Patent Description:
Furthermore, the object of the present invention is also a method of production of an internal mammary prosthesis.

As is known, reconstructive surgery is used to reconstruct parts of the body, for example after surgery for removal following pathologies or when such parts have been damaged by traumatic events. With particular reference to reconstructive surgery of the breast, the need to protect the physical integrity of women, considered important enough to drive plastic surgery to develop increasingly effective reconstruction techniques capable of repairing the extensive damages resulting from, for example, radical mastectomy, has now become well established.

With reference to breast reconstructive surgery, various types of internal mammary prostheses are known, for example anatomical prostheses (or teardrop prostheses) that allow a harmonious and natural breast to be created based on the shape of the rib cage, or round prostheses, which are very useful when a homogeneous increase in the volume of the breast without changing the shape thereof is desired.

Most of the known breast implants consist of an outer silicone casing inside of which is contained, for example, a cohesive silicone gel or a saline solution.

However, such known prostheses have some drawbacks, for example, those related to the risk of breakage of the outer casing and the resulting dispersion of filling liquid (in most cases, silicone).

Further drawbacks are related to the weight of the prosthesis, which contributes to aggravating the phenomenon of capsular contracture (or hardening). In fact, the organism reacts to the prosthesis like any other foreign body, giving rise to the formation of a fibrous "capsule". Normally, such "capsule" presents itself only as a thin containment film consisting of collagen. In some cases, because of the weight of the prosthesis, this capsule thickens and contracts making the breast hard with an unnatural appearance and consistency.

Because of all these drawbacks related to known mammary prostheses, new reconstructive surgeries are often required.

The need for a particularly lightweight internal mammary prosthesis is therefore felt in the field of reconstructive surgery.

Examples of known prostheses are described in documents <CIT>, <CIT>, <CIT> and <CIT>, that refer to prostheses having a silicone skin and a silicone foam body core, and in documents <CIT>, <CIT>, <CIT> and <CIT>, that refer to prostheses having an outer silicone casing inside of which is contained, for example, a cohesive silicone gel or a saline solution. Document <CIT> describes a prosthesis wherein the posterior surface has at least one concave curvature, to improve the fit of the prosthesis on the thorax.

The object of the present invention is to solve the problems of the prior art while taking into account the needs of the industry.

This object is achieved by an internal mammary prosthesis made of polymer foam material (or poly-foam material).

Advantageously, a prosthesis made in this way is particularly suitable for attachment in a supramuscular position.

Such object is achieved by an internal mammary prosthesis in accordance with claim <NUM> and in accordance with the related method of construction thereof according to claims <NUM> and <NUM>. The dependent claims describe preferred or advantageous embodiments of the prosthesis.

The features and advantages of the mammary prosthesis and the method of construction thereof according to the present invention will be apparent from the description given hereinafter, provided by way of non-limiting example, in accordance with the accompanying figures, wherein:.

With reference to the attached figures, an internal mammary prosthesis <NUM> is shown.

The mammary prosthesis <NUM> comprises a front portion <NUM>, which constitutes the prosthesis portion suitable to fill the area wherein the prosthesis will be implanted, and a back <NUM>, opposite the front portion <NUM>.

The mammary prosthesis <NUM> comprises a solid body <NUM> made of a spongy material.

The body <NUM> is made of polymer foam material (or poly-foam) with a density ranging from <NUM>/cm<NUM> to <NUM>/cm<NUM>. A mammary prosthesis made in this way is lighter than the known internal mammary prostheses made of a cohesive silicone gel.

Preferably, the poly-foam material is expanded silicone or silicone foam, or polyurethane foam.

Preferably, the body <NUM> is made of silicone foam with a density of between <NUM>/cm<NUM> and <NUM>/cm<NUM>, preferably between <NUM>/cm<NUM> and <NUM>/cm<NUM>.

In an alternative example, the body <NUM> is made of polyurethane foam with a density of between <NUM>/cm<NUM> and <NUM>/cm<NUM>, preferably between <NUM>/cm<NUM> and <NUM>/cm<NUM>.

