US3596292A

US3596292A - Hair implant structure

Info

Publication number: US3596292A
Application number: US800847A
Authority: US
Inventors: Robert A Erb; William B Tarpley Jr; Peter Schuyler Francis
Original assignee: Franklin Institute
Current assignee: Franklin Institute; Magna Bond Corp
Priority date: 1969-02-20
Filing date: 1969-02-20
Publication date: 1971-08-03
Anticipated expiration: 1988-08-03
Also published as: FR2035675A5; DE2007355A1

Abstract

A hair implant suitable for placement in the human scalp to overcome the appearance of baldness. The implant may be small to provide only one or a few hairs per implant, or may be larger to cover a substantial area and to provide a larger number of hairs. The implant has a percutaneous portion with elastic properties similar to those of the living skin in which it is implanted, and has a cross section diverging outwardly from the skin so that an acute angle is formed between the lateral surfaces of the percutaneous portion of the implant and the surface of the adjacent skin in which it is implanted. This construction enhances the seal between implant and surrounding skin surface so as to minimize chances of infection. To prevent rejection of the implant, the implant is made of body-compatible materials and is provided with an anchoring portion comprising a tissue-permeable structure, such as velour loops, situated below the stratum germinativum, in the corium and/or subcutaneous tissue, and permeated by the living and growing tissue.

Description

United States Patent [72] Inventors Robert A. Erb 3,220,960 1 1/1965 Wichterle et a1. 3/1 X Schuylkill Township; 3,279,996 10/1966 Long et a1 3/1 UX William B. Terpley, Jr., West Chester; 1,061,005 5/1913 Parsegan 128/330 :3" Schuyler Francs Rose valley Primary ExaminerChanning 1.. Pace 1 pp No 800,847 Attorney-Howson and Howson [22] Filed Feb. 20, 1969 [451 Patented Aug.3, 1971 {73] Ass'gnee Franklin Imam ABSTRACT: A hair implant suitable for placement in the Phlhddphh human scalp to overcome the appearance of baldness. The implant may be small to provide only one or a few hairs per im- 54 1 "Am IMPLANT STRUCTURE plant, or may be larger to cover a substantial area and to provide a larger number of hairs. The implant has a percutaneous 22 Claims, ll Drawing Flgs.

portion with elastic properties simllar to those of the llVlllg [52] US. Cl 3/1, kin in which it is implanted and has a cross section diverging 8/ 5 outwardly from the skin so that an acute angle is formed lnt. 1/00, between the lateral surfaces of the percutaneous portion of 17/00, 8 the implant and the surface of the adjacent skin in which it is Field of Search implanted. This construction enhances the seal between im- 128/330; 5 plant and surrounding skin surface so as to minimize chances of infection. To prevent rejection of the implant, the implant is [56] References cued made of body'compatible materials and is provided with an UNITED STATES PATENTS anchoring portion comprising a tissue-permeable structure, 1,059,631 4/1913 Popovics 128/330 such as velour loops, situated below the stratum ger- 3,003,155 10/1961 Mielzynski et al. 128/330 X minativum, in the corium and/or subcutaneous tissue, and per- 3,176,316 4/1965 Bodell 3/1 meated by the living and growing tissue.

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INVENTORSI ROBERT A. ERB

WILLIAM B. TARPLEY,JR. PETER SCHUYLER FRANCIS BY WW2 W ATTYS.

HAIR IMPLANT STRUCTURE BACKGROUND OF THE INVENTION This invention relates to hair implant structures and methods, and particularly to such structures and methods suitable for accomplishing the implanting of real or artificial in the living human scalp.

There are a variety of applications in which it would be desirable to provide real or artificial hair on bald areas of living skin. Perhaps chief among such applications is the overcoming of cosmetically undesirable baldness of the human scalp.

Much effort has been expended over the centuries in attempts to stimulate hair growth or regrowth, but any success in such efforts has been limited to highly specialized circumstances generally involving relatively rate metabolic or hormonal-defect diseases. In recent years techniques have been evolved for the transplantation of living hair, involving the removal by surgical means of plugs of hair containing perhaps 50 individual hairs and reinsertion of the plugs in a pattern across the bald spot. Such transplanted hair does not spread over the scalp and simply duplicates the appearance and growth pattern of its original locale, and will gradually become grey or fall out, or both.

Structures and methods have also been proposed for the implantation of nonliving natural hairs or synthetic hairs into the scalp, sometimes into a hair follicle and sometimes between hair follicles, generally with reliance upon bulbous or hooklike projections to resist pulling out of the hair after it is once installed. Typical of such proposals are US Pat. No. 1,059,631 of Popovics, issued Apr. 22, 1913; No. 1,061,005 of Parsegan, issued May 6, 19l3; No. 3,003,l55 of Mielzynski et al. issued Oct. 10, I961; No. 3,062,214 of Maxwell, issued Nov. 6, 1962; and No. 3,119,398 of Bennett et al. issued Jan. 28, 1964. In connection with any such methods and structures, it is important for the hair implant not to be rejected by the scalp or its underlying tissues and not to produce infection. So far as it is known, no structure or method for the implantation of nonliving hair implants into the human scalp has yet been found acceptable, particularly with respect to infection and rejection problems.

