SOFT FILLED PROSTHESIS SHELL WITH DISCRETE FIXATION SURFACES

Abstract

A method of augmenting or reconstructing a breast of a patient includes providing an implantable member and implanting the implantable member. The implantable member includes an exterior surface defined by an anterior face and a posterior face, wherein one of the anterior face and the posterior face includes at least one fixation region defined by a texture, roughness or sheen different from a respective texture, roughness or sheen of a balance of said one of the anterior face and posterior face. The implantable member is implanted into a breast of a patient such that the fixation region of the implantable member generally aligns with the pectoralis major muscle group or the pectoralis minor muscle group.

Claims

1. A method of augmenting or reconstructing a breast of a patient, the method comprising: providing an implantable member including an exterior surface defined by an anterior face and a posterior face, wherein one of the anterior face and the posterior face includes at least one fixation region defined by a texture, roughness or sheen different from a respective texture, roughness or sheen of a balance of said one of the anterior face and posterior face; and implanting the implantable member into a breast of a patient such that the fixation region of the implantable member generally aligns with the pectoralis major muscle group or the pectoralis minor muscle group.

2. The method of claim 1, wherein the at least one fixation region is defined by an enhanced texture relative to said balance of said one of the anterior face and posterior face.

3. The method of claim 1, wherein the implanting comprises aligning the fixation region relative to the pectoralis minor muscle group.

4. The method of claim 1, wherein the fixation region comprises an elongated configuration, and the implanting comprises aligning the elongated configuration of the fixation region with the pectoralis major muscle group or the pectoralis minor muscle group.

5. The method of claim 1, wherein the fixation region comprises a band shape.

6. The method of claim 1, further comprising positioning the implantable member over the top of the pectoralis major muscle group.

7. The method of claim 1, further comprising positioning the implantable member underneath the pectoralis major muscle group.

8. A method of augmenting or reconstructing a breast of a patient, the method comprising: providing an implantable member including an exterior surface defined by a textured posterior face and a relatively less textured anterior face, wherein roughnesses of the textured posterior face and the textured anterior face permit enhanced tissue ingrowth or adhesion along the exterior surface; and implanting the implantable member into a breast of a patient such that the implantable member is positioned over the top of the pectoralis major muscle group or underneath the pectoralis major muscle group.

9. The method of claim 8, wherein the exterior surface of the implantable member is in contact with the pectoralis major muscle group or the pectoralis minor muscle group.

10. The method of claim 8, wherein the exterior surface of the implantable member includes at least one fixation region.

11. The method of claim 10, further comprising substantially aligning the fixation region with the pectoralis major muscle group.

12. The method of claim 10, further comprising substantially aligning the fixation region with the pectoralis minor muscle group.

13. The method of claim 10, wherein the at least one fixation region is defined by an enhanced texture relative to one of the anterior face and posterior face.

14. The method of claim 10, wherein the fixation region comprises an elongated configuration, and the implanting comprises aligning the elongated configuration of the fixation region with the pectoralis major muscle group or the pectoralis minor muscle group.

15. The method of claim 10, wherein the fixation region comprises a band shape.

16. A method of augmenting or reconstructing a breast of a patient, the method comprising: providing an implantable member including an exterior surface defined by a textured posterior face and a relatively less textured anterior face, wherein roughnesses of the textured posterior face and the textured anterior face permit enhanced tissue ingrowth or adhesion along the exterior surface; and implanting the implantable member into a breast of a patient, wherein the textured posterior face and the textured anterior face are configured to disrupt capsule formation.

17. The method of claim 16, further comprising positioning the implantable member over the top of the pectoralis major muscle group.

18. The method of claim 16, further comprising positioning the implantable member underneath the pectoralis major muscle group.

19. The method of claim 16, wherein one of the anterior face and the posterior face includes at least one fixation region defined by a texture, roughness or sheen different from a respective texture, roughness or sheen of a balance of said one of the anterior face and posterior face.

