Device

Abstract

The present invention relates to devices and related methods for treating fistulas such as anal or recto-vaginal fistulas, in particular by the use of a seton to secure a tissue growth promoter such as a growth factor and/or fibrin. The various devices are particularly suitable for positioning tissue growth promoters securely within a fistula. Thus, one device comprises a seton and a tissue growth promoter. Further related aspects of the invention included devices comprising an enclosure provided in between portions of a seton, devices comprising a seton and a plurality of holes for enabling the device to be sutured to tissue, devices comprising a probe and a seton that are releasably connectable end-to-end, devices comprising an attachment device to secure the ends of a seton, and devices comprising a fistula plug adapted to be secured to a section.

Claims

1. A method of treating a fistula comprising securing a tissue growth promoter within a fistula with a seton that extends through the fistula and outside the fistula from a first end of the fistula around a body of tissue adjacent to the fistula to a different second end of the fistula, forming a seton loop securing the tissue growth promoter within the fistula, thereby encouraging tissue ingrowth and allowing healing of the fistula.

2. A method according to claim 1, wherein the seton loop lies partially outside of the body.

3. A method according to claim 1, wherein the fistula is an anal fistula or a recto-vaginal fistula.

4. A method according to claim 1, wherein the tissue growth promoter comprises a tissue growth promoting agent.

5. A method according to claim 4, wherein the tissue growth promoting agent is a growth factor.

6. A method according to claim 5, wherein the growth factor is selected from basic fibroblast growth factor (FGF-2), transforming growth factor beta (TGF-beta), epidermal growth factor (EGF), cartilage derived growth factor (CDGF), platelet derived growth factor (PDGF), insulin-like growth factor I or II (IGF-I or IGF-II), an interferon, or a mixture thereof.

7. A method according to claim 1, wherein the tissue growth promoter comprises a tissue growth promoting matrix.

8. A method according to claim 7, wherein the tissue growth promoting matrix comprises a microscopic scaffold.

9. A method according to claim 7, wherein the tissue growth promoting matrix comprises fibrin and/or collagen.

10. A method according to claim 7, wherein the tissue growth promoting matrix comprises a macroscopic scaffold.

11. A method according to claim 10, wherein the macroscopic scaffold comprises a plurality of interwoven and/or interconnected strands.

12. A method according to claim 10, wherein the macroscopic scaffold is made from a biodegradable polymer.

13. A method according to claim 12, wherein the biodegradable polymer is a polylactide, a polyglycolide or a poly(lactide-co-glycolide).

14. A method according to claim 7, wherein a segment or all of the seton consists of a tissue growth promoting matrix.

15. A method according to claim 7, wherein a tissue growth promoting matrix is attached to the seton.

16. A method according to claim 7, wherein the seton is thread through a tissue growth promoting matrix.

17. A method according to claim 1, wherein the treatment further comprises the use of one or more additional pharmaceutical agents.

18. The method of claim 17, wherein the one or more additional pharmaceutical agents are selected from anti-inflammatories, anti-bacterial agents, immunomodulators, and combinations thereof.

19. A method according to claim 1, wherein the seton comprises a biodegradable material.

20. A method according to claim 19, wherein the tissue growth promoter comprises a tissue growth promoting matrix located inbetween biodegradable portions of the seton.

21. A method according to claim 1, wherein the seton comprises a flexible non-biodegradable material.

Description

DETAILED DESCRIPTION OF THE INVENTION

(1) Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings, in which:

(2) FIG. 1 shows a planar view of a device comprising a probe and seton according to the present invention;

(3) FIG. 2 shows a perspective view of a locking device of the device in FIG. 1;

(4) FIG. 3 shows a perspective view of an alternative embodiment of the connection between the seton and the probe shown in FIG. 1;

(5) FIG. 4 shows a planar view of an embodiment of the device wherein a segment of the seton comprises a tissue growth promoting matrix;

(6) FIG. 5 shows a planar view of an embodiment of the device comprising a fibrin plug thread onto the seton;

(7) FIG. 6 shows a planar view of an embodiment of the device comprising an enclosure holding pharmaceutical agents;

(8) FIG. 7 shows a schematic diagram of a seton of the present invention positioned within an anal fistula; and

(9) FIG. 8 shows a schematic diagram of a seton of the present invention positioned within a recto-vaginal fistula.