Accordingly, it is an object of the invention to provide a new and useful hair implant structure and method.

Another object is to provide such a structure and method which reduces the possibility of infection of the skin or underlying tissues due to the implant.

Still another object is to provide such a method and structure in which rejection of the implant by normal body functions is minimized.

Another object is to provide such a method and structure which result in mechanical strength and permanence of the implant and the associated hair.

A further object is to provide such a method and structure which are medically acceptable and commercially feasible.

SUMMARY OF THE INVENTION These and other objects of the invention are achieved by the provision of a hair implant for use in living skin which comprises a structure having an anchoring portion adapted to be inserted below the surface of living skin and to be retained by intergrowth therewith of living tissue, and also having a percutaneous portion adapted to extend through the external surface of the skin, the percutaneous portion preferably having a cross section diverging in the direction extending away from said anchoring portion so as to provide an acute angle between the lateral surface of said percutaneous portion and the adjacent external surface of the skin in which it is implanted. This causes the growing and desquamating epidermis to maintain a pressure against the periphery of the percutaneous portion of the implant, thereby sealing the interface between implant and skin surface against invasion by infectious bodies. Preferably the percutaneous portion is resilient, and in the preferred embodiment has elastic properties which are similar to those of living skin, so as to maintain the desired interface seal despite normal tendencies of the skin occasionally to pull away from the implant, due to such factors as rubbing or wrinkling of the skin surfaces for example. In a preferred form of the invention the implant structure also comprises a tapered transition from the exterior end of the percutaneous portion to an exterior hairlike member, thereby mitigating tendencies for the hairlike member to break off at the external end of the percutaneous portion of the implant structure. Furthermore, the percutaneous portion of the implant is preferably impervious to tissue growth in the region which will be located in the epidermis above the stratum germanativum, so that the necessary growth and slow migration of increasingly keratinized skin cells from the stratum germanativum to the external skin surface can occur without substantial interference.

One main feature of the preferred combination in accordance with the invention relates to the arrangement for anchoring the implant to retain it against mechanically applied forces and against any bodily rejection mechanisms which may be operative. For this purpose the anchoring portion of the implant is made permeable to tissue growth and is implanted -below the stratum germanativum so that, after implanting, tissue intergrowth locks the implant positively in position. Preferably, the tissue-pervious anchoring portion ex tends into the subcutaneous tissue, but is also located partly in the corium. To further facilitate anchoring, tissue-impervious processes are preferably provided on the portion of the implant which is to be located in the stratum germanativum and in the immediately overlying epidermal layers beneath the stratum corneum. These tissue-impervious processes provide a substantial degree of bonding of the implant to the epidermal layers but do not cause a positive locking and trapping of the skin cells, which instead are capable of disengaging themselves from the tissue-impervious processes and of participating in the necessary slow migration of cells to the outer surface of the skin.

In one preferred embodiment of the invention the implant is generally hairlike in form having an outer portion simulating the appearance of human hair, a substantially conical percutaneous portion formed around the axis of the hairlike member, and a tissue-pervious portion below the percutaneous portion at a distance sufi'icient to extend into the corium and subcutaneous tissue, in addition, in the preferred embodiment, tissue-impervious processes are situated to infiltrate the lower epidermal regions. Such individual generally hairlike implants'may be inserted by any of a number of known means and methods, for example for means of a known split-injection needles or the like, of by placing a number of implants in a row in a surgically produced slit in the skin which is subsequently sutured and allowed to heal.

In another species of the invention, the percutaneous portion of the implant is of much larger scale so as to receive and hold a large number of external hair-simulating filamentary members, and may be inserted into the scalp after first surgically removing a corresponding portion of the scalp skin.

In either case the expanding percutaneous portion is preferably positioned to extend above the surface of the skin sufficiently to prevent overgrowth by surrounding skin tissue, for example by a distance of about 10 to 20 mils.

As further more specific features of certain preferred embodiments of the invention, the anchoring portions of the implant may comprise a tissue-pervious structures in the form of microvelours, microporous polymers, reticulated foam polymers or hydrated hydrogels. In the first three of these anchoring structures, the growing tissue is readily capable of growing through the interstices in the structure and thereby encompassing and locking the structure in place. In the case of the hydrogel, the molecular structure of the material is such as to permit ingrowth and intergrowth by the surrounding living tissue so that a similar type of locking bond is obtained. The

small, generally hairlike implants described above are preferably inserted between, rather than in, hair follicles in the skin to obtain maximum benefits of the invention in preventing infection and rejection.

In the case of the large-scale implant, there is preferably also employed a skirtlike tissue-pervious member secured to the periphery of the implant in a position to be placed in the surrounding corium. Such a skirt provides additional permanency of retention, particularly in the case of such largescale implants.

