WO2005082275A1

WO2005082275A1 - A prosthesis

Info

Publication number: WO2005082275A1
Application number: PCT/GB2005/000601
Authority: WO
Inventors: Michael Albert Kamm; Carolynne Jane Vaizey
Original assignee: Yarra Medica Limited
Priority date: 2004-02-24
Filing date: 2005-02-21
Publication date: 2005-09-09
Also published as: GB0404093D0

Abstract

A passive, incontinence-inhibiting prosthesis for insertion into a position substantially coaxial with and at least partially surrounding at least a portion of the anal canal or urinary passage is provided. The prosthesis comprises a resiliently flexible body having dimensions such that, in the above-mentioned position, the prosthesis constrains tissue surrounding the anal canal or urinary passage. Advantages of the prosthesis include simplicity of use and operation.

Description

A PROSTHESIS

The present invention relates to a prosthesis and, in particular, to a prosthesis for use in the treatment of faecal or urinary incontinence.

Incontinence is an inability to control defecation or urination (Mosby's Medical, Nursing and Allied Health Dictionary, 5^th ed. , 1998).

Faecal incontinence affects about 2% of the population. Common causes of faecal incontinence (passive or urge incontinence) include atrophy of either internal or external anal sphincter muscle, sphincter damage due to obstetric, surgical or accidental trauma, congenital anomalies, neurological defects including spinal injuries and rectal prolapse.

Where faecal incontinence has resulted from simple external sphincter damage, it may be treated by overlap repair. Such treatment can provide good results in the short term but not typically in the longer term. Patients with smooth muscle internal sphincter defects or degeneration, or external sphincter weakness or complex disruption, are not amenable to simple repair. It is possible to surgically "tighten up" the anal sphincter muscles. Such an operation again shows good results in the short term but the results are not so good in the longer term, e.g. after about 5 years.

The Secca procedure has been used to treat faecal incontinence. It involves "scarring down" the anal canal using radio frequency ablation. Results indicate that this procedure provides a limited improvement in faecal leakage in the short term. It is possible that destruction of tissue in this way might affect the recto-anal inhibitory reflex. However, the most likely explanation for the results is the scarring around the anal canal.

It is also possible to treat faecal incontinence by injection of sphincter bulking agents such as collagen and Bioplastique™ (now known as PTP implants) to close down the anal canal. Results show that some relief is provided in the short term but that migration or displacement of the injected product may occur with time. Rectal prolapse has been treated in the past through surgical implantation of a silver thread known as a Thiersch ring around the anus. It was applied particularly in elderly and weakened persons but is now no longer used. Severe faecal incontinence, that is where a loss of control leads to one or more episodes of incontinence per week, can be controlled through the surgical implantation of a prosthesis such as the AMS Acticon™ Neosphincter (American Medical Systems, Inc., 10700 Bren Road West, Minnetonka, MN 55343 USA) . This prosthesis is a small fluid-filled device that is implanted entirely within the body of men or women and is designed to restore natural bowel control using a hydraulic mechanism. The Neosphincter consists of an inflatable cuff, a pump and a pressure-regulating balloon, the balloon and the cuff being in fluid flow communication via the pump. The cuff is surgically implanted around the anal canal with the pump being placed in the labium or scrotum and the pressure- regulating balloon being implanted in the lower abdomen. The device is filled with a sterile isotonic radio opaque solution. The cuff is filled with fluid from the balloon and, when it is closed, it gently squeezes shut the anal canal. To have a bowel movement, the cuff is opened by activating the pump which moves fluid out of the cuff and into the balloon. As the empty cuff no longer squeezes the anal canal, stool can now pass along the anal canal and out of the body. The pressure created by the balloon automatically pushes fluid back into the cuff. After several minutes, the cuff is refilled and the anal canal is gently squeezed shut.

