Patent Application
20110152604
The present invention relates to an intravaginal incontinence device comprising a polymeric resilient material. More specifically, this invention relates to a device that has a working portion having a variable equivalent diameter, a length suitable for insertion into a vagina and an anchoring mechanism for retention in the vagina, and is made from high modulus polymers having high tensile modulus properties along with high yield strain properties. Additionally, the polymers demonstrate resistance to creep and stress relaxation. The device is useful for reducing or preventing urinary incontinence.
Stress urinary incontinence is a problem for many women. It is characterized by leakage of urine during a stressing event, such as a cough or a sneeze. Many devices have been designed to reduce or prevent stress urinary incontinence. Tutrone, Jr., U.S. Pat. No. 5,603,685, teaches inflatable devices and a means to provide a device that is small for insertion into the vagina and enlarges to a required shape and pressure to reduce or prevent urinary incontinence. Zunker et al., U.S. Pat. No. 6,090,098, teaches tampon-like devices, each made with a combination of absorbing and/or non-absorbing fibrous materials. Ulmsten et al., U.S. Pat. No. 6,645,137, teaches a coil that expands in the vagina. Biswas, U.S. Pat. No. 5,036,867, teaches a compressible resilient pessary. James, U.S. Pat. No. 6,460,542, teaches a highly shaped rigid pessary. Many patents are drawn to stents that are sized and designed to keep arteries open.
Co-pending US Pat. App. No. 2008/0009664 (Bartning et al.) teaches urinary incontinence devices that may be made from shape memory polymers, which is defined as those materials that can be shaped into an initial shape, which can be subsequently formed into a stable second shape. The material is capable of substantially reverting to its initial shape upon exposure to an appropriate event. Among the shape memory materials disclosed in this publication are elastic or superelastic materials such as metal alloys such as Nitinol, phase segregated linear block co-polymers, biostable or bioabsorbable shape memory polymers (SMPs), etc. The SMPs can also be prepared from thermoplastic elastomers made from hydrophilic polymers. These elastomers typically have low modulus and may or may not be capable of significant stretching prior to breakage.
Despite the teaching of the prior art, there is a continuing need for a device suitable for insertion into a vagina and useful for reducing or preventing urinary incontinence. This device needs to be highly resilient.
We have invented an intravaginal incontinence device that is useful for reducing or preventing urinary incontinence that can be produced reliably and economically. We have found that we can produce a highly resilient polymeric device that meets the needs of incontinent women.
In one embodiment of the invention, an intravaginal urinary incontinence device has an insertion end and an opposed withdrawal end. The device has a resilient frame including a working portion disposed proximate the withdrawal end and an anchoring portion disposed proximate the insertion end. The working portion has a resilient structure having a plurality of connected elongate elements arranged and configured to define opposed working surfaces for providing support to an associated urinary system. The anchoring portion extends beyond the working portion and has a plurality of connected elongate elements arranged and configured to expand laterally within a user's vagina. The elongate elements are formed of a high modulus polymer having an elongation at yield of at least 3% and an elastic modulus of at least 2 Gpa.
In another embodiment of the invention, an intravaginal urinary incontinence device has an insertion end and an opposed withdrawal end. The device has a working portion disposed proximate the withdrawal end and an anchoring portion disposed proximate the insertion end. The working portion has a plurality of connected struts having opposed working surfaces to provide support to an associated urinary system and an insertion equivalent diameter ranging from about 5 to about 25 mm and a length ranging from about 20 to about 60 mm. The anchoring portion extends beyond the working portion, and the device is made of a high modulus polymer having an elongation at yield of at least 3% and an elastic modulus of at least 2 Gpa.
The challenge that has faced and continues to face developers of intravaginal incontinence devices is to provide an efficient, reliable polymeric device that can be delivered with a small cross-section for relatively easy insertion. At the same time the need exists to provide enough stiffness or force to push against vaginal walls to provide the necessary support to the bladder and other elements of the female urinary system. Materials used in previous disclosures include elastic and superelastic materials including metal alloys such as nitinol, phase segregated linear block co-polymers, and biostable or bioabsorbable shape memory polymers (SMPs), etc. However, these materials are expensive and/or are not sufficiently resilient or stiff or elastic under desired operating conditions.