The method and structure of the invention are also useful when applied to the skin of animals, as distinguished from humans.

BIRIEF DESCRIPTION OF DRAWINGS These and other objects and features of the invention will be more r. .adily understood from a considerationof the following detailed description, taken with the accompanying drawings, in which:

FIG. HA is a vertical sectional view of one species of individual hair implant in accordance with the invention, shown in place in a human scalp;

FIG. 1B is a perspective view of the implant of FIG. 1A;

FIG. 2A is a vertical sectional view of another species of individual hair implant in accordance with the invention;

FIG. 2B is an enlarged fragmentary view of a portion of the implant of FIG. 2A;

FIG. 3A is a vertical section of another species of individual hair implant in accordance with the invention;

FIG. 3B is an enlarged fragmentary view of a portion of the implant of FIG. 3A;

FIGS. ms and $8 are vertical section view showing another species of individual hair implant in accordance with the invention, immediately after implantation and at a later time, respectively;

FIGS. 5A AND 53 are vertical sectional and plan views, respectively, of a, large-scale implant in accordance with the invention; and

FIG. 6 is a perspective view, with parts broken away, showing schematically an arrangement for inserting an individual hair implant into the skin.

DESCRIPTION 0F SPECIFIC EMEODIMENTS T Referring now to the embodiment of the invention shown in FIGS. 11A and 11B by way of example only, there is shown an implant 6 of the single hair type in position in the skin 8 of a human scalp. In the drawing the well-known layers of the skin are represented schematically and consists of the epidermis 10 directly overlying the corium or dermis 112, immediately under which is located the subcutaneous tissue M, The outer layer 16 of the epidermis is the stratum corneum, composed of scalelike keratinized cells which are continuously sloughed off from the skin surface. The inner layer of the epidermis is the convoluted or ridges stratum germanativum llb in which new skin cells are produced by reproductive division. The newly generated skin cells rise gradually from the stratum germanativum, growing and become flattened along the horizontal direction, work their way upward to the stratum corneum, and become increasingly keratinized as they travel outward to the external skin surface. In the epidermis there is therefore a continual generation, growth and upward migration of skin cells. The underlying corium or dermis 112 contains blood vessels and nerves which service the under side of the stratum gerrnanativum, and the cells of the corium do not participate in the above-described cell migration to the skin surface.

The hair implant 6 comprises a percutaneous portion 20 extending from the stratum corneum to the exterior of the skin surface. In this example the percutaneous portion 20 may comprise a head 22 formed on the exterior of and around the hairlike filament 24 which constitutes the external hair and which extends through bead 22 into the underlying skin and tissue. Preferably bead 22 includes a tapered transition 27 from the percutaneous portion 20 to the external portion of filament 241 so as to provide a gradually increasing flexibility of the implant with distance from the skin surface and thereby minimize tendencies for the filament 24, to break off at the ex terior of the percutaneous portion.

It is noted that, in this example, the diverging cross section of the percutaneous portion of the implant formed by bead 22 extends from the stratum germanativum 11b to the external skin surface, this portion of bead 22 preferably having a generally cross section and smooth lateral surfaces so that the epidermal cells can slide readily upward along the lateral surfaces of the percutaneous portion of the implant. The growth vectors of the individual cells in the epidermis and the effective growth pressure due to the stratum germanativum, in conjunction with the natural elasticity of the skin, tend to create a sealing pressure between the lateral surfaces of the percutaneous portion of the implant and the surrounding epidermal skin, thereby to seal the underlying skin against infectious material entering from the exterior. This is opposed to the situation which would exist if the lateral surfaces of the percutaneous portion of the implant were normal to the plane of the adjacent skin surface or at an obtuse angle with respect thereto, in which case there would be less of a sealing effect between skin and the percutaneous portion of the implant and a greater possibility of infectious invasion by foreign bodies or organisms.

In the preferred form of the invention this sealing of the interface between implant and skin surface is further enhanced by use of a material for the percutaneous portion 20 which is similar in elasticity to that of the adjacent living skin. For this purpose a medical grade of silicone rubber is preferred, such as that known by the trade name Silastic and available from the Dow Corning Corporation. Use of such a material is par ticularly effective in preserving the interfacial seal between implant and surrounding skin when the skin tends to move away from the implant due to mechanical forces, such as those that may be due to rubbing or wrinkling of the skin for example.

The tissue-penneable anchoring position of implant d is located below the percutaneous portion 20 and is positioned so as to lie in the corium and subcutaneous tissue. This portion is adapted to be. anchored or retained by intergrowth therewith of living tissue of the corium and of the tela subcutanea. In this example the tissue-permeable structure is provided by a plurality of microvelour loops such as 30 disposed along the exterior of the lower end of filament 24, in the corium and subcutaneous tissue. Each of the microvelour loops has an open central aperture through which tissue grows so that the loops become completely permeated by growing, interlocked tissue and are thereby anchored in position in the corium and subcutaneous tissue.