The Neosphincter does provide an elevation in anal resting pressure and, at least^', initially, the results are good. However, this prosthesis has been shown to be unreliable due to infections, erosions or mechanical failures. The prosthesis is complicated and requires considerable surgical expertise to insert. It is also expensive and has enjoyed only moderate success. US-B-6461292, US-B-6482145 and US-B-6503189 disclose further hydraulic implants designed to assist anal sphincter function. However, the implants require a power source inserted internally and are operated using an external remote control .

There is a definite need, therefore, for an improved prosthetic solution to faecal incontinence that is less complex than existing prosthetic solutions and which displays good long term results.

Common causes of urinary incontinence (either stress or urge incontinence) include urethral sphincter incompetence due to weakness or damage, infection, detrusor instability, congenital anomalies, neurological defects including spinal injury and urogenital prolapse. Existing treatments include treatment of the infection, bladder retraining, use of internal or external drainage devices, injecting bulking agents and various surgical repairs.

There is also an artificial urinary sphincter implant which has been used to control urinary incontinence. The device is similar to the Neosphincter discussed above but designed for use around the urinary sphincter instead of the anal sphincter.

There is also a definite need, therefore, for an improved solution to urinary incontinence.

US-A-3875928 (Angelchik) discloses a prosthesis for use in treating sliding oesophageal hernia which is one of the causes of gastro-oesophageal reflux disease. The prosthesis consists of a generally C-shaped cushion member, the inside dimensions of which generally correspond with the normal outside dimensions of the distal oesophagus. The cushion member has a generally circular cross-section and is tapered from the central portion to the free ends thereof. It may be constructed by filling an outer flexible integument with a gel liquid. A tape is secured around the outer periphery of the cushion member and the free ends of the tape extend substantially beyond the free ends of the cushion member. In use, once the hernia has been repaired, the cushion member is surgically implanted around the distal oesophagus immediately above the gastric fundus . The free ends of the tape are tied together and then sutured to the stomach to retain the cushion member in position.

It is an objective of preferred embodiments of the present invention to provide a lower cost, safe and effective prosthetic solution to faecal or urinary incontinence .

According to a first aspect of the present invention, there is provided a passive, incontinence-inhibiting prosthesis for insertion into a position at least partially surrounding at least a portion of the anal canal or urinary passage, said prosthesis comprising a resiliently flexible body having dimensions such that, in said position, said prosthesis constrains tissue of said anal canal or urinary passage. Preferably, in use, the prosthesis surrounds substantially co-axially at least a portion of the anal canal or urinary passage.

Without wishing to be bound by any particular theory, the inventors believe that preferred embodiments of the prosthesis control incontinence by supporting the anal canal or urinary passage during relaxation of the anal or urinary sphincter or preventing such relaxations or supporting a weak sphincter. The resilient flexibility of the body allows the body to return to its normal shape following deformation resulting from, for example, the passage of stool though the anal canal. It is not anticipated that the device would substantially increase pressure in the anal canal or urinary tract (urethra or bladder neck) .

The term "prosthesis" is defined as "a device designed and applied to improve function" (Mosby's Medical, Nursing and Allied Health Dictionary, 5^th ed. , 1998) . Therefore, the term "prosthesis" in the present context is intended to include devices designed and applied to improve the function of the anal canal or the urinary passage. The term "anal canal" refers to the region of the gut between the rectum and the external opening of the anus, including the anal sphincter and other peri-anal tissues. The term "urinary passage" is intended to include the bladder neck, the base of the bladder, the urethral sphincter, the urethra and other peri-urethral tissue.

In preferred embodiments, the prosthesis is designed to be inserted surrounding the anal sphincter for the treatment of faecal incontinence and surrounding or close to the urinary sphincter for the treatment of urinary incontinence.

