WO1996003940A1

WO1996003940A1 - Mammary prostheses

Info

Publication number: WO1996003940A1
Application number: PCT/GB1995/001869
Authority: WO
Inventors: Dennis Keith Gilding; Thomas Brian Rafferty; Simon Ashley Dixon
Original assignee: Innovative Technologies Limited
Priority date: 1994-08-05
Filing date: 1995-08-07
Publication date: 1996-02-15
Also published as: GB9415829D0; AU3185695A

Abstract

A method of fabricating a mammary prosthesis comprises: i) dipping a male former having a surface corresponding to the desired shape of a breast in a liquid containing a first elastomer or first elastomer precursor and producing a coating of a first elastomer on the former; ii) removing the resulting elastomer breast form from the former by means of an opening in the breast form; iii) filling the elastomer breast form, via said opening, with a gel; and iv) sealing the opening.

Description

MAMMARY PROSTHESES

The present invention relates to mammary prostheses and a method of fabricating mammary prostheses.

Millions of women throughout the world have suffered unilateral or bilateral mastectomies, mainly as a result ofthe effects of breast cancer. To alleviate the physical and psychological effects of mastectomies various forms of mammary prostheses have been developed. A common type of such prostheses is an external breast form intended to mimic a real breast.

Known external breast forms are made from a silicon gel filled polyurethane bag. The bag is fabricated from two vacuum formed halves which are joined together at their edges by heat sealing. The bag is then filled with a silicon gel before closing, again by heat sealing. Silicon gel is used so that the breast form has a turgor similar to that of a natural breast.

Such known breast forms suffer two important disadvantages. Firstly the vacuum forming process tends to produce an inconsistent product. For instance, nipples may not be well defined or may be absent altogether. Secondly, the heat sealed edges form seams which are often relatively hard and can cause skin chaffing, particularly if the skin is sensitive as. for instance, the result of radiation or chemotherapy.

It is an object of the present invention to provide a method of fabricating a mammary prosthesis which obviates or mitigates the above disadvantages.

According to a first aspect ofthe present invention there is provided a method of fabricating a mammary prosthesis comprising: i. dipping a male former having a surface corresponding to the desired shape of a breast in a liquid containing a first elastomer or first elastomer precursor and producing a coating of a first elastomer on the former; ii. removing the resulting elastomer breast form from the former by means of an opening in the breast form; iii. filling the elastomer breast form, via said opening, with a gel; and iv. sealing the opening. In a preferred embodiment of the invention, the former is dipped into a solution of an elastomer and subsequently solvent is evaporated from the elastomer solution (on the former) so that a coating of the elastomer is provided on the former. In an alternative embodiment, the former may be dipped in a solution of a first elastomer precursor (e.g. having terminal amino or hydroxyl groups) which may also contain a cross-linking agent, and the former may then be heated to effect cross-linking to provide the coating ofthe first elastomer. A further embodiment, the former may be dipped into a molten elastomer precursor which is subsequently cross-linked on the former to produce the coating ofthe first elastomer.

The fabrication method according to the present invention can be used to produce consistently shaped prostheses having well defined nipples. In addition, the resultant prosthesis is substantially seamless, having at most only a small seam where the opening is sealed. The opening may, for instance, be heat sealed.

The first elastomer is preferably pigmented to a desired skin tone. Alternatively, the gel could be pigmented as opposed to the elastomer.

Preferably, after the first elastomer coating has been formed, but before the elastomer breast form is removed from the former, the nipple/alveolar region of the breast form is provided with a second elastomer which is pigmented to an appropriate colour. This may be achieved by dip coating the nipple/alveolar region of the breast form in a solution of the second elastomer and then evaporating the solvent from the breast form. The second elastomer may be of a firmer grade than the first elastomer in order to provide a more realistic prosthesis.

The gel used to fill the breast form may be of any suitable type, for example a silicon gel or a hydrogel.

Preferably the male former is provided with a small protuberance which may be used to support the former as it is dip coated such that the protuberance is not itself coated in polyurethane thereby forming said opening.

The male former may be fabricated from any suitable material such as, for instance, a hard ceramic material. The elastomer is preferably a soft, high strength material, preferably having a Shore A hardness less than 80, a maximum tensile stress greater than 55MPa. a maximum strain greater than 750MPa, and a modulus at 100% elongation of less than 3.5.