20. The method of claim 19, further comprising substantially aligning the fixation region with the pectoralis major muscle group or the pectoralis minor muscle group.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Features and advantages of the present invention will become appreciated as the same become better understood with reference to the specification, claims, and appended drawings wherein:

[0027] FIGS. 1A and 1B are a front view and a side elevational view, respectively, of an exemplary round breast implant of the present invention;

[0028] FIGS. 2A and 2B are a front view and side elevational view, respectively, of an exemplary shaped breast implant of the present invention;

[0029] FIGS. 3A and 3B are schematic views of a woman's upper torso showing, alignment of the pectoralis major muscle group and the pectoralis minor muscle group, respectively;

[0030] FIGS. 4A and 4B are vertical sectional views through a woman's breast and adjacent chest anatomy showing, respectively, subglandular and submuscular placement of a breast implant;

[0031] FIGS. 5A and 5B are front and side elevational views of an exemplary round breast implant of the present invention having a generally elongated or band-shaped fixation surface;

[0032] FIGS. 6A and 6B are front and side elevational views of an exemplary shaped breast implant of the present invention having a generally elongated or band-shaped fixation surface;

[0033] FIG. 7 is a front elevational view of another breast implant in accordance with the invention including a first fixation region having a first texture and a second fixation region having a second texture different from the first texture;

[0034] FIGS. 8A and 8B are front and rear elevational views of an exemplary round breast implant of the present invention having a front texture and a rear texture that are different from one another.

DETAILED DESCRIPTION

[0035] The present invention provides a saline- or gel-filled soft implant shell, preferably a silicone elastomer shell, with a fixation surface over an exterior portion. The primary application for such soft implants is to reconstruct or augment the female breast. Other potential applications are implants for the buttocks, testes, or calf, among other areas.

[0036] The terms fixation surface or fixation region, as used herein, generally refer to a region or portion of an exterior surface of an implant which is positioned, structured or adapted to encourage tissue ingrowth or adhesion at a body/implant interface. For example, a fixation region may be a texture, roughness or sheen that is distinct from, for example, more pronounced than, adjacent surfaces of the implant which do not encourage tissue ingrowth of adhesion to the same degree as the fixation region. For example, other regions or surfaces of the implant exterior may be relatively smooth or less textured relative to the fixation regions.

[0037] Such a fixation region may be formed by any suitable means, for example, but not limited to, a salt removal process such as described in U.S. Pat. No. 5,007,929, with appropriate changes being made. Alternatively, the fixation surfaces may be formed by separate textured elements such as textured patches or films adhered to the outside of an otherwise smooth or less textured implant. Still, another method for forming the discrete fixation regions may be by using a relatively roughened surface portion of a mold used to form the implant. Another method for forming the present fixation regions includes texturing the exterior of the implant after formation. The present invention should not be considered limited to any particular type of texturing or fixation surface, though there might be certain advantages with one or more of these techniques.

[0038] Turning now to the Figures, FIGS. 1A and 1B are front and side elevational views of an exemplary round breast implant 20 of the present invention. Generally, the implant 20 comprises an exterior surface defined by a relatively smooth anterior face 21, a textured posterior face 22 and a textured peripheral region 24 located between the anterior face 21 and the posterior face 22. The relatively smooth anterior face may be a relatively less textured surface (relative to texture of posterior face 22), such as, for example, a fine textured surface or even a matte finish. In some embodiments, the implant 20 has a relatively smooth posterior face, a textured anterior face and a textured or smooth peripheral region. The fixation surfaces 22, 24 themselves may have differing degrees of texturing. The diameter D and front-to-back thickness T of the implant are shown and vary depending on the patient's chest size and aesthetic considerations.

[0039] In the shown embodiment, the rear fixation surface 22 extends to the apex 26 or generatrix of the convex outer periphery of the implant 20. The peripheral fixation surface 24 continues forward a short distance S onto the anterior or front surface 21. In some embodiments, the distance S is between about 10% and about 30% of the thickness T. In some embodiments, the peripheral fixation surface 24 extends substantially entirely around the periphery of the implant 20, such that the implant 20 is axi-symmetric. In other embodiments, the peripheral fixation surface 24 may be abbreviated so as to extend around only a portion of the periphery of the implant, such as the inferior or superior half, or the peripheral fixation surface may be broken up into spaced apart segments. In some embodiments, the peripheral fixation surface 24 comprises substantially evenly spaced segments resulting in alternating smooth and textured areas.

[0040] FIGS. 2A and 2B illustrate an exemplary shaped breast implant 30 of the present invention having an inferior frontal lobe 32 simulating a natural breast. Like implant 20, implant 30 includes a rear fixation surface 34 and a peripheral fixation surface 36. The width W, height H, and front-to-back thickness T of the implant are shown. If the front projection is round, then W=H, otherwise W may be greater than or less than H. When provided with a natural shape, the implant 30 has a proper orientation, namely with the inferior lobe 32 at the lower center. Accordingly, the peripheral fixation surface 36 may extend completely around the periphery of the implant, or may be formed in discrete areas and be oriented relative to the natural shape of the implant. For example, the peripheral fixation surface 36 may be formed only around the inferior or lower half of the implant, or may be formed only on the sides.

