A Breast Prosthesis and Method for Manufacturing the Same

Field of the Invention

The present invention relates to breast prostheses and methods of manufacturing same. In particular, the present invention relates to improvements in methods of

manufacturing silicone-based breast prostheses.

Background to the Invention

Breast prostheses are often required, for example, by patients who have had a breast partially or fully removed. Traditional silicone-based breast prostheses comprise a moulded silicone-based gel mixture retained in and laminated to a polyurethane membrane. Lightweight silicone-based breast prostheses of a similar construction are also known. These lightweight prostheses - which may be up to 35% lighter than traditional silicone-based prostheses - may be preferable because many wearers find the traditional types to be too heavy. The silicone-based gel mixture used in such lightweight prostheses contains an homogenous suspension of lightweight microspheres that reduce the overall density of the mixture.

One disadvantage of both the traditional and lightweight silicone-based prostheses described is that the silicone-based gel may delaminate from the retaining polyurethane membrane, causing the prosthesis to lose its shape and become unusable. Another disadvantage of the prostheses described is that the polyurethane membrane can lead to discomfort. The membrane can heat up uncomfortably as it is held against the wearer's skin, and the impermeability of the membrane can also lead to a build up of

perspiration. In general, the polyurethane membranes used in these prostheses are not conducive to prolonged contact with the skin. Such discomfort is exacerbated because it is not possible to provide well-defined contours on the skin-facing side of such prostheses because the silicone-based gel is too soft to retain well-defined contours. Accordingly, such prostheses do not allow for well- defined cooling airflow channels on the skin-facing side, nor can they be specifically shaped to the contours of the wearer's chest.

There are further disadvantages of such prostheses. If the membrane of such prostheses is accidentally perforated, the gel becomes exposed and the prosthesis is compromised. Consequently, there is also little scope to trim such prostheses for a custom fit, because it is not possible to perforate the polyurethane membrane.

The lightweight prostheses described suffer from additional drawbacks. Such lightweight prostheses are inclined to form air pockets when subjected to lower-than- sea-level atmospheric pressure. This is because the microspheres in the silicone gel mixture burst, releasing air that aggregates into pockets retained within the membrane. These air pockets deform the shape and balance of the prosthesis. Furthermore, the addition of lightweight microspheres adds to the complexity of the gel mixing process, because the lower density of the microspheres causes them to settle at the top of the mixture without intervention.

GB 2243324 describes one attempt at addressing some of these problems. This document teaches a method of manufacturing a breast prosthesis comprising a silicone- based skin and a core composed of a foam, the foam preferably formed from a creamed rubber composition containing a foaming agent. This document teaches producing cooperating male and female moulds from a cast taken from the patient prior to removal of the breast. These moulds are used to produce a silicone skin in the outline of the breast, and the silicone skin is left to cure in atmospheric conditions. The creamed rubber composition containing a foaming agent is then applied to fill the cavity defined by the skin, and allowed to cure in atmospheric conditions. A backing layer of silicone composition is then applied to the exposed surface of the foam, and allowed to cure. In this way, the silicone skin and the backing layer cooperate to form an envelope that encloses the core of creamed rubber foam. Breast prostheses manufactured in this manner address some of the problems associated with the traditional and lightweight silicone products discussed above. The prosthesis comprises a backing layer of a silicone composition, which tends to be much more conducive to prolonged contact with the skin than a polyurethane membrane. Furthermore, the foam core of the prosthesis should allow the weight of the prosthesis to be substantially reduced.

However, there remain some disadvantages with this product. Because the foam core is completely enclosed in a silicone-based envelope, air pockets may still form in the event of variations in atmospheric pressure, and this in turn may lead to delamination. In addition, the silicone-based envelope and the foam core are composed of different materials, and this may also increase the chances of delamination. Finally, foams often tend to be quite prone to degradation, and this may adversely affect the durability and hence the lifetime of the product. Alternative breast prostheses comprised of lightweight foam or fibrous material are also known. These prostheses are extremely light compared to the traditional and lightweight silicone-based prostheses described above. They are particularly suitable for post operative patients, because traditional and lightweight silicone based prostheses are too heavy to comfortably come into contact with a fresh operation site. However, these products are extremely basic in their construction, do not reproduce any of the physical properties of a real breast, and are only intended to crudely imitate the shape of a real breast.

Object of the Invention

An object of the invention is therefore to provide an improved breast prosthesis and method for making same.

It is an object of the invention to provide a prosthesis with a reduced likelihood of delamination between the retaining membrane and the prosthesis core.

