RU2393878C1 - Method for preparing implant for reconstructive surgery - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to a method for preparing an implant for reconstructive surgery which can be applied in ophthalmology to create a locomotive stump in enucleation. There is offered the method for preparing an implant for reconstructive surgery by polymerisation actuated by a redox catalyst in a ball shape with diametre 15-22 mm, 70-80% aqueous solutions of mixed monomers containing 97.0-99.0 wt % of hydroxyethylmethacrylate, 0.5-2.0 wt % of alkali acrylate and 0.5-1.0 wt % of tridecaethylene glycol dimethacrylate. Thereafter, the implant is washed in distilled water to remove completely the unreacted compounds. The polymerisation is ensured at temperature -10-(-15)°C with 0.1-0.5 wt % of a water-soluble polymer specified from polyvinyl alcohol, or poly-N-vinylpyrrolidone, or polyacrylamide, or polyacrylic acid. In 6 months after the implantation, the implant invasion size is 8-9 mm.

EFFECT: there is offered method for preparing the stable-shape invasive implant.

2 cl, 2 tbl, 9 ex

Description

The invention relates to medicine, in particular to a method for producing an implant for reconstructive surgery, which can be used in ophthalmology to form a musculoskeletal stump during enucleation.

A known method of obtaining an implant for reconstructive surgery by filling the shell of cross-linked polysiloxane with liquid polydimethylsiloxane, described in the work: Yuzelevsky Yu.A. Siloxane elastomers for medical use. L .: Knowledge. 1985. P.17.

The disadvantage of this method is the lack of connective tissue necessary for transferring the movement from the stump to the implant of the implant germination, as well as the low biocompatibility of the implant, which is caused by the adverse reaction of the tissue to contact with the crosslinked polysiloxane shell, and also by the diffusion of liquid polydimethylsiloxane through the intact shell. This can lead to the development of a toxic reaction and rejection of the implant. Once in the local lymph nodes, fragments of the liquid polymer clog them and cause lymphostasis with the subsequent development of severe toxic reactions of the surrounding tissues, liver and lung tissue.

In the patent of the Russian Federation 2119780 C1, A61F 2/14, A61L 27/00 (Bull. No. 28, 1998) a method for producing an implant for reconstructive surgery by polymerization at room temperature under the action of a redox catalyst in the form of a ball with a diameter of 15-22 mm, a 75-85% aqueous solution of a mixture of monomers containing 77.5-84.0 wt.% hydroxyethyl methacrylate, 15.0-22.0 wt.% acrylamide and 0.5-1.0 wt.% tridecaethylene glycol dimethacrylate, followed by rinsing of the implant with bidistilled water until complete removal spond compounds.

The disadvantage of this method is the lack of germination of the implant with connective tissue, as well as the instability of the shape of the implant, which leads to possible rejection of the implant and the need for reoperation. So, after implantation into the orbit of an implant in the form of a ball with an initial diameter of 16-18 mm, the diameter of the implant after 6, 12, and 18 months of being in the tissues of the orbit is 17-19, 18-22 and 20-24 mm, respectively.

The closest in technical essence and the achieved results are described in the patent of the Russian Federation 2306115 C1, A61F 2/14, A61L 27/00 (Bull. No. 26, 2007) a method for producing an implant for reconstructive surgery by polymerization under the action of a redox catalyst in a form made in the form of a ball with a diameter of 15-22 mm, a 70-80% aqueous solution of a mixture of monomers containing 97.0-99.0 wt.% hydroxyethyl methacrylate, 0.5-2.0 wt.% alkali metal acrylate and 0.5-1.0 wt.%, tridecaethylene glycol dimethacrylate, followed by washing m of the implant with distilled water until complete removal of unreacted compounds. The polymerization is carried out at room temperature.

This implant has a stable shape. After two years of monitoring the orbit cavity with implants with an initial diameter of 17.0, 15.0, 22.0 and 16.0 mm, the diameter of the implants is 16.8, 15.2, 21.5 and 16.2 mm.

The disadvantage of this method is the lack of germination of the implant with connective tissue.

The objective of the invention is to develop a method for producing an implant having a stable shape and capable of germination by connective tissue.

The technical result achieved by using the invention is the creation of an implant having a stable shape and capable of germination by connective tissue.

The technical result is achieved by the fact that in the method of obtaining an implant for reconstructive surgery by polymerization under the action of a redox catalyst in the form made in the form of a ball with a diameter of 15-22 mm, 70-80% aqueous solution of a mixture of monomers containing 97 , 0-99.0 wt.% Hydroxyethyl methacrylate, 0.5-2.0 wt.% Alkali metal acrylate and 0.5-1.0 wt.% Tridecaethylene glycol dimethacrylate, followed by washing the implant with distilled water until the unreacted compounds are completely removed secondly, polymerization is carried out at a temperature of -10 - (- 15) ° C in the presence of 0.1-0.5 wt.% water-soluble polymer by weight of the mixture of monomers.

Polyvinyl alcohol, poly-N-vinylpyrrolidone, polyacrylamide, polyacrylic acid are used as a water-soluble polymer.

The polymerization reaction is carried out in a frozen state. When freezing a mixture of monomers, regions with a high concentration of monomers and regions of pure ice are formed. As a result of polymerization, a cross-linked polymer is formed in the system containing ice particles forming macropores after the system is thawed. The water-soluble polymer acts as a stabilizer, ensuring the formation of ice particles of a similar size, which leads to a cross-linked polymer with a uniform distribution of macropores in size.

The following examples illustrate the invention, but in no way limit its scope.