(10) The devices of the present invention are particularly useful for the treatment of fistulas such as anal or recto-vaginal fistulas. Depending on the fistula to be treated however, it may be desirable and/or necessary to pre-treat the fistula prior to the use of the devices of the present invention. For instance, if the fistula is heavily infected, it may desirable to insert a drainage seton according to the prior art methods discussed above. The drainage seton may optionally incorporate antibiotics and/or anti-inflammatories in order to help reduce the extent of infection. After a period of time the drainage seton may be removed prior to the insertion of a device according to the present invention.

(11) Optionally, prior to the insertion of a device according to the present invention, the fistula tract may be cleaned, for example using a jet of water and/or a suitable brush.

(12) Referring now to FIG. 1, there is shown a device 1 according to an embodiment of the present invention comprising a probe 2 and a seton 3 for assisting in the healing of fistulas.

(13) The probe 2 comprises an elongate body having a blunt end 4 and an opposite end 5 to which the seton 3 is attached. The probe 2 is inserted into the fistula with the blunt end first such that the surgeon can use the probe to discover the track of the fistula. The end 4 is blunt rather than sharp so as to reduce damage to surrounding tissue and to minimise the possibility of the probe going off track creating false passages.

(14) The probe 2 is made out of a malleable metal or plastic that is easily bent so that it can be formed into a desired shape by the surgeon. This enables the surgeon to tailor the shape of the probe 2 to the track of the fistula so that the probe 2 can more easily be fed through the fistula with minimal damage to surrounding tissue. The probe 2 may vary in size depending on the type of fistula that is to be treated. It is envisaged that the probe is between 6 to 12 cm long and 0.5-2.0 mm in diameter.

(15) The seton 3 is in the form of a flexible thread and is preferably made out of a tough flexible rubber or plastic such as polypropylene, in particular when treating fistulas wherein the seton has to be left in position for a longer period of time. Alternatively, the seton 3 may be formed out of a biodegradable material such as polyglycolic acid such that the seton 3 biodegrades in situ with time, thereby obviating the need to remove the seton 3 from the treatment site.

(16) The end 5 of the probe 2 opposite to the blunt end 4 is hollow and an end portion of the seton 3 locates therein and is secured to the probe 2 by the end 5 of the probe 2 being reduced in diameter such that a tight fit is created between the end 5 of the probe and the end of the seton 3. The diameter of the end 5 of the probe may be reduced by passing the end 5 of the probe through an aperture of a die. The aperture is configured to be of a smaller diameter than the initial diameter of the end 5 of the probe. The diameter of the end 5 of the probe can also be reduced by shaping the end 5 by hammering. Alternatively, the end of the seton 3 may be swaged to the corresponding hollow end of the probe 5 such that the seton 3 and the probe 5 are fused together end-to-end.

(17) In an alternative embodiment, the end 5 of the probe opposite to the blunt end 4 may be solid such that an end face of the probe is directly swaged or fused to an end face of the seton 3. All of the aforementioned methods securely attach the seton 3 to the probe 2 such that as the surgeon feeds the probe 2 through the fistula the seton 3 follows the probe without detaching. In contrast, a seton that is threaded through an eye of a probe as known from the prior art may easily detach as it is pulled through the fistula such that the surgeon may have to repeat the process causing further discomfort to the patient.

(18) As can be appreciated from FIG. 1, at the point of attachment of the seton 3 and the probe 2, the longitudinal axis of the seton 3 is aligned with the longitudinal axis of the probe 2 and the overall diameter of the device in the region of the connection does not exceed the diameter of the probe 2. The region of the connection should be understood to mean the region where the seton engages with the probe, in particular where the seton is swaged to the probe or where a tight fit is created between the seton and the probe. Preferably, the region of the connection of the aforementioned embodiments is less than 2 cm in a direction parallel to the longitudinal axis of the seton and the probe.

(19) The features of the longitudinal axis of the seton 3 being aligned with the longitudinal axis of the probe 2 and/or the overall diameter of the device in the region of the connection not exceeding the diameter of the probe 2, minimise damage to surrounding tissue when the probe 2 and the seton 3 are fed through the fistula in contrast to devices known from the prior art wherein the seton is thread through an eye of a probe. That is, because as a seton is thread through an eye of a probe it is transverse to the longitudinal axis of the probe and as a result of resilient characteristics of the seton, the transverse portion of the seton thread through the eye of the probe may extend beyond the diameter of the probe thereby abrading the surrounding tissue as the probe and the seton are fed and pulled through the fistula.

