disc maybe retracted. The recess may be in the form of a through-hole. The fingers may beretained in the recess by the inner surface of the dispensing chamber. At its proximal end,the dispensing chamber may define two slots which allow the fingers to disengage from therecess when the sealing disc is fully retracted. In this way, the pull member is disengagedand separated from the dispensing chamber and may be discarded.

After the pull member is discarded, the sealing disc may be fully retracted and thedispensing chamber contains the fluid to be dispensed. The transfer assembly may then bemoved to the third transfer position. To reach the third transfer position, the transferassembly may be pivoted about the valve member until the dispensing chamber opening isaligned with the dispensing channel. When the transfer assembly is in the third transferposition, the sealing disc may be aligned with the plunger. The priming actuator may thenbe operated. When the priming actuator is operated from the first priming position to thesecond priming position, the plunger may advance the sealing disc distally within thedispensing chamber and push the fluid through the dispensing chamber opening and thedispensing channel. The proximal end of the dispensing shaft may be received within thevalve member and the through bore may be connected to the dispensing channel.Therefore fluid pushed through the dispensing channel may travel distally along thethrough bore and be dispensed from the dispensing opening at the distal end of thedispensing shaft.

If the fluid to be dispensed is not initially contained in a glass ampoule, a transfer assemblymay not be required. In an alternative embodiment, the surgical instrument may besupplied initially with the fluid already present in the dispensing chamber and the plungeraligned with the sealing disc in a configuration similar to the third transfer position. Thevalve will not be required and the dispensing chamber opening will be in fluidcommunication with the proximal end of the dispensing shaft.

The fluid may be dispensed in discrete doses. Each dose may be a predetermined amountof fluid. A single dose may be known as a delivery. Each delivery may be of apredetermined volume. The dimensions of the dispensing chamber and plunger may beconfigured so that advancement of the plunger by a set distance dispenses thepredetermined volume.

The predetermined volume of a delivery may be up to 50 mm3. The predetermined

-1 -J delivery volume may be from 10 mm to 40 mm . Preferably the predetermined deliveryvolume is from 20 mm3 to 30 mm3, more preferably the predetermined delivery volume isapproximately 25 mm .

If the predetermined delivery volume is approximately 25 mm3 and the internal diameter ofthe dispensing chamber is 7mm, the plunger will advance approximately 0.65mm for eachseparate delivery of fluid.

The surgical instrument may be capable of dispensing a predetermined number ofdeliveries. The predetermined number of deliveries may be up to 50 deliveries. Preferablythe predetermined number of deliveries is from 20 to 50 deliveries, more preferably from30 to 40 deliveries. The predetermined number of deliveries may be 35 deliveries.

After the dispensing actuator has been operated for a number of times equal to thepredetermined number of deliveries, a hard stop on the dispensing assembly may preventthe dispensing actuator from being operated again. Preferably the hard stop featureprevents further operation of the trigger after the trigger has been operated a predeterminednumber of times.

Preferably the hard stop is provided by a stop projection on the plunger drive assemblyengaging the housing. The stop projection may be located in a slot on the housing. Theslot may be in an exterior surface of the housing so that the stop projection is visible to theuser of the surgical instrument. The stop projection may advance in the slot as the plungeradvances the sealing disc in the dispensing chamber. The hard stop may be provided bythe stop projection reaching an end of the slot. The slot may be located so that the stop projection reaches the end of the slot when the predetermined number of deliveries isreached.

By being visible to the user, the relative position of the stop projection in the slot mayadvantageously indicate the number of deliveries the surgical instrument has made. Anindicator or scale may be marked on the housing to allow the user to judge the number ofdeliveries more accurately. For example, if the stop projection is located at a first end ofthe slot initially and reaches the second end of the slot when the predetermined number ofdeliveries is reached, then if the stop projection is in the middle of the slot, approximatelyhalf of the predetermined number of deliveries have been made.

The surgical instrument may be suitable for use in a minimally invasive surgical procedure.The surgical instrument may be suitable for hernia mesh fixation. The surgical instrumentmay be a hernia mesh fixation device.

When the surgical instrument is a hernia mesh fixation device, the fluid may be acyanoacrylate adhesive for securing a hernia mesh in place at the operative site in thehuman or animal body. The hernia mesh may be secured in place by a number ofdeliveries of adhesive from the surgical instrument. Each delivery of adhesive may have asimilar function to a suture or tack. The hernia mesh may be secured in place by between20 and 30 deliveries of adhesive. The hernia mesh may be secured in place byapproximately 25 deliveries of adhesive.