Preferably there are also employed tissue-impervious implant-stabilizing elements in the form of filamentary processes M, secured to the implant s in the vicinity of the stratum germanativum lb and the adjacent epidermis but below the stratum corneum 36. Because of some unavoidable variability in the degree of insertion of the implant into the skin and in the dimensions of the skin layers, the tissue-permeable loops 3b are limited to a region spaced below the bottom of the stratum germanativum and the filamentary processes 34 are provided over a length of the implant extending from slightly below to slightly above the stratum germanativum. In this example the filamentary processes 34 may be provided by clipped velour or micropile, applied as a fabric or as individual filaments and secured to the outer surface of the implant. These implant-stabilizing filamentary processes contain no closed loops or interstices, and in this sense are not pervious to tissue growth. Accordingly, while they will become imbedded in the skin so as to provide a positionally stabilizing influence on the upper portion of the implant, they do not interfere with the necessary release and upward gradual migration of the cells of the epidermis, since the cells are not trapped by the filamentary processes and can readily pull away from the processes and move upwardly to the external skin surface as required. All portions of the implant inserted within the skin and subcutaneous tissue are preferably composed of medicalgrade body-compatible materials.

Accordingly, our novel configuration and composition of the percutaneous portion of the implant greatly reduce the possibility of local infection from the exterior, and our novel construction of the anchoring position of the implant maintains positional stability and avoids rejection problems.

In the embodiment shown in FIGS. 1A and 1B the filament 24 is arranged to extend at an angle less than normal to the surface of the adjacent skin for cosmetic effect, but it will be recognized that it is possible to utilize a normally extending external filament in which case an implant structure can be utilized which is symmetrical about the axis of the filament 24.

Without thereby in any way limiting the scope of the invention, the following specific example of an arrangement in accordance with FIGS. 1A and 1B is supplied in the interest of complete definiteness. Filament 24 may be a natural hair, or a synthetic hair of a material such as that known as Dynel, or a filament of any other suitable material having the requisite appearance and strength. if desired, the external visible portion of filament 24 may be selected entirely for cosmetic appearance, and that part which is in contact with living tissue may be subjected to a surface treatment to render it more highly tissue-compatible, as by coating it with any of various known inorganic or organic films which have a high degree of compatibility with living tissue. The percutaneous portion 20, and in fact the entire bead 22, may be composed of Silastic or similar high-quality medical silicone rubber, or may comprise some other body-compatible mechanically stable material having appropriate elastic properties, such as highly hydrated hydrogel compositions with or without fibrilar reinforcement. The microvelour loops utilized for bonding by tissue intergrowth in the corium and subcutaneous tissue may be of a synthetic body-compatible material such as Dacron, and the micropile fragmentary processes 34 may be of the same material. Suitable microvelours and micropiles may be made by recently-developed microknit processes.

Various methods for installing the implant of FIGS. 1A and 18 will readily occur to one skilled in the art, While sophisticated equipment may readily be designed for the purpose of expediting the implantation of a large number of implants simultaneously or in rapid sequence, satisfactory through slower implanting may be accomplished, one implant at a time, by presently known apparatus. In these methods it is important to emplace the tissue-permeable artificial hair anchor in a position which will permit optimum intergrowth of body cells and thus provide a natural anchoring. This must take place in or below the corium since the growth pattern of the epidermis is generally outward and any intergrowth will only carry the hair along with it, leading ultimately to expulsion. Generally, therefore, the lower end of the anchor will be in the subcutaneous tissue. Hair follicles should be avoided for optimum intergrowth.

The outwardly diverging taper of the percutaneous portion of the hair implant should be so located in the epidermis that as the skin cells gradually become keratinized, shrink and die, they will slide outwardly along the cone surface while maintained in tension by the elastic divergent-cone configuration.

To insure proper placement, therefore, the anchor and the cone should be located sufficiently far apart to permit subcutaneous implantation of the anchor, while the upper end of the cone is located above the skin surface by a distance sufficient to prevent overgrowth by adjacent tissue, i.e. l-20 mils. This may be controlled visually or by setting of a depth stop on the implanting apparatus which uses the epidermal surface as a reference, as will now be described.

FIG. 6 shows schematically one form of apparatus which can be used for implanting an individual hair implant, A hollow externally threaded barrel 35 is mounted in an axially adjustable position with respect to a depth-stop frame 36 having indexing arms 35A AND 353 extending outwardly at about to the axis of the barrel. A hollow split needle 37 is divided into the two

segments

37A and 37B, mounted for movement apart and together by means of

arms

38A and 38B respectively. Boss 39 supports the pivots for

segments

37A and 37B, and is upwardly slidable on barrel 35 against light spring pressure from spring 39A; downward motion of boss 39 is prevented by snap ring 393.