It is another object of the invention to provide a prosthesis with reduced heat build up and improved ability cope with perspiration when in use. It is another object of the invention to provide improved airflow between the prosthesis and the wearer's skin when in use. It is a further object of the invention to provide a prosthesis having improved cooperation with the bodily point of contact when in use.

A further object of the invention is to provide a prosthesis that will not be compromised by accidental perforation.

An additional object of the invention is to provide a prosthesis that is less susceptible to the formation of air pockets when subjected to a reduction in atmospheric pressure. An additional object of the invention is to provide a breast prosthesis that offers the wearer a greater sense of security as the product offers improved adherence to the chest wall.

An further object of the invention is to provide a breast prosthesis that offers an accurate structural representation of a real breast when in a bra.

An additional object of the invention is to provide a breast prosthesis with a lifelike nipple and areola outline when worn in a support garment. An additional object of the invention is to provide for a simplified method of

manufacturing prostheses.

Summary of the Invention One aspect of the invention comprises a method of manufacturing a prosthesis comprising a distal wall, a proximal wall, and a core, the method comprising: applying a layer of silicone-based curable composition to a prosthesis mould; curing the layer of curable composition to form the distal wall defining a cavity; applying a mixture to the cavity, the mixture comprising a dispersed phase of dissolvable granular bodies suspended in a suspension medium comprising the curable composition; moulding the curable mixture so that it is adapted to fill the cavity curing the curable mixture to form the core, such that the surface of the curable mixture not in contact with the distal wall forms the proximal wall; and dissolving the granular bodies from the suspension medium to form a cellular structure.

Prostheses produced in this way are lightweight due to the cellular structure of the core, have a reduced susceptibility to the formation of air pockets when the prosthesis is subjected to reductions in atmospheric pressure, and also has a proximal wall formed from a composition that is conducive to prolonged contact with the skin.

The mould used in the method may be a mould for a prosthetic breast further comprising an integrated nipple and areola shaped mould.

The curable composition may further comprise a property-enhancing additive.

The property-enhancing additive may comprise at least one of a vitamin E containing composition, an Aloe Vera gel, a cooling agent, a temperature regulating agent, a thermally conductive agent, an ointment, a fragrance, a friction-reducing agent, a friction-enhancing agent, a mineral oil, or an antimicrobial agent.

The mixture may be first applied to the cavity defined by the distal wall, and then moulded and cured in the cavity defined by the distal wall.

Alternatively, the mixture may first be moulded and cured in a second mould and then applied to the cavity defined by the distal wall. The silicone-based composition may comprise a room temperature vulcanized liquid silicone rubber.

The granular bodies may comprise sugar beads, salt granules, and/or soluble capsules. The method may further comprise coating the outer surface of the prosthesis with a friction-reducing coating, for example commercial products coatings such as Topcoat or CoatOSil 3501, or powdered coatings such as talcum powder or icing sugar. The surface of the prosthesis may alternatively be coated with a friction-enhancing coating.

The step of moulding a curable mixture may further comprise moulding the proximal wall to have contours that are adapted to cooperate with the contours of a wearer's chest.

The step of moulding a curable mixture may also further comprise shaping the proximal wall to comprise a non-smooth surface that defines airflow channels.

The method may further comprise applying a pigment to the curable composition to give the composition the approximate skin colour of the intended wearer of the prosthesis. Another aspect of the invention is a prosthesis obtainable by any of the methods described herein.

A further aspect of the invention is a method of manufacturing a mould for use in the production of a breast prosthesis comprising the steps of: creating a first part of a breast mould based on a three dimensional representation of a breast; creating a first part of a nipple mould based on a three dimensional representation of a nipple; associating the first part of the breast mould and the first part of the nipple mould to form a first part of an integrated mould defining a three dimensional representation of a breast and nipple. This allows an integrated mould defining a three dimensional representation of a breast and nipple to be produced wherein the three dimensional representation of the nipple is of sufficient accuracy.

The method of manufacturing a mould may be wherein the first part of the breast mould is the male part and the first part of the nipple mould is the male part.

The method of manufacturing a mould may be wherein the first part of the breast mould is the female part and the first part of the nipple mould is the female part, and wherein the method further comprises creating a hole in the first part of the breast mould in which the first part of the nipple mould may reside to form an integrated three dimensional representation of a breast and nipple.

The method of manufacturing a mould may further comprise wherein the nipple mould is further based on the three dimensional representation of an areola.

A further aspect of the invention comprises a first part of a mould defining a three dimensional representation of a breast and nipple obtainable by the method of any of claims.