[0041] FIG. 3A illustrates a woman's upper torso schematically showing on one side placement and alignment of the pectoralis major muscle group, while FIG. 3B illustrates the placement and alignment of the pectoralis minor muscle group. These two muscle groups overlap one another and extend generally from the shoulder or collarbone region to the rib cage underneath the breast. One aspect of the present invention is to provide an implant including fixation surfaces such as described elsewhere herein, which are substantially aligned with these muscle groups when the implant is placed in the body.

[0042] While not wishing to be bound by any specific theory of operation, the regions or lines of contact of the implant with the primary chest muscles experience greater movement than other areas of the implant not interfacing the muscles. It is believed by the present inventors that by providing a fixation region of the implant that is substantially coincident with or in substantial alignment with one or more of these muscle groups is more likely to remain secured (i.e., they move with the muscle). In addition, it is contemplated that such discrete fixation regions may provide the benefit of disrupting capsule formation and/or reducing the potential for capsular contraction.

[0043] FIG. 4A is a vertical sectional view through a woman's breast and adjacent chest anatomy showing a subglandular placement of a breast implant 40. The implant 40 is positioned over the top of the pectoralis major muscle group 42, which in turn overlays the pectoralis minor muscle group 44. The chest wall 48 showing a plurality of ribs 50 is also indicated underneath the pectoralis minor muscle 44. FIG. 4B is a vertical sectional view as in FIG. 4A but showing a submuscular placement of the implant 40, underneath the pectoralis major muscle group 42. Both these two implant placements are utilized primarily depending on the surgeon's clinical determination, sometimes influenced by a dialogue between patient and the surgeon and desired outcome. Depending on the implant placements, the implant 40 may be in contact with one or both muscle groups. In some embodiments of the invention, the implant includes substantially elongated fixation regions as described and shown herein, and said fixation regions being in substantial alignment with the appropriate muscle group which interface the implant when the implant is placed in the body.

[0044] For example, FIGS. 5A and 5B are front and side elevational views of an exemplary round breast implant 60 of the present invention having a posterior face 62, a peripheral region 64, and an anterior face including an elongated or band-shaped fixation region 66. The band-shaped fixation region 66 extends generally along a diagonal angle and commences at the front border of the peripheral fixation surface 64. The illustrated embodiment, the fixation region 66 has a substantially constant width W as seen from the front in FIG. 5A. In one embodiment, the width W is between about 1 mm to about 20 mm, for example, between about 2 mm to about 15 mm. Alternatively, although not shown, the fixation region 66 may have a configuration that is other than a constant width.

[0045] In one embodiment, the band-shaped fixation surface 66 is generally oriented or aligned with either the pectoralis major muscle group or pectoralis minor muscle group when the implant is implanted in the breast. For instance, if the implant 60 is destined for a submuscular placement such as in FIG. 4B, the fixation surface 66 may be oriented to be generally aligned with the pectoralis major muscle group, as seen in FIG. 3A. Alternatively, the angle at which the insertion surface 66 is oriented may be an approximation of the average angle of the pectoralis major and pectoralis minor muscle groups. In this way, the implant 60 has a fixation surface 66 to encourage tissue ingrowth or adhesion along the major stress lines of the implant. Preferably, the fixation surface 66 is angled between about 30-60 with respect to a vertical plane through the implant 60. Of course, if the implant 60 is round as shown, the fixation surface 66 itself defines the orientation thereof. In one embodiment, the band-shaped fixation surface 66 is centered about the center of the implant 60, therefore creating two symmetric orientations about 180 apart. This arrangement facilitates implant by providing two possible orientations for the surgeon.

[0046] The band-shaped fixation region 66 may extend substantially across the anterior face of the implant and may be defined by a texture that is different from a balance of the anterior face. The fixation region 66 may also have a different texture, for example, a more pronounced or more aggressive texture, than the rear fixation surface 62 or peripheral surface 64.

[0047] FIGS. 6A and 6B illustrate another exemplary shaped breast implant 70 of the present invention. The implant 70 again features a rear fixation surface 72, a peripheral fixation surface 74, and a plurality of separate band-shaped fixation surfaces 76a, 76b, 76c. These discrete fixation surfaces 76a, 76b, 76c are positioned or configured to align with one or more of the muscle groups described above. For example, the three fixation surfaces 76a, 76b, 76c may be generally oriented relative to the fan-shaped pectoralis minor muscle group. Because the shaped implant 70 is orientation-specific, proper placement of the implant orients the fixation surfaces 76a, 76b, 76c with the particular muscle group. As mentioned above, the various fixation surfaces 72, 74, 76a, 76b, and 76c may be formed with a similar level of roughness, or some may be less textured, such as with a matte finish. For instance, the rear and peripheral fixation surfaces 72, 74 may have a fine, matte finish, while the frontal fixation surfaces 76a, 76b, 76c are more densely textured. The present invention contemplates all permutations of texturing choices.

