METHOD OF PROVIDING AN IMPLANTATION SITE IN SOFT TISSUE

Abstract

A method of providing a channel filled with aqueous gel in soft tissue comprises injecting a biocompatible aqueous gel into the tissue. Also disclosed is a corresponding device, the combination of the device and a guide for its insertion into tissue, and a system comprising the combination and a reservoir filled with aqueous gel comprising means for exerting pressure on the gel.

Claims

1. A method of defining a channel filled with aqueous gel in soft tissue using a device that comprises an oblong rotationally symmetric pin comprising a distal section extending from the distal towards the proximal end, a central section extending from the distal section towards the proximal end, and a proximal section extending from the central section to the proximal end, a central conduit extending from the proximal end to the distal section, the central conduit providing fluid connection between a reservoir for aqueous gel, and lateral passages extending radially from the central conduit disposed in the central section, the method comprising: inserting the device into the soft tissue; supplying the aqueous gel to the central conduit from the reservoir during insertion and/or upon insertion of the device; pressing out the aqueous gel from the passages; and withdrawing the device from the tissue while leaving the aqueous gel in the channel that is formed in the soft tissue by the device to define the channel filled with the aqueous gel.

2. The method of claim 1, wherein the gel is native gelatin, recombinant gelatin, cross-linked gelatin and combinations thereof.

3. The method of claim 1, wherein the gel is carbohydrate or protein gel.

4. The method of claim 3, wherein the carbohydrate gel is selected from the group consisting of arabinogalactan gel, arabinoxylan gel, galactan gel, galactomannan gel, lichenan gel, xylan gel, hydroxymethylpropyl cellulose gel and gels of other gel-forming cellulose derivatives.

5. The method of claim 3, wherein the protein gel is selected from the group consisting of whey protein gel, soy protein gel, casein gel.

6. The method of claim 1, wherein the tissue is nervous tissue.

7. The method of claim 1, wherein the reservoir comprises a means for exerting pressure on the gel.

8. The method of claim 7, wherein the means is selected from compressible reservoir wall and mechanical pump.

9. The method of claim 1, wherein the device is mounted at the site selected for forming the channel by means of an insertion guide comprising a tubiform element into which the device is insertable and in which it is displaceable in an axial direction.

10. The method of claim 9, wherein the device is kept in a first position in the tubiform element in which position the outer openings of the lateral passages are closed by the tubiform element.

11. The method of claim 10, wherein the device is kept in a second position in the tubiform element in which a distal and a central portion of the tubiform element extends from the distal opening of the tubiform element and in which the outer openings of some or all openings of the lateral passages are not shielded by the tubiform element, which second position is one in which a distal and central portion of the device is inserted into soft tissue.

12. The method of claim 1, wherein the distal section of the pin narrows towards the distal end of the pin.

13. The method of claim 12, wherein the pin is cylindrical form, optionally except for at its proximal end.

14. The method of claim 1, wherein the device is of metal and/or polymer.

15. The method of claim 1, wherein the device comprises an electrode or optical fiber.

16. The method of claim 1, wherein the aqueous gel is cross-linked.

17. The method of claim 1, wherein the aqueous gel when pressed out from the openings, forcing the tissue abutting the outer face of the central section away from the pin to form a layer of aqueous gel around the central section.

18. The method of claim 1, wherein the aqueous gel preventing shrinkage of the channel inwardly thereby stabilizing the geometry of the channel.

19. The method of claim 1, wherein the reservoir is disposed at the proximal end of the conduit.

20. The method of claim 1, wherein the central conduit is closed at its distal end.

21. A system configured for forming an aqueous-gel-filled channel in soft tissue comprising: an oblong rotationally symmetric pin comprising a distal section extending from a distal end towards a proximal end, a central section extending from the distal section towards the proximal end, and a proximal section extending from the central section to the proximal end, a central conduit extending from the proximal end to the distal section, and through bores disposed in the central section radially extending from the central conduit; a reservoir that stores aqueous gel; and a fluid connection between the conduit and the reservoir

22. The system of claim 21, wherein the reservoir is disposed at the proximal end of the conduit.

23. The system of claim 22, wherein the distal section narrows towards the distal end of the pin.

24. The system of claim 21, wherein the pin is cylindrical except at its proximal end.

25. The system of claim 21, further comprising an electrode or an optical fiber.

26. The system of claim 21, further comprising an insertion guide comprising a tubiform element having a lumen; and a radially extending flange disposed at one end of the tubiform element, wherein the lumen of the tubiform element is slightly wider than the diameter of the device.