We have found that it is important to balance the resilience of the material that forms the device against its ability to be reduced in cross-section to provide easy insertion. Thus, it is useful to consider resilience and stiffness of the materials. If using a material for the device that is too stiff, it may be difficult to compress the device into a configuration that can be contained within the much smaller diameter of an applicator.
As used herein, the term “high modulus polymer” and variants thereof relate to polymers having high tensile modulus properties and high yield strain properties. The materials produced with these polymers are very tough with high impact strength.
As used herein the specification and the claims, the term “stent” and variants thereof relate to a device used to support a bodily orifice, cavity, vessel, and the like. The stent is resilient, flexible, and collapsible with memory. The stent may be any suitable form, including, but not limited to, scaffolding, a slotted tube or a wire form.
Suitable shapes of devices according to the present invention are taught in US Pat. App. No. 2008/0009664, the disclosure of which is hereby incorporated by reference in its entirety. Referring to
In one embodiment, the flexible enclosure 16 contains a resilient frame 20, such as shown in
Working portion 24 includes a high modulus polymeric structural material that compresses and recovers with sufficient force to provide the desired effect. Such high modulus polymers have an elongation at yield of at least 3% and an elastic modulus of at least 2 Gpa. A representative, non-limiting list of suitable high modulus polymers includes polyetherimide, polyetheretherketone, polycarbonate, co-polymers, specialized and/or modified plastics, filled plastics, and the like, that can provide these high modulus properties. Particularly preferred high modulus polymers include polyetherimides and polyetheretherketones.
Again, high modulus polymers have high tensile modulus properties and high yield strain properties. Preferably, polymer has a tensile modulus, or elastic modulus, of at least about 2 Gigapascal (Gpa). In addition, it is preferred that the polymer has a high yield strain or an elongation at yield of at least about 3%, more preferably an elongation at yield of at least about 4.5% and most preferably an elongation at yield of at least about 5%. It is also preferred that the high modulus polymer is resistant to creep and stress relaxation.
In one embodiment, the working portion 24 comprises a plurality of connected elongate elements, such as struts 30. One or more of these elongate elements 30 may directly or indirectly tie the working portion 24 to the anchoring portion 22. The longitudinal projection of the working portion elongate elements defines the working portion length L1. The working pressure exerted by the working portion 24 is determined by the particular high modulus material selected and by the dimensions of the elongate elements. Thicker elongate elements and/or shorter elongate elements generally provide greater working pressures. In addition, the angle between the elongate elements also influences the working pressure.
The elongate elements 30 have a diameter much less than that of the working and/or anchoring portions. Preferably, the elongate elements have a diameter of less than about 5 mm, more preferably between about 1 mm and about 4 mm, even more preferably, between about 1.5 mm and about 3 mm. If the diameter of the elongate element is too large, the device may become too stiff and too large to appropriately compress the device for easy insertion. If the diameter is too small, the device may not be able to provide sufficient force to support the urinary system.
For some applications, the working portion exerts an expansion force, as described below, of from about 2 to about 8 Newtons (“N”) in the working state, preferably about 2 to about 6 N, and more preferably about 3 to about 6 N. Frame 20 also has an anchoring portion 22. Anchoring portion 22 is shaped suitable to keep the device 10 in place while in use. Suitable shapes include, but are not limited to, a basket handle, a dog bone, wings, and rabbit ears. The anchoring portion 22 may be made of the same material as the working portion 24 or they may be made of different materials. The working portion 24 and anchoring portion 22 may be made as a uni-body construction, or may be made separately and joined by attachment means. The frames 20 may be treated to provide improved biocompatibility. The frame 20 may be partially or completely covered, e.g., by placing inside tubing, by coating, molding, etc., to improve biocompatibility and/or comfort. The embodiment of
Devices according to the present invention may be useful for treating or preventing urinary incontinence. For this application, the device is sized to fit comfortably in the vagina. The devices described below may have working portions with initial equivalent diameters of from about 20 to about 170 mm. Preferably, the working portion has a working portion that may have an initial equivalent diameter ranging from about 20 to about 170 mm, preferably about 20 to about 45 mm, or more preferably about 30 mm; an insertion equivalent diameter ranging from about 5 to about 25 mm, preferably about 10 to about 20 mm, or more preferably about 18 mm; a use equivalent diameter ranging from about 10 20 to about 40 mm, preferably about 25 to about 30 mm, or more preferably about 25 mm; and a length ranging from about 20 to about 60 mm, preferably about 20 to about 30 mm, or more preferably about 25 mm.