Regardless of the poly-foam material used, the mammary prosthesis <NUM> is provided with a film (or coating), preferably of silicone. It should be noted that film refers to a thin plastic film. This film has a barrier function, i.e., it is suitable to make the spongy surface of the body <NUM> impermeable, so that such surface is suitable for implanting the prosthesis <NUM> inside the patient's body.

The silicone film is obtained by dipping, that is by immersing (preferably several times) the body <NUM> made of spongy material in suitable silicone solutions.

Preferably, the prosthesis <NUM> is provided with a certain surface roughness or undulation, that is to say that the surface finish of the self-supporting prosthesis is of the type known as textured. Such constructive choice allows the superficial adhesion of the tissues on the self-supporting prosthesis to be improved and facilitated once the latter has been implanted inside the patient's body.

Since the mammary prosthesis <NUM> has a solid body <NUM> made of spongy material, therefore less adaptable than traditional silicone gel prostheses, the shape of the prosthesis is particularly important to ensure the most natural effect possible and a positioning more adaptive to the body.

For example, the front portion <NUM> has a teardrop shape (as in <FIG>).

Preferably, the mammary prosthesis <NUM> has an edge that tapers outwards, to better follow the natural shape of the mammary gland and to facilitate the positioning of the prosthesis under the muscle.

Preferably, moreover, the mammary prosthesis <NUM> has a geometry such as to take into account the irregularity of shape, volume and surface typical of the mammary gland of the patient to whom it will be applied. Such geometry is obtainable by using a three-dimensional (3D) mold that traces exactly the shape of the mammary gland portion that must be removed from the patient, to minimize or even avoid changes in the natural shape of the patient's breast. Preferably, therefore, such three-dimensional mold is obtained by means of a particular method described hereinafter.

With reference to <FIG>, the prosthesis <NUM> implanted in the patient's body is shown. In particular, <FIG> shows a sectional view wherein is visible the sternum S, the right portion of the rib cage C, and the spinal column CV. <FIG> also shows the sternal point PS (to be understood as the most medial point of the prosthesis) and the lateral thoracic point PTL (to be understood as the most lateral point of the prosthesis).

The points PS and PTL delimit the base of the prosthesis.

α is defined as the plane passing through the point PS and parallel to the sternum S, and β is defined as the plane passing through the point PTL and parallel to the sternum S, the height H is defined as the distance between the planes α and β.

Moreover, Ω is defined as the plane passing through the point PTL and orthogonal to the sternum S; the intersection between the planes α and Ω defines the point PL.

The length L is defined as the distance between the points PS and PL.

Along the plane α are defined the points L<NUM>/<NUM>, at a distance equal to one third of the distance L calculated from point PS, and L<NUM>/<NUM>, at a distance equal to two thirds of the distance L calculated from the point PS.

Along the plane Ω are defined the points H<NUM>/<NUM> at a height equal to one third of the height H calculated starting from the point PL, and H<NUM>/<NUM> at a height equal to two thirds of the height H calculated starting from the point PL.

Furthermore, Δ defines the plane passing through point L<NUM>/<NUM> and orthogonal to the plane α, and µ the plane passing through point H<NUM>/<NUM> and orthogonal to the plane Ω.

The reference points P<NUM>/<NUM> and P<NUM>/<NUM> are thus defined.

Point P<NUM>/<NUM> corresponds to point L<NUM>/<NUM>.

Point P<NUM>/<NUM> is given by the intersection of the planes Δ and µ.

The prosthesis <NUM> is therefore provided, at the back <NUM> and in cross section (<FIG>), with a particular curvature C1.

Such curvature C1 is obtained by interpolating at least the points PS, P<NUM>/<NUM> and PTL.

Preferably the curvature C1 is obtained by interpolating all the points PS, P<NUM>/<NUM>, P<NUM>/<NUM> and PTL.

Such curvature C1 allows the back <NUM> of the prosthesis <NUM> to follow as much as possible the natural curvature of the patient's chest.