in use, the

arms

38A and 38B are squeezed inwardly to open the split needle and the implant 6 inserted so that its upper conical surface extends into and bears against the lower end of barrel 35, with hair 24 extending upward through the barrel to the exterior, and the arms moved outwardly to close the needle. The interior bore of the split needle is preferably small enough to exert some compressive force on the anchor portion of the implant, and if desired a spring may be used to urge

arms

38A and 38B apart and the needle segments together. Needle 37 is inserted into the skin until indexing

arms

35A and 35B bear against the external skin surface. The implant is thereby positioned at the desired depth of the skin. While holding arms 35A and 358 in contact with the skin, the

arms

38A and 38B are squeezed together to open the split needle, and are then pulled axially upward against spring 39A to remove the needle from the skin. The entire instrument may then be moved away from the skin, leaving the implant in place. The expansion of the previously compressed anchoring portion will provide substantial fixing of the implant in position during the latter step; however, any tendency toward pulling-out of the implant due to its adherence to barrel 35 may be obviated by automatically or manually restraining the implant against such outward movement while the entire instrument is being removed from the immediate vicinity of the skin.

In one example of the implantation procedure, an artificial implant having an external hair of the desired length attached to its is selected from a sterile-sealed envelope, in which it has been stored in a manner similar to that used for storage of surgical sutures. The skin surface is vigorously scrubbed with a disinfectant cleanser such as alcohol, Phisohex, or the like. Appropriate anesthesis may be administered as desired. The implant is place in a split needle tool, which may be like that of FIG. 6 or some other form of implantation tool such as that described in the above-cited U.S. Pat. No. 1,061,005. The depth stop is adjusted so that the divergent conical portion of the implant will extend to 10 to 20 mils above the surface of the skin. The needle is inserted, as described above, at an angle of about 70 to 80 to the skin surface until the depth stop contacts the skin. The needle is then released and removed, and then the entire tool is removed as set forth above. Surface dressing are preferably applied, as in any minor skin wound.

Greater automation of the implantation process can be achieved by various known mechanical techniques, such as those described in the cited U.S. Pat. No. l ,061 ,005.

As mentioned above, by appropriate dimensioning and shaping of the bore in the split needle, the anchor portion can be compressed while in the needle so that, upon subsequent release in the skin, the resulting expansion of the anchor portion will enhance the implant stability.

The principle of the Hypospray injector can also be applied to the emplacement of the hair implants. With such a device, each hair, contained in normal sterile saline, can be injected without mechanically puncturing the skin. The unit would be adjusted to accommodate the skin resistance, and thus control the depth of penetration to achieve that desired. The skin is sterilized as described above.

In many instances, implantation of rows of hair would be preferred. Such can be accomplished by preparing a row of appropriately spaced hair implants adhering to and extending laterally from a tape of adsorbable gelatin sponge. The skin is sterilized as described above, and a scalpel cut is made at an angle through the skin and into the subcutaneous layers. The gelatin sponge tape, with the positioned hair implants on it is laid edgewise into the slit at the appropriate depth with the hairs protruding, and a few sutures used to close the wound. its natural healing occurs, the gelatin will be metabolized, thus permitting the desired tissue ingrowth and permeation of the anchoring position of each of the hair implants.

FIGS. 2A and 2B illustrate a modification of the implant of FIGS. 1A and ER with respect to the nature of the anchoring structure employed. Thus in the embodiment of H68. 2A and 2B the microvelour loops of HG. l are replaced by the microporous polymer Ml arranged along, and appropriately secured to, the lower or internal end of the implant as shown. FIG. 2B shows 28 more detail one possible general appearance of such a microporous polymer. The polymer material again is one which is of high purity and high compatibility with human tissue, and its construction is that of a plurality of interconnecting internal pores whereby intergrowth of tissue through the tissue-pervious polymer will result in a positive locking of the anchoring portion in desired position in the skin and subcutaneous tissue. Such microporous elastomers may be formed, for example, by pouring the liquid unset polymer material around a plurality of leachable of soluble particles of filaments in contact with each other and then causing the elastomer to set; one suitable leachable material, for example, is polyvinyl alcohol in the form of fine particles. The leachable material is then dissolved in an appropriate solvent which in the case of polyvinyl alcohol may be water, to remove the leachable material and to leave corresponding interconnected pores throughout the interior of the structure. The size of the leachable inclusions can be selected and adjusted to provide optimally sized and shaped channels for cellular intergrowth.

FlGS. 3A and 3B illustrate a modification of the arrangement in FlGS. HA and lb, in which the microvelour anchoring structure is replaced by molded reticulated polymer material 42. This shape of material is well-known and is similar to small-pore reticulated polyurethane foam, but in this case it is preferably coated with, or made entirely from, a more bodycompatible material. For example, reticulated polyurethane foam of the type known a Scott Foam, and manufactured by Scott Paper Company, can be coated with Silastic or other suitable air-cured polymer, or with any other suitable bodycompatible surface film, FlG. 3A shows one possible configuration of such a reticulated elastomer, although many other forms and shapes may be used instead.