Brief Description of the Drawings

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

Figure 1 is a cross sectional view of an embodiment of a breast prosthesis in accordance with an aspect of the invention;

Figure 2 is a perspective view of the breast prosthesis of Figure 1;

Figure 3 is a flow diagram illustrating a first stage in a manufacturing process in accordance with an aspect of the invention;

Figure 4 is a flow diagram illustrating a second stage in a manufacturing process in accordance with an aspect of the invention;

Figures 5a and 5b are cross sectional views of male and female parts of a mould used in a method of manufacture in accordance with an aspect of the invention;

Figure 6 is a cross sectional view of a partially completed female part of a mould produced in accordance with an aspect of the invention; and Figure 7 is a cross sectional view of the finished version of the mould of Figure 6 produced in accordance with an aspect of the invention.

Detailed Description of the Drawings

Figures 1 and 2 depict a breast prosthesis 100 comprising a distal wall 101, a core 103 and a proximal wall 104. The distal wall 101 is formed from a membrane 102, the membrane 102 preferably having a tapered perimeter 107. The membrane 102 is in contact with a first surface of the core 103. The core further comprises a second surface that is not in contact with the membrane 102. The second core surface forms the proximal wall 104. When in use, the prosthesis is worn such that the proximal wall is in contact with the wearer. The core is comprised of a cellular structure composed of a series of cells 105 and surrounding cell walls. As can be seen from Figure 2, in this embodiment, the proximal wall 104 comprises contours 108 to cooperate with the contours of a prosthesis wearer's chest (such as the outline of ribs) when in use. As can be further seen from Figure 2, the proximal wall comprises a series of surface irregularities 109 that give the proximal wall a non-smooth surface. This non-smooth surface defines a series of air channels through which air may flow, thereby improving ventilation between the skin and the prosthesis when the prosthesis is in use.

Figure 3, illustrates a first stage in the manufacture of a breast prosthesis in accordance with an aspect of the invention. While this invention is described with respect to production of a prosthetic breast, it will be appreciated that the production of other prostheses are also contemplated. At step 301, a three dimensional representation of a breastform shape as supported in a bra is made. Using precision tooling, an aluminium mould comprising complementary male and female parts is produced 302, based on the three-dimensional breastform. This may be done by machining the mould from an aluminium blank. The complimentary male and female parts together define a gap, preferably of uniform thickness, representative of the outline of the three dimensional breastform. Preferably, the contact surfaces of the male and female mould parts are sandblasted to reduce the shiny finish on the contact surfaces, which in turn prevents the formation of a shiny surface on the moulded object. While the use of an aluminium mould is described, it will be appreciated that the mould may alternatively comprise other robust materials that will provide a tight tolerance between male and female mould parts to ensure a thin, even gap between the parts. Furthermore, while a uniform gap is described, it is also envisaged to provide for deliberate variations in the distance between moulds, for example to provide for the outline of a nipple and areola shape, as will be described further below with respect to figures 5a and 5b. Alternatively or additionally, the gap may be defined such that it produces a moulded object having tapered edges.

At step 303, a curable composition is applied to the female part of the mould.

Preferably, the curable composition may comprise a platinum-catalysed two-component silicone compound such as a room temperature vulcanized liquid silicone rubber with a cured hardness that falls on the Shore 00 or Shore A range. Examples of such compositions include EcoFlex 00-30 and Dragon Skin FX Pro, as supplied by Smooth- On ^® , Inc. Such compounds are suitable because of their flexible, high tear strength properties. However, it will be appreciated that other compounds with similar physical properties may be equally suitable. At step 304, the male part of the mould is applied such that the curable composition resides in the gap between the male and female parts of the mould. The curable composition is then cured 305 to form a membrane in the outline of the breastform. This membrane may correspond to the membrane 102 described with reference to Figures 1 and 2, and may form the distal wall of the prosthesis. In one embodiment, curing takes place by subjecting the composition to a comparatively high temperature, between approximately 40 and 100°C (preferably approximately 60°C), and for between approximately 5 and 40 minutes (preferably approximately 20 minutes). If necessary, the membrane may then be trimmed in the mould using a precision cutter so that the edges of the membrane are evenly tapered.