Example 1

A solution of 75 g of water, 24.25 g of hydroxyethyl methacrylate (HEMA, 97% by weight of monomers), 0.5 g of sodium acrylate (2.0% by weight of monomers) and 0.25 g are added to a glass container in the form of a sphere with a diameter of 16 mm; tridecaethylene glycol dimethacrylate (TGM-13, 1% by weight of monomers) and 0.025 g (0.1% by weight) of poly-N-vinylpyrrolidone.

A polymerization catalyst was added to the solution (0.05 g of ammonium persulfate and 0.05 g of N, N, N ', N', tetramethylethylenediamine). The solution is evacuated to 10 mm Hg. The solution was quickly frozen with liquid nitrogen (-196 ° C) and polymerization was carried out at -10 ° C for 2 days. The implant is removed from the mold and washed with distilled water until the unreacted substances are completely removed. Monitoring the completeness of removal is carried out by measuring the refractive index of the source water and wash water. The difference in refractive indices should not exceed 0.005 units.

The assessment of implant permeability for high molecular weight proteins, which determines the possibility of implant germination after implantation in the orbit, is carried out by immersing the implant in 25 ml of a 3% solution of serum albumin (molecular weight 68,000) and measuring the decrease in protein concentration in the solution by spectrophotometric method. The diffusion coefficients of serum albumin in the volume of the implant are shown in table 1.

The implant is sterilized by autoclaving. After retrobulbar anesthesia, 0.5 ml of a 2% novocaine solution is injected under the conjunctiva of the rabbit's eye around the limb. The conjunctiva and tenon membrane are separated by 360 g., 1 mm from the limb. Each of the rectus muscles is secreted to the maximum available depth and absorbable sutures are applied to the tendons before cutting. The limb is flashed with two suture-holders to fix or rotate the eyeball during surgery. Cross oblique eye muscles. Complete separation of the muscles and tenon capsule from the eyeball into the depths of the orbit. Enucleation scissors start for the eyeball from the temporal or nasal sides. Slightly raising the eyeball by the suture-holders, localize the optic nerve. Produce a neurotomy 3-5 mm from the sclera. The eyeball is removed from the tissues of the orbit. Make a thorough hemostasis. The resulting implant is immersed in the muscle cone of the orbit. The rectus muscles are sutured crosswise. A continuous suture is applied to the tenon shell, and the usual purse string suture to the conjunctiva.

To create aseptic healing conditions and accelerate the recovery process in the postoperative period, a solution of kanamycin and dexazone is instilled into the conjunctival cavity 4 times a day for 1 month.

The observation period for the animal is 6 months. Over the entire observation period, the anterior surface of the supporting stump is completely epithelized, there are no purulent discharge from the conjunctival cavity and mobility in all meridians is completely preserved.

The degree of germination of the implant and vascularization is determined by the method of ultrasound diagnostics. It is 8 mm.

Examples 2-6.

The process is carried out as in example 1, using various amounts of monomers and water-soluble polymers, as well as glass forms of various diameters (tables 1 and 2).

Examples 7-8 (control).

The process is carried out using the declared amounts of monomers, but either in the absence of a water-soluble polymer, or at room temperature (tables 1 and 2).

Example 9 (control).

The process is carried out according to the prototype method (tables 1 and 2).

The authors experimentally selected the parameters of the invention. A decrease in the concentration of a water-soluble polymer below 0.1 wt.% Does not stabilize the freezing water droplets, which leads to an implant with an extremely heterogeneous pore size distribution and a low (and non-uniform) degree of implant germination by connective tissue. An increase in the concentration of a water-soluble polymer does not lead to a change in the parameters of the resulting implant, but only increases the washing time of the implant to remove this polymer.

The most optimal temperature is -10 - (- 15) ° C. An increase in temperature above -10 ° C can lead to thawing of the monomer mixture as a result of heat generation during polymerization, and a decrease in temperature below -15 ° C does not change the parameters of the resulting implant.

Thus, a method of obtaining a stable form of the implant capable of germination by connective tissue. So, the size of the area of implant germination by connective tissue 6 months after implantation reaches 8-9 mm compared to 1-2 mm by the prototype method.

Table 1 Example No. one 2 3 four 5 6 7 8 9 Ball diameter, mm 16 fifteen 16 eighteen 22 eighteen 16 16 16 D * × 10 ¹⁰ m ² / s 0.4 0.4 0.4 0.5 0.3 0.3 0.05 0.02 0.02 R **, mm 7-8 7-8 8-9 8-9 6-8 7-8 2-3 1-2 1-2 * - diffusion coefficient of serum albumin in the volume of the implant (diffusion coefficient of serum albumin in water is 0.6 × 10 ^-10 m ² / s).
** - the size of the implant germination area by connective tissue 6 months after implantation.

Claims (2)

1. A method of obtaining an implant for reconstructive surgery by polymerization under the influence of a redox catalyst in the form made in the form of a ball with a diameter of 15-22 mm, 70-80% aqueous solution of a mixture of monomers containing 97.0-99, 0 wt.% Hydroxyethyl methacrylate, 0.5-2.0 wt.% Alkali metal acrylate and 0.5-1.0 wt.% Tridecaethylene glycol dimethacrylate, followed by washing the implant with distilled water until complete removal of unreacted compounds, characterized in that the polymerization prov DYT at a temperature of (-10) - (- 15) ° C in the presence of 0.1-0.5% by weight of water-soluble polymer by weight of the monomer mixture.. 2. The method according to claim 1, characterized in that polyvinyl alcohol or poly-N-vinylpyrrolidone, or polyacrylamide, or polyacrylic acid is used as the water-soluble polymer.