Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROSTHESIS
This invention relates to a prosthesis which is
capable of being temporarily or permanently inserted or
implanted in the human body in order to fill in some
irregularities, to increase the volume and/or to modify the
external shape thereof.
A typical application of such prosthesis is in mammo-
plasty where the prosthesis takes the form of a mammary
implant. The following description will be directed to
such implants as a non-limitative aspect of the invention.
It is well-known that the present mammary prostheses
are generally made of an envelope of flexible silicone
film, having a more or less flattened spherical shape,
which is filled with a silicone gel, a physiological salt
solution or both. A disadvantage to the use of silicone
gel is the risk of leakage of the gel through the flexible
silicone film by transudation, or the loss of gel caused by
rupture or tearing of said film. This sometimes results in
reabsorption of the gel by the body with possible local or
even general complications. A disadvantage to the use of a
physiological salt solution is the risk of loss of solution
due to tearing or rupture of the flexible silicone film or
due to leaks, e.g. at the filling valve. Although this
does not have negative physiological consequences, a
decrease of the volume of the prosthesis occurs resulting
in an aesthetically unacceptable appearance necessitating
further surgery.
In an attempt to avoid such disadvantages prostheses
comprising a central portion filled with silicone gel and a
peripheral portion filled with physiological solution have
been suggested in order to hinder the transudation of the
gel. In fact such composite prostheses suffer from all
the drawbacks described above.
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Prostheses have also been proposed which comprise
means of progressive temporary or permanent expansion
effected by injection of e.g. saline solution in situ
during surgery or over a longer or shorter period in order,
for example, to induce skin development (tissue expansion)
in the area concerned. However, in addition to the above
mentioned drawbacks the use of such prostheses involves
several surgical interventions in order to obtain a
permanent implant or to remove the filling valve.
It should also be remembered that the insertion of an
implant into an organism results in the spontaneous
creation, around said implant, of an exclusion membrane
which can be retractile and which can cause the formation
of a hard capsule, especially in the case of a mammary
implant (capsule retraction phenomenon). Such capsule
necessitates surgical intervention for its removal.
The object of the present invention is to provide a
prosthesis which overcomes the above mentioned
disadvantages. This is achieved by using a new structure
which avoids the use of a silicone gel and which prevents
the risk of loss or leakage of the physiological solution.
Furthermore the new structure allows the modification of
the volume of the prosthesis as desired so as, for example,
to obtain a permanent implant without the need for any
further surgical intervention.
The present invention, in one aspect, resides in a
prosthetic implant comprising:
a flexible membrane defining a closed compartment filled
with a continuously-adjustable amount of bio-compatible
fluid contained within a plurality of individual closed
cells each containing a small closed volume of less
than 1 cc of the bio-compatible fluid, whereby no
visible or tactile irregularities are presented and
only minimal loss of fluid is allowed upon puncture.
CA 02000566 1999-06-28
3 (a)
The present invention also provides a prosthetic
implant comprising:
a first flexible membrane defining a first closed
compartment;
a second flexible membrane, spaced inwardly from the first
membrane and enclosing a second closed compartment
which is contained within the first compartment, the
second compartment being filled with a continuously-
adjustable amount of bio-compatible fluid; and
a distinctive intermediate unit, disposed within a
peripheral space defined between the first and second
membranes, the unit comprising individual closed
microcapsules each containing a small closed volume of
less than 1 cc of bio-compatible fluid.
The present invention further provides a prosthesis
comprising a peripheral silicone membrane which defines
a first closed compartment characterised in that the
volume delimited by said membrane is filled with a
number of individual closed cells, each delimited by a
silicone membrane and filled with bio-compatible
fluid, said small cells being distributed around a
second compartment, delimited by a closed silicone
membrane which is thicker than the silicone membrane
delimiting the individual cells, said compartment being
filled with an adjustable quantity of a physiological
salt solution, the said membranes comprising a
predetermined portion thicker than the rest of each of
said membranes, which is self sealing after being
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3 (b)
punched by a needle adjusting the quantity of said
physiological salt solution.