Figure 4 illustrates a second stage in the manufacture of a breast prosthesis in accordance with an aspect of the invention. After the membrane is cured in accordance with step 305 of Figure 3, the male mould is removed 401, leaving the membrane residing in the female mould. The membrane and female mould together define a cavity. The cavity is then filled 402 with water-soluble sugar beads. It will be appreciated that while water-soluble sugar beads are disclosed, other dissolvable granular bodies, such as salt or soluble capsules may also be suited for use in this context. The curable composition used to form the membrane in Figure 3 is then also applied 403 to the mould, filling the gaps between the sugar beads until the cavity is full of a mixture of the curable composition and the sugar beads. The exposed surface of the mixture may define proximal wall 104 of the prosthesis as described with reference to Figures 1 and 2. Optionally, the exposed surface of the mixture may then be further shaped as required. For example an auxiliary mould may be applied to the exposed surface of the mixture to shape it with desirable contours 108 as described with reference to Figure 2. Such contours may complement the chest contours of the intended prosthesis wearer, and could - for example - comprise undulations to accommodate the wearer's ribcage. An auxiliary mould may additionally or

alternatively be used to introduce iregularities in the topography of the exposed surface of the mixture. This may be done, for example, to provide airflow channels on the exposed surface of the mixture (and thus the proximal wall of the prosthesis), to allow for improved ventilation between the prosthesis and the wearer's skin.

The mixture is then cured 404 to form the core of the prosthesis in the shape of the breastform. In one embodiment, curing of the core takes place by subjecting the mixture to a comparatively high temperature, between approximately 40°C and 100°C

(preferably approximately 60°C), and for between 10 minutes and 1 hour (preferably approximately 40 minutes). Curing the mixture at this step also causes the mixture to adhere to the previously-cured membrane to form the prosthesis. An effective bond is formed between the mixture and the membrane, because they both comprise the same curable composition. The prosthesis is then removed 405 from the female mould for further treatment. The prosthesis is then washed 406 in a suitable solvent (preferably a water-based solvent) to dissolve the granular bodies suspended in the core. Dissolution of the granular bodies suspended in the cured mixture leaves a series of voids in the core, giving it a cellular structure. The core may then be dried 407, preferably in an air circulating oven until dry. The edges of the prosthesis may then be further trimmed if necessary to ensure that the edges are tapered, resulting in a snug fit against the chest wall when worn. This also reduces the likelihood of gaping when the wearer bends forward, giving an increased sense of security. Figure 5a and Figure 5b are cross sectional views of the complimentary male part 501 and female part 503 of the mould produced at step 302 of Figure 3. Figure 5a illustrates the male part 501 and the female part 503 of the mould in an open configuration. Figure 5b illustrates the male part 501 and the female part 503 in a closed configuration, thereby defining the gap 505 in which the membrane is formed at step 305 of Figure 3. In the depicted embodiment of the invention, the gap 505 narrows around its periphery such that the moulded membrane may be formed comprising tapered edges.

The mould produced at step 302 of Figure 3 and as depicted in Figures 5a and 5b (hereafter referred to as the "main mould") defines a three dimensional representation of a breast. However, such a mould may not comprise an accurate three dimensional representation of the nipple and/or areola of the breast. It can be difficult, impractical and time consuming to achieve an accurate three dimensional representation of a nipple and areola by machining an aluminium mould from a blank as described with reference to Figure 3. Accordingly, the mould produced at step 302 of Figure 3 may be further modified so that it comprises an accurate three dimensional representation of the nipple and/or areola.

Figure 6 depicts a cross section of the female part 503 of the main mould depicted in Figure 5 further comprising a hole 601 in the contact surface 605 of the female part 503 of the mould. This hole 601 is formed by machining the female part 503 of the main mould in an appropriate fashion. The hole 601 is positioned to correspond to the desired nipple location on the female part of the main mould. As depicted in Figure 7, the hole 601 is then filled with the female part of an accurate nipple and areola mould 703, such that the contact surface 705 of the nipple and areola mould 703 is flush with the contact surface 605 of the female part 503 of the main mould. The result of this is the female part of an integrated mould defining a three-dimensional representation of a breast, areola and nipple. The precise nipple and areola outline of contact surface 705 is not shown in Figure 7.

The nipple and areola mould may be produced using a different technique and/or a different substance to that used to produce the main mould. For example, a male cast defining an accurate three-dimensional representation of a nipple and areola may be used to produce the female part of the nipple and areola mould 703. In this example, the nipple and areola mould may be formed from a curable resin, or other such appropriate material. Using such techniques allows for the production of sufficiently accurate nipple and areola mould. It will further be understood that the female part of the nipple and areola mould 703 may be formed in situ in the hole 601, or formed separately and subsequently inserted into and secured in the hole 601.

