This patent application has not been assigned to a company or institution.
The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention generally relates to medical implants and more specifically relates to materials suitable for implantation in a mammal which provide a reduced capsular contracture response around breast prostheses.
"Prostheses or implants for augmentation and/or reconstruction of the human body are well known. Capsular contracture is a complication associated with surgical implantation of prostheses, particularly with soft implants, and even more particularly, though certainly not exclusively, with fluid-filled breast implants.
"Capsular contracture is believed to be a result of the immune system response to the presence of a foreign material in the body. A normal response of the body to the presence of a newly implanted object, for example a breast implant, is to form periprosthetic tissue, sometimes in the form of a capsule containing collagen fibers around the implant. Capsular contracture occurs when the capsule begins to contract and squeeze the implant. This contracture can be discomforting or even extremely painful, and can cause distortion of the appearance of the augmented or reconstructed breast. The exact cause of contracture is not known. However, some factors that may influence contracture include bacterial contamination of the implant prior to placement, submuscular versus subgladular placement, and smooth surface implants versus textured surface implants, and bleeding or trauma to the area.
"Surface texturing has been shown to reduce capsular contracture when implants are placed in the subglandular position compared to what are known as 'smooth' surface implants. In other words, it is generally well known in the art that patients fitted with textured implants are less likely to exhibit contracture, relative to patients fitted with non-textured or smooth surface implants placed subglandularly. However, there is still a need for a textured implant that is specifically designed to encourage optimal tissue integration and potentially reduce capsule formation and collagen fiber alignment described herein."
In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventors' summary information for this patent application: "Accordingly, materials including optimal surface textures are provided, such materials being useful as components of prostheses, for example, as components of breast implants, for example, soft, saline or silicone gel-filled breast implants.
"The present materials are generally designed to achieve an optimal biological response in the patient after implantation thereof, for example, in the breast. The materials, sometimes herein referred to as 'biomaterials', are generally elastic and porous and comprise microstructures which contribute to healthy periprosthetic tissue ingrowth and reduced aligned fibrous capsule formation about a soft implant, resulting in reduced potential for capsular contracture.
"The presently described materials enhance healthy periprosthetic tissue ingrowth, sometimes without the formation of an identifiable capsule. This integration of tissue into the textured surface of the materials may prevent, or substantially prevent, the formation of an organized, collagen-dense capsule around a soft tissue implant and disrupts the linearly aligned capsule/collagen fibers found with non-textured or lightly textured implants. Hence, contracture of any capsular tissue that may form around a soft tissue implant including the present microstructures may be avoided, or at least the potential therefor reduced.
"In one aspect, the material is a soft, elastomeric open-cell material, for example, a foam-like material, having a microstructure discovered to enhance healthy tissue ingrowth.
"The materials may be substantially non-biodegradable, and may comprise, for example, an elastomeric polymeric material, such as a medical grade silicone elastomer. In one embodiment, the materials consist essentially or entirely of a silicone elastomer.
"In a specific embodiment, the porous materials, hereinafter sometimes referred to as, 'microporous materials' are defined by highly interconnected cavities. The pore size, interconnectivity of pores and/or number of pore interconnections of the materials produce an optimal biological response, as defined elsewhere herein, when implanted in the human body, for example, when the material makes up a exterior surface or a covering of a breast prosthesis.
"'Pore size', as used herein, is defined as generally the diameter of a pore if spherical or the average of the major and minor axis of a pore if elliptical in shape.
"In some embodiments, the microporous materials have a mean pore size of between about 30 .mu.m to about 900 .mu.m, for example, between about 300 microns and about 600 microns, for example, between about 350 .mu.m to about 550 .mu.m. In a particular embodiment, the mean pore size is about 450 .mu.m. In another particular embodiment, the mean pore size is about 470 .mu.m.
"'Mean interconnection size', as used herein, is defined as the approximate diameter of the opening between pores.
"The microporous materials of the invention may have a mean interconnection size between the pores of about 50 .mu.m to about 300 .mu.m, for example, between about 150 microns to about 300 microns.
"'Mean number of interconnections per pore', as used herein, is defined as the average number of openings in each pore that connect to another pore.
"In some embodiments, the materials have an a mean number of interconnections per pore of between about 2 to about 14, for example, about 3 to about 10, for example, about 9.
"'Open cell', as used herein, is defined as a characteristic of some of the materials of the present invention, in which pores or cells of the material are generally open to the surface of the material. In certain embodiments, the surface openness of the material is at least about 30%, for example, at least about 40%, for example, at least about 50%. This material can further be characterized in that the open cells are 'interconnected' beneath the surface of the material, meaning that that pores or cells below surface-exposed pores or cells are in open communication, e.g. open connection, with each other. These open cell structures can be distinguished from 'closed cell' structures in which each pore generally defines a discrete cavity, each cavity being completely surrounded by the solid material.
"In one aspect, a material useful as a component of a mammary prosthesis is provided, the material comprising a textured surface. The textured surface has an open cell structure with the physical and morphological characteristics described herein. Mammary prostheses including these materials are also provided.
"Methods for treating a patient in need of a mammary prosthesis are also provided.
"In one aspect, the method comprises implanting the mammary prosthesis in the patient, the mammary prosthesis having a textured surface, wherein within a period of time of about six months to about one year or more after the implanting step, periprosthetic tissue formed in proximity to the textured surface is tissue that has reduced circumferential alignment of collagen fibers, improved adhesion, and will have a reduced risk of contracture, even for the useful life of the prosthesis. In certain embodiments, the method may be a breast augmentation procedure or a breast reconstruction procedure.
