RU193833U1 - CONDUIT FOR REGENERATION OF A DAMAGED PERIPHERAL NERVE - Google Patents

Abstract

The utility model relates to medicine, namely to medical equipment and can be used in neurosurgery for the treatment of peripheral nerve defects in experimental animals. Conduit for the regeneration of a damaged peripheral nerve is made in the form of a hollow cylinder. The conduit is made of polyamide RA 2201 natural. The cylinder contains a central part and two end cuffs. Three rectangular plates are longitudinally located inside the central part of the cylinder, fixedly connected to the cylinder wall and converging to the cylinder axis at an angle of 120 °. Along the edges of the circumference of the cuffs, holes are located in the cylinder wall. The ratio of the length of the central part of the conduit and the end cuffs is 1: 4: 1. Using the utility model allows to increase the efficiency of treatment of a damaged peripheral nerve by reducing the body's response to foreign material, increasing the device's resistance to compression of the nerve located in it, and preventing disorientation of regenerating axons. 1 ave., 1 tablet, 2 ill.

Description

The utility model relates to medicine, namely to medical equipment and can be used in neurosurgery for the treatment of peripheral nerve defects in experimental animals.

Traumatic lesions of the peripheral nerves is one of the most important problems of neurosurgery. In the structure of neurological patients, the pathology of the peripheral nervous system is 48-52%, taking first place in terms of degree of disability. The greatest difficulties are the treatment of patients with damage to nerve trunks in the presence of a defect. Every year in Russia, up to 7 thousand people need surgical treatment for injuries of peripheral nerves [1].

The relevance of this problem is confirmed by the high proportion of nerve damage mainly in young and middle-aged people. Damage leads to long-term disability, and in most cases to disability. All this requires special attention to the problem of surgical treatment of post-traumatic lesions of the peripheral nerves [2].

Currently, a large number of methods and devices have been proposed to replace a peripheral nerve defect and stimulate its regeneration: direct suturing of the nerve ends, nerve autotransplantation, cell-free allografts, the use of guide tubes (conduits) from biological and synthetic materials [3].

However, along with the undeniable advantages, all the proposed methods have significant drawbacks that make us look for new effective methods and devices for the regeneration of nerve fibers.

A device for the regeneration of a damaged peripheral nerve, taken as a prototype [4]. The device is made in the form of a hollow tube with smooth edges. The wall of the tube is made of silicone with a thickness of 0.5-2 mm [5]. The length and diameter of the tube depend on the thickness of the nerve fiber and the size of the defect. Using the device promotes the germination of nerve fibers in a certain direction; due to the anti-adhesive properties of silicone, the device prevents the growth of fibroblasts in the area of the defect, which reduces the likelihood of the formation of a neuroma [6].

However, when using this device, complications from the introduction of foreign material may develop [7]. Due to the fact that the tube wall is made of thin elastic material, compression of the regenerating nerve by surrounding tissues is possible, and, as a result, the formation of a compression syndrome, as well as an associated increase in the risk of impairment of the integrity of the nerve suture in the proximal and distal sections [8]. This device can only be used with a nerve defect of not more than 5 mm [9]. In addition, despite the fact that the silicone tube promotes the regeneration of nerve fibers in a certain direction, disorientation of the regenerating nerve fibers within the conduit itself is possible, which undoubtedly reduces the effectiveness of the treatment and the result as a whole [10].

To increase the effectiveness of treatment of a damaged peripheral nerve by reducing the body’s response to foreign material, increasing the device’s resistance to compression of the nerve located in it, preventing disorientation of the regenerating axons, the conduit is made in the form of a hollow cylinder containing a central part and two end cuffs. Three rectangular plates are longitudinally located inside the central part of the cylinder, fixedly connected to the cylinder wall and converging to the cylinder axis at an angle of 120 °. On the edges of the circumference of the cuffs in the cylinder wall are 6-12 holes.

The diameter and length of the cylinder depend on the thickness of the damaged nerve and the size of the defect. The optimal ratio of the length of the central part of the conduit and the end cuffs is 1: 4: 1. The thickness of the walls and plates of the device is 0.5-1.0 mm.

The device is made of polyamide (RA 2201 natural) based on linear synthetic macromolecular compounds containing amide groups -CONH- in the main chain.

Today, polyamide is one of the best and most common synthetic materials for the manufacture of medical devices. This is due to its hypoallergenicity, biocompatibility, elasticity and high strength, resistance to environmental influences, as well as high precision manufacturing of products [11].

