Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Having bio-absorbable component
Reexamination Certificate
1999-08-24
2001-07-24
Prebilic, Paul B. (Department: 3738)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Having bio-absorbable component
C623S023760, C606S213000, C602S049000
Reexamination Certificate
active
06264702
ABSTRACT:
The present invention concerns a composite prosthesis for preventing post-surgical adhesions, in particular in the field of visceral, parietal or neurological surgery. The invention will be described more particularly in relation to a composite prosthesis intended for use in parietal surgery, in the repair of eventrations or hernias.
Post-surgical adhesions include all non-anatomical fibrous connections accidentally induced by a surgical act during the normal process of cicatrization. They may occur in all surgical disciplines regardless of the operation in question. They are generally all the more severe, the greater the surgical trauma and the more affected the tissues which normally ensure the planes of division (interstitial connective tissue, the synovial membranes, the tendon sheaths, peritoneal and pleural serosa, etc.). Any surgical trauma to tissue is followed by a cascade of physiological events, the main times of which can be simplified as follows:
time zero (t
0
): surgical trauma, capillary invasion;
time zero plus a few minutes: coagulation, formation of fibrin network, release of chemotactic factors;
time zero (t
0
) plus 12 to 48 hours: influx of leukocytes, predominantly polynuclears;
time zero (t
0
) plus 24 hours to 5 days: influx of leukocytes, predominantly macrophages;
time zero (t
0
) plus 4 to 8 days: influx of fibroblasts;
time zero (t
0
) plus 5 to 14 days: conjunctive differentiation of the cicatricial reaction;
time zero (t
0
) plus 15 to 180 days: cicatricial remodeling.
Although some of the exact mechanisms are still unknown, particularly as regards determination of the intensity of the reaction, it appears that the first few days are decisive since they condition the influx of fibroblasts responsible for the formation of adhesions.
For this reason, such post-surgical adhesions can provoke syndromes which can be classed principally as chronic pain, occlusive syndromes and female infertility. Furthermore, they increase very substantially the risks of making errors in follow-up surgery (myocardial or intestinal invasion during repeat thoracotomy or laparotomy), while prolonging the operating times, since the preliminary dissection can be very awkward in such cases.
One solution to this problem consists in interposing a physical barrier between the structures which one does not wish to see adhering. However, the desired barrier effect poses the problem of the intrinsic adhesive power of this barrier. The reason is that if the barrier is made of a non-absorbable material, it can itself be the source of adhesions over the course of time; and if it is absorbable, its absorption must be sufficiently non-inflammatory so as not to cause adhesions itself.
Several properties are therefore necessary if a material is to be able to reduce the risk of adhesions, namely, among others:
the material must be substantially smooth and non-porous on at least one of its surfaces, so as not to offer space for cell recolonization;
the surface of the material must limit the original cell adhesion.
Nevertheless, and in particular in visceral and parietal surgery, the barrier must also have a certain mechanical strength allowing it to fulfill its function as an element of surgical reconstruction. Generally speaking, the known prosthetic fabrics, particularly in the treatment of parietal insufficiencies, for example hernias and eventrations, afford an additional mechanical strength to the surgical reconstruction. Such fabrics are all the more effective and their local tolerance is all the better, the earlier and the more intimate their tissue integration. For this reason, the most effective of the known prosthetic fabrics for these indications are generally highly porous and are designed in such a way as to be integrated in the body as rapidly as possible. The term “porous” is intended to signify the characteristic according to which at least one of the surfaces of the fabric is rough, so as to present alveoli, distributed regularly or irregularly, and promoting all cell colonization. It is for this reason that upon contact with the viscera for example, these fabrics promote adhesion, which limits their use at the so-called preperitoneal or retroperitoneal sites. Now, in a number of cases, and more particularly in the case of multiple recurring eventrations, implantation strictly in the preperitoneal site is difficult, even impossible, on account of the existence of an extensive deficit of serosa.
There is therefore a requirement to make available a product which is able to solve the problem of preventing post-surgical adhesions, while at the same time offering a prosthetic reinforcement subject to cell recolonization and tissue integration, and which can be used, for example, to treat an eventration involving substantial peritoneal loss, or small eventrations, by laparoscopy, and hernias.
To this end, patent application WO-A-96/08277 describes a composite prosthesis comprising a prosthetic fabric, in this case an absorbable or non-absorbable lattice, and at least one film made of a crosslinked absorbable collagenous substance, in this case a collagen gel coagulated in the dry state, combined with one surface of the prosthetic fabric. The composite prosthesis thus formed finds an application in the treatment of eventrations and hernias and, according to the inventors, prevents post-operative adhesions because the collagenous membrane constitutes a zone of separation permitting release of any early post-operative adhesions that may develop.
The composite prosthesis according to document WO-A-96/08277 must be improved in respect of the necessary independence, once it is implanted, between, on the one hand, the phenomenon of cell colonization and tissue insertion, which must if possible be directed, and, on the other hand, the absorption of the film, which must be relatively rapid in vivo, in such a way as to limit the phenomena of inflammation.
Such is the object of the present invention.
According to the invention, in combination, on the one hand the prosthetic fabric has a three-dimensional structure separating its two surfaces, at least one of which is open to all post-surgical cell colonization, and, on the other hand, the film of absorbable material is linked at least superficially to the other surface of said fabric.
The term “open surface” is intended to signify that said surface includes alveoli having a certain depth according to the thickness of the three-dimensional fabric, these alveoli passing completely or incompletely through the thickness of the fabric, from one surface to the other. In the case of a complete passage of the alveoli, this will be referred to as an openwork prosthetic fabric or one having an openwork structure.
According to the invention, that surface of the absorbable film opposite the prosthetic fabric is preferably substantially smooth and non-porous.
The absorbable film is preferably made up of at least one polysaccharide derivative forming a hydrogel which is insoluble in aqueous medium.
By virtue of the invention, and in a controllable manner:
the prosthesis prevents immediate post-surgical cell colonization on the side including the absorbable film, which is absorbed during a period of time compatible with the tissue restoration, for example that of the peritoneum;
the prosthesis facilitates the immediate post-surgical cell colonization, on the surface including the fabric, open in such a way as to permit a rapid and mechanically effective integration thereof, in particular when it is used as a parietal or visceral reinforcement.
Preferably, but not exclusively, the prosthetic fabric comprises two opposite porous surfaces, connected to one another by connecting yarns, one of which is open to all post-surgical cell colonization, and the other of which is closed to said colonization by means of the film of absorbable material. For example, the weave of the prosthetic fabric determines, within the thickness of the latter, a multiplicity of alveoli or transverse channels, substantially parallel to one another, opening out on either side of sai
Ory Francois Régis
Therin Michel
Oliff & Berridg,e PLC
Prebilic Paul B.
Sofradim Production
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