WO2008034793A1

WO2008034793A1 - Hand-held actuator device

Info

Publication number: WO2008034793A1
Application number: PCT/EP2007/059776
Authority: WO
Inventors: Jürgen Dorn; Michael Vogel; Martin Wübbeling
Original assignee: Angiomed Gmbh & Co. Medizintechnik Kg
Priority date: 2006-09-20
Filing date: 2007-09-17
Publication date: 2008-03-27
Also published as: GB0618516D0

Abstract

A device for pulling a length of wire relative a tube surrounding the wire (8) out of the tube, comprising a housing (10) having a distal and a proximal end, a reel (24) mounted in the housing for receiving the length of wire (8) and a reel-drive system for urging the reel to pull back the length of wire out of the tube, whereby the reel-drive system includes a one-way element (32).

Description

HAND-HELD ACTUATOR DEVICE

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a device for pulling a wire axially, relative to a tube surrounding the wire. More particularly, but not exclusively, the invention relates to a device that is a sheath retraction system for retracting an outer sheath relative to an inner support catheter and more particularly to a hand-held actuator device of a stent delivery system.

2. Background

Pull wire devices have been proposed for a medical system for delivering a self-expanding stent that is installed in surrounding co-axial engagement at the distal end of a support catheter, the stent being constrained in a reduced-diameter configuration about the catheter by the outer sheath, which surrounds both the stent and catheter. The sheath and catheter are usually sized to be insertable, distal end first, into the bodily lumens of the cardiovascular system, to deliver the stent percutaneously to a treatment site, at which the sheath is withdrawn to release the stent, which expands to a larger diameter configuration to maintain the bodily lumen passageway unobstructed.

US 2005/0060016 discloses a delivery system for implantation of a self -expanding medical device in a body which includes a control handle and a catheter portion. The control handle has a rotatable thumbwheel to actuate a retraction mechanism. This retraction mechanism includes a slideable gear rack, which is moved when the thumbwheel is actuated, thereby retracting an outer restraining member like the above mentioned catheter. The outer restraining member includes the self-expanding medical device and an inner catheter member.

The gear rack can pull back a length of the outer restraining member not longer than a distance, which is designated for moving the gear rack into the housing, but not exceeding a distance of its length. This is a problem especially for longer medical devices. Therefore, a device like this would have to be built very big for delivering longer medical devices. This would be very obstructive during an operation with such a device.

WO 02/087470 discloses a hand device for a catheter stent delivering system. The restraint function Is performed by a hub that is mounted within the hand-held actuator and itself receives the proximal end of the tube. To deliver a stent, in WO 02/087470 is provided an index~finger-triggering-system, which causes a mechanical apparatus within the device to pull In the outer sheat of a catheter and deliver the stent. Again, one disadvantage of the index- finger-triggering-system Is that it can only deliver a short stent. The maximum length which can be delivered by successive squeezes of the trigger is defined by the length of the track in the hand unit, rendering it incapable of releasing a self -expanding stent which is longer than the track.

WO 2005/039448 discloses an actuator, which can cause relative motion between an inner and an outer tube. The outer tube surrounds the Inner tube so that a medical device can be positioned between the inner and outer tubes. The actuator is formed of a rotatable member having a radius that increases as the actuator rotates. Therefore, the mechanical advantage of the actuator changes, in particular decreases, during the movement of the actuator. The system further includes a windable wire that couples the rotatable member to the outer tube . The first disadvantage of this system is that the mechanical advantage falls progressively. This reduces its usefulness to release long medical devices, because firstly there is a need of a high release force during the complete delivering of such a medical device, secondly the system has to be built uncomfortably big, otherwise the mechanical advantage jumps and this is not only uncomfortable for the operator but also the control over the release is much more difficult and, therefore not without risk for the patient. Furthermore, the mechanical advantage may not big enough for longer medical devices unless the system is, again, being built uncomfortably big.

Furthermore, WO 2005/039448 discloses nothing to inhibit reverse motion of the windable member. During actuating the rotatable member the contact between the operator and the actuator is likely to be discontinuous or intermitted and, because a wire has resilience, the system may have a reverse motion of the rotatable member which causes loss of control over the delivering of medical devices.

