Surgery – Instruments – Surgical mesh – connector – clip – clamp or band
Reexamination Certificate
2000-01-24
2002-09-03
Reip, David O. (Department: 3731)
Surgery
Instruments
Surgical mesh, connector, clip, clamp or band
C623S011110, C623S014130
Reexamination Certificate
active
06443964
ABSTRACT:
The present invention relates to a three-dimensional fabric, useful in particular in parietal and/or visceral surgery, but also able to be applied in other areas of surgery.
The present invention will be described more particularly with respect to a prosthetic fabric of said type, intended to be used for the repair of hernias or eventrations.
For a long time, surgeons have used flat prosthetic fabrics, that is to say two-dimensional, for repairing or replacing any part of the body, such as an aponeurosis, or a muscular wall, destroyed or damaged, for example as a result of a traumatism. Consequently, there are at present a very large number of such prosthetic fabrics, manufactured or obtained using various processes, for example weaving, knitting, or moulding, and which were designed often to carry out specific functions within the body in which they are implanted.
Such two-dimensional fabrics are for example described in the documents US-C-5 569 273 and 3 124 136.
However, such fabrics have several disadvantages, related to the very structure of the fabric, or to the choice of the base material used for making the threads, or again to the way in which the prosthetic fabric is manufactured. Thus, for example, the known prosthetic fabrics made of synthetic polymer material, are relatively inflexible.
It is also known that the tissual reaction to an implant is the result of a normal process of cicatrizing. Any tissual surgical traumatism is followed by a cascade of physiological events, the principal times of which are as follows:
t0: surgical traumatism, capillary breach;
t0 plus a few minutes: coagulation, fibrin network, release of chemotactic factors;
t0 plus 12 to 48 hours: polynuclear dominant leukocytic afflux;
t0 plus 4 to 8 days: fibroblast afflux
t0 plus 24 hours to 5 days: macrophagic dominant leukocytic afflux;
t0 plus 8 to 21 days: connective differentiation of the cicatrizing reaction;
t0 plus 15 to 180 days: cicatrizing remodelling on contact with the implant.
Even if the exact mechanism are still unknown in certain cases, particularly with regard to the determinism of the intensity of the reaction, it therefore appears that the first 8 days are determinant since they condition the fibroblast afflux.
In non-bony tissue, the equilibrium of the reaction leads to the formation of a fibro-connective membrane which constitutes the interface between the implanted material and the surrounding healthy tissue. Whatever the type of implant, the zone directly affected by a conventional biocompatible material is a minimum of about 50 &mgr;m.
Furthermore, in the treatment of parietal inadequacies (principally hernias and eventrations), the prosthetic fabric has the task of providing additional mechanical strength to the surgical reconstruction, and it becomes more effective, and its local tolerance becomes better, as its tissue integration becomes more intimate and more advanced.
The Applicant has established, by its own research, whose results led to the present invention, that several parameters influence the tissual response to a prosthetic implant, namely:
the constituent material of the prosthesis and its possible products of degradation in a biological medium, which must not induce a toxic effect or an effect contrary to the sought effect. In the case of a prosthetic fabric implanted long-term, the aging of the material and its consequences (wear, ejection of components, etc.) are the most difficult factor to predict; only raw materials validated over a long period provide a maximum of safety;
as the organism, so to say, only sees the surface of the material, the properties of the latter assume significant importance. Among all of the surface parameters, the surface energy and the roughness have an important role. In effect, when it is sought to promote cellular adhesion, the surface must be hydrophilic (high surface energy) and smooth in comparison with a cell (of the order of one micron);
only the porosity accessible by the organism is useful with regard to the anchoring of the prosthetic fabric. This porosity in a given volume must be interconnected, and the interconnecting interstices must be sufficient for significant cellular penetration (of the order of 20 to 80 &mgr;m approximately), and for tissual differentiation (100 to 300 &mgr;m generally constitute a minimum for complete differentiation). It has been recalled above that the minimum distance for setting aside the tissual reaction from the direct influence of the prosthetic material is of the order of 50 &mgr;m, which means that for sizes of porosity less than 100 &mgr;m, the rehabilitation tissue will be entirely under the influence of the presence of the implant, with little possibility of completed tissual differentiation;
the vascularization and the biomechanical environment of the receiving site condition the intensity of the tissual response. A richly vascularized site (skin, muscles, etc . . . ) will react faster and more intensely than less vascularized tissues (rear chamber of the eye, bone, etc . . . ). Furthermore, the very nature of the receiving site conditions the capacity of regeneration to be identical to that of the wounded tissue. Bone, the connective tissues, mucous membranes, certain parenchymas (the liver for example) can regenerate identically with no significant fibrous scarring. On the other hand, other very specialized tissues (muscles, nerve tissues, etc . . . ) have lost all capacity to regenerate, the cicatrizing of these tissues therefore occurring only by fibrosis;
surgical traumatism constitutes one of the principal factors triggering the previously described cascade reaction. The bigger this is, the more intense the reaction will be and the more pronounced its consequences will be (cicatrizing delay, fibrous sequelae, pain, etc . . . ).
Considering the above, one of the objectives of a good prosthetic fabric is a tissual integration that is as fast as possible, procuring a mechanically satisfactory anchoring without extensive fibrosis, a source of discomfort and pain.
In order to try to achieve this objective, the Applicant has designed, manufactured and marketed, under the name “PAT” or “TET”, a three-dimensional prosthetic fabric, comprising two opposite surfaces, porous or relatively rough, separated from each other by the thickness of the fabric, but linked to each other by binding threads, whose texture depends on the method of obtaining the fabric, for example by weaving and/or knitting.
One such three-dimensional fabric is for example described in the document EP-A-0 621 014, as the central part of a prosthetic assembly furthermore comprising edges formed from a single knitted layer.
In certain cases, the pattern of the prosthetic fabric determines, within its thickness, a plurality of transverse channels or cells substantially parallel to one another, emerging on either side of said fabric on the two porous surfaces respectively, in such a way that it is then possible to speak of an open-worked fabric, allowing direct progress of the repairing cells, starting from each of the surfaces of the fabric.
In the present application, certain terms have the following significance:
“fabric” refers to an assembly of threads, obtained in particular by knitting and/or by weaving;
“porous surface” refers to a surface of the fabric which exhibits numerous small orifices, or holes emerging in its surface, thereby conferring upon it a rough appearance.
This type of fabric has widely demonstrated its effectiveness, particularly in terms of the fastest possible integration in the receiving anatomical site, by procuring a mechanically satisfactory anchoring without extensive or significant fibrosis.
The present invention has however sought to improve the tissual integration of a three-dimensional prosthetic fabric such as previously defined, whilst lowering its intrinsic inflammatory power.
According to the present invention, the pattern of the fabric also determines, for each transverse channel or cell, an internal porous wall interconnecting with the adjacent channels.
Preferably, the
Meneghin Alfredo
Ory François Régis
Therin Michel
Oliff & Berridg,e PLC
Reip David O.
Sofradim Production
Woo Julian W.
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