Surgery – Instruments – Surgical mesh – connector – clip – clamp or band
Reexamination Certificate
2000-01-24
2002-09-17
Jackson, Gary (Department: 3731)
Surgery
Instruments
Surgical mesh, connector, clip, clamp or band
C424S445000
Reexamination Certificate
active
06451032
ABSTRACT:
The present invention concerns a composite prosthesis for preventing postsurgical adhesions, and in particular finds application in the field of visceral or parietal surgery. The invention will be described by way of example in relation to a composite prosthesis intended for use in parietal surgery, in the repair of eventrations or hernias.
Postsurgical 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 (t0): surgical trauma, capillary invasion;
time zero plus a few minutes: coagulation, formation of fibrin network, release of chemotactic factors;
time zero (t0) plus 12 to 48 hours: influx of leukocytes, predominantly polynuclears;
time zero (t0) plus 24 hours to 5 days: influx of leukocytes, predominantly macrophages;
time zero (t0) plus 4 to 8 days: influx of fibroblasts;
time zero (t0) plus 5 to 14 days: conjunctive differentiation of the cicatricial reaction;
time zero (t0) 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 postsurgical 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 nonabsorbable material, it can itself be the source of adhesions over the course of time; and if it is absorbable, its absorption must be sufficiently noninflammatory 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 of which it is made up or composed must be substantially smooth and nonporous 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.
In order to remedy this problem, hydrophobic and inert artificial polymers have been used, for example expanded PTFE, or absorbable polymer substances, for example those based on hyaluronates, or on modified cellulose, which substances rapidly form a hydrogel by hydration in the body.
Nevertheless, and in particular in visceral and parictal surgery, but also in orthopedic or neurological 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 postsurgical 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 nonabsorbable lattice, and at least one film of a crosslinked collagenous material, in this case a collagen gel coagulated in the dry state, associated 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 postoperative adhesions because the coliagenous membrane constitutes a zone of separation permitting release of any early postoperative adhesions that may develop. It is apparent from experiments carried out on pigs and described in the application that the absorption time of the collagenous membrane remains long.
Since any absorption of material is relatively proinflammatory, the persistence beyond about ten days of an absorbable material can lead to a delay in the disappearance of inflammatory cells at the site. This persistent presence of active inflammatory cells (essentially macrophages) will trigger an activation cascade resulting in the stimulation of fibroblasts, which themselves are responsible for the direct formation of adhesions. While mesothelial cells, which are responsible for the peritoneal covering, are known for their rapid regeneratability (appearance as of the fifth or sixth day), it is therefore not only unnecessary, but also substantially contrary to the principles of adhesion prevention, to keep the material on which the barrier effect relies beyond eight to ten days after surgery.
Thus, the use of the collagenous membrane combined with the synthetic lattice, as described in the aforementioned patent application, may in some cases be responsible for initial adhesions because of its relatively slow absorption and may therefore be unsuitable for solving the problem of preventing postsurgical adhesions, while at the same time offering a prosthetic reinforcement subject to cell recolonization and tissue integration. Moreover, its relatively slow absorption limits effective and early recolonization of the synthetic lattice, the latter being masked by the collagenous membrane at the moment when it has to be integrated, that is to say during the first two weeks.
Consequently, the subject of the invention is a composite prosthesis of the kind defined in document WO-A-96/08277, allowing effective tissue integration while remaining compatible with rapid absorption of the film of collagenous material.
According to the invention, this compromise is achieved by the cooperation of three characteristics, namely:
a) the choice of a particular lattice, in this case a three-dimensional prosthetic fabric, that is to say a fabric having a certain thickness separating its two surfaces; and one surface of the fabric is open to any postsurgical cell colonization;
b)
Gravagna Philippe
Ory François Régis
Tayot Jean-Louis
Therin Michel
Jackson Gary
Oliff & Berridg,e PLC
Sofradim Production
LandOfFree
Composite prosthesis for preventing post-surgical adhesions... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composite prosthesis for preventing post-surgical adhesions..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composite prosthesis for preventing post-surgical adhesions... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2877479