Urethral Prosthesis

Abstract

A prosthesis to resist the flow of urine through the urethra, which comprises a fluid-impervious, flexible and deformable capsule having a gel-filled, or gel and liquid-filled cavity therein. A cover encapsulates the capsule, and two flexible sling ties extend beyond the cover. The material of the cover and of the ties is such as to enhance fiber ingrowth into openings formed by the material, whereby mechanically to stabilize the prosthesis when it is implanted in the human body.

Description

This invention relates to a prosthesis for resisting the flow of urine through the urethra, thereby to give a patient, either male or female, control over incontinence of urine.

Protheses to resist the incontinent flow of urine have been the subject of many investigations. Reference is made here to Foley F.E.B., An Artificial Sphincter, Journal of Urology, 50:250 (1947); to U.S. patent No. 3,384,073, issued May 21, 1968 to Van Winkle, Jr.; and to Girgis and Veenema, Perineal Urethro-plasty, A New Operation for Correction of Urinary Incontinence in the Male Patient, Journal of Urology, 93, 703-8 (1965).

It is known to implant a deformable capsule so that it bears against the urethra to occlude its lumen and thereby resist the flow of urine. Previously known prostheses for this purpose have suffered from a number of problems, not the least of which is pressure necrosis in the urethra. It appears that this necrosis resulted from wrapping the capsule and its supporting means around the urethra, which created multiple folds in the capsule and in the urethra. By means of this invention, a deformable capsule can be utilized which simply presses against the urethra without forming such folds, and which can reliably be stabilized in the body by means of tissue ingrowth into exterior surfaces. The force exerted on the urethra can be adjusted by varying the amount of material contained in the capsule, and also by varying the tension of a supporting sling.

A prosthesis according to this invention comprises a fluid-impervious, flexible and deformable capsule which has a cavity therein that can be filled with a gel or with a combination of liquid and gel. A sling is attached to the capsule. The sling provides two flexible ties that extend therefrom. A cover encapsulates the capsule. The material of which the cover and the flexible ties is made is such as to provide openings for ingrowth of fibrous tissue, whereby mechanically to stabilize the prosthesis after it is implanted in the human body.

According to a preferred but optional feature of this invention, the capsule has a portion of greater thickness and a portion of lesser thickness, the portion of lesser thickness being adapted to bear against the urethra through the cover, and being made of material which is inherently resilient, and the portion of greater thickness being thick and stiff enough to close a hole which is made in it by a needle which penetrates it and then is withdrawn.

According to still other preferred but optional features of this invention, the capsule is made entirely of a silicone elastomer, the cover is made of polyurethane open cell foam, and the sling is made of a loop pile material, preferably a dacron velour.

The above and other features of this invention will be fully understood from the following detailed description and the accompanying drawings, in which:

FIG. 1 is an axial cross-section of the presently-preferred embodiment of the invention, taken at line 1--1 in FIG. 2;

FIG. 2 is a top view of FIG. 1;

FIG. 3 is a side view of FIG. 2;

FIG. 4 is a cross-section taken at line 4--4 in FIG. 3;

FIG. 5 is a plan view of an intermediate step in the implantation of this prosthesis;

FIG. 6 is a view similar to FIG. 5 with the prosthesis implanted;

FIG. 7 is a side view partly in cutaway cross-section, showing the lumen of the urethra closed by the prosthesis; and

FIG. 8 is a semi-schematic fragmentary showing of the construction of one material from which the sling of the prosthesis can be made.

A prosthesis 10 according to the invention is shown in FIG. 1. It includes a fluid-impervious, flexible and deformable capsule 11 which is formed by portions 12 and 13. Portion 12 is in the nature of a base. It is substantially flat and disc-like, and is substantially thicker than portion 13. Portion 13 is dome-like, with a turned-in lower rim 14 having a central opening 15 which is closed by attaching portion 12 across it, with the portions overlapped around the edge and cemented together. If desired, a reinforcement 16 of mesh material, such as dacron cloth, may be embedded in portion 12.

The two portions are preferably made of silicone elastomer, such as medical grade silicone rubber. When this material is used, portion 12 will be made on the order of about 0.050 inches thick, and portion 13 on the order of about 0.020 inches thick.

The said thickness of portion 12 provides sufficient stiffness to close a needle track (not shown) which is made by a needle which has penetrated the portion and then been withdrawn for purposes yet to be described. The reinforcement 16 when used will assist the closing of the track, because it tends to trap the elastomer between its strands and resists the spreading of the material.