An embodiment of the invention will now be described by way of example only withreference to the accompanying drawings, in which like reference numerals indicate likeparts and in which:

Figure 1 is a view of the surgical instrument from the right hand side;

Figure 2 is an exploded view of the surgical instrument from above the right hand side;Figure 3 is a view inside the housing of the surgical instrument from the left hand side;Figure 4 is an exploded view of the transfer assembly of the surgical instrument;

Figure 5 is a view of the transfer assembly of the surgical instrument from the right handside;

Figure 6 is a cross-section of Figure 5 showing the valve of the transfer assembly in thesecond transfer position;

Figure 7 is a magnified view of a part of Figure 6;

Figure 8 is a view of the surgical instrument from the left hand side with the pull memberdisengaged from the dispensing chamber;

Figure 9 is a view of the surgical instrument from the left hand side with the transferassembly in the third transfer position;

Figure 10 is a similar view to Figure 9 with the left hand side of the housing removed’Figure 11 is a cross-section from the right hand side showing the valve of the transferassembly in the third transfer position;

Figure 12 is a view of the priming assembly from the left hand side;

Figure 13 is an exploded view of Figure 12;

Figure 14 is a cross-section of the surgical instrument from the right hand side showing thepriming assembly in the first priming position;

Figure 15 is a cross-section of the surgical instrument from the right hand side showing thepriming assembly in the second priming position;

Figure 16 is an exploded view of the dispensing assembly from the right hand side;

Figure 17A is a view of the trigger gear wheel from the right hand side;

Figure 17B is a view of the trigger gear wheel from the left hand side;

Figure 18A is a view of the trigger from above the right hand side;

Figure 18B is a view of the trigger from the left hand side;

As shown in Figure 1, the surgical instrument 10 comprises a housing 20 and a dispensingshaft 30. The housing 20 comprises a handle 22 which allows the surgical instrument 10 tobe gripped in one hand to allow one-handed operation of the surgical instrument 10. Thehousing 20 also comprises a body 24. The dispensing shaft 30 extends from the body 24.The housing 20 has a ‘pistol’ configuration in which the handle 22 extends from the body24 in a similar configuration to a pistol handle extending from a pistol barrel.

As shown in Figures 1 and 2, the dispensing shaft 30 is elongate and has a proximal end 31and a distal end 32. The proximal end 31 of the dispensing shaft 30 is received within thehousing 20 and the distal end 32 defines a dispensing opening 33 for dispensing the fluid12. The fluid 12 is shown in Figures 7 and 14. The dispensing shaft has a longitudinalaxis 34 which defines a proximo-distal axis for the surgical instrument 10. The proximo-distal axis is oriented so that the distal direction is generally towards the distal end 32 ofthe dispensing shaft 30 and the proximal direction is generally away from the distal end 32.

As shown in Figure 7, the dispensing shaft 30 comprises an inner tube 35 and an outer tube36. The inner tube 35 defines a through bore 37 which allows the fluid 12 to pass alongthe dispensing shaft 30. The outer tube 36 is made of metal and the inner tube 35 is madeof PTFE for low friction to assist the movement of the fluid 12 along the through bore 37by reducing shear stress.

The fluid 12 is a cyanoacrylate adhesive with a viscosity similar to water at roomtemperature. To ensure its sterility, the fluid 12 is stored in a sealed glass container 42before the surgical instrument 10 is used.

As shown in Figures 4 to 11, the surgical instrument 10 include a transfer assembly 40which enables transfer of the fluid 12 from the container 42 to a dispensing chamber 82.The dispensing chamber 82 is attached to the transfer assembly 40.

The transfer assembly 40 is moveably mounted to the housing 20. The transfer assembly ismoveable between a first transfer position (shown in Figures 3, 6 and 7), a second transferposition (not shown in the Figures) and a third transfer position (shown in Figures 9, 10and 11).

The transfer assembly includes a container holder 44 which holds the container 42. Thecontainer holder includes a filter 46. The apertures of the filter 46 are sized to allow thefluid 12 to pass through the filter but to retain any fragments of the container 42 which areproduced when the container 42 is opened. A PTFE sleeve 43 partially surrounds the container 42. When the container 42 is opened, the PTFE sleeve 43 prevents the fluid 12from spilling out of the container holder 44.

