WO2004075942A1

WO2004075942A1 - Method for the production of a suture reinforcement device

Info

Publication number: WO2004075942A1
Application number: PCT/FR2004/000160
Authority: WO
Inventors: Philippe Maingault
Original assignee: Les Laboratoires Brothier
Priority date: 2003-01-27
Filing date: 2004-01-23
Publication date: 2004-09-10
Also published as: FR2850281A1

Abstract

The invention relates to a method for the production of a suture reinforcement device wherein a textile web is manufactured from calcium alginate, the textile web is impregnated with propylene glycol alginate solution and the web is dried. The method is characterized in that said calcium alginate is of the guluronic variety and the glycol propylene alginate which is used to impregnate the web has an esterification rate of more than 70 %, preferably more than 80 %. The immersion time of the web in said solution is short less than 1 minute.

Description

Method for manufacturing a suture reinforcement device

The invention relates to the manufacture of a device used in surgery to strengthen the tissue areas during the placement of sutures made using staples or threads.

Patent application WO 99/55397 describes such a device or implant consisting of a textile sheet made from polyuronic acid or its salts. The sheet may be of the woven, knitted or non-woven type, and the material particularly targeted is calcium alginate in the form of fibers or filaments. The tablecloth can be used in flat splints. However, when it is used with a suture forceps, it preferably has the shape of a sheath which is fitted onto each pin of the latter.

When gas and blood tightness is required, such as, for example, in the case of sutures made on pulmonary tissues, the sheet of calcium alginate is impregnated with an alginate ester.

The coating is carried out in particular by soaking in a solution of sodium alginate ester at 3%, in particular propylene glycol alginate (PGA).

Patent FR 2 789 885 describes a method of manufacturing a device intended to be fitted onto a spindle of a suture forceps.

A linear knitting loom is supplied with calcium alginate fibers. We make a tabular knit in jersey whose diameter is substantially equal to that of the pin of the pliers. We put the knit on a form whose material is non-stick, Tel (registered trademark) for example. dressed form of the knitted fabric in a bath containing a 3% aqueous solution of alginate ester in order to coat the knitted fabric. The excess solution is removed and then dried with hot air, at 45 ° C. example given Finally we remove the device.

The alginate, forming the textile web and the coating material, has interesting properties for sutures. It facilitates tissue healing. It gives the devices good mechanical resistance to strengthen the sutured wound during healing. On contact with blood, the coating alginate softens and becomes charged with biological fluid. It spreads over the entire surface of the fabric and envelops the staples, sealing all the web gaps and perforations, thus ensuring air and liquid tightness.

The process described above however has the disadvantage of not taking sufficient account of the chemical reactivities of the materials present, ie the calcium alginate of the support and the propylene glycol alginate solution (PGA). coating. In fact, there is a basic incompatibility between these two chemical species: A calcium alginate fiber gels, disintegrates and gradually dissolves in a PGA solution until it disappears. Even if the material is dried quickly after the immersion step, the product produced is imperfect, it appears in particular mechanically weakened.

The present invention relates to a method of manufacturing a suture reinforcement device overcoming the incompatibility between the materials and leading to a product whose mechanical strength is sufficient to absorb, without yielding, the forces exerted by the staples or the threads. sutures.

The present invention also relates to the manufacture of a suture reinforcement which when brought into contact with a physiological liquid leads to a progressive dissolution of the coating.

The process according to the invention in which a textile web is produced from a calcium alginate, the web is coated with propylene glycol alginate in solution and the web is dried, is characterized in that said calcium alginate is of the guluronic type and the said propylene glycol alginate with which the web is coated has an esterification rate greater than 70% and preferably greater than 80%.

Preferably, the coating is carried out by immersion, the immersion time of the sheet in the solution is less than 1 minute and the concentration of propylene glycol alginate in said solution is between 3 and 10%. The concentration is determined so as to obtain a viscosity of the solution of between 8000 and 16000 ctp at 25 ° C.

Thanks to this process, we surprisingly manage to control the incompatibility between the materials. Without being bound by an interpretation, we know that a fraction of the carboxyl groups is inactivated by P esterification. Thus, depending on the rate of esterification, the PGA has a more or less significant calcium fixing capacity (the chelation of the divalent requires adjacent free carboxyls). By choosing an esterification rate greater than 70 - 80%, the reactivity is reduced. Furthermore, tests of resistance over time of devices based on calcium alginate impregnated with PGA, and immersed in demineralized water on the one hand in a physiological medium on the other hand, have shown the superiority of alginate of guluronic type calcium compared to mannuronic type alginate. It was thus possible by a selection of materials combined with an appropriate process to achieve the production of a perfectly adapted product.

We also take advantage of this incompatibility because when the dry reinforcement is brought back into contact with a biological fluid such as blood, serosity or a surgical rinsing solution, the PGA coating layer gradually dissolves. It causes immediate adhesion to tissue. It induces a rapid sealing, in a few minutes, of the sheet by embedding the latter in a viscous layer of PGA. It causes a gradual and slow gelation, within a few days, of the water table. It thus facilitates the biodegradation of the water table, in a few months, at the implanted site.

According to a preferred embodiment, the propylene glycol alginate solution (PGA) is emulsified beforehand. The quantity of alginate deposited is reduced by air bubbles, and the bubbles slow down the penetration of the PGA into the sheet.