FIGS. 4A and 4B illustrate a modified form of the implant of H68. 1A and 113 using a hydrogel for anchoring, shown at different successive times following its implantation. Thus FlG. 4A illustrates this species of implant after just implantation, and FIG. 4B shows the same structure sometime later, after it has absorbed fluid from the tissues so as to have expanded substantially, and after tissue intergrowth has occurred to provide the desired anchoring action. in this case the microvelour is omitted from the implant and instead the corresponding portion of the filamentary member 2 is coated before implantation with a layer 5% of a polymeric highly hydrated hydrogel of a type which will swell in a aqueous system and in body fluids to a controlled water content of about 50 percent to 85 percent. Such gels are hydrophilic, but water insoluble. Exam ple are, simple hydrogels of polyacrylic acid and polyvinyl alcohol, prepared from an aqueous solution containing equal quantities of the acid and alcohol by casting on a glass plate, drying and curing. These materials may be applied to the lower portion of the filamentary member where bonding is to occur with the living tissue. A short time after insertion, typically about 1 to 8 hours, the hydrogel will assimilate sufficient fluid from the body tissues to swell substantially, as illustrated in H6. 43 for example. This swelling in itself provides a useful mechanical anchoring property. However, the principal anchoring effect is by virtue of the fact that the hydrogels have a molecular structure which permits ready ingrowth and intergrowth by surrounding living tissue, so as to lock the anchoring portion of the implant firmly in the desired position.

in the embodiment of the invention shown in FlGS. 5A and 5B the hair implant comprises a relatively large-scale button 70 anchored in the skin and underlying subcutaneous tissue and adapted to retain a large number of external hairs such as 72 on the outer surface thereof. in this case the plug 70 is generally circular in cross section, but it may have any desired cross-sectional shape, such as elliptical for example, and may cover a major portion of the scalp region. Plug 761 comprises a percutaneous portion 741 extending through the external surface of the skin, the cross section of button 70 in this region being divergent toward the exterior so as to provide again an acute angle between the periphery of the external portion of the button 70 and the immediately adjacent and surrounding skin surface. Hairs 72 may be secured in any convenient manner, as by cementing into corresponding small bores in plug '70.

Plug 76) is also preferably of a resilient material having elastic properties similar to those of the adjacent skin, and may be of medical-grade silicone rubber. The implant again has an anchoring portion extending below the surface of the skin and into the subcutaneous tissue, comprising tissue-pervious means such as microvelour loops lit) along the bottom and lower side surfaces of the button, as well as a skirt til of a mesh of body-compatible material such as Dacron extending laterally outward around the periphery of the button and into the surrounding corium. Tissue-impervious filamentary processes M, which again may be in the form of micropile, are disposed along the side surfaces of the button 70 from just below to just above the stratum germanativum, for additional positional stability. To insert the implant, a portion of the skin may be surgically removed over an area into which the implant may fir closely. The skin at the sides of the opening may be slit at several places, along a radial direction with respect to the vertical axis of the implant, and also split horizontally in the corium. The implant may then be placed in position, the skirt laid-out between the split layers of the corium, and the corium closed by suturing. Upon healing and subsequent regrowth, the implant will be anchored by the intergrowth of tissue through the loops hill and through the open mesh of the skirt bl, as well as by growth around the micropile 82. The acute angle formed between the percutaneous portion and the adjacent external skin surface again enhances sealing of the interface between skin surface and implant to reduce possibilities of infection.

Without thereby limiting the scope of the invention, the following examples are given of some of the ways in which the implants of the invention may be fabricated.

To fabricate the velour-loop embodiment of FlG. llA, either an artificial hair (e.g. Dynel) or a natural hair is selected and the Silastic bead is formed and secured to the hair by casting in a mold. Alternatively, the bead may be cast with a central bore through which the hair is later passed and to which the hair is cemented. Velour loops of a body-compatible material such as Dacron are formed and placed in a container. The end of the hair to be inserted in the scalp is coated with an appropriate adhesive, and agitated in the assemblage of tiny loops before the adhesive sets, until said end is covered with the adhering loops. Medical-grade silicones may be used as the adhesive in most cases. Alternatively, the adhesive-coated hair may be given an electrostatic charge to aid in picking-up the small loops. Those loops affixed to the hair above the level which will be located in the corium are cut at their outer ends to produce cut pile" filamentary processes. The uncut loops may typically extend about 10 cured, to 20 mils from the sides of the hair, when not compressed. The adhesive is then curved, and the entire implant thoroughly washed with warm or hot water, sterilized by autoclaving or by ethylene oxide treatment, and then hermetically sealed in a normal salinecontaining envelope in the manner usual for storage of medical sutures. When implantation is to be performed, the im plant is removed from the envelope and implanted as described previously herein, appropriate medical sterilization and antisepsis techniques being used throughout the procedure.