The anchoring portion extends beyond the working portion in a direction away from the vaginal opening and may have an initial equivalent diameter ranging from about 30 to about 200 mm, preferably about 40 to about 60 mm, or more preferably about 50 mm; an insertion equivalent diameter ranging from about 10 to about 25 mm, preferably about 10 to about 20 mm, or more preferably about 18 mm; a use equivalent diameter ranging from about 20 to about 100 mm, preferably about 40 to about 60 mm, or more preferably about 50 mm; and a length ranging from about 10 to about 50 mm, preferably about 20 to about 40 mm, or more preferably about 30 mm.
The anchoring portion of the device has a length and width in the insertion state, the working state, and upon removal. The insertion state length may range from about 25 to about 40 mm, for example about 30 mm. The insertion state width may range from about 15 to about 20 mm, for example about 18 mm. The working state length at rest and during a cough may range from about 25 to about 40 mm, for example about 30 mm. The working state width at rest and during a cough may range from about 25 to about 35 mm, for example about 30 mm.
As shown in
The withdrawal element 18 may be crisscrossed between the elongate elements 30 of the frame 20 to create a “cinch sac” mechanism. Any string or cord known in the sanitary protection art may be useful for this purpose. As the strings are pulled during removal, the struts are gathered together to create a smaller diameter device during removal. Cinching the device at its base may make removal of the device more comfortable and easier as it makes the diameter of the device smaller and the shape conducive to remove easily.
As shown in
The resilient frame 20 can be made by any known polymer manufacturing methods. Preferably, the frame is injection molded, and the high modulus polymer can be selected for processability in these systems. The resilient frame 20 can then be further coated and or enclosed in a bag by known means.
The following examples are illustrative of devices according to the present invention. The claims should not be construed to be limited to the details thereof.
Following the procedure as detailed in ASTM D 638-08, as published on Feb. 6, 2009, the following measurements were made:
As shown by Table 1, not all polymers have both the appropriate elastic modulus and elongation capability.
The outward force that the polymeric frame exerts at various compression states was measured using an Instron Universal Testing machine (Model 1122, Instron Corp., Canton, Mass.) in a room at 23°±2° C. The Universal Testing machine was equipped with two opposing and rigid horizontal plates. One plate was attached to the crosshead. The other plate faced the first one and was attached to the upper fixed surface. The lower plate moved upward with the crosshead to compress the sample. Both plates were otherwise rigid and made of aluminum or steel. The upper plate was affixed to a load cell capable of measuring forces compression forces between 0 and 30 Newtons.
To run the test, the plates were brought to an initial spacing of 37 mm. Each inventive device was placed with the two sides of the working section placed against the plates. Where the working portion of the device is cylindrical, opposing sides of the cylinder contact the plates. For non-cylindrical devices, the front and rear faces contact the plates. Via crosshead movement, the plates were brought together at a rate of 1.0″/minute until they are 10 mm apart. Force against the load cell is recorded automatically as the plates moved together. The expansion force at 20 mm spacing is the recorded measurement. For the initial time (no storage) samples, the devices were not placed within an applicator. For the 5 minute storage time point, each device was tested after being contained in a 15.6 mm inner diameter applicator for 5 minutes at room temperature. After the pre-determined time, the devices were expelled and allowed to come to room temperature without constraint for 15 to 30 minutes. For each time point, n=3.
Note: The applicator had an inner diameter of 15.6 mm and an outer diameter of 18 mm. It was injection molded of polyethylene. These dimensions and materials were chosen to minimize deformation during storage.
The specification and embodiments above are presented to aid in the complete and non-limiting understanding of the invention disclosed herein. Since many variations and embodiments of the invention can be made without departing from its spirit and scope, the invention resides in the claims hereinafter appended