(20) Furthermore, as the seton is thread through the eye of the probe a double layer of the seton is formed which also may extend beyond the diameter of the probe. As discussed in the introduction, it is also known from the prior art to overlap an end of the seton with an end of the probe and thereafter to lash or suture the ends together. The overall diameter of the region in which the seton and the probe are connected is therefore bulky and extends beyond the diameter of the probe. Again, this may abrade and damage surrounding tissue as the probe and the seton are fed and pulled through the fistula.

(21) The seton 3 of the present invention is optionally secured to the probe 2 by any of the methods discussed herein during manufacturing so that the surgeon is not required to assemble the seton 3 and the probe 2 prior to use. For instance, the seton may be glued or welded onto the probe. Therefore, the device 1 is easier to use than those known from the prior art which require the surgeon to carefully thread or tie the seton to the probe. Furthermore, the fact that the device is pre-assembled reduces the required surgical preparation time.

(22) As best shown in FIG. 1, on one side of the seton 3 proximal to its attachment to the probe 2 ratchet teeth 7 are formed. In FIG. 1 (and also FIGS. 2 and 4-6), the ratchet teeth 7 are shown to protrude from the seton 3 such that they extend beyond the diameter of the seton 3. In an alternative embodiment, it is envisaged that the ratchet teeth do not extend beyond the diameter of the seton. This may be achieved by making or moulding incisions into the seton transversely to the longitudinal axis of the seton so as to form ratchet teeth.

(23) The ratchet teeth 7 engage with a locking device 8 also referred to as an attachment device as shown in FIGS. 1 and 2. The locking device 8 comprises a housing 9 formed with an aperture 10 that is transverse to the plane of the housing 9. A resiliently deformable pawl (not shown) extends into the aperture 10 for engagement with the ratchet teeth 7 when the seton 3 is inserted through the aperture 10, such that the seton 3 cannot be withdrawn from the aperture 10.

(24) It is envisaged that once the surgeon has inserted the probe 2 and the seton 3 through the fistula such that either ends of the seton 3 extend from either ends of the fistula, the surgeon feeds the blunt end 4 of the probe 2 followed by the seton 3 through the aperture 10 of the locking device 8 so as to form a loop. Thereafter, the surgeon cuts the seton 3 proximal to the probe 2. In an alternative method, the surgeon may cut the seton 3 adjacent to the probe and thereafter feed the free end of the seton 3, provided with ratchet teeth 7, through the aperture of the locking device 8. In either method, cooperation between the ratchet teeth 7 and the pawl permits the seton 3 to be pulled through the aperture 10 of the locking device 8 to the required extent.

(25) By the locking device 8 securing the opposite end of the seton 3 so as to form a loop, the seton 3 remains in its position throughout the treatment period. Therefore, the problem of a knot securing the seton becoming undone as known from the prior art is overcome and so the probability of the surgeon having to re-insert a seton is reduced.

(26) The ratchet teeth 7 and the locking device 8 enable the seton 3 to form a loop of variable size, as the seton can be pulled through and secured to the locking device at any desired length where the ratchet teeth 7 are formed. Therefore, the device 1 can be specifically adjusted to individual patients and their needs.

(27) As can be appreciated from FIG. 2, the housing 9 of the locking device 8 is formed with four holes 11. These holes enable a surgeon to suture the locking device 8 to the wall of the anal canal. Advantageously, as the seton 3 is held in place and the locking device 8 is retained internally, discomfort caused by a knot of two tied ends of a seton as known from the prior art is overcome.

(28) A portion of the seton 3 adjacent to the locking device 8 is formed with a coupling element so as to be secured to a corresponding coupling element formed at the same end as the ratchet teeth 7. In the illustrated embodiment shown in FIGS. 1 and 2, the coupling elements of the seton 3 comprise protrusions 12 formed adjacent to the locking device 8 and corresponding recesses 13 formed on the opposite side of the ratchet teeth 7. The protrusions 12 are a friction fit within corresponding recesses 13 to secure the end of the seton 3 that has been passed through the aperture 10 of the locking device 8, to a portion of the seton 3 adjacent to the ratchet teeth 7. The redundant end of the seton 3 is thereby aligned with the remaining seton 3 and any excess cut off.