The design of the utility model is illustrated by drawings, where in FIG. 1 shows a general view of the device, FIG. 2 shows a cross section of a conduit at the level of the central part. The numbers indicate:

1. - The central part;

2. - End cuffs;

3. - Rectangular plates;

4. - Holes;

5. - The wall of the cylinder;

The device operates as follows:

1. - Under anesthesia, the proximal and distal sections of the affected nerve are isolated;

2. - Epineuria is removed (perineuria is secreted) by 1-2 mm, depending on the diameter of the nerve, from both ends of the defect;

3. - Select the size of the conduit, depending on the size of the defect;

4. - Apply a conduit to the defect area;

5. - The distal section of the damaged nerve is installed in the end cuff (2) until it stops with longitudinal plates (3) of the central part (1) of the device;

6 - Perform the application of fixing sutures of the epineuria of the distal end of the nerve with conduit through the holes (4) of the end cuff (2);

7 - Similar actions are performed with the proximal nerve, while observing the coaxial direction of the perineuric nerve bundles.

To test the operability of the device, an experiment was conducted on rabbits of crossed breed Giant and Flanders in the amount of 8 females; the weight of the animals was 6–8 kilograms, and the age was 6–8 months. Animals were kept under standard vivarium conditions with a day / night regime, with free access to water and food. The keeping and use of laboratory animals was in accordance with generally recognized rules, recommendations of the local ethics committee and national law.

Rabbit experiments were performed under general anesthesia with Propofol 10 mg / ml (dosage: 18-25 mg / kg / h). A skin incision 4-5 cm long is made along the posterior surface of the thigh from the left knee joint in the proximal direction in the projection of the sciatic nerve. In a blunt manner, the muscles of the posterior surface of the thigh are disconnected and the sciatic nerve is secreted. Using a sharp razor, strictly transverse to the axis of the nerve trunk, under the optical magnification of the binocular magnifier, a defect of the allocated left sciatic nerve is formed with a length of 5-8 mm, the proximal and distal sections of the affected nerve are isolated, epineuria of 1-2 mm is removed, depending on the size of the defect, from both ends of the nerve (perineurium is secreted), a conduit is applied to the area of the nerve fiber defect with a length corresponding to the size of the defect, with a diameter of 4-5 mm (rabbit sciatic nerve diameter of 4-5 mm). The distal section of the injured nerve of animals, freed from epineuria, is inserted into the end cuff until it stops with longitudinal plates of the central part of the device, the conduit-nerve fixing sutures (Nylon 9/0) are applied by stitching the epineuria with the end cuff through the holes. Similar actions are performed with the proximal nerve of experimental animals, while observing the coaxial direction of the perineuric nerve bundles. After this, layer-by-layer suturing of the surgical wound and immobilization of the limb are performed. Surgical interventions are performed subject to all the rules of asepsis and antiseptics. Postoperative animals are kept separately, providing thorough care and good nutrition. The condition of the operated animals was monitored throughout the experiment.

An example of a specific implementation.

A rabbit No. 48 under general anesthesia Propofol 10 mg / ml (dosage: 80 mg), a 4 cm skin incision was made along the posterior surface of the thigh from the left knee joint in the projection of the sciatic nerve. In a blunt manner, the muscles of the posterior thigh were separated and the sciatic was isolated nerve. Using a sharp razor, strictly transverse to the axis of the nerve trunk, under the optical magnification of a binocular magnifier, a defect of an isolated left sciatic nerve with a length of 8 mm was formed on the rabbit. The proximal and distal sections of the affected nerve were isolated. 2 mm epineuria was removed from both ends of the nerve, a conduit 10 mm long, 4 mm in diameter was placed on the area of the nerve fiber defect. The distal part of the damaged nerve, freed from epineuria, was inserted into the end cuff to the stop with the longitudinal plates of the central part of the device to a distance of 2 mm, then 6 conduit-nerve fixation sutures (Nylon 9/0) were applied by stitching the epineuria with the end cuff through the holes. Similar actions were performed with the proximal part of the rabbit nerve, while observing the coaxial direction of the perineuric nerve bundles. After this, the surgical wound was sutured in layers and immobilization of the limb was performed.

On day 28, we evaluated the restoration of limb motor activity (SFI), electromyography (EMG). On the 35th day, the animal was removed from the experiment - under general anesthesia, Propofol 10 mg / ml (dosage: 80 mg) was administered potassium chloride (dosage: 400 mg) intravenously, after stopping breathing and heartbeat, sciatic nerves of the hind limbs were taken. For morphological studies of the nerve site, the drug was fixed in a 10% neutral formalin solution.

The efficiency of nerve fiber regeneration was carried out according to the functional test for assessing recovery of limb motor activity (SFI) [12], electromyography (EMG) data [13]. Intact sciatic nerves of the right extremities of these rabbits served as a comparison of efficacy. Assessment of the reliability of the results of the study was carried out according to the criterion of Mann Whitney (p <0.05) [14].