Stents are getting longer. For example, an in the past commonly used self-expanding stent had a length of about 2-3 cm and were delivered only to designated places. Stents are being envisaged which have a length of about 20 cm or more (e.g. a stent for a long artery in the leg) . It is one object of the present invention to provide a hand-held actuator useful for release of a self-expanding stent with a length longer than the known hand-held actuators can handle.

Another object of the present invention to provide ways in which the release force and the pull -velocity to which the stent is subject can be adjusted, in dependence upon the nature and characteristics of the medical procedure and prosthesis . Generally, the present invention aims to improve on the performance of the devices of WO 02/087470, US 2005/0060016 and WO 2005/039448, in the respects mentioned above.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a device for pulling a length of wire out of a tube, of the form discussed above and defined in claim 1 below. The preferred use of the device is releasing into the body from a delivery system a medical prosthesis, such as a stent. Optional or preferred features of the invention are mentioned in the dependent claims.

In a first embodiment, the device comprises an elongate housing with a distal and a proximal end, a reel mounted in that housing for receiving the length of wire, a first hub mounted on the distal end of the housing for receiving the tube with the wire and reel -drive system for urging the reel to rotate, thereby pulling the length of wire out of the tube. The reel -drive system includes a one-way element that transmits motion/rotation in one direction, and has a lost motion in the converse direction.

The reel -drive system further advantageously includes an exposed roller, which may be a thumbwheel, to be contacted by the hand which holds the housing, to impart the manual drive to the reel-drive system.

Advantageously, the reel -drive system includes a latch element which is movable between a first locking and a second release disposition. In the locking disposition the roller is locked against rotation while in the release disposition the roller is free and the latch element does not restrain rotation of the roller. The axis of rotation of the roller is spaced from the axis of rotation of the reel. In another embodiment the reel -drive system includes a drive connection that comprises at least one intermediate element that passes the drive from the roller to the reel.

This intermediate element can be a belt that runs between two pulleys and has evenly spaced formations. A complementary series of evenly spaced formations is provided on each of the pulleys. These spaced formations could be raised portions on the belt receiving surfaces of the pulleys, and through apertures on the belt.

In another embodiment the intermediate element is a toothed gear or a plurality of toothed gears, arranged in a sequence. These gear wheels can be mounted as a sub-assembly for inclusion in the housing.

The sub-assembly can utilise a frame by which it can be mounted within the housing.

In another embodiment, the device includes further a second hub for the introduction of flushing liquid to the tube that contains the wire that is to be wound on the reel.

Advantageously, the housing is defined by two half housings that mate together at a mating line which runs lengthwise of the elongate housing. One reel -drive system can be mounted in one of the half housings prior to mating to one half housing the other of the two half housings.

It may be attractive to provide a second reel -drive system in addition to the first one. The second reel-drive system can be a trigger system that includes a trigger which is arranged so as to urge the reel to rotate on each squeeze of the trigger. Both systems can be mounted in one of the half housings prior to mating to one half housing the other of the two half housings . According to another aspect of the present invention, the device comprises a reel drive power transmission system that includes a gearbox that enables a switch from one predetermined mechanical advantage to another.

In one embodiment a replaceable sub-assembly is provided and in another embodiment, a component such as a trigger can be switched between several rotational axis locations.

Optional and preferred features of the first aspect of the invention are available for inclusion in devices in accordance with the second aspect. Preferred embodiments can embody both aspects of the invention and many of the optimal features identified above.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 shows a longitudinal section of a first preferred embodiment ;

Fig. 2 shows a longitudinal section of a second preferred embodiment ;

Fig. 3 shows a section along the line III- III in Fig 1; and

Fig. 4 shows a section along the line IV-IV in Fig 3;

DETAILED DESCRIPTION

The invention can be embodied in a device for pulling a wire out of a tube and which can be activated manually, preferably with only one hand.

The invention has particular application to the situation in which the tube is a catheter with a shaft comprising an outer tube that defines a lumen containing a pull wire and an inner tube for flushing liquid in the lumen. In Figure 1 the device has a moulded, elongate housing 10 in two halves. The housing serves both as a frame for mounting the inner components of the device and as a hand grip. The housing has a distal end 12 and a proximal end 14. To improve handling with the device, a portion shaped to be gripped in a hand is covered by a grip- improving rubber material (not shown) . After assembling the inner components in one half housing, the housing halves are fixed together at a mating line which runs lengthwise of the elongate housing. This can be with adhesive bonding or, alternatively or commutatively at designated places 16 with screws, rivets or plugs.