The present invention still further provides an implantable
mammary prosthesis comprising:
a first flexible silicone membrane defining a first closed
compartment;
a second flexible membrane having an upper hemisphere with a
thick silicone film punchable and self-sealing and a
lower hemisphere made of extensible silicone film
adapted to distend the shape of the implant, the second
membrane being spaced inwardly from the first membrane
and enclosing a second compartment which is contained
within the first compartment, the second compartment
being filled with a continuously-adjustable amount of
physiological salt solution; and
a distinctive intermediate unit, disposed within a
peripheral space defined between the first and second
membranes, the unit being filled with individual closed
microcapsules each containing a small closed volume of
less than 1 cc of physiological salt solution and being
glued together with a silicone adhesive.
The peripheral silicone membrane is preferably
comparatively thin, for example 1 to 5mm, in order to be
flexible, deformable and adaptable to varying shapes.
Silicone compositions which are useful for the preparation
of such membranes are well-known in the art and have been
described in the literature. the membrane may comprise a
r'' I~v.
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thicker portion which can be punched by a needle, e.g. to
inject physiological solution into the prosthesis, said
thicker portion being a self-sealing silicone film.
According to a modification of the invention the peripheral
silicone membrane or film can be made of a self-sealing
flexible silicone film in order to allow expansion of the
peripheral membrane may comprise one or more rigidified
portions, e.g. portions made of thick strips of silicone,
with a view to give the filled prosthesis a different shape
e.g. a more flattened spherical shape due to the relative
resistance by these strips to lateral pressure.
The small individual closed cells which fill the
peripheral silicone membrane are of a hermetic nature, are
delimited by a thin membrane, e.g. having a thickness of 0.1
to 1 mm, and are filled with a fluid such as air, another
bio-compatible gas, a physiological salt solution or another
bio-compatible liquid. When the content of the small cells
is for example a physiological solution the cells will be
incompressible. On the other hand, if the small cells are
filled with air they will be somewhat 'elastic' in nature.
Due to the hermetic nature of each small cell the assembly
of these cells cannot be simply drained of its content. A
substantial loss of fluid can therefore not happen
accidentally. It is, however, true that punching a needle
through the prostheses in order to reach the central
compartment will rupture some of the individual small cells
but the resulting loss of fluid is small and of little
CA 02000566 1999-06-28
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significance due to the limited size of these yells. It is
consequently preferred that each small individual closed
cell should be as small as possible and most preferably have
a volume smaller than lcm3. The invention accordingly also
covers the use as small cells of microcapsules well-known
e.g., in the art of carbonless copying and in the
pharmaceutical field.
According to a modification of the invention the
assembly of small individual closed cells can comprise a
silicone foam consisting of closed alveoli. Commercially
available silicone foams tend to comprise a spongy mass of
open alveoli which are intercommunicating. Such silicone
foams are not acceptable as in case of leakage the entire
mass would be drained of the fluid and the structure
comprising such mass might collapse. In the modification
of the invention using the silicone foam consisting of
closed alveoli however, it might prove difficult to fill
the closed alveoli with the bio-compatible fluid. This
could be achieved e.g. by polymerisation of the foam in an
aqueous medium or by dipping the already polymerised foam
into an aqueous medium under very high pressure or by any
other means which does not open the alveoli.
The central compartment has a silicone membrane which
is at least in part similar in nature to the part of the
peripheral membrane which is made of self-sealing flexible
silicone. Preferably the silicone membrane of the central
compartment is made of two hemispheres, one hemisphere
being made of self-sealing needle punchable material, e.g.
a thick silicone wall or any other anti-leakage material
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whilst the other hemisphere is made of extendible silicone
film allowing variation of the volume of the central
compartment and hence of the prosthesis. The central
compartment is filled with a physiological solution. The
self-sealing needle punchable part of the compartment
allows the addition to, or extraction from, the central
compartment of physiological solution, e.g. during a
surgical intervention.