The dimensions of the body of the prosthesis are preferably such that, when in position, the prosthesis exerts no more than sufficient pressure on the tissue with which it is in contact to remain in position. It is envisaged that preferred embodiments of the present invention close down the lumen of the anal canal or the urinary passage such that stool or urine may still pass through. However, it is believed that there is no substantial change in anal or urinary pressure as a result of use of these preferred embodiments . The body of the prosthesis may be in a pre-formed arcuate shape or may be deformable into an arcuate shape. For example, the prosthesis may be arcuate before use or may be flexible^' such that it is deformed into an arcuate shape on insertion. The term "arcuate" is intended to include any suitable curved shape such a ring or a cylinder (either whole, i.e. of O-shaped cross section, or split, i.e. of C- shaped cross section) . The body is most preferably in the form of a cuff. Preferably, the ends of the cuff overlap not only to provide a convenient location for attachments means but also to allow the cuff to be adjustable to fit different sizes of anal canal or urinary passage.

The body may be hollow. Usually, the hollow body would take the form of a tillable envelope. The envelope is typically formed from a physiologically acceptable plastics or similar material. In such embodiments, the body may be filled with a powder, liquid or gel. The filling is preferably physiologically acceptable in case the prosthesis body ruptures and filling is leaked into the body. The powder, liquid or gel is preferably radio-opaque so that the prosthesis may be located using radio imaging.

Where the body is hollow, it may be inflated and/or deflated, either prior to insertion or once in position. In such embodiments, the body comprises a port for passing or injecting powder, liquid or gel filling into and/or out of the body. Alternatively,' the body may be solid, that is not having an internal hollow cavity. In such embodiment, the body may be formed from a physiologically acceptable polymeric material such a silicone elastomer. Preferably, the body is radio-opaque.

Once in position, the prosthesis exerts sufficient pressure to remain in position but not so much pressure that the lumen of the anal canal or the urinary passage is closed. Preferably, the prosthesis exerts no more that enough pressure to remain in position. However, it may also be desirable to anchor the prosthesis in position to reduce further the risk of migration of the prosthesis out of position. Therefore, the prosthesis may further comprise at least one lug for a suture.

The body of the prosthesis may be wrapped around the required portion of either the anal canal or the urinary passage. Typically, the circumference of the body will be more than the outer circumference of the anal canal or urinary passage around which it is wrapped. In such cases, the ends of the body will overlap. The overlapped portion may be secured together using any suitable attachments means to secure the prosthesis in position. Such embodiments have the added advantage that the diameter of the prosthesis can be adjusted rather like a belt to accommodate anal canals or urinary passages of different sizes. In embodiments where the ends of the body do not overlap, the ends may be attached together using any suitable means of attachment. Suitable attachment means include laces, sutures or an adjustable device or clip. As the prosthesis is to be inserted into the human or animal body, the prosthesis may have antibacterial properties to prevent infection. The prosthesis may be coated with an antibacterial composition, for example an anti-staphylococcal paste, or the body of the prosthesis may be impregnated with an antibacterial substance.

Preferred dimensions of the prosthesis depend on whether it is for use as a solution to faecal or urinary incontinence. For the avoidance of doubt, the "circumference" (c) , "axial length" (1) and "thickness" (t) of the prosthesis are depicted in Figure 1.

Where the prosthesis is to be inserted into a position at least partially surrounding at least a portion of the anal canal, the circumference may be between from about 4 to about 15cm and preferably between from about 6 to about 12cm. The axial length may be between from about 0.25 to about 6cm, preferably between from about 0.5 to about 4.5cm and more preferably between from about 1 to about 2.5cm. The thickness may be between from about 0.1 to about 1.5cm, preferably between from about 0.1 to about 1cm and most preferably about 0.5cm.

Where the prosthesis is to be inserted into a position at least partially surrounding at least a portion of the urinary passage, the circumference may be from about 2 to about 14cm and preferably between from about 4.5 to about 11cm. The axial length may be between from about 0.25 to about 4cm and preferably between from about 0.5 to about 2cm. The thickness may be from about 0.05 to about 1cm, preferably between from about 0.1 to about 0.75cm and more preferably about 0.4cm. The aspect ratio between the thickness (at the thickest point) of the prosthesis to the axial length may be 1 . at least 1.25, preferably 1 : at least 2, more preferably 1 : between from about 2 to about 10 and most preferably 1 : between from about 3 to about 5.