On the distal end 12 of the housing 10 is provided a first hub 20 acting as an abutment and bearing element for setting the spacial relationship between the outer tube (not shown) and the housing 10 and to separate axial movement of the wire 8 from the axial position of the tube. The outer tube defines a lumen that possibly includes an inner tube 9 which extends to a second hub 22 at the proximal end 14 of the housing 10. The second hub 22 provides a female luer connector to engage a corresponding male luer, for flushing liquid directly for the lumen of the inner tube 9, but finally the liquid flushes into the lumen of the outer tube .

A reel 24 (Fig. 2) is mounted rotatably in the housing 10 to take up the wire 8 by rotating and thereby coiling up the wire 8. The reel 24 can be made to rotate by a reel -drive system, which can be provided according to different embodiments as described below.

To attach the wire 8 to the reel 24, there is provided a ball- end on the wire 8 and a first and second borehole 26, 27 in the reel 24. Both boreholes 26, 27 are nearly radial with a slightly incline to the rotatory axis of the reel 24. Further there is a groove 28 circular in the middle of the reel 24 transverse to the rotatory axis co-axial with the borehole 26. The end of the wire 8 carries a sleeve and a ball welded to the end of the wire 8. The wire 8 is put with the free end into the sleeve and the ball stops the wire 8 from sliding through the sleeve. Another way fixing the sleeve to the wire 8 could be to weld the ball on the wire 8 after putting it through the sleeve.

In another embodiment the wire 8 and the sleeve are pressed together such the sleeve is fixed on the wire 8.

The wire 8 is threaded into the groove 28 into the second borehole 27 and the sleeve is advanced into the first borehole 26. Pulling the wire 8 urges the sleeve to slide into the borehole 26, which has a diameter slightly bigger than the sleeve, and blocks the wire 8 from being pulled further.

Referring to figures 3 and 4, the reel 24 has teeth 30 formed respectively as two adjacent spikes divided by the groove 28. These spikes are shaped vertical on the outer side, but inclined to the middle of the reel 24 so as to urge the wire 8 to slip into the groove 28.

To avoid releasing the coiled up wire 8, a detent 32 (a backstroke stopper) that serves to inhibit reverse rotation of the reel is provided near the reel 24. The detent 32 engages the teeth 30 of the reel 24 and prevents it from rotating backwards again, so as to keep the wire 8 tight. The teeth 30 of the reel 24 are formed such that the detent 32 does not prevent the reel from rotating in one direction (e.g. direction A in Fig. 2) , but stops the reel 24 rotating in the other direction.

To urge the reel 24 to rotate, a reel -drive system is provided. Conveniently, this reel -drive system is manually driven, so that it must have an interface to the operator. The motion axis of this interface (e.g. a roller) is different from the rotation axis of the reel. Furthermore, the reel- drive system comprises means to switch between predetermined mechanical advantages. This can be changing of a sub-assembly that works as a gearbox in the power transmission module for driving the reel .

In a first embodiment (Fig.l) the reel -drive system is a roller-system which comprises a roller 34 that is preferably a thumbwheel, a roller release element 36, an intermediate element between the roller 34 and the reel 24, a toothed wheel 38 and a one-way transmission 40 that utilises for example a slip clutch such as one based on a needle roller bearing.

The roller 34 is mounted in the housing 10 and a portion of the roller 34 protrudes out of the housing 10. The roller 34 Is either integrally fixed or otherwise connected to a first toothed wheel 42. In an initial position the roller 34 is blocked from rotating by a roller release element 36, which can be regarded as something in the nature of a safety catch.