(29) It will be appreciated that the coupling elements of the seton 3 are optional. Alternative means for attaching the redundant end of the seton to the end of the seton proximal to the locking device may be used or omitted altogether.

(30) It should be understood by those skilled in the art that the present invention is not limited to the locking device described above. Any locking device that securely holds the two loose ends of the seton together falls within the scope of the present invention.

(31) An alternative embodiment will now be described with reference to FIG. 3. The configuration of this embodiment only differs to the aforementioned embodiment in how the seton is attached to the probe and so a general description of the device will be omitted.

(32) In FIG. 3, an end 25 of a probe 22 is shown. The end 25 is formed with a threaded screw 26 for receiving a seton 23. The screw 26 extends from the end 25 of the probe 22 and its longitudinal axis is aligned with the longitudinal axis of the probe and its diameter is preferably smaller than that of the probe 22. Preferably, the probe 22 and the screw 26 are integrally formed. The seton 23 is formed with corresponding screw attachment means in that it has a hollow end 27. Although the hollow end 27 of the seton 23 is not threaded it is screwed onto the screw 26 by the flexible nature of the material used for the seton 23. In an alternative embodiment, the internal surface of the hollow end 27 of the seton 23 is threaded so that the seton 23 is screwed onto the threaded screw 26 of the probe 22.

(33) It shall be understood that the threaded screw may alternatively be formed on an end of the seton and the probe may be formed with a corresponding threaded screw attachment means such as a hollow end so that the probe can be screwed onto the seton. In this embodiment, the seton and the screw may be integrally formed.

(34) The aforementioned embodiments described with reference to FIG. 3, have the same advantages as those described with reference to FIG. 1. In particular, as the longitudinal axis of the probe and the longitudinal axis of the seton are aligned at the point of attachment the probability of damaging surrounding tissue as the probe and seton are pulled through is reduced. This is also achieved by the fact that the diameter of the screw is smaller than the diameter of the probe and the seton so that as the seton and the probe are connected, the outer surfaces of the probe and the seton are flush or the diameter of the seton is smaller than that of the probe. As a result, the diameter of the region of the connection does not exceed the overall diameter of the device. The region of connection should be understood to mean the region where the screw is received in the corresponding screw attachment means. Preferably, the region of the connection of the seton and the probe of the present embodiments is less than 2 cm in a direction parallel to the longitudinal axis of the seton and the probe.

(35) It should be appreciated that the seton of the device according to the present invention can be secured to the probe by alternative means than those described hereinbefore. For example, the seton and the probe may be secured by click fitting. In this un-illustrated embodiment, an end of the seton may be formed with a protrusion having a resilient flange and the probe may comprise a hollow end having a recess corresponding to the shape of the flange. By inserting the protrusion of the seton into the hollow end of the probe, the flange temporarily deforms until it locates in the corresponding recess. In this embodiment, the means of connection are configured such that the force required to insert the protrusion of the seton into the hollow end of the probe is greater than the force required to pull the probe and the seton through a fistula so as to avoid the seton from detaching from the probe as the seton is being fitted.

(36) An advantage of the probe and the seton being releasably connectable, such as by means of the screw attachment or click-fitting described above, is that in use the surgeon can rapidly interchange probes without having to undertake the fiddly and time-consuming task of threading the seton through an eye of the probe. Furthermore, where it is desired to treat complex fistulas such as horseshoe fistulas, the use of two or more setons may be required. In such a scenario, a further advantage of the probe and the seton being releasably connectable is that a single probe may be used for the insertion of both setons, thus saving on the equipment required and hence the cost of the procedure.

(37) In another un-illustrated embodiment, the device is spring loaded so that the seton will retain a snug fit through the fistula for an extended period of time. Often, for a seton to promote optimal healing of a fistula, it is desirable for the seton to be snugly fitted throughout the treatment period. This is particularly important in cases where the seton is used to gradually cut through the sphincter muscle. However, setons as known from the prior art may become slack as they gradually cut through the sphincter muscle resulting in the seton becoming less effective in dividing the remaining muscle tissue. To overcome this problem, the device according to the present invention may be spring loaded so as to absorb any slacking so that the seton is continuously snugly fitted through the fistula for a desired period of time. Preferably, a spring is fitted between the locking device and the seton so as to absorb any slacking. Alternatively, the device may be fitted with a spring loaded cog which engages with corresponding teeth formed on the seton. The cog could be configured to comprise a coil spring and preferably the cog would engage with the redundant end of the seton that has been pulled through the locking device such that the cog pulls the seton through the locking device as the seton starts to slack.