Movement of the transfer assembly 40 from the first transfer position to the second transferposition causes the container 42 to be opened by a projection 48 on the transfer assembly40 being pushed into the container 42 to break the wall of the container 42. Any glassfragments created by the opening of the container 42 will be retained by the filter 46.

The projection 48 is pushed into the container 42 by relative movement of the containerholder 44 with respect to the projection 48. The transfer assembly 40 includes a breakersection 50 which is moveable with regard to a holder section 52. The projection 48 islocated on the breaker section 50 and the container holder 44 is attached to the holdersection 52.

In the first transfer position (as shown in Figures 3 and 6) the transfer assembly 40 is at anangle of approximately 25° to the longitudinal axis 34 of the dispensing shaft 30. Whenthe transfer assembly 40 is moved from the first transfer position to the second transferposition, the holder section 52 is moved to an angle of approximately 35° to thelongitudinal axis 34. The breaker section 50 is retained by the engagement of a hookmember 49 with a catch 21 on the housing 20 (shown in Figure 16) so that it cannot movefurther than 25° to the longitudinal axis 34. In this way, moving the holder section 52 toits maximum extent of approximately 35° will move the holder section 52 relative to thebreaker section 50 and will cause the projection 18 to break open the container 42 andrelease the fluid 12.

Once the fluid 12 is released from the container 42, it is directed to the dispensing chamber82. As shown in Figures 6, 7 and 11, a valve 120 is positioned between the container 42and the dispensing chamber 82.

The valve 120 comprises an outer valve body 122 and an inner valve member 124. Thevalve member 124 is a cylinder with a cylindrical surface and axial ends. The valve body122 is annular and encircles the valve member 124. The valve member 124 is attached to the housing 20 at its axial ends and the valve body 122 is attached to the transfer assembly40. In this way the valve member 124 acts as a pivot around which the valve body 122 andtransfer assembly 40 rotates when the transfer assembly 40 moves between the firsttransfer position (see Figure 6), second transfer position and third transfer position (seeFigure 11). A transfer channel 126 is defined by the valve member 124 as a channel on its cylindricalsurface. The valve member 124 further defines a dispensing channel 128 a diametricalchannel through the valve member 124.

The valve body 122 defines a container holder opening 130 which is in fluidcommunication with the container holder 44. The valve body 122 also defines adispensing chamber opening 132 which is in fluid communication with the dispensingchamber 82.

When the transfer assembly 40 is in the second transfer position, the transfer channel 126is aligned with the container holder opening 130 and the dispensing chamber opening 132to provide a fluid path between the container holder opening 130 and the dispensingchamber opening 132. In this way, fluid 12 released from the container 42 may flow fromthe container holder 44 to the dispensing chamber 82 when the transfer assembly 40 is inthe second transfer position.

Before the surgical instrument 10 is used, a sealing disc 108 is located at a distal end of thedispensing chamber 82. To draw the released fluid 12 through the transfer channel 126from the container holder 44 when the transfer assembly 40 is in the second transferposition, the sealing disc 108 is retracted proximally in the dispensing chamber 82. A pullmember 54 is releasably attached to the sealing disc 108 to allow the user to retract thesealing disc 108. As shown in Figure 3, when the transfer assembly 40 is in the firsttransfer position, the pull member 54 is restrained from movement by the housing 20.When the transfer assembly 40 is moved from the first transfer position to the secondtransfer position and the holder section 52 is moved to an angle of approximately 35° to the longitudinal axis 34, the pull member 54 moves above the housing 20 so that it is nolonger restrained.

Once all the fluid 12 has been drawn into the dispensing chamber 82 and the sealing disc108 is fully retracted, the pull member 54 disengages from the sealing disc 108. The pullmember comprises two fingers 56 which engage a recess 110 on the sealing disc 108 sothat the sealing disc 108 may be retracted. The recess 110 is in the form of a through-hole.The fingers 56 may be retained in the recess 110 by the inner surface 83 of the dispensingchamber 82. At its proximal end, the dispensing chamber defines two slots 81 (shown inFigure 8) which allow the fingers 56 to disengage from the recess 110 when the sealingdisc 108 is fully retracted. In this way, the pull member 54 is disengaged and separatedfrom the dispensing chamber 82 (as shown in Figure 8) and is then discarded.