The release element 36 is an elongation with a distal end 41 and a proximal end 43 and serves as a latch. In a first position, a locking disposition, the distal end 41 of the elongation is plugged In a corresponding hole 45 in the roller 34. Near the proximal end 43 of the elongation a button 46 is provided. The button 46 has an upper side which protrudes through an opening of the housing, and a lower side that is preferably integrally fixed on the elongation. A spring element 54 is mounted on a plate 50 which Is integrally formed with the housing 10. The spring element 54 is either fixed on the plate 50, e.g. by small barriers around it, or fixed on the button 46 and one of both, either the elongation or the plate 50 are able to slide on the spring element 48. Finally, on the proximal end of the elongation is a small knob 52. In the first position of the roller release element 36, the knob 52 protrudes In the opening, touches the inner wall of the opening and prevents the release element 36 from sliding. To urge the release element 36 in a second position, thereby freeing the rol ler 34 , the button 46 together with the knob 52 and the spring element 48 are pressed down . The knob 52 moves into the hous ing 10 beneath the inside wall and allows the release element 36 to sl ide . In the second position the distal end 41 of the elongation is drawn out of the hole 45 in the rol l er and the button 46 i s not longer pressed down. Thus, the spring el ement 48 wil l urge the button 46 and the knob 52 to move upwards again and the knob 52 will be plugged in a small corresponding cavity 54 in the housing 1 0, preventing the rel ease element 36 from sliding back into the first position.

When the rol l er 34 i s free to move , its rotation is induced by the integrated toothed wheel 42 through the gear to a drive wheel or a pinion 38 adj acent to the reel 24. The drive wheel 38 is connected by a one-way transmi ss ion 40 to the reel 24 and transmits the rotation . The one -way transmission is preferably an overtake- clutch ( otherwi se called a slip clutch) . Such clutches are known per se .

The intex"mediate element is a sub-assern-bly that comprises at least one toothed wheel (otherwise called gear) or a plurality of toothed wheels 55, 56a, 56b, 57 which are mounted in sequence on a frame 58 providing as gear trains with different transmission or gear ratios. The frame 58 is plugged with at least one aperture 60 on at least one plug (not shown) in the housing. This interface on the frame between the sub-assembly and the housing allows using a sub-assembly with a mechanical advantage (in this case the ratio of the toothed wheels 55, 56a, 56b, 57) as needed. I.e. it is possible to choose between alternative mechanical advantages differing in steps by using the suitable power transmission module. The frame 58 preferably comprises two side plates which are connected by bearings 62 for the toothed wheels 55, 56a, 56b, 57. The side plate adjacent to the housing has the at least one aperture 60 o plug the frame on the housing 10. On a bearing 62 are espectively mounted either one 57 or two 56a, 56b toothed wheels 56a, 56b. One of them (56a) is driven by the adjacent wheel (not shown, behind 55) in the sequence, the other wheel (e.g. 56b) drives the following wheel (57) . In the illustrated embodiment are provided three bearings for the wheels. This enables the sub-assembly to provide a wide scope of different mechanical advantages. Because the sub-assembly has a standardized plug, it is exchangeable, i.e. it can be removed and replaced by another sub-assembly. Thus, the chosen power transmission module can provide a predetermined user-defined gear ratio that can be selected to achieve a desired mechanical advantage or rate of coiling up the wire 8 on the reel 24. The number of bearings for the toothed wheels in the gear is preferably odd, so that the reel 24 rotates in the same direction as the roller 34.

In another embodiment the gear sequence is replaced by a belt. In such a case, the wheel adjacent to the roller and the wheel adjacent to the reel are replaced by two wheels that are pulleys. For preventing the belt from slipping on the wheels raised portions (e.g. knobs) could be provided on the pulleys and, on the belt, complementary through apertures or corresponding cavities. Belts require only little space and provide simultaneously a good transmission of force.

It is possible, to build a belt-construction that can serve as an exchangeable sub-assembly. The pulley adjacent to the roller and the pulley adjacent to the reel can be chosen so as to reach a mechanical advantage as needed. A frame to carry both pulleys can be provided and eases to exchange such a sub- assembly. All advantages of the above sub-assembly apply also in this case.

In a further embodiment of the hand device (such as in Fig. 2) the reel-drive system comprises a Finger-Trigger-System which comprises a trigger 70, a trigger release element 72, an intermediate element, preferably a toothed elongation 74, a return element 76, preferably a spring-force-return element with linear springs and a toothed wheel 78 on a one-way transmission 80. In other embodiments, the device can offer the operator more than one way to drive the reel. For example, the device can have both a thumb wheel and a trigger, to drive a single reel .

