Surgically implantable breast prosthesis

[57] ABSTRACT

A surgically implantable breast prosthesis formed from a flexible container having a front wall and a back wall; the front wall having an outer shape approximately that of the human breast and the back wall having a shape approximately that of the chest wall. The container includes a prolongation extending angularly outwardly toward the axilla region of the anatomy and overlying the pectoral muscle. The container is filled with a silicone gel and a fabric impregnated with the same material used to form the container is secured to the back wall to increase the rigidity of the back wall. A strip of Dacron felt is secured to the outer periphery of the back wall around the axilla prolongation and a small portion of the back wall of the container to support the prosthesis by tissue ingrowth into the Dacron felt.

Claims, 4 Drawing Figures

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3,665,520

SURGICALLY IMPLANTABLE BREAST PROSTHESIS

BACKGROUND OF THE INVENTION

Gel-filled silicone rubber breast prostheses have been employed for a number of years to maintain the natural appearance ofthe breast. The most common breast prostheses of the gel filled type is shown in U. S. Pat. No. 3,293,663 issued to T. D. Cronin on Dec. 27, 1966. This prosthesis included a flexible container having an outer peripheral ridge and a fabric material secured to the back wall of a flexible container to secure the container to the chest wall. This prosthesis is implanted solely within the breast area ofthe patient. It has been found, however, that due to the natural tendency of the body to reject foreign objects, the prosthesis tends to lose its shape often becoming distorted or out of place. This tendency is due to the force exerted by the growth of scar tissue around the implant. This scar tissue growth forces the edges of the prosthesis to roll up or to be pushed away from the chest wall, forming a ridge or bulge around the upper portion of the breast.

SUMMARY OF THE INVENTION

The breast prosthesis of the present invention retains the natural appearance of the breast by the inclusion of a prolongation on the prosthesis which extends outwardly from the breast area towards the axilla region of the anatomy. This prolongation when implanted in the patent will overlie the pectoral muscle. This prosthesis is held in position by a strip of felt material provided around the periphery ofthe back wall ofthe prolongation and around a portion ofthe back wall ofthe container. Tissue ingrowth is promoted only in the region of the strip of material leaving the major portion of the back wall free. Since the major portion of the back wall of the prosthesis is now physiologically inert, the prosthesis has greater freedom to follow the natural movements of the breast.

Distortion of the prosthesis by the force ofthe scar tissue is minimized by a fabric material which has been pre-impregnated with the polycarbonate material used to form the container and is secured to the inside surface ofthe back wall of the container. This fabric mesh increases the rigidity of the back wall with sufficient force to counteract the forces of tissue ingrowth. The fabric mesh extends across the entire back wall of the container and also across the back wall ofthe prolongation.

Other objects and advantages will be apparent from the following description when read in connection with the accompanying drawings.

THE DRAWINGS

FIG. 1 is a front view of a portion of the anatomy showing the approximate location of the prosthesis of this invention;

FIG. 2 is a front view of a prosthesis according to this invention for implanting on the right side ofthe patient;

FIG. 3 is a back view of the prosthesis of FIG. 2; and

FIG. 4 is a section view taken on line 4-4 ofthe prosthesis of FIG. 2 showing the position of the fabric mesh.

DESCRIPTION OF THE INVENTION

Referring to FIG. 1 of the drawing, the location of the prosthesis 10 is shown in position in the right upper torso of the anatomy 12. The prosthesis 10 is so located that it follows generally the same contour for the right side ofthe anatomy as shown for the normal breast line 14 on the left side of the anatomy. The prosthesis 10 can be located behind the mammary gland of the patient to augment the appearance of the breast but will not interfere with the ability of the patient to nurse in the normal way, and does not interfere in any way with the functioning of the mammary gland.

In accordance with the invention, the breast prosthesis 10 is formed from a container 20 which is filled with a soft gel 22. The container 20 is made of a material that has characteristics that resemble that of the normal human breast, such as soft. 2 ness and resiliency. The material must also be of a type which does not cause tissue reaction after implantation. A suitable material for the container 20 is an organopolysiloxane polycarbonate block copolymer.

The container 20 is formed with a front wall 24 having the general shape of a natural breast and a back wall 26 which follows the contour of the chest. In this respect, the back wall 26 has a generally concave appearance to fit comfortably against the chest wall. The container 20 can be formed on a mold having the general shape of the prosthesis. The mold is dipped in a liquid copolymer and rotated to form the container on the outside of the mold. The mold is repeatedly dipped and rotated to cure the copolymer until the container has the desired wall thickness. The wall of the container formed of this material has the same thickness and has little, if any, rigidity, being very soft and very flexible in compression but has great tensile strength. It should be noted that the edge or peripheral wall 25 of the container is round or curved as seen in FIG. 4.