Portion 13 is made of material which is inherently resilient. Of course, silicone elastomer is inherently resilient. Portion 13 is intended to be readily flexible and deformable and will usually be made thinner than portion 12. Also, because it is not intended to be pierced by a needle, it need not be as thick, nor need it be reinforced. When silicone elastomer is used for portion 13, its thickness may be on the order of about 0.020 inch.

When the portions 12 and 13 are joined to each other, they form a continuous, fluid-impervious structure enclosing a cavity 17 which is filled by a gel 18, or by a combination of a gel and a liquid. As will later be described in more detail, the capsule is initially filled with a gel, and after implantation, if more material is needed in the capsule, a saline solution is injected through a needle. Therefore, this invention contemplates the use of gels and gel-liquid combination.

The gel used in the capsule is a "silicone gel" sold under that name by General Electric Corporation and by Dow Corning Corporation. For purposes of this invention, the grade of silicone gel which will be ordered is selected for its penetration rating, which for use in this device will ordinarily be in the range between about 10 and 20 mm with 191/2 gr. 1 inch dia. Lexan foot on a precision scientific penetrometer. Such a range resists any tendency of the capsule to deform to one side or the other, and lends some structural integrity to the unit.

A sling 20 is cemented to portion 12 and provides two flexible ties 21, 22, which project through and extend beyond the capsule. The ties are preferably in the form of a ribbon. The term "ribbon" is used to connote a shape which has a greater width than thickness, so as to have a substantial surface area, and is flexible so it can be tied or turned back and sutured. A cover 25 encapsulates the capsule, and also the central section of the sling. The ties are preferably provided as shown as the two ends of a ribbon which passes through the cover.

The material of the cover is preferably polyurethane open cell foam. It is of uniform thickness, and is cemented to the capsule. It may conveniently be on the order of about 0.125 inches thick, and is readily compressible.

The material of the sling is preferably a loop-pile fabric, i.e., a woven fabric with upstanding loops. A velour is the preferred example, and the presently preferred material for the velour is dacron.

It is a feature of the material used for the cover and for the flexible ties of the sling that it will enhance fiber ingrowth into openings formed by the material. As to the cover, the openings are the cells which open onto the outside surface, and also the cells which interconnect with these and with each other inside the body of the foam. It is a feature of this foam material that encourages the growth of fibers into these openings, and after enough of these fibers have grown into them, the cover is attached to the surrounding tissue.

Similarly, as to the material of the sling, it, too, should be of a material which is compatible with human tissue. It should be flexible so that it can be folded so as to be sutured or tied, and should have openings which encourage the ingrowth of fibrous tissue. A woven material meets these requirements, and a woven cloth, such as Dacron cloth, can be used. It is advantageous to use a loop-pile fabric such as a velour, because the loops provide additional openings for tissue ingrowth. A fragmentary illustration of a velour is shown in FIG. 8, wherein woven material 30 is shown with cross-woven fibers 31 in one direction and 32 in the other, and at their intersections, closed loops 33. Each loop forms an opening 34. Openings 35 are also formed between the woven fibers. Tissue can readily grow into the openings in the loops and in the weave. Therefore, over a period of time, the surrounding tissue will grow into and attach itself to the sling as well to the cover of the capsule.

In its free and undistorted form as shown in FIGS. 1-4, the prosthesis has a substantially flat base surface 40, and a dome-shaped pressure surface 41. The pressure surface is symmetrical around an axis 42 normal to the base surface. The prosthesis is generally circular in plan view (FIG. 1).

The prosthesis is intended to be installed so as to be supported by the sling by being sutured (in the male patient) into the heavy Bucks fascia of the penis, rather than being supported by a wrapping of a strap around the urethra. In this manner, the undesirable pressure necrosis described above is avoided.

FIG. 5 shows the prosthesis located at the crus of the penis, in the bulbocavernosis 43. Ties 21 and 22 are shown brought under the ischiocavernosis 44, 45. In FIG. 6, the ties are shown brought together and tied or sutured in a joinder 46. Obviously the tension produced in the ties is directly reflected in the firmness of support of the prosthesis. The more tension in the installed sling, the more resistance there is to displacement of the prosthesis.

In FIG. 7, the prosthesis is shown bearing against urethra 47 and pressing it against surrounding tissue 48. Its lumen 49 is closed because upstream pressure is insufficient to deform the capsule and deflect the pressure surface to open the lumen. Such upstream pressure can be generated by some persons with the use of bladder muscles. For others, a mechanical force on the bladder, such as by pressing the hand strongly against the body in the proper area, will open the lumen.