After the pull member 54 is discarded, the sealing disc 108 is fully retracted and thedispensing chamber 82 contains the fluid 12 to be dispensed. The transfer assembly 40may then be moved to the third transfer position as shown in Figures 9 to 11. To reach thethird transfer position, the transfer assembly 40 is pivoted about the valve member 124until the dispensing chamber opening 132 is aligned with the dispensing channel 128 asshown in Figure 11.

When the transfer assembly 40 is in the third transfer position, the sealing disc 108 isaligned with a plunger 84 as shown in Figure 14.

As shown in Figures 12 to 16, the surgical instrument 10 further comprises a primingassembly 60. The priming assembly 60 includes a priming actuator 62 which is operableto drive the priming assembly 60. The priming actuator 62 is rotatably mounted to aproximal end of the housing 20. The priming actuator 62 is rotatable from a first primingposition shown in Figure 14 to a second priming position shown in Figure 15.

The priming assembly 60 includes a safety element which is moveable from an engagedposition to a disengaged position and which prevent the priming assembly 60 from beingoperated when it is in the engaged position. The safety element is in the form of a pull tab 64 attached to the priming actuator 62. In its engaged position (as shown in Figure 14) thepull tab 64 engages a recess 28 on the housing 20 to prevent the priming actuator 62 frombeing operated. The pull tab 64 is separable from the priming actuator 62 so that in itsdisengaged position, the pull tab 64 is separated from the priming actuator 62 to allow thepriming actuator 62 to be operated.

When the priming actuator 62 is rotated from the first priming position to the secondpriming position, a plunger 84 advances and pushes the sealing disc 108 distally within thedispensing chamber 82 to push the fluid 12 through the dispensing chamber opening 132and the dispensing channel 128. The proximal end 31 of the dispensing shaft 30 isreceived within the valve member 124 and the through bore 37 is connected to thedispensing channel 128. Therefore fluid 12 pushed through the dispensing channel 128may travel distally along the through bore 37 and be dispensed from the dispensingopening 33 at the distal end 32 of the dispensing shaft 30.

Rotation of the priming actuator 62 from the first priming position to the second primingposition rotates a priming cap 66 with an internal screw thread 65. The priming cap 66 islinearly moveable with respect to the priming actuator 62 by the engagement of a splinefeature 67 on the priming cap 66 with a groove 63 on the priming actuator 62. The internalscrew thread 65 on the priming cap 66 engages a complementary screw thread 87 mountedon a plunger drive assembly 86. The priming cap 66 is connected to a proximal end 78 ofthe plunger 84. In this way, rotation of the priming actuator 62 causes the internal screwthread 65 on the priming cap 66 to advance along the complementary screw thread 87 onthe plunger drive assembly 86. Since the plunger 84 is connected to the priming cap 66,the plunger 84 will advance distally with respect to the plunger drive assembly 86 asshown in Figures 14 and 15. The advancement of the plunger 84 primes the through bore37 of the dispensing shaft 30 with fluid 12 by advancing the sealing disc 108 in thedispensing chamber 82 and urging the fluid 12 out of the dispensing chamber 82.

The priming assembly 60 includes an interlock 70 as shown in Figures 12, 14 and 15. Theinterlock 70 is moveable from a locked configuration in which it prevents the dispensingassembly 80 from being operated to a released configuration in which the dispensing assembly 80 is operable. The interlock 70 is only moveable to the released configurationonce the priming actuator 62 is in the second priming position. An advantage of theinterlock 70 is that accidental operation of the dispensing assembly 80 is not possible untilthe priming assembly 60 has been operated and the priming actuator 62 is in the secondpriming position.

As shown in Figures 12 and 13, the interlock 70 includes a locking member 72. Thelocking member is elongate and is slidably mounted in the housing 20 to contact a lockingformation 106 on the dispensing assembly 80 (see Figures 14 and 15) and to contact thepriming actuator 62. When the priming actuator 62 is in the first priming position and theinterlock 70 is in the locked configuration, the locking member 72 is unable to move andlocks the trigger 94 in the second trigger position by contact with the locking formation106.

The priming actuator 62 includes an interlock recess 74 positioned so that when thepriming actuator 62 is in the second priming position, the interlock recess 74 is alignedwith the locking member 72 to allow the locking member 72 to move into the interlockrecess 74. The spring 96 exerts a force on the trigger 94 which causes the lockingformation 106 to move the locking member 72 into the interlock recess 74 and thisreleased configuration allows the trigger 94 to move from the second trigger position to thefirst trigger position. Once the trigger 94 is in the first trigger position, it is operable by theuser.