In Fig. 2 the release element 72 is an elongation with a blocked end 82 which intrudes in a corresponding hole 83 in the trigger 70, a free end 84 which is in a first position adjacent to a small wall 86 and a button 88 on the elongation that protrudes outwards the housing for being pressed. A spring element 90 is provided between the release element 72 and a plate 92 that is integrally formed with and protrudes from the housing 10. To release the trigger 70, the release element 72 has to be moved from a first initial position to a second position. The button 88 has to be pushed down against the spring force of the spring element 90 thereby lifting the free end 84 over the wall 86. The release element 72 can be pushed and slides in a second position pulling the blocked end 82 out of the hole 83 and freeing the trigger 70.

The trigger 70 has a rotating movement around his bearing 91. On the trigger 70 is fixed an intermediate element as a power transmission module for transmitting the power from the trigger to the reel. Preferably, the power transmission module is a toothed elongation 74 which is formed as a ratchet or as an arcuate shaped elongation that can be more particular a planetary gear portion with involute teeth. In one embodiment the elongation is integrally moulded with the trigger (shown in Fig. 2) . This trigger including the power transmission module corresponds to the sub-assembly of the first embodiment. It can be replaced by another trigger.

In another embodiment the trigger provides different predetermined slots 73 or plug- in places where the elongation 74 can be fixed onto the trigger. These slots 73 serve as relative rotational axis of the elongation 74. This allows changing the mechanical advantage as it is needed. If the elongation 74 is near the rotational axis 91 of the trigger, the mechanical advantage is bigger, the pull-length shorter. The further from the rotational axis 91 the elongation 74 is fixed, the more length of wire 8 is pulled in by triggering, but the less mechanical advantage is provided. In this case only the intermediate element 74 corresponds to the sub- assembly of embodiments 1 or 2 and provides the same advantages of adjusting the mechanical advantage. I.e. it is possible to change the mechanical advantage stepwise by choosing the suitable lever ratio of the relative rotational axis 73 of the elongation in view of the rotational axis 91 of the trigger 70.

When the trigger is freed it can be pushed and the toothed elongation urges a toothed wheel 78 adjacent to the reel 24 to rotate. Through a one-way element SO the rotation is transferred to the reel. The one-way element can be a one way bearing as well as an overtake-clutch like in the roller-based embodiment or any other one-way transmission. Additional, the teeth of the elongation 74 and the toothed wheel 78 can be shaped similar like the teeth 30 of the reel 24, so that they transmit force in direction A and slip over in the reverse direction.

In another embodiment, the elongation is built as a planetary gear portion {arcuate shaped) with involute teeth. The corresponding toothed wheel then has also involute teeth.

A plate 94 integrally moulded in the housing 10 is arranged adjacent and parallel to the elongation 74 of the trigger 70. One or more linear springs 76 are fixed on one end of the plate 94, preferably with a bolt 96 integrally moulded in the housing 10. The at least one linear spring 76 is also fixed on the end of the elongation 74, preferably on a bolt 98 integrally moulded in the elongation 74. When the trigger 70 is urged to rotate the toothed wheel 78, the springs 76 become stretched such, that they will pull back the elongation 74 till the wall 99 on the end of the elongation 74 stops on the plate 94. The plate 94 thereby prevent the springs 76 from being touched by the toothed wheel 78 or other parts of the elongation 74 than the bolt 98.

In another embodiment two reel -drive systems can be assembled, one respectively for each half housing. For example, the reel- drive systems of the first and the second embodiment could be provided together, one in each of the two halves of the housing, and both operating on the same single reel.

This allows using two different mechanical advantages in one device. In the above given example, the roller-based reel- drive system could facilitate a stronger slow release option by a gear ratio of 1:4 what may be 6 mm per roll, and the trigger-based reel -drive system could facilitate a weaker fast release option of 1:2 what may be 12 mm per squeeze/pump of the trigger. If one reel-drive system is actuated, the other runs free, because of its one-way transmission.

By making the wire storage capacity of the reel large enough, the hand unit can release a prosthesis of any length. The features of the illustrated embodiments are available for inclusion in other embodiments differing from the illustrated, as the skilled reader will appreciate. The invention is defined in the claims and the illustrated embodiments are exemplary.