[0048] In cross-section, the textured implant shells of the present invention may be single- or multi-layered. The overall thickness of the textured implant shell wall may be somewhat greater than a similar smooth-walled shell because of the extra layers of texture.

[0049] Turning now to FIG. 7, an anterior (front) view of another breast implant of the present invention is shown generally at 110. The implant 110 includes a shell 112 having an exterior surface including a first fixation region 114 having a first texture 116 and a second fixation region 118 having a second texture 122 that is different from the first texture 116. In the shown embodiment, the first texture 116 is a more aggressive texture than the second texture 122. The first texture 116 is structured to encourage a greater degree of tissue interaction than the second texture 122.

[0050] In lieu of the second texture 122, it is contemplated that the second fixation region 118, and perhaps the entire balance of the exterior of the shell 112, may be a low sheen surface, for example, a matte finish.

[0051] Turning now to FIGS. 8A and 8B, anterior (front) and posterior (rear) views, respectively, of another breast implant in accordance with the invention are shown generally at 210. The implant 210 includes a shell 212 having an anterior face 212a and a posterior face 212b, and including a first fixation region 214 having a first texture 216 and a second fixation region 218 having a second texture 222 that is different from the first texture 216. In the shown embodiment, the first texture 216 may encompass the entire, or substantially entire, anterior face 212a of the implant 210. The first texture 216 is defined by a first distribution of pores, crevices or caverns that is relatively less dense than that of the second texture 222. The second texture 222, which may encompass the entire, or substantially entire, posterior face 221b of the implant 210, may be structured to encourage a greater degree of tissue interaction and adhesion than that of the first texture 216.

[0052] The shells 112 and 212 may be manufactured by a method of the invention comprising the steps of providing a shell precursor; applying a layer of silicone elastomer to the shell precursor, applying solid particles of a first configuration to a portion of the layer of silicone elastomer and applying solid particles of a second configuration to another portion of the layer of silicone elastomer before the layer is fully cured. After the layer including the solid particles embedded therein is cured, the solid particles are then dissolved, for example, by means of a solvent that does not dissolve the silicone elastomer to any appreciable extent. The resulting elastomer shell includes a first open cell texture region formed by said application of the solid particles of the first configuration, and a second open cell texture region formed by said application of the solid particles of the second configuration.

[0053] One process for forming flexible implant shells for implantable prostheses involve dipping a suitably shaped mandrel into a silicone elastomer dispersion. Many such dispersions are used in the field. Basically they contain a silicone elastomer and a solvent. The silicone elastomer is typically polydimethylsiloxane, polydiphenyl-siloxane or some combination of these two. Typical solvents include xylene or 1,1,1-trichloroethane. Different manufacturers vary the type and amount of the ingredients in the dispersion, the viscosity of the dispersion and the solid content of the dispersion. Nonetheless, the present invention is expected to be adaptable to have utility with a wide variety of silicone rubber dispersions.

[0054] The mandrel is withdrawn from the dispersion and the excess silicone elastomer dispersion is allowed to drain from the mandrel. After the excess dispersion has drained from the mandrel at least a portion of the solvent is allowed to volatilize or evaporate. Normally this is accomplished by flowing air over the coated mandrel at a controlled temperature and humidity. Different manufacturers use various quantities, velocities or directions of air flow and set the temperature and humidity of the air at different values. However, the desired result, driving off the solvent, remains the same.

[0055] It is also common for prostheses manufacturers to repeat this dip and volatilize procedure a number of times so that a number of layers are built up on the mandrel to reach a desired shell thickness. A layered structure like most current silicone elastomer shells can be made by sequentially dipping the mandrel in different dispersions. Alternatively, the steps may be repeated in a single dispersion so that the finished product is a single homogenous material or layer. That is, the dipping process may be done in multiple stages or steps, each step adding more material, yet the finished product exhibits no distinct layers and the entire shell wall is homogenous or uniform in composition.

[0056] An exemplary process for forming the fixation surfaces on either a multi-layered shell or a single-layered shell will now be described. After the mandrel is raised out of the dispersion with what is to be the final layer adhering thereto, this layer is allowed to stabilize. That is, it is held until the final coating no longer flows freely. This occurs as some of the solvent evaporates from the final coating, raising its viscosity.