"In another aspect, the method comprises implanting into the patient, a prosthesis comprising a open cell material having particular characteristics when tested in a test mammals. For example. In one embodiment, the material is characterized in that, when a one centimeter disc of a test material identical to the material is implanted subcutaneously in a
"For example, in one embodiment, the material comprises a nonresorbable, open cell, interconnected cellular material, which, after 6 weeks of being implanted in a rat, a collagen fiber alignment assay reveals that at least 22%, at of collagen fibers of the periprosthetic tissue are non-aligned with respect to a circumferential plane, or a major planar surface, defined by the test material.
"In another embodiment, the material comprises an open interconnected cell material, which, after 6 weeks of being implanted in a rat, a collagen fiber alignment assay reveals that at least 25% of collagen fibers of the periprosthetic tissue are non-aligned with respect to a circumferential plane, or a major planar surface, defined by the test material.
"In yet another embodiment, the material comprises an open interconnected cell material, which, after 6 weeks of being implanted in a rat, a collagen fiber alignment assay reveals that at least 50% of collagen fibers of the periprosthetic tissue are non-aligned with respect to a circumferential plane, or a major planar surface, defined by the test material.
"In still yet another embodiment, the material comprises an open interconnected cell material, which, after 6 weeks of being implanted in a rat, a collagen fiber alignment assay reveals that at least 56% of collagen fibers of the periprosthetic tissue are non-aligned with respect to a circumferential plane, or a major planar surface, defined by the test material.
"In some embodiments, the periprosthetic tissue, after six weeks of being so implanted in a rat, adheres to the test material with a force of at least 6 Newtons or greater.
"In yet another aspect of the invention, methods are provided for quantifying collagen fiber alignment in periprosthetic tissue in a mammal. In an exemplary embodiment, the method comprises obtaining a sample to be analyzed wherein the sample comprises periprosthetic tissue and adjacent material to be characterized that has been explanted from a mammal. At least one section, for example, two, three or more sections of the sample are then obtained using standard procedures wherein each section includes both periprosthetic tissue and at least a portion of the explanted adjacent material. Next, the section or sections are stained to reveal collagen fibers in the tissue under examination. The method further comprises providing a magnified image of the stained section and placing a reference vector on the magnified image, the reference vector being parallel to the major plane of the material at a tissue and material interface. In addition, a plurality of alignment vectors are placed on the image, for example, at least 10 or more, for example, about 25 alignment vectors, the alignment vectors being indicative of alignment of said collagen fibers revealed on the image. The method further comprises recording an angle of each of the alignment vectors with respect to the reference vector and calculating a variance of the recorded angles to thereby quantify a collagen fiber alignment of the sample of periprosthetic tissue. The method may further comprise grouping the recorded angles into bins, to create a histogram. The histogram is useful for making a determination of the degree or severity of collagen alignment in the periprosthetic tissue formed as a result of the implanted material. For example, the step of representing the alignment angles on a histogram may further include calculating the number of angles falling between about 80 degrees and 100 degrees, or between about 75 degrees and 105 degrees, which represent those collagen fibers that are most aligned with the major planar surface of the explanted material. In another aspect, the method may further comprise the step of performing a mathematical conversion on the alignment vectors to obtain a more quantitative analysis of the degree or severity of collagen alignment.
BRIEF DESCRIPTION OF THE DRAWINGS
"FIG. 1 graphically illustrates capsular contracture rates of textured implants of the prior art versus smooth implants, from various published studies.
"FIG. 2A is a bar graph representing data of thickness of capsules from various materials, the values being normalized to 'Textured 1', and represented as a percent of 'Textured 1', a prior art textured material (BIOCELL.RTM.,
"FIG. 2B is a bar graph representing disorganization of collagen in periprosthetic tissue from the various materials, normalized to 'Textured 1' and represented as a percent of 'Textured 1', a prior art textured material (BIOCELL.RTM.,
"FIGS. 2C-2D are graphical representations of angle measurements of collagen alignment in samples of tissue adjacent an implant.
"FIGS. 2E-2F are diagrammatic representation vectors for a highly aligned tissue sample (FIG. 2E) and a highly unaligned tissue sample (FIG. 2F).
"FIGS. 3A-3B show histogram representations of collagen fiber alignment assays described in this specification for different test materials.
"FIG. 4 is a bar graph showing data from a tissue adhesion test of various materials. Results are shown as mean.+-.standard deviation.
"FIG. 5 is bar graph showing data of stiffness of capsule/ingrowth formed over various tissue expanders at time 0 and at 6 weeks (n=8). Results are shown as mean.+-.standard deviation.
"FIGS. 6-11 show images of a periprosthetic tissue adjacent various textured implants in animal studies.
"FIGS. 12A-12D are images of materials in accordance with the invention, control and at selected time periods after implantation in a laboratory animal showing minimal or no loss of the structural integrity of the texture.
"FIGS. 13A-13D are images of bioresorbable PRIOR ART materials, control and at selected time periods after implantation in a laboratory animal showing loss of structural integrity in a open cell bioresorbable matrix."
URL and more information on this patent application, see: Van Epps, Dennis E.; Nofrey, Barbara; Goraltchouk, Alexei; Ren, Cindy. Method for Quantifying Collagen Fiber Alignment in Periprosthetic Tissue. Filed
Keywords for this news article include: Pharmaceutical Companies, Silicones, Siloxanes.
Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC
Most Popular Stories
- Tesla's Alt-Energy Future Aims for Massive Lithium-Ion Battery Production
- FAA to Appeal Court Decision Allowing Commercial Drone Use
- New Chat App, Yik Yak, Causes Problems for Students
- Rand Paul Tops Presidential Straw Poll at Conservative PAC Conference
- Obama Meets with Ukraine Prime Minister Wednesday
- Gas Prices May Jump from Calif. Emissions Law