To fabricate the microporous-elastomer implant of FIGS. 2A and 2B, uncured medical-grade silicone elastomer (preferably Silastic) is mixed with a soluble powder of sized (e.g. -50 micron) powder. Sodium chloride, calcium carbonate and zinc oxide are examples of materials which may be used, in addition to materials like the above-mentioned polyvinyl alcohol. Enough powder is used to assure that most of the particles will touch other particles in the mixtures, and preferably so that mixture will hold its shape. The mixture is placed in a mold having the shape and size desired for the hair anchor, using a split die. A Teflon-coated rod is placed into the center of the mixture and extends outwardly above it. The die is then removed, and the surfaces of the molded mixture lightly abraded to assure exposure of particle material. The soluble powder is then dissolved out, using hot water or dilute acid or whatever solvent is appropriate for the particular soluble material, to produce the desired pore structure. Removal of the Teflon-coated rod provides an opening to receive the hair end, which is then cemented in the opening. The percutaneous bead may be formed and applied generally as described with reference to fabrication of the implant of FIG. I, as may the cut pile.

To fabricate the reticulated foam elastomer embodiment of FIG. 3A, a polyurethane or other appropriate polymeric material having the form of a reticulated foam of appropriate cell size (e.g. 200-500 mesh) is cut to the size desired for the hair anchor. Each filament of this structure is then coated with successive layers of Silastic cement cured between each coating until all of the material is covered by the coating and the cell size is in the desired range (e.g. 50l00 microns). The percutaneous bead may be formed, the hair secured, and the cut pile provided generally as described in connection with the previous examples of FIGS. IA and 2A.

To fabricate the hydrogel embodiment of FIG. 4A, a hydrogel (such as glycol methacrylate or ionic type) is polymerized (or formed) into the desired shape for the hair anchor. After washing, it is dehydrated, as by vacuum-freeze drying or lyophyllization. Its upper surface is then coated with a glow-discharge-pclymerized coating which is controlled to be compatible with an adhesive appropriate to the material which is used for the percutaneous bead. In this example, ethylene-propylene rubber is preferred as the material for the bead. Other steps of fabrication of bead and cut pile may be similar to those for FIG. I.

To fabricate and install the larger-scale implant of FIG. 5A, or a complete scalp piece, many of the techniques described with reference to the individual hair implants are applicable. The skin preparation is first carried out as previously described, and the skin then excised in the implant region to the depth necessary to locate the implant at the depth previously described. Care is taken to assure a close peripheral fit between the implant and excision. Normal surgical procedures are used to fix and protect the implant temporarily until tissue ingrowth provides a satisfactory anchor and peripheral seal.

It will also be understood that the implant and method of the invention as useful even if, due to variations in implant dimension or in position of implantation, some of the implants are not effective and are not retained, so long as a satisfactory percentage are properly effective and retained. In some cases preliminary skin tests and examination will be helpful in enabling selection of the optimum dimensions of implant and depth of implantation for a particular skin area of a particular implant-recipient.

While FIGS. 5A and SB illustrate the large-scale implant anchored by loops as in the FIG. 1 embodiment, the microporous polymer, reticulated foam polymer or hydrogel anchoring structures of FIGS. 2A, 3A and 4A may also be used. In the case of hydrogel anchoring, more extensive suturing may be required for initial fixation while awaiting tissue intergrowth.

While the invention has been described with particular reference to specific embodiments thereof in the interest of complete definiteness, it will be understood that it may be embodied in any of a variety of forms diverse from those specifically described without departing from the scope of the invention.

We claim:

I. A hair implant stnicture for use in living skin, comprising: a percutaneous portion; at least one hairlike filament secured to and extending in a first direction from said percutaneous portion; and a tissue-growth pervious anchor portion on the opposite side of said percutaneous portion from said filament; whereby when said anchor portion is inserted through the surface of the skin into living tissue subsequent intergrowth of said tissue through said anchor portion will form a positive lock against removal of the implant.

2. The implant structure 'of claim 1, comprising an intermediate tissue-growth impervious portion between said anchor portion and said percutaneous portion.

3. The implant structure of claim 2, comprising a plurality of tissue-growth impervious filamentary processes secured to said intermediate portion and each short compared to said hair like filament.

4. The implant structure of claim 1, in which said tissuegrowth pervious anchor portion extends to a distance from said percutaneous portion which isgrcater than the maximum thickness of the epidermis of the normal human scalp, whereby when said structure is implanted in a human scalp said tissue-growth pervious anchor portion will extend into the living tissue below the stratum germinativum.

5. The implant structure of claim 4, in which said distance is greater than about 2 mils.

6. The implant structure of claim 4, in which said structure has a substantially tissue-growth impervious portion extending from a distance, measured from said percutaneous portion in the direction of said anchor portion, which is slightly greater than the maximum thickness of the epidermis of the normal human scalp.

7. The implant structure of claim 6, in which said lastnamed distance is slightly greater than about 2 mils.

8. The implant structure'of claim 6, in which said tissuegrowth impervious portion is provided with tissue-growth impervious filamentary processes for stabilizing said structure in its implanted position.

9. The implant of claim 1, comprising a tissue-growth pervious skirt secured to and surrounding a pair of said anchor portion.

10. The implant structure of claim 1 in which said percutaneous portion has a cross section diverging in the direction extending away from said anchoring portion toward said filament, thereby to provide an acute angle between the lateral surface of said percutaneous portion and the adjacent surface of the skin in which it is to be implanted.

