Medical implant

Abstract

The invention relates to a medical implant which has a film-like, flexible planar substrate in which material-inherent, shape-determining restoring forces are impressed which shape the film-like, flexible planar substrate, without application of external force, into a straight-cylindrical wound sleeve in such a way that, after formation of a first complete wound layer, the latter is wrapped around by at least one further wound layer, at least in the form of a partial winding. The invention is characterized in that at least one locally limited pattern of a first type is applied to the film-like, flexible planar substrate in the region of the first wound layer, and at least one locally limited pattern of a second type is applied thereto in the region of the at least one further wound layer, and in that the at least one locally limited pattern of the first type and that of the second type are applied to the film-like, flexible planar substrate in such a way that they are visually perceptible radially from the outside.

Description

[0001] Medical implant

[0002] Technical area

[0003] The invention relates to a medical implant comprising a film-like flexible surface substrate in which material-inherent, shape-determining restoring forces are impressed, which are capable of forming the film-like flexible surface substrate into a straight-cylindrical winding sleeve without the application of external force, such that after forming a first complete winding layer, this is wrapped by at least one further winding layer, at least in the form of a partial winding.

[0004] State of the art

[0005] EP 3204 105 B1 discloses a wound cuff electrode arrangement, also referred to as a cuff electrode, consisting of a flexible, biocompatible, film-like carrier substrate, preferably a polyimide film. A plurality of individual electrodes are arranged on at least one surface of the carrier substrate. Inherent restoring forces are imprinted in the film-like carrier substrate through a tempering process, which enable the carrier substrate to wind itself into a straight-cylindrical cuff shape without the application of external force. This property is used for the application of the cuff electrode around a nerve fiber bundle. The known cuff electrode is used for the spatially resolved recording of neuronal electrical signals and for the selective electrical stimulation of individual nerve fibers running within a nerve fiber bundle.

[0006] In order to ensure the permanent and reliable function of the cuff electrode in the implanted state, the large number of electrodes arranged on the foil-like carrier substrate must be contacted with as uniform a contact pressure as possible on and in a precisely specified spatial arrangement relative to the epineurium of the nerve fiber bundle, preferably the vagus nerve.

[0007] For this purpose, the foil-like carrier substrate of the cuff electrode must be dimensioned and assembled according to the shape and size of the vagus nerve in order to generate the most uniform contact pressure possible from the cuff electrode on the surface of the vagus nerve when implanted. This pressure ensures both a solid hold and functional electrical contact between the numerous electrodes on the epineurium of the vagus nerve. Ideally, the cuff electrode, designed as a wound sleeve, takes on the shape of a straight cylinder when implanted. In this cylinder, the carrier foil, using its inherent material restoring forces, independently forms preferably several wound layers surrounding the vagus nerve. These wound layers lie loosely on top of one another in a congruent radial manner. The axial boundary edges assigned to each of the wound layers on both sides are radially aligned with one another.

[0008] In practice, however, mismatches between the dimensions of the cuff electrode and the thickness or actual cross-section of the nerve fiber bundle can result in excessive or insufficient contact pressure between the cuff electrode and the nerve fiber bundle. Incorrect wrapping of the cuff electrode around the vagus nerve can also result in winding geometries that severely constrict or constrict the nerve fiber bundle axially on one side, while on the other hand, only loosely fitting or even spaced apart from the epineurium.

[0009] Although the process of wrapping or looping the cuff electrode around the nerve fiber bundle occurs largely autonomously, the person carrying out the implantation procedure requires great concentration to qualify the wrapping result and, if necessary, to make adjustments accordingly. Such measures to correct the position and fit of the cuff electrode after it has already been applied to a nerve fiber bundle require a great deal of experience and caution in order to avoid injury to the nerve fiber bundle. In addition, the film-like, biocompatible carrier substrate of a cuff electrode is usually transparent, i.e. made of light-transparent material, which makes visual detection of a possible mismatch in the winding geometry of a cuff electrode applied to the nerve fiber bundle at the very least difficult.

[0010] The document DE 10 2007 036 862 A1 discloses a fastening device designed in the form of a cable tie for an electrode arrangement for intraoperative nerve stimulation.

[0011] The document WO 2011 / 147876 A1 describes an implantable collecting electrode with a direction-marked connecting cable.

[0012] Description of the invention

[0013] The invention is based on the object of further developing a medical implant which has a film-like, flexible surface substrate in which material-inherent shape-determining restoring forces are impressed, which are able to form the film-like, flexible surface substrate into a straight-cylindrical wound cuff without the application of external force, so that after forming a first complete wound layer, this is wrapped by at least one further wound layer at least in the form of a partial winding, so that it is easier and safer for a person carrying out the application process of the wound cuff around a nerve fiber bundle to visually record and qualify the winding result, i.e. to determine whether the wound cuff has assumed an ideal straight-cylindrical cuff shape or a winding geometry which deviates therefrom.Depending on this, it must be decided whether the cuff electrode remains on the nerve fiber bundle or needs to be readjusted.