Preferred materials are hydrophobic, medical grade polyetherurethanes and polyesterurethanes.

According to a second aspect of the present invention there is provided a mammary prosthesis, comprising a gel filled elastomer breast form, the breast form being substantially seamless, having only a relatively small closure sealing an opening through which the breast form has been filled with the gel.

The closure is preferably positioned at an upper portion of the breast form where a front surface ofthe breast form meets a back surface thereof.

In one preferred embodiment, the breast form comprises at least two independent compartments filled with gels of differing viscosity.

Preferably the breast form has a nipple/alveolar region which is coated in a nipple colour pigmented elastomer which is of a firmer grade than elastomer from which the breast form is formed.

Specific embodiments ofthe present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Fig. 1 is a cross-section of a master breast form;

Fig.2 illustrates formation of a polyurethane breast form on a male former;

Fig. 3 is a cross-section ofthe polyurethane breast form of Fig. 2;

Fig. 4 illustrates a finished prosthesis in accordance with a first embodiment of the present invention;

Fig. 5 is a cross-section of a first part of a prosthesis in accordance with a second embodiment ofthe invention;

Fig. 6 illustrates the part of Fig. 5 fixed to former for formation of the finished prosthesis; and

Fig. 7 is a cross-section of the finished prosthesis the formation of which is illustrated in Fig. 6. In one preferred embodiment of the invention, the first step in the fabrication of a mammary prosthesis is to create a plaster breast form 1 (see Fig. 1 ) from a paster cast (not shown) of a real breast. At this stage the breast form 1 can be created to any required size and shape and the nipple/alveolar region can be enhanced as required. (It will be appreciated that as an alternative the initial breast form could be modelled from any suitable material.) The plaster breast form 1 is created with a small protuberance la the purpose of which is described below.

A hard ceramic male former 2, is then produced from a female mould taken from the plaster original 1 , the former 2 having the same shape as the original 1 including a protuberance 2a corresponding to the protuberance la. The ceramic male former 2 can be used for the fabrication of as many prostheses as required in the manner described below.

The male former 2 is supported by the protuberance 2a and dip coated in a first solution of polyurethane, which is pigmented to the required flesh tone, so that the polyurethane forms a layer 3 (see Fig. 2) around the former 2 but not entirely covering the protruding portion 2a. (The thickness of the layer 3 is exaggerated in Fig. 2 for clarity.) The solvent is then allowed to evaporate so that the polyurethane layer 3 dries on the male former 2. This dip coating procedure may be repeated as many times as required. The polyurethane is preferably a soft, high strength, hydrophobic. medical grade polyetherurethane or polyesterurethane. A particularly suitable material is available from Innovation Technologies under the designation IT C54.

The nipple/alveolar region of the polyurethane covered former 2 is then dip coated in a second solution of polyurethane which is pigmented to an appropriate colour.

The nipple colour pigmented polyurethane is preferably of a firmer grade than the first polyurethane used, in order to produce a more realistic prosthesis. (The additional layer of polyurethane over the nipple/alveolar region is not shown in the drawings.)

Once fully dry, the polyurethane breast form 4 (see Fig. 3). which is in the form of a bag with a small opening 5 (which is formed around the protuberance 2a of the male former 2) is peeled from the male former 2, the elasticity of the polyurethane allowing the breast form 4 to be pulled over the former 2 without damage. The breast form 4 is then filled, via the opening 5, with silicon gel (or any other suitable material) prepared in and supplied from a static mixer (not shown). Finally, the opening 5 is heat sealed, forming a small seam 5a. to provide the finished prosthesis shown in Fig. 4.

The finished prosthesis has a well defined and relatively realistic nipple/alveolar region and has only a very small heat seal seam. The prostheses therefore does not suffer the disadvantages ofthe known external breast forms discussed above.

A modification of the above method which produces an even more realistic prosthesis is described below.

Firstly, the male former 2 is dip coated in a first solution of flesh coloured polyurethane to form a thin layer around the former 2. Once this first polyurethane has dried the polyurethane bag 6 (see Fig. 5) is removed from the former without first being dipped in a nipple/alveolar colour pigmented polyurethane. The bag 6 is then only partially filled with silicon gel and is sealed and shaped to produce a breast form having a concave rear surface 7 as shown in Fig. 5.