The container 20 is formed with a prolongation 28 which is arranged to extend outwardly from the breast area toward the axilla region 30 of the anatomy. The prolongation 28 should overlie the area 32 of the pectoral muscle 32 and should be tapered outwardly toward the outer end. The axillary prolongation 28 follows the anatomical contour of the anatomy, thus providing a more natural appearance when implanted in the breast.

The container 20 is filled with the silicone gel 22 to give the prosthesis the proper shape and resiliency. Silicone gel made 30 in accordance with U.S. Pat. No. 3,020,260 which issued on Feb. 6, 1962 and entitled, “Organosiloxane Potting Compound” is a good example of a gel suitable for use in the prosthesis of this invention. The preferred gel for use in this invention is a liquid methyl silicone resin capable of being vul35 canized to an elastomer blended with a dimethyl silicone fluid. A suitable fluid is General Electic’s VISCASIL and an appropriate resin recommended for this use is General Electric’s elastomeric resin TRV-615. The proportion of resin to fluid may vary from 1; 1 to 1:10 in order to obtain the proper gel consistency. The resin contains RzSiO-1/2 groups, RzSiO groups, and SiOz groups, where R represents methyl groups. The ratio of the groups one to the other determines the consistency of the gel.

Means are provided in the backwall 26 of the container 20 for stiffening or increasing the rigidity ofthe back wall in compression and thereby resist the tendency ofthe container to be deformed due to the force of the scar tissue. In this respect, it has been found that the scar tissue ingrowth in the entire back wall of a prosthesis as described in Cronin U.S. Pat. No. 3,293,663 tends to deform the prosthesis forcing the rigid edges of the prosthesis outward. A bulge will eventually appear around the periphery of the breast of the patient. This is prevented by means of a bio-compatible fabric material 40 55 such as a polyester, polypropylene or polyamide fabric in the form of a mesh which is secured to the back wall 26 of the container 20. The fabric material can be secured to the inside of the back wall or embedded therein. Any suitable means can be used for securing the fabric to the back wall, such as a sil60 icone adhesive, or by heat sealing, or by laminating with the copolymer.

The fabric material 40 can be initially impregnated with the organosiloxane copolymer and cured to reduce the probability of tissue ingrowth and to increase the rigidity ofthe mesh. The impregnated mesh 40 can be secured to either the inside or outside surface of the back wall of the container. Impregnating the mesh with the copolymer will prevent tissue ingrowth if secured to the outside of the container. The fabric mesh 40 thereby increases the strength of the back wall in compression 70 without increasing the thickness of the container nor the strength of the front wall 24.

The prosthesis 10 is secured to the chest wall of the patient by means of a strip 50 of felt-like material formed from a polyester material such as Dacron which is provided around 75 the periphery of the axillary prolongation 28, and across the

3,665,520 top portion of the back wall 26 of the container. The strip of felt SO limits the amount of tissue ingrowth and at the same time provides sufficient support to maintain the prosthesis 10 in position. The felt strip 50 is secured to the container by a silicone adhesive and is provided only along the upper edges of the prosthesis. The felt-like material limits the penetration of the adhesive to one side of the strip leaving the other side free for tissue ingrowth. The prosthesis is secured to the area of the pectoral musclealong the upper portion of the container only since the normal forces acting on the prosthesis are downward, thus leaving the major portion of the back wall 26 free or unattached to the chest wall. This arrangement for supporting the prosthesis in the breast allows for a more natural amount of movement of the breast.

Another important feature of the present invention is the elimination of any ridge or bulge around the prosthesis 10 which can be seen or felt after the prosthesis has been implanted in the patient. This has been achieved by forming the container as an integral unit having a curved wall or edge 25 between the front and back walls. Since the container material has no compressive strength and is very thin, the edge 25 will collapse when touched and cannot be felt through the skin of the patient.

RESUME

The prosthesis of this invention includes a number of important features which have not previously been available in a breast prosthesis. The most important of these features is the axillary prolongation which tapers outwardly toward the axilla region of the patient. This prolongation provides a more natural appearance to the prosthesis after implant. The felt strip which is used to support and maintain the implant in position allows for greater freedom of movement of the prosthesis again providing a more natural appearance. The curved edge provided between the front wall and back wall of the container has eliminated the bulge or ridge which generally occurs around the prosthesis. The fabric material secured to the back wall of the container has increased the strength or rigidity of the back wall of the container 20 so that the prosthesis does not become distorted after implant.