The prosthesis <NUM> is also provided, at the back <NUM> and in longitudinal section (<FIG>), with a slight curvature C2, or a slight recess, to follow as much as possible the natural curvature of the patient's chest. That is, the back <NUM> of the prosthesis <NUM> is slightly concave.

It is therefore important to provide the prosthesis <NUM> with a back <NUM> with a recess adapted to follow as much as possible the natural curvature of the patient's chest.

Advantageously, the prosthesis <NUM> is insertable interlocking under the skin of the patient and kept in position by the skin itself only by virtue of the lightness of the prosthesis (the body <NUM> is made of polymer foam material with a density ranging from <NUM>/cm<NUM> to <NUM>/cm<NUM>), of its shape (curvature C1 that allows the back <NUM> of the prosthesis <NUM> to follow as much as possible the natural curvature of the patient's chest) and its volume (reproducing the volume of the removed mammary gland), and by the fact that being solid (solid body <NUM> made of spongy material) there are no internal movements of liquid/gel to be controlled. Advantageously, the presence of edges which taper outwards facilitates the interlocking attachment, allowing the prosthesis to remain in position without the need for sewing.

In a variant embodiment, the body <NUM> is also provided with an attachment portion <NUM> suitable to allow the prosthesis to be fixed directly on the muscular tissue of the area wherein the prosthesis will be implanted. That is to say, the attachment portion <NUM> constitutes a support for sewing, and in particular for sutures, of the prosthesis <NUM> directly onto the muscular tissue.

In particular, the attachment portion <NUM> is an integral part of the body <NUM>, i.e. it is made in one piece therewith and is made of the same material.

The attachment portion <NUM> protrudes externally with respect to the body <NUM>.

The attachment portion <NUM> is positioned between the back <NUM> and the front portion <NUM>.

The attachment portion <NUM> lies on the same plane as the back <NUM>, i.e. it is coplanar with the back <NUM>. That is, the attachment portion <NUM> is an extension of the back <NUM>, which projects at least partially outwardly with respect to the front portion <NUM>.

In the embodiment of <FIG>, the attachment portion <NUM> is a continuous element arranged around the body <NUM>. Preferably, the attachment portion <NUM> is a continuous annular edge <NUM>. Such constructive choice allows greater freedom when fixing the self-supporting prosthesis, as it is possible to make a suture at any point of the profile of the body <NUM>.

The attachment portion <NUM> is therefore suitable to be perforated and penetrated by a needle or in general by a pointed element to allow the prosthesis, and therefore the body <NUM>, to be stitched directly onto the muscular tissue of the area wherein the prosthesis will be implanted.

Preferably, the attachment portion <NUM> is continuous with respect to the body <NUM> to ensure continuity in the shape and geometry of the prosthesis itself (i.e. between the body <NUM> and the attachment portion <NUM> there are no steps or discontinuities).

Preferably, moreover, the attachment portion <NUM> is an edge that tapers outwards to better follow the natural shape of the mammary gland and to facilitate the positioning under the muscle of the prosthesis.

In the variant of <FIG>, the attachment portion <NUM> comprises a plurality of slots <NUM>, uniformly distributed, each defining a hole <NUM> (or an opening or a passage) for the passage of the suture thread.

In such variant embodiment, therefore, being that the mammary prosthesis <NUM> is composed of a solid body <NUM> made of lightweight, spongy material and provided with an attachment portion <NUM>, such prosthesis may be sewn directly onto the muscular tissue of the area wherein the prosthesis will be implanted.

In such example embodiment, the prosthesis <NUM>, and in particular the body <NUM>, is made of a two-component silicone foam. The catalysis process by addition takes place by means of a specific platinum or palladium catalyst which gives the compound biocompatibility characteristics.

The expansion is activated at room temperature.

The calculation of the dosage of components A and B, expressed in volume (VA and VB), is carried out as a ratio of the final volume V (VF) of the prosthesis <NUM> to be obtained. Preferably, the dosage is calculated as: VA + VB = <NUM>% VF.