27. The system of claim 26, wherein the axial extension of the tubiform element is greater than the axial extension of the central section of the pin.

28. The system of claim 26, wherein the insertion guide comprises a stiff holding element fastened at the tubiform element and or the flange at its one end, the holding element being securable, directly or indirectly, at its other end at a person or an animal comprising said soft tissue or at a support on which the person or animal is immobilized.

29. The system of claim 26, further comprising a means for applying pressure to the gel in the reservoir.

Description

BRIEF DESCRIPTION OF THE DRAWING(S)

[0037] FIGS. 1 and 1a are axial (A-A) and radial (E-E) sections of a first embodiment of the device of the invention;

[0038] FIGS. 2a, 2b are axial F-F and radial G-G sections of a second embodiment of the device of the invention;

[0039] FIG. 1b is an axial section of a third embodiment of the device of the Invention, in the same axial section as the device of FIG. 1;

[0040] FIG. 2c 2f in combination with FIGS. 2a, 2b illustrate the formation of a channel in soft tissue filled with aqueous gel by disposing a device of the invention at the tissue surface and securing it in the selected position by means of an insertion guide, in an axial view and a radial view (FIG. 2b).

DESCRIPTION OF PREFERRED EMBODIMENTS

Example 1. First Embodiment of the Device of the Invention

[0041] The device 1 of the invention has the form of an oblong cylindrical (central axis B-B) hollow pin 1. The pin is substantially rigid and made of a suitable material, such as a metal or a polymer. An axial passage or bore 6 in the pin 1 extends from its open proximal end 4 to near its distal end 2 at which the passage 6 is closed. The 1 pin comprises a central section C provided with constant radius, disposed between a distal section D with a radius decreasing towards the distal end 2 and a proximal section P comprising an annular bulge 5 for attaching a flexible tube 8. The central section C is provided with radially extending bores 7 communicating with the central passage 6 and opening at the cylindrical outer face of the pin 1. Sets of bores each comprising four are arranged at regular axial distance intervals in a radial plane. The illustrated arrangement of radially extending bores is not critical, the important feature being that sufficient bores of this kind are provided over the entire central section. The axial extension of the central section C corresponds roughly to the depth of a channel in soft tissue filled with aqueous gel provided by means of the pin 1. Near the proximal end the holding element 10 is fastened to the proximal section P of the pin 1 by means of an annular clamp 9. The holding element 10 extends from the annular clamp 9 in a radial direction; its other end (not shown) is firmly connected, directly or indirectly, to the person or animal in a soft tissue of which a channel of the invention is intended to be provided. By indirectly is meant, for instance, fixation to a support on which the person or animal rest during the channel forming procedure.

Example 2. Second Embodiment of the Device of the Invention

[0042] The second embodiment of the device 1 of the invention in form of a pin 1 shown in FIGS. 2a, 2b in axial (D-D) and radial (E-E) sections differs from the first embodiment by omission of holding element 10 fastened at the proximal section P of the pin 1 by means of the annular claim 9 and by the axial length of the proximal section P exceeding the axial length of the central section C. While the second embodiment is provided at its proximal end with a flexible tube corresponding to the tube 8 of the first embodiment, the tube is not shown in FIGS. 2a-2b for reasons of drawing space economy. Reference numbers 2, 3, 4, 6 as well as reference letters D, C, P correspond to respective features 2, 3, 4, 6, D, C, P of the first embodiment.

[0043] In FIGS. 2a, 2c and 2d the pin 1 is mounted at the site for its insertion into soft tissue 14 by means of insertion guide 17 comprising a sleeve 12 into the lumen of which the pin 1 can be inserted. The radial diameter of the sleeve 12 lumen is slightly larger than the radial width of the pin 1 so as to allow the pin 1 to be slidingly displaced within the sleeve 12. According to an advantageous aspect of the invention the axial length of the sleeve 12 is somewhat greater than the axial length of the central section C section provided with radial conduits 7. According to a further advantageous aspect of the invention the insertion guide 17 comprises a radially extending flange 11 mounted at the distal end of the sleeve 12. The width of the flange 11 is substantially greater than the width of a channel filled with aqueous gel 15 produced by means of the device 1 of the invention. The insertion guide 17 is secured in an insertion position in which its flange 11 abuts the surface 16 of the tissue 14 in which the channel of the invention is desired to be provided, the insertion guide 17 being centered so as to make its center coincide with the imaginary center of the channel. This is achieved by immobilizing the insertion guide 17 in a so selected position by firmly connecting it, directly or indirectly with the immobilized The channel 6 is in communication person or animal of which a tissue 14 is to be provided with a channel of the invention filled with aqueous gel 15 via a holding element 13 comprised by the insertion guide 17 and firmly mounted at its sleeve 12 and/or the flange 11 thereof. By a flexible tube (not shown) attached to the proximal end of the pin 1 the channel is in fluid communication with a reservoir (not shown) holding aqueous gelatin gel.