According to a second aspect of the present invention, there is provided a method of treatment or prophylaxis of incontinence comprising inserting a prosthesis according to the first aspect of the present invention into a position at least partially surrounding at least a portion of the anal canal or urinary passage. The term "treatment" is intended to include control . The method may further comprise applying an antibacterial composition to the prosthesis either prior to or immediately following insertion. The method may further comprise securing the prosthesis in position using at least one suture.

Further aspects of the present invention include:

• A prosthesis according to the first aspect of the present invention for use in the treatment or prophylaxis of faecal or urinary incontinence; • Use of a prosthesis according to the first aspect of the present invention in the treatment or prophylaxis of faecal or urinary incontinence; and

• Use of a resiliently flexible body as described above in the manufacture of a prosthesis for use in the treatment or prophylaxis of faecal or urinary incontinence .

The following is a description, by way of example only and with reference to the accompanying drawings, of presently preferred embodiments of the invention. In the drawings; FIGURE 1 is a diagrammatic representation of a prosthesis according to the invention indicating the relevant dimensions; FIGURE 2 is a diagrammatic cross section of a prosthesis according to the invention in position around the anal sphincter; FIGURE 3 depicts a prosthesis according to the invention in position around the anal sphincter in both a woman and a man; FIGURE 4 depicts a prosthesis according to the invention in position around a portion of the urinary passage in both a woman and a man; FIGURE 5 depicts a first embodiment of the present invention; FIGURE 6 depicts a second embodiment of the present invention; and FIGURE 7 depicts a third embodiment of the present invention.

In Figure 1, the circumference of the prosthesis 10 is indicated by the letter "c" , the axial length is indicated by the letter "1" and the thickness by the letter "t" .

Figure 2 depicts a cross section of the anal sphincter in its default or "at rest" position with the lumen 12 of the sphincter closed. The sphincter is composed of submucosal tissue 13 surrounded by an internal anal sphincter ("IAS") muscle 14 which in turn is surrounded by an external anal sphincter ("EAS") muscle 16. The prosthesis 10 is wrapped around the EAS 16 so as to constrain the muscle tissues. The prosthesis 10 exerts passive pressure on to the muscle tissue. The magnitude of the pressure is sufficient to retain the prosthesis 10 in position but is not sufficient to increase substantially the pressure in the lumen 12 of the sphincter.

Figure 3 depicts the prosthesis 10 in position around the anal sphincter at the distal end of the rectum 18 so as to control faecal incontinence in both a woman and a man.

Figure 4 depicts the prosthesis 10 in position around a portion of the urinary passage, in this case around the urinary sphincter just after the neck of the bladder 20 at the upper end of the urethra 22, so as to control urinary incontinence in both a woman and a man.

Three embodiments of the prosthesis 10 are depicted in Figures 5 to 7. In Figure 5, the prosthesis 10 is in the form of a split ring, the ends of which are tied together with laces 24. In Figure 6, the prosthesis 10 is in the form of a split cylinder or cuff, the ends of which are tied together using a pair of sets of laces 24. In Figure 7, the prosthesis 10 is also in the form of a cuff. In this embodiment, one end of the cuff 10 has a tongue 26 which overlaps the other end of the cuff 10 and which is secured in position at points 26. These fixtures may comprise studs and eyes, sutures or even spots of adhesive between the tongue 26 and the end of the cuff.

Preferred embodiments of the present invention are less complex than known prosthetic solutions to incontinence.

Prostheses of the present invention are more straightforward to surgically insert into position. Importantly, once inserted, the prosthesis will function without input from the patient. Therefore, there is little or no need for the patient to adjust his or her lifestyle after implantation. In addition, the prosthesis of the present invention is indicated for control of faecal or urinary incontinence results from any of the causes discussed above. Throughout the specification, the term "means" in the context of means for carrying out a function, is intended to refer to at least one device adapted and/or constructed to carry out that function. It will be appreciated that the invention is not restricted to the details described above with reference to the preferred embodiments but that numerous modifications and variations can be made without departing from the spirit or scope of the invention as defined by the following claims.