Claims

1. A device for pulling a length of wire out of a tube, comprising

an elongate housing to be held in the hand, and having a distal and a proximal end,

a reel mounted in the housing for receiving the length of wire,

a first hub mounted on the distal end of the housing for receiving the tube and

a first reel-drive-system for urging the reel to rotate thereby pulling back the length of wire out of the tube characterized in that the reel -drive system includes a one-way element, that drives the reel in one rotational sense but not in the reverse rotational sense.

2. Device as claimed in claim 1, wherein the first reel-drive system includes an exposed roller that can be contacted by the hand that holds the housing, to impart the drive to the reel- drive system.

3. Device as claimed in claim 2, wherein the roller is a thumbwheel .

4. Device as claimed in claim 2 or 3 , wherein the roller rotates on an axis that is spaced from the axis of rotation of the reel

5. Device as claimed in any one of claims 2 to 4 , wherein the first reel-drive system includes a drive connection that comprises at least one intermediate element that passes the drive from the roller to the reel.

6. Device as claimed in claim 5, wherein the intermediate element is a belt that runs between two pulleys.

7. Device as claimed in claim 6, wherein the pulleys have a series of evenly spaced formations that co-operate with a series of complementary spaced formations on the belt.

8. Device as claimed in claim 7, wherein the spaced formations on the belt are through apertures, and those on the pulleys are raised portions in the belt-receiving surfaces of the pulleys.

9. Device as claimed in claim 8 wherein the intermediate element is a toothed gear.

10. Device as claimed in claim 9, wherein drive connection comprises a plurality of toothed gears, arranged in sequence.

11. Device as claimed in claim 10, wherein the sequence of gear wheels is mounted as a sub-assembly for inclusion in the housing .

12. Device as claimed in claim 11, wherein the sub-assembly has a frame by which the sub-assembly can be mounted within the housing.

13. Device as claimed in claim 1, wherein the reel drive system includes a trigger arranged to rotate the reel on each squeeze of the trigger.

14. Device as claimed in claim 13, wherein the reel drive system includes a toothed elongation (74} connected to the trigger .

15. Device as claimed in claim 14, wherein the elongation is a planetary gear portion.

16. Device as claimed in claims 1-15, wherein the reel drive system includes a latch element that is moveable between a locking disposition to avoid the reel drive system being actuated and a release position in which the latch element no longer restrains the reel element from being actuated.

17. Device as claimed in any one of the preceding claims, wherein the device includes a second hub for the introduction of flushing liquid to said tube.

18. Device as claimed in any one of the preceding claims, wherein the device includes a detent to inhibit reverse rotation of the reel.

19. Device as claimed in any one of the preceding claims, wherein the housing has a form that is defined by two moulded half housings that mate together at a mating line that runs lengthwise of the elongate housing.

20. Device as claimed in claim 19, wherein the reel -drive system can be mounted in one of the half housings prior to mating to said one half housing the other of the two half housings .

21. Device as claimed in any one of the preceding claims, further including a second reel -drive system as claimed in any of the preceding claims which is mounted in the other half of the housing.

22. A device for pulling a length of wire out of a tube, comprising

an elongate housing to be held in the hand, and having a distal and a proximal end, a reel mounted in the housing for receiving the length of wire,

a first hub mounted on the distal end of the housing for receiving the tube and

a reel -drive power transmission system for urging the reel to rotate thereby pulling back the length of wire out of the tube characterized in that the reel -drive system includes a gearbox that enables a switch from one predetermined mechanical advantage to another.

23. Device as claimed in claim 22, wherein the mechanical advantage is switched by replacing one sub-assembly with another .

24. Device as claimed in claim 23, wherein the reel -drive system includes an exposed roller that can be contacted by the hand that holds the housing, to impart the drive to the reel- drive system.

25. Device as claimed in claim 23 or 24, wherein the roller is a thumbwheel .

26. Device as claimed in claims 24 or 25, wherein the reel- drive system includes a latch element that is moveable between a locking disposition to lock the roller against rotation and a release disposition in which the latch element no longer restrains the roller against rotation.