Considering that the two components (A and B) have a mixing ratio of <NUM>:<NUM>, the dosage is calculated as:
VA = <NUM>% VF and VB = <NUM>% VF.

For example, to make a prosthesis (and therefore to recreate a breast) with a <NUM> volume, <NUM> of component A and <NUM> of component B must be combined, for a total of <NUM> (sum of components A + B), which represents precisely <NUM>% of the final volume of the prosthesis.

In this example, the density of the silicone foam is between <NUM>/cm<NUM> and <NUM>/cm<NUM>.

The method of making the prosthesis <NUM> provides for the use of a three-dimensional (3D) mold, preferably a mold that exactly traces the shape of the mammary gland portion that must be removed from the patient.

The mold may be, for example, of the open type, i.e., comprising a female portion closed by a cover, said female portion defining therein the cavity of the mold.

Alternatively, the mold may be, for example, of the closed type, i.e., comprising a female portion provided with a hole for feeding the material, said female portion defining therein the cavity of the mold.

The method of construction of the prosthesis <NUM> provides for the step of combining in the mold cavity at room temperature the components A and B, and mixing, preferably quickly, to avoid the formation of bubbles.

If an open mold is used, the method then provides, when the expansion volume of the silicone foam reaches about <NUM>/<NUM> of the total volume of the mold cavity, for closing the mold with the cover.

The method then provides for keeping the mold closed until the complete formation of the spongy body <NUM>, for example, after <NUM> minutes.

The method also provides for waiting for the silicone foam to stabilize before removing the spongy body <NUM> from the mold, for example, after another <NUM> minutes.

At this point, a silicone coating for closing the pores is required for the spongy body <NUM>. The method of making the prosthesis <NUM> therefore provides for a step of covering the body <NUM> with at least one layer, preferably several layers, of silicone to form a thin film on the spongy body <NUM> of the prosthesis. Such operation provides for dipping the spongy body <NUM> in the liquid silicone and drying at room temperature; this operation may be repeated several times, until the desired thickness of the silicone cover is obtained.

Finally, the method provides for the sterilization step of the prosthesis <NUM>, for example in ethylene oxide.

Polyurethane is obtained by reaction between a diisocyanate (aromatic or aliphatic) and a polyol (e.g. a poly-propylene glycol or a polyester-diol).

The reaction is carried out in the presence of catalysts to increase the speed of the reaction, and other additives, to impart certain characteristics to the material to be obtained. In the example embodiment, a surfactant is used to lower the surface tension and thus promote the formation of the foam.

In particular, for the device in question, crosslinked polyurethane foams, and therefore biostable, with a high percentage of open porosity, may be used, using a suitable mixture of polyether polyols and catalysts able to obtain high open porosity and adequate values of rigidity and mechanical strength.

The isocyanate, which makes it possible to obtain the crosslinking bridges with the side groups of the polyols, is, for example, diphenylmethane diisocyanate (polymeric MDI).

The polyurethane foam is obtained by gas foaming using water as an expanding agent in an amount varying from <NUM> to <NUM>% as a percentage by weight W/W of the polyol.

In such example, the density of the expanded polyurethane is between <NUM>/cm<NUM> and <NUM>/cm<NUM>.

Also in this case, the method of making the prosthesis <NUM> therefore provides a step of covering the body <NUM> with at least one layer, preferably several layers, of silicone to form a thin film on the spongy body <NUM> of the prosthesis. Such operation provides for dipping the spongy body <NUM> in the liquid silicone and drying at room temperature; this operation may be repeated several times, until the desired thickness of silicone cover is obtained.

It is also described a method of construction of a custom-made prosthesis <NUM>, i.e. a prosthesis provided with a shape and a volume corresponding to the portion of mammary gland that must be removed from the patient. Advantageously, therefore, the internal mammary prosthesis <NUM> traces the uniqueness of the mammary gland to be replaced.