It will be appreciated that while Figures 6 and 7 depict the modification of the female part of the main mould to form the female part of an integrated mould defining a three dimensional representation of a breast, areola and nipple, it would equally be possible to produce the male part of an integrated mould defining a three-dimensional

representation of a breast, areola and nipple using similar techniques.

A coating may be applied to the prosthesis, for example, by spraying. The coating may be chosen to enhance or reduce the frictional properties of the prosthesis surface. For example, the coating may comprise a friction reducing agent, for example commercial products such as commercial productsTopcoat or CoatOSil ^® 3501 as produced by Momentive Performance Materials, Inc to give the surface of the prosthesis a smooth skin-like feel, or powdered coatings such as talcum powder or icing sugar.

Alternatively, a coating may be chosen to increase the frictional properties of the prosthesis surface to ensure a more secure fitting of the prosthesis in a bra pocket. Increasing the frictional properties of the proximal wall (the skin-facing surface of the prosthesis), and/or ensuring a tapered edge through trimming as described above can also give the prosthesis a degree of suction, increasing its ability to adhere to the chest wall. In an alternative embodiment of the invention, friction enhancing or reducing additives may be added to the curable composition prior to the curing steps described with reference to Figures 1 and 2.

Forming the core of the prosthesis from a cellular structure in accordance with the invention substantially reduces the weight of the prosthesis when compared to the traditional silicone prostheses described above. Prostheses manufactured in accordance with an aspect of the invention may also be approximately 15 % lighter then the existing lightweight silicone prostheses described, without suffering from any of the drawbacks of such lightweight prostheses as mentioned above. Furthermore, prostheses produced in accordance with an aspect of the invention may be suitable for use by amputation patients post-operatively because of the reduced weight of the prosthesis. Existing post operative products having a core made from extremely light foamed material or from fibre do not accurately replicate the physical properties of a real breast, and only very crudely replicate the shape of a real breast. Prostheses produced in accordance with an aspect of this invention are preferable because of their more accurate shape and replication of the real breast's physical properties. The reduced weight also makes the prostheses made in accordance with the invention suitable for use by lymphoedema patients and for those in danger of developing lymphoedema. Compared with existing prostheses, prostheses made in accordance with the invention reduce the level of sustained weight on the wearer's shoulders throughout the day. As a result, there is a reduced resistance to flow/drainage of fluid from the arm. In addition, the decreased weight of prosthesis in accordance with the invention also make them suitable for patients who have undergone a double mastectomy, as the weight of two existing prostheses - particularly larger sizes - can be uncomfortably heavy. A further advantage of the cellular structure core of the present invention is that it is more durable than alternative lightweight cores, such as foams, but similarly light in weight. The process of mechanically forming the core using dissolvable granular bodies produces a cellular structure that is more robust than foams formed using a foaming agent.

Using silicone-based compounds in surfaces of the prosthesis that will come into contact with skin when in use may be advantageous due to silicone's scar-healing properties. As such, when the prosthesis is worn, contact of the silicone-based prosthesis surfaces with scar tissue can improve the appearance of a scar area.

Furthermore, silicone-based compounds having hydrophilic properties may be chosen to aid in moisture management and/or sweat absorption when in use. In addition, property enhancing additives may also be included in the curable compound. These property enhancing additives may improve the properties of the prosthesis, for example, by enhancing the beneficial effects to the prosthesis wearer, or by enhancing the

functionality of the prosthesis. Additives that enhance the beneficial effects to the prosthesis wearer may include vitamin E-containing compounds, Aloe Vera gels, cooling agents, temperature regulating agents, thermally conductive agents, fragrances, ointments, antimicrobial agents, mineral oils, or other skin care additives. Additives that enhance the functionality of the prosthesis may include friction enhancing or friction reducing additives. Forming the core of the prosthesis from such silicone-based compounds in accordance with embodiments of thie invention means that it is not necessary to provide a separate silicone-based proximal wall, as the silicone-related advantageous properties are already inherent in the prosthesis core. It is advantageous not to provide a separate silicone-based proximal wall, because such a separate wall together with the distal wall of the prosthesis would form an airtight envelope. If such a prosthesis was subjected to a decrease in atmospheric pressure, air pockets could potentially form within the envelope, deforming the prosthesis. By contrast, prostheses made in accordance with embodiments of this invention, where the core itself forms the proximal wall and is therefore exposed to the atmosphere is able to accommodate atmospheric pressure variations while reducing the risk of air pocket build-up.

The words "comprises/comprising" and the words "having/including" when used herein with reference to the present invention are used to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.