The advantages of the structure of the prostheses
according to the invention are clear and include the fact
that in case of accidental rupture or tearing of the
peripheral membrane of the prosthesis, or of non-closing of
said membrane after puncturing it with a needle for
inflation or deflation of the prosthesis, only the ruptured
small cells are emptied of their contents whilst the
remaining untouched small cells help to retain the overall
shape and volume of the unit. The well-known phenomenon of
'waves' displayed by the prior art mammary prosthesis is
thereby prevented. Due to the presence of the central
compartment it is possible to adjust the volume of the
prosthesis, both during and after, a surgical intervention
by simply inserting into the prosthesis a needle in order
to extract or inject the requested amount of physiological
solution from, or into, the central compartment. Such
adjustment may be done with a single extraction or
injection or with a number of consecutive extractions and/
or injections. The prosthesis usually has an initial
volume which can be adjusted during a surgical operation
directly through the peripheral membrane into the central
compartment, or after the operation through e.g. the breast
into the prosthesis. The advantage lies therefore in the
possibility of modifying the volume of the prosthesis
without the need for extra surgical intervention.
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A practical application is, for example, the
combating of the capsule retraction phenomenon. This may
be achieved by hyperinflation of the prosthesis at the time
of the implantation, followed by a decrease of the volume
after some weeks. If the capsule formation occurs at a
later stage the prosthesis can be inflated at that time by
transcutaneous punching, and decreasing its volume upon
cessation of the capsule retraction phenomenon, without the
need for further surgery. Another application lies in the
use of the prosthesis as a valueless tissue-expansion
system which is especially useful in the case of mammary
reconstruction when it is desired by distension and growth
of new thoracic skin to recreate local conditions on
obtaining a new breast. In this case the prosthetic
implant may be distended by transcutaneous punchings,
followed by a further punching when the cutaneous state is
found to be satisfactory in order to reach the desired
mammary volume.
The prostheses according to the invention may alter-
natively, or additionally, comprise peripheral compartments
such that the prosthesis consists of several portions which
can be inflated or deflated independently. This modifica-
tion allows the accommodation of the prosthesis to specific
or complex thoracic distortions or to the distension of a
given portion of the prosthesis, for example the lower
portion of a mammary implant in the process of breast
reconstruction.
In a further modification a peripheral compartment,
which may be located around the peripheral silicone
membrane, is provided with facets which swell when the
compartment is pressurised by injection of physiological
solution. Said facets give rise to discontinuities in the
peripheral silicone membrane or film of the prosthesis,
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thus minimising the contractile possibilities of a peri-
prosthetic capsule. This peripheral compartment may be
inflated and deflated by transcutaneous punching.
In order to ensure coherence of the prosthesis
comprising a central compartment and many small volumes it
is preferred to have the different parts coated with an
adhesive, e.g. a silicone adhesive, thereby joining each
part to its neighbour.
Prostheses according to the invention may have
different shapes according to the intended use and the
region of the body in which they are to be inserted or
implanted, for example breast, leg, chin and scalp. In
each case the prosthesis provides the main advantage of
adaptability during, and particularly after, an operation
without necessitating further surgery.
Prostheses according to the invention may be provided
in an aqueous medium, for example in a bag of physiological
solution. This would avoid any dehydration of the pros-
thesis and also prevent any direct contact with the
surgeon's hands when the prosthesis is inserted.
There now follows a description which is to be read
in conjunction with the accompanying drawing of a
prosthesis according to the invention adapted for use as
a mammary implant. The drawing is a section of a mammary
prosthesis.
The prosthesis is delimited by the peripheral
silicone membrane (1). This membrane (1) is relatively
thin, 1 to 5mm, in order to maintain its flexibility and
variable shape. It comprises equatorial portions (2) which
are comparatively thicker, 5 to lOmm, in order to make them
more rigid, thus imparting a flattened spheroidal shape to
the prosthesis. A portion (3) of the membrane (1) has a
self-sealing needle punchable nature in order to allow the
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injection or extraction of physiological solution from the
prosthesis. This portion (3) is relatively thicker than
the rest of membrane (1), 2 to 5mm.
Central to the prosthesis is a central compartment
(4) which comprises a membrane with an upper portion (6),
the thickness of which is such that the membrane is self-
sealing when punctured by an injection needle and a lower
portion (7), which is thinner than (6), in order to be
extensible to allow the implant to change its volume or
shape.
Between the membrane (1) and the central compartment
(4) are a great number of small closed volumes (5) each
being hermetically delimited by a thin membrane, 0.1 to
lmm. These volumes (5) may be filled with air, a physio-
logical solution or any other bio-compatible gas or liquid
medium. Each of the volumes (5) has a volume which is
preferably smaller than lcm3 the size being compatible with
the process for filling the volumes (5).