The results are presented in the table.

* p <0.05

The presented data reflect the positive dynamics of the process of repairing a damaged peripheral nerve: there is a tendency to restore the amplitude of muscle contraction during stimulation by a pulsed current and the duration of the response, as well as to restore the indicators of motor activity of animals.

Histological examination of regenerating nerve fibers was carried out on the 35th day on sections with a thickness of 0.5-60 microns; color: hematoxylin-eosin; increase: about. 40 approx. 10; on a Leica DM2500 microscope. Young granulation tissue predominates in the preparations, the number of adipocytes is increased. The regenerating axial cylinders in the seam area have a uniform, longitudinal direction, are interconnected, forming syncytial plexuses, the progress of Schwann cells and the growth of axial cylinders are traced. Blood vessels stretching along the path, penetrating into the epineural tissue, are noted. Between the ends of the interrupted nerve there are repeatedly dividing, and having longitudinal direction axons that actively grow inside Schwann cords.

Thus, the use of the proposed conduit is effective in surgical interventions to restore a damaged peripheral nerve in experimental animals.

1. Dreval ON, Ogleznev K.Ya., Kuznetsov A.V. et al .: Pathology of the peripheral nervous system. In the book: Guide to Neurosurgery. Edited by prof. Drevalya O.N. Volume 2 Geotar Media. Moscow. 2015 S. 635-734.

2. Ogleznev K.Ya., Akhmetov K.K., Sak L.D. et al .: Diagnosis and microsurgery of traumatic injuries of the brachial plexus and the roots of the spinal cord that form it. On Sat scientific Tr .: Microsurgery of traumatic injuries of peripheral nerves. Moscow, 1983, pp. 10-29.

3. Chelyshev Yu.A., Gods A.A. Experimental substantiation of the use of nerve conduits // Neurological Bulletin. - 2008 .-- T.XL, no. 4. - from 101-109

4. Chen YS, Hsieh CL, Tsai CC, et al. Peripheral nerve regeneration using silicone rubber chambers filled with collagen, laminin and fibronectin. Biomaterials 2000; 21: 1541-1547

5. P. Konofaos and J. P. Ver Halen, "Nerve repair by means of tubulization: past, present, future," Journal of Reconstructive Microsurgery, vol. 29, no. 3, pp. 149-164, 2013.

6. Lundborg G, Rosen B, Dahlin L, Danielsen N, Holmberg J. Tubular versus conventional repair of median and ulnar nerves in the human forearm: early results from a prospective, randomized, clinical study. J Hand Surg Am 1997; 22: 99-106

7. Dahlin, LB Tissue response to silicone tubes used to repairhuman median and ulnar nerves / LB Dahlin, L. Anagnostaki, G. Lundborg // J. Plast. Reconstr. Surg. Hand Surg. - 2001. - Vol. 35, ¹ 1. - P. 29-34.

8. G. Lundborg, B. Rosen, L. Dahlin, J. Holmberg, and I. Rosen, "Tubular repair of the median or ulnar nerve in the human forearm: a 5-year follow-up," Journal of Hand Surgery , vol. 29, no. 2, pp. 100-107, 2004.

9. P. Konofaos and J.P. Ver Halen, "Nerve repair by means of tubulization: past, present, future," Journal of Reconstructive Microsurgery, vol. 29, no. 3, pp. 149-164, 2013.

10. G. Lundborg, L.B. Dahlin, and N. Danielsen, "Ulnar nerve repair by the silicone chamber technique," Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery, vol. 25, no. 1, pp. 79-82, 1991.

11. W.E. Nelson. Polyamide-based plastics technology. - Per. from English / Ed. AND I. Malkin. - M .: Chemistry, 1979. - 256 p., Ill. London, Boston, 1976.

12. Thomas M. Brushart. “Nerve Repair” - Oxford University, 2011 - p. 146-152.

13. Kasatkina LF, Gilvanova OV, Electromyographic research methods in the diagnosis of neuromuscular diseases. Needle electromyography, M., 2010.

14. Gubler E.V., Genkin A.A. Application of nonparametric statistical criteria in biomedical research. - L., 1973.

Claims (1)

A conduit for the regeneration of a damaged peripheral nerve made in the form of a hollow cylinder, characterized in that it is made of polyamide RA 2201 natural, while the cylinder contains a central part and two end cuffs, three rectangular plates are longitudinally located inside the cylinder, fixedly connected to the cylinder wall and converging to the cylinder axis at an angle of 120 °, holes are located on the edges of the circumference of the cuffs in the cylinder wall, and the ratio of the length of the central part of the conduit to the end cuffs is 1: 4: 1.

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