27. Device as claimed in any one of claims 24 to 26, wherein the roller rotates on an axis that is spaced from the axis of rotation of the reel

28. Device as claimed in any one of claims 23 to 27, wherein the replaceable sub-assembly passes the drive from the roller to the reel .

29. Device as claimed in any one of claims 23 to 28, wherein the sub-assembly comprises a toothed gear.

30. Device as claimed in claim 29, wherein the sub-assembly comprises a plurality of toothed gears, arranged in sequence to mesh one with another.

31. Device as claimed in any one of claims 23 to 30, wherein the sub-assembly comprises a frame by which it can be mounted within the housing.

32. Device as claimed in any one of claims 23 to 28, wherein the sub-assembly comprises two pulleys and a belt.

33. Device as claimed in claim 32, wherein the pulleys have a series of evenly spaced formations that co-operate with a series of complementary spaced formations on the belt.

34. Device as claimed in claim 33, wherein the spaced formations on the belt are through apertures, and those on the pulleys are raised portions in the belt-receiving surfaces of the pulleys.

35. Device as claimed in claim 22, wherein the replaceable sub-assembly is a trigger integrally formed with a toothed elongation.

36. Device as claimed in claim 21, wherein the mechanical advantage is switched by moving a component of the drive system from a first rotational axis location to a second rotational axis location.

37. Device as claimed in claim 36, wherein the configurable component is a lever with a plurality of locations for said rotational axis .

38. Device as claimed in claim 37, wherein the lever is a trigger.

39. Device as claimed in any one of claims 21 to 38, wherein the device includes a second hub for the introduction of flushing liquid to said tube.

40. Device as claimed in any one of claims 21 to 39, wherein the device includes a detent to inhibit reverse rotation of the reel .

41. Device as claimed in any one of claims 21 to 40, wherein the housing has a form that is defined by two moulded half housings that mate together at a mating line that runs lengthwise of the elongate housing.

42. Device as claimed in claim 39, wherein the reel-drive system can be mounted in one of the half housings prior to mating to said one half housing the other of the two half housings .

43. Device as claimed in any one of claims 21 to 42, further including a second reel -drive system.

44. Device for as claimed in claim 42, as dependent on claim 43, wherein the second reel-drive system can also be mounted in said one half housing prior to mating the two half housings together.

45. Method for assembling a device for pulling a length of wire out of a tube, including an elongate housing to be held in the hand, and having a distal and a proximal end,

a reel mounted in the housing for receiving the length of wire and

a hand actuated interface to introduce the power to drive the reel into the hand unit, the method comprising the steps of :

a} providing a hand unit ready to receive a power transmission module;

b) choosing a power transmission unit with a desired transmission ratio from a plurality of power transmission units, the power transmission unit transmits the introduced power to the reel;

c) aesembl iπg the power transmission module in the hand unit .

46. Method according to claim 45, further comprising between steps a) and b) the step of selecting a prosthesis for the distal end of the tube and choosing the power transmission module in step b) according to the transmission ratio necessary for the selected prosthesis.

47. Method according to claim 45 or 46, including a device according to one of the claims 1-45.

48. A device for pulling a length of wire out of a tube, comprising

a first hub mounted on the distal end of the housing for receiving said tube and

a second hub for the introduction of flushing liquid to said tube

a first reel-drive-system for urging the reel to rotate thereby pulling back the length of wire out of the tube, the reel drive system further includes

a trigger for introduce the power into the reel drive system,

a planetary gear portion that transmits the power from the trigger and

a latch that is moveable between a locking disposition to prevent the trigger from being triggered and a release disposition in which the trigger is released from the latvh element ,

wherein the reel-drive system includes a one-way element, that drives the reel in one rotational sense but not in the reverse rotational sense.

49. A device for pulling a length of wire out of a tube, comprising

a reel mounted in the housing for receiving the length of wire, a first hub mounted on the distal end of the housing for receiving said tube and

a second hub for the introduction of flushing liquid to said tube

a trigger for introduce the power into the reel drive system,

a planetary gear portion that transmits the power from the trigger and

a latch that is moveable between a locking disposition to prevent the trigger from being triggered and a release disposition in which the trigger is released from the latch element ,

wherein the reel -drive system includes a gearbox that enables a switch from one predetermined mechanical advantage to another .