As shown in Figures 11,14 and 15, the dispensing assembly 80 comprises a dispensingchamber 82. The fluid 12 is held in the dispensing chamber 82 before it is moved into thedispensing shaft 30. The elongate plunger 84 is positioned to advance or retract within thedispensing chamber 82. When the plunger 84 is advanced within the dispensing chamber82, the fluid 12 is urged out of the dispensing chamber 82 and into the through bore 37 ofthe dispensing shaft 30. The plunger advances within the dispensing chamber 82 in a distaldirection. Fluid 12 urged out of the dispensing chamber 82 enters the through bore 37 of atthe proximal end 31 of the dispensing shaft 30.

The plunger 84 has a distal end 79 which abuts against a sealing disc 108 which engagesthe internal surface 83 of the dispensing chamber 82 to form a seal. Advancement of theplunger 84 advances the sealing disc 108 within the dispensing chamber 82.

As shown in Figures 13, 14 and 15, the plunger 84 is connected to a plunger driveassembly 86 which includes a rack 88 and pinion gear wheel 90. The pinion gear wheel 90is mounted within the housing 20 . Turning the pinion gear wheel 90 engages the rack 88to advance or retract the plunger 84. When the plunger 84 advances the sealing disc 108 ispushed along the dispensing chamber 82. Retraction of the plunger 84 will not cause thesealing disc 108 to move because the plunger 84 abuts the sealing disc 108 instead of beingphysically connected to the sealing disc 108.

The dispensing assembly 80 comprises a dispensing actuator 92 which is operable to drivethe dispensing assembly 80. The dispensing actuator 92 is connected by an intermediategear wheel 104 to the pinion gear wheel 90 of the plunger drive assembly 86.

As shown in Figures 14, 15 and 16 the dispensing actuator 92 includes a reciprocabletrigger 94 mounted to the housing 20 between the handle 22 and the body 24 of thehousing 20. The trigger 94 is operable by a user’s finger from a first trigger position to asecond trigger position. The trigger 94 is biased by a spring 96 to return to the first triggerposition when the user’s finger is released at the second trigger position. The spring 96 isattached to the housing 20 at a first end 95 and attached to the dispensing actuator 92 at asecond end 97.

As shown in Figures 18A and 18B, a pawl 98 is moulded into the trigger 94 and a ratchet100 is connected to a trigger gear wheel 102. When the trigger 94 is moved from the firsttrigger position to the second trigger position the pawl 98 engages the ratchet 100 to turnthe trigger gear wheel 102. When the trigger 94 is moved from the second trigger positionto the first trigger position the pawl 98 and ratchet 100 disengage so that the trigger gearwheel 102 does not turn.

As shown in Figures 14 and 15, turning the trigger gear wheel 102 will turn theintermediate gear wheel 104 to turn the pinion gear wheel 90 to advance the plunger 84.The relative sizes of the trigger gear wheel 102, intermediate gear wheel 104 and piniongear wheel 90 are chosen to provide an overall gear ratio between the trigger gear wheel102 and the pinion gear wheel 90 of 4 to 1. Therefore a 10° rotation of the trigger 94results in a 2.5° rotation of the pinion gear wheel 90. The size of the pinion gear wheel 90is chosen to advance the rack 88 by a predetermined amount when the trigger 94 isoperated from the first trigger position to the second trigger position. This will cause theplunger 84 to advance by a predetermined amount to dispense a predetermined volume ofthe fluid 12 from the dispensing opening 33 of the surgical instrurhent 10.

As shown in Figures 17A and 17B an indexing wheel 101 is attached to the trigger gearwheel 102. The indexing wheel 101 enables the movement of the trigger 94 between thefirst trigger position and the second trigger position to be indexed. The indexing wheel101 includes indentations 99 on its circumference which engage an indexing formation 103on the housing 20 (see Figure 16) to provide the indexing. The engagement of theindentations 99 with the indexing formation 103 also provides an additional frictional forceon the ratchet 100 to assist the trigger 94 to move from the second trigger position to thefirst trigger position without moving the ratchet 100.

The surgical instrument 10 dispenses the fluid 12 in discrete doses. A single dose isknown as a delivery and each delivery is a predetermined volume of fluid 12. The internaldiameter of the inner surface 83 of the dispensing chamber 82 is chosen to be 7mm so thatadvancement of the plunger 84 by a set distance of 0.65mm will dispense a predeterminedvolume of approximately 25 mm .