[0014] The solution to the problem underlying the invention is defined in claim 1. Features that advantageously further develop the inventive concept are the subject of the dependent claims and the further description, in particular with reference to the exemplary embodiments.

[0015] The medical implant according to the invention with the features of the preamble of claim 1 is characterized in that at least one locally limited pattern of a first type is applied to the film-like, flexible surface substrate in the region of the first winding layer, and at least one locally limited pattern of a second type is applied in the region of the at least one further winding layer. The at least one locally limited pattern of the first and second type is applied to the film-like, flexible surface substrate in such a way that it is visually perceptible radially from the outside.

[0016] Based on the radially visible patterns of the first and second type from the outside, a surgeon can directly determine from their relative positions whether the cuff electrode has a cross-section or diameter that is too small or too large for the nerve fiber bundle and / or whether a lateral offset has occurred when the cuff electrode was wound or wrapped around the nerve fiber bundle, i.e. whether the cuff electrode deviates from an ideal straight cylinder shape in the manner of a cone or a triangle.

[0017] The cuff electrode is wrapped around the nerve fiber bundle in a truncated cone. In this case, the surgeon can adjust the position of the cuff electrode on the nerve fiber bundle, repeat the wrapping process, or, if the cuff electrode is too small or too large, select and use a more suitable cuff electrode.

[0018] A preferred embodiment of the medical implant according to the invention provides a light-transparent, film-like, flexible surface substrate that allows the at least one locally limited pattern of the first type to be visually perceived radially from the outside through the at least one further wound layer. In order to also reliably detect the relative position between the at least one locally limited pattern of the first and second type, it is advantageous for the at least two patterns of the first and second type to be visually distinguished and distinguished from the light-transparent, film-like, flexible surface substrate and from one another by high contrast. This can be achieved, in particular, by a suitably selected, different coloring.

[0019] As an alternative to, or in combination with, the different color choices for the purpose of achieving the greatest possible contrast between the two patterns of the first and second type, it is also possible to support differentiation through different shapes and sizes. For example, it is conceivable to design at least one locally limited pattern of the first type as rectangular, while at least one pattern of the second type is circular.

[0020] Preferably, the at least one locally delimited pattern of the first and second type is each applied to a radially outwardly oriented surface of the film-like, flexible surface substrate formed into the winding sleeve, for example by means of a printing and / or surface structuring process. In order to ensure the visibility of the at least one locally delimited pattern of the first and second type even in the case of a non-light-transparent surface substrate, at least that surface area within the at least one further winding layer which radially covers the at least one locally delimited pattern of the first type in the region of the first winding layer is either light-transparent or provided with a correspondingly large viewing opening through which the locally delimited pattern of the first type radially covered by the further winding layer can be visible radially from the outside.

[0021] To ensure an ideal spatial reference arrangement between the at least one pattern of the first and second type, the at least one locally limited pattern of the first type and the at least one locally limited pattern of the second type are arranged along a common plane orthogonally intersecting the winding axis when the cuff is formed. This means that, in the case of an ideal application of the cuff electrode around a nerve fiber bundle, the at least two patterns of the first and second type are arranged serially behind or next to one another along a common circumferential edge line around the cuff.The shape and number of the locally limited patterns of the first and second type arranged on the foil-like, flexible surface substrate are preferably selected such that the locally limited patterns of the first and second type are arranged uniformly distributed in a serially alternating sequence along a circumferential edge line, viewed radially from the outside.

[0022] Typically, the foil-like, flexible surface substrate from which the cuff electrode is made has, in a flat, i.e. non-wound state, a rectangular or square basic shape with two opposite surface substrate side edges, which, after corresponding independent winding of the surface substrate, axially delimit the winding cuff on both sides.

[0023] Preferably, the at least one locally limited pattern of the first and second type is arranged along a circumferential edge line immediately adjacent to both surface substrate side edges.

[0024] The locally limited patterns of the first and second type, arranged on both sides close to the surface substrate side edges that axially delimit the wrap cuff, make it easy for the surgeon to determine whether the cuff electrode is correctly positioned on the epineurium of a nerve fiber bundle. Such control is particularly important when applying a cuff electrode arrangement along a nerve cord or nerve fiber bundle, especially along the vagus nerve, for the purpose of site-selective detection of neuronal signals and the spatially and temporally resolved application of neuronal stimulation signals.