In order to obtain the unique shape of the mammary gland to be replaced, it is necessary to define the patient's mammary gland in three dimensions (i.e. in 3D). The method therefore provides for:.

For example, step a) provides for calculating the volume of the patient's mammary gland, for example by breast scanner, ultrasound to measure the thickness of the skin and the depth of the mammary gland.

The method of making the custom prosthesis therefore provides for creating a three-dimensional mold based on the specific measurements of the patient's breast, and in particular the portion of the mammary gland that must be removed from the patient, in order to minimize or even avoid changes in the natural shape of the patient's breast.

The mold may be, for example, of the open type or of the closed type.

The mold may be made, for example, by three-dimensional printers or by methods of material removal (for example, by milling).

It is also described an implantation method of the mammary prosthesis <NUM>.

The implantation method of the mammary prosthesis <NUM> provides for the steps of:.

In an example embodiment, the prosthesis <NUM> is provided with an attachment portion <NUM>, for example in the form of an externally protruding edge (between the front portion <NUM> and the back <NUM>), and the attachment step provides for sewing the attachment portion <NUM> directly to the muscular tissue via a suture stitch.

Innovatively, a mammary prosthesis according to the present invention is particularly lightweight compared to traditional silicone implants.

Advantageously, such a lightweight mammary prosthesis may be implanted directly on the muscle tissue, reducing post-operative recovery times and the risks of relocation.

Advantageously, a mammary prosthesis according to the present invention avoids the typical drawbacks of known prostheses, such as the risk of dispersion of filling liquid.

Advantageously, a mammary prosthesis is provided with a shape that follows the portion of the mammary gland that must be removed from the patient, in order to avoid any change in the natural shape of the patient's breast.

Claim 1:
An internal mammary prosthesis (<NUM>), implantable inside the body of the patient in reconstructive surgery, has a solid body (<NUM>) of polymer foam material having a density between <NUM>/cm<NUM> and <NUM>/cm<NUM> so as to be particularly lightweight, the body (<NUM>) being provided with a coating and comprising a front portion (<NUM>) and a back (<NUM>), and having defined, on a cross-section of the prosthesis in a transverse plane virtually sectioning the sternum of a patient when the prosthesis is in use:
- the sternal point (SP), at the most medial point of the prosthesis, and the lateral thoracic point (PTL), at the most lateral point of the prosthesis, the sternal point (SP) and the lateral thoracic point (PTL) delimiting the base of the prosthesis;
- a plane α passing through the sternal point (SP) and parallel to the sternum (S);
- a plane β passing through the lateral thoracic point (PTL) and parallel to the sternum (S);
- the height (H) as the distance between the planes α and β;
- a plane Ω passing through the lateral thoracic point (PTL) and orthogonal to the sternum (S);
- the point of intersection (PL) between the planes α and Ω;
- the length (L) as the distance between the sternal point (SP) and the point of intersection (PL);
- the points L<NUM>/<NUM>, at a distance equal to one third of the length (L) calculated starting from the sternal point (SP), and L<NUM>/<NUM>, at a distance equal to two thirds of the length (L) calculated starting from the sternal point (SP);
- along the plane Ω, the points H<NUM>/<NUM> at a height equal to one third of the height (H) calculated starting from the point of intersection (PL), and H<NUM>/<NUM>, at a height equal to two thirds of the height (H) calculated starting from the point of intersection (PL);
- the plane Δ passing through the point L<NUM>/<NUM> and orthogonal to the plane α;
- the plane µ passing through the point H<NUM>/<NUM> and orthogonal to the plane Ω;
- the reference points P<NUM>/<NUM> as corresponding to L<NUM>/<NUM>, and P<NUM>/<NUM> as given by the intersection between the planes Δ and µ;
the internal mammary prosthesis being characterized in that the the back (<NUM>) of the body (<NUM>) has, in cross-section, a curvature (C1) obtained by interpolating at least the sternal point (SP), the reference point P<NUM>/<NUM> and the lateral thoracic point (PTL).