The surgical instrument 10 is capable of dispensing a predetermined number of deliverieswhich is 35 deliveries. After the dispensing actuator 92 has been operated 35 times, a hardstop on the dispensing assembly 80 prevents the dispensing actuator 92 from beingoperated again. The hard stop is provided by a stop projection 112 on the plunger driveassembly 86 (as shown in Figure 13) engaging the housing 20.

As shown in Figures 9 and 16, the stop projection 112 is moveable within a slot 26 on thehousing 20. The slot 26 is in an exterior surface of the housing 20 so that the stopprojection 112 is visible to the user of the surgical instrument 10. The stop projection 112advances in the slot 26 as the plunger 84 advances the sealing disc 108 in the dispensingchamber 82. The hard stop is provided by the stop projection 112 reaching a distal end ofthe slot 26. The slot 26 is located so that the stop projection 112 reaches the distal end ofthe slot 26 when the predetermined number of 35 deliveries is reached. By being visible tothe user, the relative position of the stop projection 112 in the slot may provide a visualindication of the number of deliveries the surgical instrument 10 has made.

Use of the surgical instrument 10 in a hernia mesh fixation procedure will now bedescribed.

The fluid 12 is a cyanoacrylate adhesive suitable for securing a hernia mesh in place at theoperative site in the human or animal body. The hernia mesh is secured in place by anumber of deliveries of adhesive from the surgical instrument 10. Each delivery ofadhesive has a similar function to a suture or tack. The hernia mesh is secured in place byapproximately 25 deliveries of adhesive. Since the predetermined maximum number ofdeliveries of the device is 35 deliveries, there are approximately 10 extra deliveries ofadhesive available for the surgeon to use as necessary. The surgeon may use some of theseextra deliveries for closure of the peritoneum if appropriate.

The detailed sequence of the steps for using the surgical instrument 10 is as follows. Inthis description, it is assumed that a scrub nurse and a surgeon will be present during theprocedure but the surgical instrument 10 may also be prepared and used by a single person.

The surgical instrument 10 is provided in sterile packaging with the transfer assembly 40 inthe first transfer position at an angle of 25° to the longitudinal axis 34 of the dispensingshaft 30. The scrub nurse removes the surgical instrument 10 from the packaging andmoves the transfer assembly 40 to the second transfer position at an angle of 35° to breakthe container 42 within the container holder 44. The move to the second transfer positionaligns the dispensing chamber 82 and the container holder 44 with the transfer channel 126 on the valve 120. Next the scrub nurse retracts the sealing disc 108 in the dispensingchamber 82 by pulling the pull member 54 to draw the adhesive fluid 12 into thedispensing chamber 82. The pull member 54 self-detaches at the end of its travel and isdiscarded.

The scrub nurse then moves the transfer assembly 40 to the third transfer position (asshown in Figures 9, 10 and 11) which moves the dispensing chamber 82 from alignmentwith the transfer channel 126 of the valve 120 to alignment with the dispensing channel128.

At this stage, the transfer sequence has been completed and the priming sequence can bestarted. To start the priming sequence the scrub nurse removes the safety element 64which releases the priming actuator 62. Next the scrub nurse rotates the priming actuator62 which advances the plunger 84 to push the sealing disc 108 forward distally in thedispensing chamber 82 which in turn pushes adhesive fluid 12 through the dispensingchannel 128 of the valve 120 and along the through bore 37 of the dispensing shaft 30 tonear the dispensing opening 33 of the surgical instrument 10. Once the priming actuator62 has been rotated 320° from the first priming position to the second priming position, thelocking member 72 of the interlock 70 is pushed backwards into the interlock recess 74 onthe priming actuator 62 by the force of the spring 96 on the dispensing actuator 92. Thiscauses the trigger 94 to be released to the first trigger position which completes thepriming sequence and the surgical instrument 10 is now ready for use.

The scrub nurse hands the surgical instrument 10 to the surgeon to use. When the surgeonuses a finger to pull the trigger 94 from the first trigger position to the second triggerposition, the plunger drive assembly 86 advances the plunger 84 to make a delivery of fluidadhesive 12 from the dispensing opening 33. When the surgeon releases the trigger 94 thedispensing actuator 92 is rotated by the spring 96 from the second trigger position back tothe first trigger position without the ratchet 100 rotating, ensuring that the plunger 84remains stationary. The Surgeon uses up to 25 deliveries of adhesive fluid 12 to attach thehernia mesh in the desired position.