[0025] Brief description of the invention

[0026] The invention is described below, without limiting the general inventive concept, using exemplary embodiments with reference to the drawings. They show:

[0027] Fig. 1 straight cylindrical winding cuff,

[0028] Fig. 2 foil-like, flexible surface substrate of a winding sleeve in the unrolled state and Fig. 3 a,b,c representation of different winding states

[0029] Ways of implementing the invention, industrial applicability

[0030] Figure 1 shows a self-winding winding sleeve 1, which consists of a foil-like, flexible surface substrate 2, into which material-inherent, shape-determining restoring forces are impressed during a tempering process, by means of which the foil-like, flexible surface substrate 2, after self-winding, takes on the shape of a straight cylinder with a predetermined inner diameter d x. Due to the multiple winding layers 3 that lie loosely against one another during the automatic winding of the winding sleeve 1, each winding sleeve 1 has a certain "path reserve" in order to also accommodate larger diameter nerve fiber bundles, whose diameter is slightly larger than the inner diameter d predetermined by the tempering process. x is, but can still be functionally encompassed.

[0031] In order to provide the person applying the wrap cuff 1 around a nerve fiber bundle 9 with a decision criterion as to when the “path reserve” explained above is used up or exceeded, the markings M illustrated in Figure 2, which are applied directly to the edge of the film-like, flexible surface substrate 2, are used, and which are explained in the following reference.

[0032] Figure 2 shows a film-like, flexible flat substrate 2 in the unwound state, i.e., flat. The rectangular flat substrate 2 is bounded by two parallel flat substrate side edges 4 and by a further side edge 5 oriented orthogonally to both flat substrate side edges 4. The flat substrate tab F, which extends laterally from the flat substrate 2 and serves to conduct electrical lines, is mentioned only for the sake of completeness; however, it is irrelevant in connection with the invention.

[0033] When the film-like, flexible surface substrate 2 is wound up automatically, it winds around the side edge 5 to form a straight cylinder whose cylinder axis corresponds to the winding axis, which is oriented parallel to the side edge 5. In the case shown in Figure 2, the first surface section I forms the first radially inner winding layer directly adjacent to the epineurium of a nerve fiber bundle, and the adjoining second surface section II of the surface substrate 2 forms a radially outer winding layer that radially encompasses the inner winding layer. A serial sequence of locally limited patterns of a first type 6 and a second type 7 is arranged close to the edge of both surface substrate side edges 4. The locally limited patterns of the first type 6 are each located close to the edge in the first surface section I, which corresponds to the inner winding layer.The locally limited patterns of the second type 7 are located in the second surface section II, which corresponds to the radially outer winding layer of the winding cuff 1. The locally limited patterns of the first and second type 6, 7 are formed as rectangular fields in the case shown in Figure 2 and differ from one another by their coloring, which contrasts as much as possible. Alternatively, the selected colors can also be fluorescent and react to a uniform excitation frequency with different emitter frequencies, such as immunostains in anatomical work.

[0034] The arrangement of the locally limited patterns of the first and second types 6, 7 is selected such that they each lie along a circumferential edge line 10 assignable to the winding sleeve 1. Between each two adjacent patterns 6, 7, a spacing field 8 is provided, which either consists of the preferably light-transparent, film-like, flexible surface substrate or, if the surface substrate 2 is not or not sufficiently light-transparent, is designed as a through-opening, in the form of a viewing opening, particularly in the second surface region II.

[0035] If the prefabricated wrapping cuff 1 is wrapped around a nerve fiber bundle 9, then after an ideal wrapping process, in which the wrapping cuff 1 has an inner diameter d xwhich approximately corresponds to the outer diameter of the nerve fiber bundle 9, the winding result shown in Figure 3a. In this case, the locally limited patterns of the first and second type 6, 7 each lie along a circumferential edge line 10 running close to the edge of both surface substrate side edges 4. The locally limited patterns of the first and second type 6, 7, which are each visually perceptible radially from the outside, directly border one another in an alternating sequence and are each recognizable as surface patterns of the same size.

[0036] This radial appearance of the wrap cuff, marked by the locally limited patterns of the first and second type 6, 7, which is visually perceptible to a surgeon from the outside, signals to the surgeon that the wrap cuff has been correctly applied around the nerve fiber bundle 9. If a deviating appearance occurs, this is a sign for the surgeon to correct the wrap cuff 1, if necessary to completely detach it from the nerve fiber bundle 9 and to reapply it.

[0037] Such a case is illustrated in Figure 3b, in which the wrap cuff 1 is applied obliquely, ie, forming a slightly conical shape along the nerve fiber bundle 9. In this case, the locally limited patterns of the first and second type 6, 7 are not arranged along a circumferential edge line 10 as in the case according to Figure 3a, but are laterally, ie, axially offset.