Claims

1. A passive, incontinence-inhibiting prosthesis for insertion into a position at least partially surrounding at least a portion of the anal canal or urinary passage, said prosthesis comprising a resiliently flexible body having dimensions such that, in said position, said prosthesis constrains tissue of said anal canal or urinary passage.

2. A prosthesis as claimed in Claim 1 for insertion into a position coaxial with and surrounding at least a portion of the anal canal or urinary passage.

3. A prosthesis as claimed in Claim 1 or Claim 2 wherein the dimensions of said body are such that, in said position, the prosthesis exerts no more than sufficient pressure on said tissue to remain in position.

4. A prosthesis as claimed in any of Claims 1 to 3 wherein said body is of pre-formed arcuate shape.

5. A prosthesis as claimed in any of Claims 1 to 3 wherein said body is deformable into an arcuate shape.

6. A prosthesis as claimed in any of the preceding claims wherein said body is hollow.

7. A prosthesis as claimed in Claim 6 wherein the body is filled with a physiologically acceptable powder, liquid or gel .

8. A prosthesis as claimed in Claim 7 wherein the physiologically acceptable powder, liquid or gel is radio- opaque .

9. A prosthesis as claimed in any of Claims 6 to 8 wherein said body comprises port for passage of a physiologically acceptable liquid or gel into and/or out of said body.

10. A prosthesis as claimed in any of Claim 6 to 9 wherein the body is formed from a physiologically acceptable plastics material.

11. A prosthesis as claimed in any of Claims 1 to 5 wherein the body is solid.

12. A prosthesis as claimed in Claim 11 wherein said body is formed from a physiologically acceptable polymeric material .

13. A prosthesis as claimed in Claim 11 or Claim 12 wherein said body is formed from silicone.

14. A prosthesis as claimed in any of the preceding claims wherein said body is radio-opaque.

15. A prosthesis as claimed in any of the preceding claims further comprising at least one lug for a suture.

16. A prosthesis as claimed in any of the preceding claims in the form of a flexible cuff.

17. A prosthesis as claimed in Claim 16 further comprising attachment means to attach the ends of the cuff together.

18. A prosthesis as claimed in any of the preceding claims 5 wherein said body has antibacterial properties.

19. A prosthesis as claimed in any of the preceding claims for insertion into a position at least partially surrounding at least a portion of the anal canal. 0

20. A prosthesis as claimed in any of the preceding claims for insertion into a position at least partially surrounding at least a portion of the urinary passage. 5

21. A prosthesis as claimed in any of the preceding claims wherein the aspect ratio between the thickness (at the thickest point) of the prosthesis and the axial length is 1 : at least 1.25. 0

22. A prosthesis as claimed in Claim 21 wherein the aspect ratio is 1 : at least 2.

23. A prosthesis as claimed in Claim 21 or Claim 22 wherein the aspect ratio is 1 : between from about 2 to about 10.

.5 24. A prosthesis as claimed in any of Claims 21 to 23 wherein the aspect ration is 1 : between from about 3 to 5.

25. A prosthesis substantially as hereinbefore described O with reference to the accompanying drawings.

26. A prosthesis as claimed in any of the preceding claims for use in the treatment or prophylaxis of faecal or urinary incontinence .

5 27. Use of a prosthesis as claimed in any of Claims 1 to 25 in the treatment or prophylaxis of faecal or urinary incontinence .

28. Use of a resiliently flexible body as defined in any of 10 Claims 4 to 14 in the manufacture of a prosthesis for use in the treatment or prophylaxis of faecal or urinary incontinence .

29. A method of treatment or prophylaxis of incontinence 5 comprising inserting a prosthesis as claimed in any of Claims 1 to 25 into a position substantially coaxial with and at least partially surrounding at least a portion of the anal canal or urinary passage.

!0 30. A method as claimed in Claim 29 further comprising applying an antibacterial composition to the prosthesis either prior to or immediately following insertion.

31. A method as claimed in Claim 29 or Claim 30 further 5 comprising securing the prosthesis in position using at least one suture.