(38) A preferred embodiment is now described which may comprise any combination of individual features as described above. In this embodiment the seton is provided with a tissue growth promoter such as fibrin so as to further promote tissue repair of the fistula. The seton may further be provided with one or more additional pharmaceutical agents so as to reduce inflammation or infection by locally delivering the specific agents to the treatment site. In this manner, many of the drawbacks associated with systemic drug delivery are avoided and relatively high concentrations of the required pharmaceutical agent can be targeted at the point of need with minimal side effects.

(39) In one embodiment, the seton is provided with fibrinogenic materials which include any material based on fibrin. The seton may be coated directly in fibrinogenic material or the fibrinogenic material may be incorporated into a biodegradable polymer such as alginate which coats the seton.

(40) Alternatively, as illustrated in FIG. 4, a segment 29 of the seton may itself be made from a tissue growth promoting matrix such as fibrin, with the remainder of the device 28 being as described in relation to FIG. 1.

(41) Thus, in use the portion of the seton being made from or provided with a tissue growth promoter is positioned within the fistula tract so as to encourage tissue growth therein.

(42) It is envisaged that fibrinogenic material can best be used in cases where there has been no active sepsis, that is to say when the tract of the fistula is a single tunnel with no blind tracts and no intervening abscess cavity in the path of the fistula.

(43) In another embodiment, the seton may be provided with a fibrin plug, as illustrated in FIG. 5. For example, the seton 50 may be threaded through the centre of a fibrin plug 51 commercially sold as Biodesign and manufactured by Cook Medical. The seton is thus able to hold the fibrin plug firmly in place. When used in conjunction with the previously described locking device 52, the seton and hence the fibrin plug may be further secured in an exact position by the use of sutures through the holes 53.

(44) Referring now to FIG. 6, a cage 30 is shown which is attached to the seton 33. The cage 30 is made out of a biodegradable material and it comprises a wall 31 shaped into a hollow cylinder. The wall 31 is formed out of a mesh so as to allow tissue in-growth and efficient release of pharmaceutical agents. The cage 30 is also formed with means of attachment 34, for example screws, on either end. A portion of the seton 33 is attached to either end of the cage 30 via the means of attachment 34. One portion comprises the locking device 38 and the cooperating elements and the other portion comprises the ratcheting 37 and the corresponding cooperating elements as described in relation to the aforementioned embodiments. The cage 30 defines a space for holding pharmaceutical agents such as a fibrin plug (not shown), for example the fibrin plug manufactured by Cook Medical, or pellets of fibrinogenic material. The fibrin plug or any other pharmaceutical material that is to be used is inserted into the cage prior to attaching the portions of seton 33 to the means of attachment 34. Thus, access to the inside of the cage is either at one or other end at the point of attachment 34 of the cage to the seton 33. Alternatively, it could be in the middle of the cage using a separate screw attachment device not shown or numbered in FIG. 6. The seton 33 provided with the cage 30 is inserted through a fistula using a probe 32 in a similar way as described above. The seton is cut proximal to the probe and is secured by inserting the freed end of the seton 33 through the aperture 39 of the device. Preferably, the locking device 38 is formed with holes 40 so that the locking device 38 can be sutured to the wall of the anal canal which thereby prevents the loop of seton 33 from moving or rotating. The advantage of the seton 33 being provided with a cage 30 is that it retains the fibrin plug in its position throughout the treatment period thereby promoting primary healing.

(45) Preferably, the seton provided with fibrinogenic materials or a fibrin plug with or without a cage is formed out of biodegradable material. After a period of time, typically 4 to 6 weeks, this allows for the seton to be cut off at the entry and exit points of the fistula such that a segment of the seton and the fibrin with or without a cage remain in the fistula as they are gradually broken down by the body and fully or partially replaced by new tissue formation.

(46) Depending on the type of fistula to be treated the fibrinogenic material and the fibrin plug with or without the cage may extend for a length of 2 to 6 cm, and preferably for a length of 3 to 5 cm. The cage is preferably 2.5 mm in diameter.