[0038] Figure 3c illustrates the case in which the wrap cuff 1 is too small for the nerve fiber bundle 9, i.e., the nerve fiber bundle 9 excessively expands the wrap cuff 1 radially, so that the locally limited patterns of the first and second types 6, 7 do not appear as equally sized marking fields along the circumferential edge lines. As in the case shown in Fig. 3b, in this case, the wrap cuff 1 must be detached from the nerve fiber bundle 9 and reapplied.

[0039] The mismatches shown in Figures 3b and 3c can also occur in combination, which the surgeon can easily detect based on a pattern arrangement that deviates from the ideal (see Figure 3a). Particularly in the case of the wrap-around cuff 1 being designed as a cuff electrode, which prefers a plurality of individual electrodes 11 in the first surface section I, which are to be applied in a predefined position along the epineurium of the nerve fiber bundle 9, the cuff electrode must be applied in a precisely predetermined ideal position, as illustrated in Figure 3a, along the nerve fiber bundle 9. The measure according to the solution of providing locally limited markings of a first and second type 6, 7, which differ from one another at least in shape, size, or color, serves the surgeon as a decision criterion as to whether the wrap-around cuff has been applied correctly or incorrectly along a nerve fiber bundle 9.

[0040] List of reference symbols

[0041] 1 wrap cuff

[0042] 2 Surface substrate

[0043] 3 wrapping layers

[0044] 4 Surface substrate side edge

[0045] 5 Side edge

[0046] 6 localized pattern of the first kind

[0047] 7 locally limited pattern of the second type

[0048] 8 light-transparent distance

[0049] 9 nerve fiber bundles

[0050] 10 peripheral border lines

[0051] 11 electrodes

[0052] I first area section

[0053] II second area section d x inner diameter

[0054] M marking

Claims

Patent claims 1. A medical implant comprising a film-like flexible sheet substrate (2) in which material-inherent, shape-determining restoring forces are impressed, which form the film-like flexible sheet substrate (2) into a straight-cylindrical winding sleeve (1) without external force, such that after forming a first complete winding layer (3, I), this is wrapped by at least one further winding layer (3, II), at least in the form of a partial wrapping, characterized in that at least one locally limited pattern of a first type (6) is applied to the film-like flexible sheet substrate (2) in the region of the first winding layer (3, I) and at least one locally limited pattern of a second type (7) is applied in the region of the at least one further winding layer (3, II), and that the at least one locally limited pattern of the first (6) and second type (7) is applied to the film-like flexible sheet substrate (2) in such a way,so that they appear radially and visually perceptible from the outside.

2. Medical implant according to claim 1, characterized in that the film-like, flexible surface substrate (2) is light-transparent and the at least one locally limited pattern of the first and second type (6, 7) each stand out in a high-contrast manner from the light-transparent film-like, flexible surface substrate (2) and are visually distinguishable from one another.

3. Medical implant according to claim 1 or 2, characterized in that the at least one locally limited pattern of the first and second type (6, 7) is each applied to a radially outwardly oriented surface of the film-like, flexible surface substrate (2) formed into the wound sleeve (1), and in that at least that surface area (II) within the at least one further wound layer which radially covers the at least one locally limited pattern of the first type (6) in the area of the first wound layer (3, I) is light-transparent or provided with a viewing opening.

4. Medical implant according to one of claims 1 to 3, characterized in that the at least one locally limited pattern of the first and second type (6, 7) can be distinguished from one another by one of the following visually perceptible appearances: color, shape, size.

5. Medical implant according to one of claims 1 to 4, characterized in that the at least one locally limited pattern of the first type (6) and the at least one locally limited pattern of the second type (7) are arranged along a common plane orthogonally intersecting the winding axis when the winding sleeve (1) is formed.

6. Medical implant according to one of claims 1 to 5, characterized in that the film-like flexible surface substrate (2) has a rectangular or square basic shape with two opposite surface substrate side edges (4) which delimit the winding sleeve (1) axially opposite one another, and in that the at least one locally delimited pattern of the first and second type (6, 7) is arranged adjacent to the edge of both surface substrate side edges (4).

7. Medical implant according to claim 5 or 6, characterized in that at least two locally limited patterns of the first and second type (6, 7) are arranged on the film-like flexible surface substrate (2) in such a way that they appear radially visible from the outside in an alternating sequence along a circumferential edge line (10) that can be assigned to the winding sleeve (1).

8. Medical implant according to one of claims 1 to 7, characterized in that the at least one locally limited pattern of the first and second type (6, 7) is rectangular or square and that the first and second type (6, 7) differ from each other in color.

9. Medical implant according to one of claims 1 to 8, characterized in that the wound cuff (1) is designed as a cuff-electrode arrangement for extravascular or extraneuronal application around a vessel or around a nerve fiber bundle.

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