Claims

1. A surgical instrument for dispensing a fluid comprising: a housing; a dispensing shaft which is elongate and which has a proximal end and adistal end, wherein the proximal end of the dispensing shaft is received in thehousing and the distal end defines a dispensing opening for dispensing the fluidand the dispensing shaft includes a through bore which extends along thedispensing shaft from the proximal end to the dispensing opening at the distalend; a dispensing assembly connected to the housing with said dispensingassembly including a trigger mounted to the housing, said dispensing assemblyfurther including a dispensing chamber, having a plunger mounted therein, forholding the fluid before the fluid is dispensed, wherein the dispensing chamberis in fluid communication with the through bore of the dispensing shaft and thedispensing assembly being operable, by means of the plunger to move the fluidfrom the dispensing chamber along the through bore for dispensing the fluidfrom the dispensing opening; said fluid movement being effected by the trigger acting on the plungervia a pawl and ratchet mechanism, the trigger being movable between a firstposition and a second position, movement of the trigger from the first positionto the second position effecting movement of the plunger and movement of thetrigger from the second position to the first position not effecting movement ofthe trigger; and a priming assembly connected to the housing, said priming assemblybeing operable for moving an amount of fluid into the through bore of thedispensing shaft to prime the through bore with the fluid before the dispensingassembly is operated, said dispensing assembly then being operable repeatedlyto dispense a predetermined amount of fluid each time the trigger is operatedthe priming assembly and the dispensing assembly forming an interlock so thatthe dispensing assembly cannot be operated until the priming assembly hasbeen operated.

2. A surgical instrument as claimed in Claim 1 wherein the priming assemblyincludes a priming actuator which is operable from a first priming position to asecond priming position and which includes an interlock recess; and the interlock includes a locking member which is able to enter theinterlock recess when the priming actuator is in the second priming position torelease the interlock and allow the dispensing assembly to be operated.

3. A surgical instrument as claimed in claim 1 or claim 2 wherein thepredetermined amount of fluid is a predetermined delivery volume of from 20mm3 to 30 mm3.

4. A surgical instrument as claimed in any preceding claim including a hardstop feature which prevents further operation of the trigger after the trigger hasbeen operated a predetermined number of times.

5. A surgical instrument as claimed in claim 4 wherein the hard stop feature isprovided by a stop projection on the dispensing assembly engaging the housingto prevent further operation of the dispensing assembly.

6. A surgical instrument as claimed in any preceding claim wherein thepriming assembly includes a safety element which is moveable from an engagedposition to a disengaged position; wherein when the safety element is in the engaged position it preventsthe priming assembly from being operated and when the safety element is inthe disengaged position the priming assembly is operable.

7. A surgical instrument as claimed in any preceding claim wherein theplunger abuts against a sealing disc which is slidably mounted within thedispensing chamber, wherein operation of the dispensing assembly causes theplunger to advance the sealing disc within the dispensing chamber to urge the fluid out of the dispensing chamber and along the through bore in thedispensing shaft.

8. A surgical instrument as claimed in any preceding claim which includes: a container in which the fluid is stored before the surgical instrument isused; and a transfer assembly connected to the housing which is operable to openthe container and transfer the fluid from the opened container to the dispensingchamber before the priming assembly is operated.

9. A surgical instrument as claimed in claim 8 wherein the container is sealedand the transfer assembly is moveable from a first transfer position to a secondtransfer position to open the sealed container to release the fluid.

10. A surgical instrument as claimed in claim 9 wherein the container is asealed glass container and the transfer assembly includes a filter for separatingglass fragments produced when the sealed glass container is opened from thefluid which is released from the opened container.

11. A surgical instrument as claimed in claim 9 or claim 10 wherein the transferassembly is moveable to a third transfer position and the transfer assemblyincludes a valve which is positioned between the container and the dispensingchamber wherein in the second transfer position the valve allows the fluid toflow from the container into the dispensing chamber and wherein in the thirdtransfer position the valve allows the fluid to flow from the dispensing chamberinto the dispensing shaft.

12. A surgical instrument as claimed in any preceding claim wherein the fluid isan adhesive.

13. A surgical instrument as claimed in claim 12 wherein the adhesive is acyanoacrylate adhesive.