The partially filled bag 6 is then attached with wax to a second ceramic former 8 (see Fig. 6), the concave rear surface 7 of the bag 6 fitting over a concave surface 9 of the former 8 which is shaped so that the combination of the former 8 plus bag 6 is the desired shape ofthe prosthesis, with the exception of a protuberance 8a.

The second former 8 with bag 6 attached is then dipped into the flesh coloured polyurethane solution so that a second layer of polyurethane 10 is formed around both the former and the breast form, again leaving a small opening around the protuberance 8a. The result is that a second bag compartment 11 is formed on the back ofthe original partially filled bag but without a seam between the two.

Once the second polyurethane coating has dried the nipple/alveolar region is dipped into a nipple colour pigmented solution of polyurethane (again preferably of a firmer grade than the first solution) to enhance the realism of the prosthesis. The resultant breast form 12 (see Fig. 7) is then peeled from the second former 8 and the second compartment 11 is filled with a silicon gel of a different viscosity to the silicon gel used in the front portion ofthe breast former in the bag 6. The result is a prostheses which is even more lifelike than that produced by the first method described above.

It will be appreciated that many modifications can be made to the fabrication methods discussed above. For instance, the materials used could vary considerably. For example, instead of silicon gel a hydrogel (such as Hypol (trade mark) produced by W.R. Grace) could be used. Such hydrogels are 80-90% water and significantly cheaper than silicon gels. In the above description the second described method is used to produce a prostheses having two separate compartments filled with gels of differing viscosities. It will be appreciated that the method could be modified to produce a prostheses having more than two cavities filled with different gels if this were desirable.

Claims

1. A method of fabricating a mammary prosthesis comprising: i. dipping a male former having a surface corresponding to the desired shape of a breast in a liquid containing a first elastomer or first elastomer precursor and producing a coating of a first elastomer on the former; ii. removing the resulting elastomer breast form from the former by means of an opening in the breast form; iii. filling the elastomer breast form, via said opening, with a gel; and iv. sealing the opening.

2. A method as claimed in claim 1 wherein, in step (i), the mole former is dipped in a solution of the first elastomer and said coating of the first elastomer is formed by evaporation ofthe solvent.

3. A method according to claim 1, wherein the first elastomer is pigmented to a desired skin tone.

4. A method according to any one of claims 1 to 3, wherein before the elastomer breast form is removed from the former, the nipple/alveolar region of the breast form is provided with a second elastomer which is pigmented to an appropriate colour.

5. A method according to claim 4, wherein the second elastomer is of a firmer grade than the first elastomer.

6. A method according to any preceding claim, wherein said opening is heat sealed.

7. A method according to any preceding claim, wherein the gel is a silicon gel or a hydrogel.

8. A method according to any preceding claim, wherein the male former has a small protuberance which may be used to support the former as it is dip coated such that the protuberance is not itself coated in polyurethane thereby forming said opening.

9. A method according to any preceding claim, wherein the male former is made of a hard ceramic material.

10. A method according to any preceding claim, wherein the first elastomer is a soft, high strength material.

11. A method according to claim 10, wherein the elastomer has a Shore A hardness less than 80. a maximum stress greater than 55MPa, a maximum strain greater than 750MPa, and a modulus at 100% elongation of less than 3.5.

12. A method according to any preceding claim, wherein the first and/or second elastomer is a hydrophobic, medical grade polyetherurethane or polyesterurethane.

13. A mammary prosthesis, comprising a gel filled elastomer breast form, the breast form being substantially seamless, having only a relatively small closure sealing an opening through which the breast form has been filled with the gel.

14. A mammary prosthesis according to claim 13. wherein the closure is positioned at an upper portion ofthe breast form where a front surface ofthe breast form meets a back surface thereof.

15. A mammary prosthesis according to claim 13 or claim 14. wherein the breast form comprises at least two independent compartments filled with gels of differing viscosity.

16. A mammary prostheses according to any one of claims 13 to 15, wherein the breast form has a nipple/alveolar region which is coated in a nipple colour pigmented elastomer which is of a firmer grade than elastomer from which the breast form is formed.

17. A method of fabricating a mammary prostheses, substantially as hereinbefore described, with reference to the accompanying drawings.

18. A mammary prostheses, substantially as hereinbefore described, with reference to the accompanying drawings.