The described deflection occurs as a consequence of changing the shape of the capsule. The volume of the capsule will not change, but its surface area can be changed when its shape is altered. The resistance to such change is partially determined by sling tension, and partly by the amount of filling in the cavity. Obviously if rather little gel is injected into the cavity, the pressure surface will be slack, and exert relatively little force. If the capsule is filled so as to stretch the capsule material, a tight pressure surface will result. Evidently the resistance of the capsule to change of shape can be adjusted by selectively injecting different amounts of gel or gel and solution into the cavity.

The gel is formed by reaction and heating of its components in the course of manufacture, and therefore will not be injected into the capsule after implantation in the body. For this reason, an amount of gel suitable for average implantation is formed in the capsule during manufacture. Should this amount of gel be insufficient to provide the propoer action, then it is an important advantage that, without opening the body again, a needle may be pierced through the body and through portion 12, and a liquid such as saline solution, is added to the gel to increase the amount of material in the capsule. Therefore the implantation can be adjusted to suit the needs of the patient after implantation. The use of a gel for at least a part of the filler material for the capsule provides the capsule with the property of resisting sudden changes of shape because of the viscosity of the material. However, the material filling the capsule must not be too rigid, or the opening of the lumen may be made too difficult.

This prosthesis is useful in the female patient, by implantation in a respective location where the pressure surface can compress the urethra between itself and a neighboring surface as a consequence of a sling support which biases the pressure surface toward and against the urethra.

This invention is not to be limited by the embodiment shown in the drawings and described in the description, which is given by way of example, and not of limitation, but only in accordance with the scope of the appended claims.

Claims

1. A prosthesis to resist the flow of urine through the urethra, comprising: a fluid-impervious, flexible and deformable capsule having a cavity therein; a sling comprising a pair of flexible ties extending therefrom; a gel or combination of a gel and a liquid substantially filling the cavity; and a cover encapsulating the capsule, the material of the cover and of the flexible ties having openings to receive fiber ingrowth, whereby mechanically to stabilize the prosthesis when implanted in the human body, and the material of at least a part of the capsule being inherently resilient, the flexibility and firmness of the filled capsule being such as to exert, when suitably supported from surrouding tissues by the sling and filled with gel or a combination of a gel and a liquid to a suitable firmness, a lateral force against the urethra sufficient to deform the urethra and close its lumen to passage of urine under less than a predetermined upstream pressure in the urethra, and to be deformable by the urethra when a greater upstream pressure is exerted

2. A prosthesis according to claim 1 in which the sling is a continuous ribbon attached to the outside surface of said portion of greater thickness, the flexible ribbon passing through the cover to form the ties.

3. A prosthesis according to claim 2 in which the capsule has a portion of greater thickness and a portion of lesser thickness, the portion of lesser thickness being adapted to bear against the urethra and being the part made of material which is inherently resilient, and the portion of greater thickness being sufficiently thick and stiff enough to close a track made

4. A prosthesis according to claim 3 in which the portion of lesser thickness is dome-shaped, and has an opening therein, and in which the region of greater thickness is substantially flat, and extends across and

5. A prosthesis according to claim 1 in which the capsule is made entirely of silicone elastomer, the cover is made of polyurethane open cell foam,

6. A prosthesis according to claim 5 in which the loop pile material is

8. A prosthesis according to claim 7 in which the capsule is made entirely of silicone elastomer, the cover is made of polyurethane open cell foam,

9. A prosthesis according to claim 8 in which the loop pile material is

10. A prosthesis according to claim 8 in which the capsule has a portion of greater thickness and a portion of lesser thickness, the portion of lesser thickness being adapted to bear against the urethra and being the part made of material which is inherently resilient, and the portion of greater thickness being sufficiently thick and still enough to close a track made

11. A prosthesis according to claim 10 in which the portion of lesser thickness is dome-shaped, and has an opening therein, and in which the region of greater thickness is relatively flat, and extends across and

12. A prosthesis according to claim 11 in which the sling is a continuous ribbon attached to the outside surface of said portion of greater thickness, the flexible ribbon passing through the cover to form the ties.

13. A prosthesis according to claim 12 in which the sling is made of a loop

14. A prosthesis according to claim 1 in which the ties are ribbon-shaped.

15. A prosthesis according to claim 14 is which the ties are made of a loop

16. A prosthesis according to claim 15 in which the loop pile material is

17. A prosthesis according to claim 1 in which the capsule is substantially circular in plan view, has a substantially flat base surface from which the ties extend, and a dome-shaped pressure surface symmetrical around an axis normal to the base surface.