Example 3. Third Embodiment of the Device of the Invention

[0044] The second embodiment 20 of the device of the invention in form of a pin 20 shown in FIG. 1b in an axial section corresponds generally to the pin 1 of FIG. 1 from which it differs by omission of the annular clamp 9 and the holding element 10 and by comprising a conductor 21 which is an electrode 21 or optical fiber 21 disposed centrally in the conduit 6. At its distal detection end 22 the electrode or fiber 21 is embedded in the distal portion P of the pin 20 in a manner that its distal face 22 forms a central section of the face of distal portion P at the distal end 2 of the pin 20. Except for at its distal end 2 the electrode 21 is insulated (not shown). The conductor leaves the conduit 6 laterally near the lateral end 4 thereof.

[0045] The electrode 21 or optical fiber 21 can be used, for instance, for assisting in guiding insertion of the pin 20 to a desired depth by optically or electrically detecting a structure in the tissue, for instance a nerve cell, in the vicinity of which the front end of the channel filled with aqueous gel of the invention is desired to be located.

Example 4. Provision of a Channel of the Invention in Soft Tissue Filled with Aqueous Gel

[0046] The process of providing a channel of the invention in soft tissue 14 filled with aqueous gel 15 is shown in FIGS. 2a, 2c, 2d.

[0047] In the state of FIG. 2a the sleeve 12 fully covers the radially extending bores 7 of the central section C; pressure exerted on the aqueous gel in the reservoir, for instance by compression of the reservoir if comprising a flexible wall, results in the gel filling the central passage 6 and the radially extending bores 7 but not escaping from there due to the high viscosity of the gel. On the other hand, air or other gas present in the central passage 6 and the radial bores 7 can escape through the radial bores 7 since the sleeve 12 does not completely seal them. Thereby the state shown in FIG. 2b is reached.

[0048] In the next step the pin 1 is inserted fully into the tissue 14, that is, to a desired position. The state reached by the insertion is shown in FIG. 2c by insertion during no pressure is exerted on the aqueous gel. Alternatively a slight or a high pressure is exerted on the aqueous gel during insertion, which makes aqueous gel escape from bores 7. While the application of a slight pressure is beneficial for insertion due to the escaped gel functioning as a glidant and protecting the tissue from mechanical damage by the pin 1, the application of a high pressure is not beneficial since gel may easily escape from the channel being formed. It should also be kept in mind that forcing the gel to pass through narrow conduits affects its rheological properties so as to temporarily reduce gel strength.

[0049] By increasing the pressure on the gel in the reservoir gel 15 is forced out from the bores 7 forming a cylinder of gel 15 around the central portion C of the pin and an adjacent part of the distal portion D (FIG. 2d).

[0050] Withdrawal of the pin 1 from the cylinder of gel 15 makes the gel 15 shrink due to pressure from surrounding tissue 14 to form the channel 18 of the invention filled with aqueous gel 15 (FIG. 2e). Prior to withdrawal of the pin 1, in particular prior to insertion of a device of a rigidity which does not allow direct insertion into soft tissue the gel 15 in the channel 18 should be given time to fully stabilize. The time required for stabilization of different kinds of gels has to be experimentally determined.

[0051] Upon withdrawal of the pin 1 the insertion guide 17 can be left mounted at the channel 18 site for protecting the channel until it is used for implantation; in such case its distal opening has to be provided with a closure. Alternatively and additionally, the insertion guide 17 can be used as a guide for a syringe or pipette or other instrument for injection or insertion of a microelectrode, an optical fiber, a suspension or aggregate of living cells, a tissue fragment, a pharmaceutical, etc. into the channel 18.

Example 4. Manufacture of the Device of the Invention

[0052] Pins of the invention are preferably manufactured in two halves. The axial section of FIG. 1 can be taken to represent one such half if considered to be a side view rather than a section. Halves of non-resilient metal can be made by pressure forming thin metal sheet in a mould. The halves can be united by welding or soldering. Halves of a polymer can be produced by, for instance, injection moulding and be united in consideration of the particular polymer properties, such as by fusing them together at their meeting faces or by adhesive means. Suitable polymers include but are not restricted to PVC, polyacrylate, polycarbonate and polystyrene. The manufacture of the insertion guide is trivial and need not be commented on.