(47) In some embodiments, the seton may further be provided with antibiotics, anti-inflammatories such as steroids or tumour necrosis factor (TNF) inhibitors, or immunomodulators and the like. A seton provided with antibiotics such as gentamicin would be used for treating local septic areas of the fistula, thereby avoiding or reducing systemic side effects associated with oral medication. A seton provided with steroids or immunomodulators would be particularly useful in patients suffering from Crohn's disease where local treatment of affected tissue may increase the rate of tissue regeneration and potentially reduce any systemic side effects resulting from oral medication. Similarly, a seton provided with a TNF inhibitor would provide effective targeting of tumour cells in the area of the fistula.

(48) For the embodiments described above wherein the seton is provided with one or more tissue growth promoters and/or pharmaceutical agents, it is preferred to suture the locking device to the anal wall. This ensures that the portion of the seton provided with active agents is always located in the fistula and prevents the loop of the seton from rotating.

(49) Referring to FIG. 7, a schematic diagram of a seton 70 of the present invention positioned within an anal fistula 71 is illustrated. A segment 72 of the seton 70 provided with a tissue growth promoter is secured within the anal fistula 71. The seton loop is held together by means of the attachment device 73 which is positioned within the anal canal 74.

(50) The attachment device is sutured to the wall of the anal canal by means of sutures 75 so as to prevent displacement of the tissue growth promoting segment out of the fistula by rotation of the seton loop. The redundant second end 76 of the seton that has passed through the attachment device and from which the probe has been removed is securely aligned against the first end 77 of the seton by means of the previously described cooperating elements. Discomfort to the patient caused by loose ends of the seton is thereby avoided.

(51) By securely positioning the tissue growth promoting segment 72 within the fistula 71 by means of the seton 70, tissue in-growth is encouraged, thereby allowing the fistula to heal.

(52) Furthermore, the seton ensures that the tissue growth promoter is robustly held in place within the fistula, thus the problems encountered in the prior art due to fistula plugs falling out of the fistula are obviated.

(53) Finally, referring to FIG. 8 a schematic diagram of a seton 80 of the present invention positioned within a recto-vaginal fistula 81 is illustrated.

(54) Thus, in use the seton 80 attached to the probe (not shown) may be thread through the recto-vaginal fistula 81 from the vaginal opening and then through the attachment device 82 attached to the other end of the seton, which may be located inside the anal canal 83 so as to secure the seton loop. The probe may then be cut off and the redundant end 84 of the seton that has passed through the attachment device may be securely aligned against the other end 85 of the seton by means of cooperating elements. The attachment device may be sutured to the wall of the anal canal by means of sutures 86.

(55) Accordingly, it can be seen that a segment 87 of the seton 80 provided with a tissue growth promoter is secured within the recto-vaginal fistula 81. Thus, tissue in-growth is encouraged, thereby allowing the fistula to heal. Typically, after a 4 to 6 week healing period, the seton is cut proximal to the entry and exit of the fistula, so as to leave the absorbed tissue growth promoter within the fistula tract whilst allowing the attachment device and the remainder of the seton to be removed.

(56) Of course, it will be appreciated that the devices according to the present invention may be used by the person skilled in the art to treat simple anal and recto-vaginal fistulas using variations of the techniques exemplified above. For instance, when used to treat a recto-vaginal fistula, the probe may be thread through the recto-vaginal fistula from the rectal opening and/or the attachment device may be sutured to the wall of the vagina.

(57) Similarly, it will be appreciated that whilst uses of the devices according to the present invention have been described above in relation to simple anal and recto-vaginal fistulas, the person skilled in the art will understand that the devices may also find application in many other types of fistula.

(58) The devices of the present invention find particular application in fistulas adjacent to which there is a substantial body of tissue about which the seton loop may be affixed. Preferably the fistulas to be treated comprise or are located near at least one external opening such that the seton loop lies partially outside of the body. That said however, the use of the devices of the present invention entirely internally is also envisaged.

(59) Furthermore, the devices and the uses described may be best adapted by the surgeon in view of the particular fistula to be treated. For instance, where a fistula is complex, two or more such devices may be used to ensure that a tissue growth promoter is positioned within each tract.

(60) Although embodiments of the invention have been shown and described, it will be appreciated by those persons skilled in the art that the foregoing description should be regarded as a description of preferred embodiments only. The examples are not intended to limit the scope of the invention. Various modifications and embodiments can be made without departing from the scope and spirit of the invention, which is defined by the following claims only.