U.S. patent number 3,596,292 [Application Number 04/800,847] was granted by the patent office on 1971-08-03 for hair implant structure.
This patent grant is currently assigned to The Franklin Institute. Invention is credited to Robert A. Erb, Peter Schuyler Francis, William B. Tarpley, Jr..
United States Patent |
3,596,292 |
Erb , et al. |
August 3, 1971 |
HAIR IMPLANT STRUCTURE
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.
Inventors: |
Erb; Robert A. (Schuylkill
Township, PA), Tarpley, Jr.; William B. (West Chester,
PA), Francis; Peter Schuyler (Rose Valley, PA) |
Assignee: |
The Franklin Institute
(Philadelphia, PA)
|
Family
ID: |
25179526 |
Appl.
No.: |
04/800,847 |
Filed: |
February 20, 1969 |
Current U.S.
Class: |
623/15.11;
132/200; 606/187 |
Current CPC
Class: |
A61F
2/10 (20130101) |
Current International
Class: |
A61F
2/10 (20060101); A61f 001/00 (); A61b 017/00 ();
A41g 005/00 () |
Field of
Search: |
;3/1 ;128/330
;132/5 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Pace; Channing L.
Claims
We claim:
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.
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 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.
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 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.
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 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.
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.
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.
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.
Description
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 U.S. Pat. No. 1,059,631 of
Popovics, issued Apr. 22, 1913; No. 1,061,005 of Parsegan, issued
May 6, 1913; No. 3,003,155 of Mielzynski et al. issued Oct. 10,
1961; 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 extends 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 sufficient 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 large-scale
implants.
The method and structure of the invention are also useful when
applied to the skin of animals, as distinguished from humans.
BRIEF DESCRIPTION OF DRAWINGS
These and other objects and features of the invention will be more
readily understood from a consideration of the following detailed
description, taken with the accompanying drawings, in which:
FIG. 1A 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. 4A and 4B 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 5B 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 OF SPECIFIC EMBODIMENTS T
Referring now to the embodiment of the invention shown in FIGS. 1A
and 1B 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 12, immediately under which is located the
subcutaneous tissue 14, 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 18
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 12 contains blood vessels and nerves
which service the under side of the stratum germanativum, 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 bead 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 24 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 exterior 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 18 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 particularly 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-permeable anchoring position of implant 6 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
34, secured to the implant 6 in the vicinity of the stratum
germanativum 18 and the adjacent epidermis but below the stratum
corneum 16. 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 30 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 medical-grade 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 1B 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. 10--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
35B extending outwardly at about 80.degree.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 39B.
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 35B 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.degree. to
80.degree. 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. 1,061,005.
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. As 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 1B with respect to the nature of the anchoring structure
employed. Thus in the embodiment of FIGS. 2A and 2B the microvelour
loops of FIG. 1 are replaced by the microporous polymer 40 arranged
along, and appropriately secured to, the lower or internal end of
the implant as shown. FIG. 2B shows 2B 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.
FIGS. 3A and 3B illustrate a modification of the arrangement in
FIGS. 1A and 1B, 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 body-compatible 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 body-compatible surface film, FIG. 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 FIGS.
1A and 1B using a hydrogel for anchoring, shown at different
successive times following its implantation. Thus FIG. 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 24 is coated before implantation with a
layer 50 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. Example 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 FIG. 4B 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 FIGS. 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 70 comprises a percutaneous portion 74
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 70 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 80 along the bottom and lower side surfaces of
the button, as well as a skirt 81 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 82, 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 80 and through the open
mesh of the skirt 81, 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 FIG. 1A, 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 saline-containing envelope
in the manner usual for storage of medical sutures. When
implantation is to be performed, the implant 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. 15--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. 1, 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. 50--100 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. 1A 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-polymerized
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. 1.
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 5B 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.
* * * * *