11. The implant structure of claim I in which said anchoring portion comprises closed microvelour loops.

12. The implant structure of claim I in which said anchoring portion comprises a microporous polymer pervious to growing tissue.

13. The implant structure of claim 1 in which said anchoring portion comprises a reticulated foam polymer pervious to growing tissue.

14. The implant structure of claim 1 in which said anchoring portion comprises a hydrogel pervious to tissue growth.

15. A hair implant for use in living human skin, comprising a generally hairlike member having at one end a tissue-growth pervious anchoring portion having a resilient percutaneous portion and having another portion disposed on the opposite side of said percutaneous portion from said anchoring position and having the appearance of human hair;

said percutaneous portion having a cross section diverging in the direction extending away from said anchoring portion toward said other portion thereby to provide an acute angle between the lateral surface of said percutaneous portion and the surface of the skin when it is implanted.

ill

16. The implant of claim 115 in which said percutaneous portion is in the general form of a cone having its altitude disposed generally along the length of said hairlike member.

H7. The implant of claim 15, in'which said member comprises a tapered resilient transition from said percutaneous portion to said other portion.

18. The implant of claim R5, in which said percutaneous portion is of a material having elastic properties similar to the skin of the human scalp.

19. The implant of claim 18, in which said material is silicone rubber.

20. The implant of claim 115, in which at least a part of said anchoring position is spaced from said percutaneous portion by a distance greater than the approximate distance between the external surface of the human skin and the outer side of the subcutaneous tissue, whereby said anchoring portion may be positioned at least partly in subcutaneous tissue.

Zll. ln a'hair implant having a percutaneous portion, having an anchoring portion on one side of said percutaneous portion and having at least one hairlike filament extending from the side of saidpercutaneous portion opposite from said anchoring portion, the improvement wherein said percutaneous portion has a cross section which increases in the direction extending away from said anchoring portion toward said filament, thereby to provide an acute angle between said percutaneous portion and the external surface of the skin in which it is to be implanted.

22. The structure of claim 21 in which said percutaneous portion is of a resilient material having elastic properties similar to those of human skin.

Claims

1. A hair implant structure for use in living skin, comprising: a percutaneous portion; at least one hairlike filAment secured to and extending in a first direction from said percutaneous portion; and a tissue-growth pervious anchor portion on the opposite side of said percutaneous portion from said filament; whereby when said anchor portion is inserted through the surface of the skin into living tissue subsequent intergrowth of said tissue through said anchor portion will form a positive lock against removal of the implant.

2. The implant structure of claim 1, comprising an intermediate tissue-growth impervious portion between said anchor portion and said percutaneous portion.

4. The implant structure of claim 1, in which said tissue-growth pervious anchor portion extends to a distance from said percutaneous portion which is greater than the maximum thickness of the epidermis of the normal human scalp, whereby when said structure is implanted in a human scalp said tissue-growth pervious anchor portion will extend into the living tissue below the stratum germinativum.

7. The implant structure of claim 6, in which said last-named distance is slightly greater than about 2 mils.

8. The implant structure of claim 6, in which said tissue-growth impervious portion is provided with tissue-growth impervious filamentary processes for stabilizing said structure in its implanted position.

11. The implant structure of claim 1 in which said anchoring portion comprises closed microvelour loops.

12. The implant structure of claim 1 in which said anchoring portion comprises a microporous polymer pervious to growing tissue.

15. A hair implant for use in living human skin, comprising a generally hairlike member having at one end a tissue-growth pervious anchoring portion having a resilient percutaneous portion and having another portion disposed on the opposite side of said percutaneous portion from said anchoring position and having the appearance of human hair; said percutaneous portion having a cross section diverging in the direction extending away from said anchoring portion toward said other portion thereby to provide an acute angle between the lateral surface of said percutaneous portion and the surface of the skin when it is implanted.

16. The implant of claim 15 in which said percutaneous portion is in the general form of a cone having its altitude disposed generally along the length of said hairlike member.

17. The implant of claim 15, in which said member comprises a tapered resilient transition from said percutaneous portion to said other portion.

18. The implant of claim 15, in which said percutaneous portion is of a material having elastic properties similar to the skin of the human scalp.

19. The implant of claiM 18, in which said material is silicone rubber.

20. The implant of claim 15, in which at least a part of said anchoring position is spaced from said percutaneous portion by a distance greater than the approximate distance between the external surface of the human skin and the outer side of the subcutaneous tissue, whereby said anchoring portion may be positioned at least partly in subcutaneous tissue.

21. In a hair implant having a percutaneous portion, having an anchoring portion on one side of said percutaneous portion and having at least one hairlike filament extending from the side of said percutaneous portion opposite from said anchoring portion, the improvement wherein said percutaneous portion has a cross section which increases in the direction extending away from said anchoring portion toward said filament, thereby to provide an acute angle between said percutaneous portion and the external surface of the skin in which it is to be implanted.