After coating, the sheet is drained and then dried with dry air at a temperature of 40 ° C. to 50 ° C., preferably 45 ° C., until a residual water content of less than 15% is obtained after drying.

The method is described below in more detail, applied to the manufacture of suture reinforcement sheaths.

Calcium alginate wire was previously produced in a conventional manner. The wire title is chosen between 100 and 160 dTex. According to a characteristic of the invention, the alginate is of the guluronic type. The molar ratio between the two basic monomers: mannuronic acid M and guluronic acid G is chosen such that M / G <1 # We knit with the thread on a circular knitter. The mesh is a locked jersey of the “locked stitches” type with a gauge 32. It allows to obtain a knitted fabric with a tight mesh when the thread is fine, as here. The diameter of the sheath is determined according to the type of clamp for which it is intended.

The sheath is put on, unrolled and cut on a form of non-stick material such as Teflon (registered trademark) with a polygonal section corresponding to that of the branches of the clamp.

The whole is immersed in a PGA solution for a determined time, less than one minute.

According to another characteristic of the invention, the rate of esterification of the selected PGA is high. 11 is preferably greater than or equal to 80%. For example, the product sold under the name Protanal ester L-25 A H by the company FMC was selected. The product is obtained from seaweed. Its degree of esterification is between 80 and 90%.

Preferably, the concentration of the PGA solution is between 3 and 10% depending on the viscosity which is itself between 8000 and 16000 ctp at 25 ° C. A 5% solution was prepared here with a viscosity of about 12,000 ctp.

More preferably, an emulsion of the solution was formed by mechanically incorporating air into an emulsifier. The foam has the advantage by its bubbles of reducing the contact zones with the material constituting the knitted fabric and of slowing down the penetration of the solution within the knitted fabric.

Optimally, after coating, the knitted fabric has an internal part of calcium alginate and an external part of PGA.

We remove the shape of the solution and let it drain for a few moments.

The sheath is then dried. This must satisfy a speed constraint to reduce the destructuring effect of PGA on knitting. In fact, once dry, the PGA is compatible with calcium alginate. The temperature should also be moderate to avoid destroying the PGA. If the solution is in the form of a foam, vacuum drying should be avoided.

Drying was carried out by sweeping dry air at 45 ° C. We used a system supplied by the company JVTUNTERS which works with Silicagel (registered trademark) and delivers an air flow of 700 m ³ / h at a hygrometry of 5 to 10% for a temperature between 40 and 45 ° C.

A drying cycle in a 0.5 m ³ enclosure makes it possible to process 7000 cm ² to 14000 cm ² , depending on the formats. 14000 cm ² containing 2.3 liters of water, it takes 34.5 minutes to bring the sample to a residual water content of less than 15% in the finished product. The dryer used has a capacity of 21 of water evaporated in 30 'at a temperature of 45 ° C.

The product, once dried, is demolded. To make this operation easier, the form is subjected to a thermal shock, for 10 minutes at -25 ° C. for example.

Finally, the treated sheaths are cut to the length of use adapted to the pins of the suture forceps.

A product was thus produced which, when analyzed, has the following characteristics

Knitting weight 8-9 mg / cm ² Coating weight 3.5 - 4.5 mg / cm ²

Sodium <= 5%

Calcium alginate dosage> 95%

Water content <15%

To show the advantage of using a guluronic alginate in this application, a comparative study of resistance over time of pulmonary suture reinforcements was carried out after immersion in demineralized water on the one hand, in the middle. physiological on the other hand (physiological serum at 0.9%.

The products were reinforcements based on mannuronic (M) and guluronic (G) calcium alginate impregnated with PGA. Samples were immersed simultaneously in beakers containing 40ml of deionized water and in beakers containing 20ml of 0.9% NaCl _* The appearance of the samples was observed at different contact times and evaluated on a scale of 0 to 4, 0 being the weak resistance and 4 being the strong resistance.

In demineralized water

In both cases, the reinforcement based on alginate type M / G <1 has greater resistance to destructuring over time than the reinforcement based on calcium alginate type M G> 1.

Claims

claims

1) Method for manufacturing a suture reinforcement device according to which a textile sheet is made from a calcium alginate, the sheet is coated with propylene glycol alginate in solution and the sheet is dried, characterized by the fact that said calcium alginate is of the guluronic type and that said propylene glycol alginate with which the web is coated has an esterification rate greater than 70%, preferably greater than 80%. 2) Method according to the preceding claim, wherein the immersion time of the sheet with the solution is less than 1 minute. 3) Method according to one of the preceding claims wherein the concentration of propylene glycol alginate in said solution is between 3 and 10%. 4) Method according to the preceding claim, the viscosity of the solution is between 8000 and 16000 ctp at 25 ° C.

5) Method according to one of the preceding claims wherein said propylene glycol alginate solution forms an emulsion.

6) Method according to one of the preceding claims wherein the sheet after coating is drained and then dried with dry pair at a temperature of 40 ° C to 50 ° C.

7) Method according to the preceding claim wherein the dry air is at a humidity between 5 and 10%.

8) Method according to one of claims 6 and 7 wherein the residual water content after drying is less than 15%.

9) Method according to one of the preceding claims wherein the web being produced in the form of a sheath, it is mounted before coating, on a form made of a non-stick material.

10) Method according to the preceding claim which once the sheaths dried, the assembly is subjected to a thermal shock of shrinking the shape and the sheath is removed.