[0057] Again, it should be understood that alternative methods are contemplated for forming the flexible shell prior to the texturing process. The dip molding process advantageously results in the flexible shell pre-mounted on a dipping mandrel, which can then be used for the texturing process. However, if the flexible shell is made by another technique, such as by rotational molding, it can subsequently be mounted on a dipping mandrel and the process continued in the same manner.

[0058] Once the flexible shell has been stabilized and mounted on the mandrel, any loose fibers or particles are removed from the exterior of the shell, for example, with an anti-static air gun. A tack coat layer is then applied. The tack coat layer may be sprayed on, but is desirably applied by dipping the flexible shell on the mandrel into a tack coat dispersion. The operator immerses the flexible shell into the dispersion and returns the mandrel to a rack for stabilization. The time required for stabilization typically varies between 5-20 minutes. A suitable tack coat layer is desirably made using the same material employed in the base layers.

[0059] At this point, granulated solid particles (i.e., salt crystals) are applied over that portion of the exterior surface that will end up as the fixation surface. The solid particles may be applied manually by sprinkling them over the surface while the mandrel is manipulated, or a machine operating like a bead blaster or sand blaster could be used to deliver a steady stream of solid particles at an adequate velocity to the coating on the mandrel. However, a preferred method of solid particle application is to dip the mandrel/shell into a body of the solid particles or expose it to a suspension of the solid particles. It should be understood that the present invention is not intended to be restricted to any one particular method of applying particles. One possible method to apply solid particles to some but not all of the shell is to mask off areas of the shell for which particles are not to be applied and then apply the particles to the non-masked areas.

[0060] The tacky flexible shell may then be immersed in a fluidized (air-mixing) aqueous salt bath having regular cubic salt crystals between about 10 to about 600 microns, or round crystals between about 50-2000 microns or a combination thereof. Varying degrees of texturing may be formed with the salt removal process by using differently sized or shaped salt granules (for example, round salt crystals versus angular salt crystals, large salt crystals versus relatively small salt crystals, high density distribution of salt crystals versus relatively low density distribution of salt crystals), on different areas of the shell. The shell is rotated for even coverage, removed, and then allowed to stabilize. After a suitable period of stabilization, such as between about 5-20 minutes, the flexible shells may be dipped into an overcoat dispersion. A suitable overcoat dispersion may be made using the same material employed in the base layers. The flexible shells on the mandrels are then mounted on a rack and allowed to volatilize, such as, for example, about 15 minutes.

[0061] The entire silicone elastomer shell structure is vulcanized or cured in an oven at elevated temperatures. The temperature of the oven is preferably kept between about 200 F. and about 350 F. for a curing time preferably between about 20 minutes and about 1 hour, 40 minutes. Upon removal from the oven, the mandrel/shell assembly is placed in a solvent for the solid particles, and the solid particles allowed to dissolve. The solvent does not affect the structure or integrity of the silicone elastomer. When the solid particles have dissolved, the assembly is removed from the solvent and the solvent evaporated. The shell can then be stripped from the mandrel. At this point, it is preferable to place the shell in a solvent for the solid particles and gently agitate it to ensure complete dissolution of all the solid particles. When the shell is removed from the solvent, the solvent is evaporated.

[0062] Dissolving the solid particles leaves behind open, interconnected, cavities in the surface of the shell where the salt had been.

[0063] After finishing the shell according to the steps described above, the steps required to make a finished breast implant prosthesis may be similar to those known in the art. For example, an opening left by the dip molding process is patched with uncured sheeting, usually made of silicone rubber. Then, if the prosthesis is to be filled with silicone gel, this gel is added and cured, the filled prosthesis packaged, and the packaged prosthesis sterilized. If the prosthesis is to be inflated with a saline solution, a one-way valve is assembled and installed, the prosthesis is post cured if required, and the prosthesis is then cleaned, packaged and sterilized. A combination breast implant prosthesis can also be made wherein a gel-filled sac is positioned inside the shell to be surrounded by saline solution.

[0064] In addition to the aforementioned dipping process, the flexible shell for the prosthetic implant may be formed using a molding process. For example, a rotational molding process such as described in Schuessler, U.S. Pat. No. 6,602,452 the entire disclosure of which is incorporated herein, may be used. The process for forming texturing on the exterior surface may be done using a dipping technique after the shell is molded, but another method is to roughen the inside of the mold. For example, a mold having a generally smooth interior surface except for rough areas as described above will produce an implant shell having discrete fixation surfaces. The rotational molding process is advantageous because the entire implant shell may be formed in relatively few manufacturing steps.

[0065] Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the combination and arrangement of parts can be resorted to by those skilled in the art without departing from the scope of the invention, as hereinafter claimed.