Sleeve-like medical implant

Abstract

The invention relates to an oversleeve-like medical implant having a film-like flexible surface substrate which, by means of a material-inherently pressed-in shape, assumes a shape of the straight cylindrical shape type by itself and without external forces, in which shape the surface substrate provides a cylindrical inner surface, the cylindrical inner surface can form extravascular or extranerve surface contact along in vivo strip-shaped structures in the form of in vivo blood vessels or nerve fiber bundles in an implanted state. The invention is characterized in that the film-like flexible surface substrate has two edge regions which lie opposite each other in the implanted state along a cylindrical axis assigned to the straight cylindrical shape and which are each delimited by an undulating edge contour.

Description

Technical Field

[0001] This invention relates to a sleeve-shaped medical implant having a thin-film flexible surface substrate that is shaped by being pressed in a manner inherent to the material and, without the application of external force, naturally forms a straight cylindrical shape. In this shape, the surface substrate provides a cylindrical inner surface that, in the implanted state, can form extravascular or extraneural surface contacts along an in vivo strip structure in the form of a bundle of blood vessels or nerve fibers. Background Technology

[0002] Document EP3204105B1 discloses a sleeve electrode device, also known as a sleeve electrode, which is composed of a flexible biocompatible carrier substrate (preferably made of a polyimide film) and has multiple individual electrodes on at least one side of the upper side of the carrier substrate. Known sleeve electrodes are used for spatially resolved acquisition of neural electrical signals and for selective electrical stimulation of individual nerve fibers extending within a nerve fiber bundle. To ensure that the sleeve electrode is gentle on tissues while maintaining a fixed position relative to the nerve fiber bundle (preferably along the vagus nerve), an inherent mechanical prestress of the material is imprinted in the thin-film carrier substrate. This prestress causes the thin-film carrier substrate to automatically form a straight cylindrical rolled sleeve, forming at least one complete rolled layer. The shape of the straight cylindrical rolled sleeve imprinted in the thin-film carrier substrate is selected according to the extraneural morphology and size of the nerve fiber bundle, such that the adhesion pressure applied by the sleeve electrode to the outer membrane of the nerve fiber bundle ensures that the position along the nerve fiber bundle is fixed while avoiding constriction or excessive mechanical load on the nerve fiber bundle.

[0003] Therefore, it cannot be ruled out that tissue irritation or agitation may occur at the axially opposite edges of the cylindrical carrier base due to the relative movement between anatomically related organic structures (such as the vagus nerve) and the sleeve electrode. This must be eliminated or significantly reduced as much as possible to avoid irreversible damage or injury to the epineurium of the nerve fiber bundles.

[0004] Another example of a sleeve-like implant is disclosed in document DE102017222362B4, which relates to a thin-film rolled sleeve having at least one planar rolled structure that at least partially overlaps itself to form a cylindrical cavity, and is used solely for fixation along intravascular blood vessels or nerve fiber bundles via form-locking and / or force-locking connections. The rolled sleeve, used as a pure fixation device, is intended to withstand tensile forces acting on the implant. In this case, it is equally important to avoid any negative irritation or even damage to the organic structure caused by the fixation rolled sleeve.

[0005] Another example of a sleeve-like implant is described in document EP3833425B1, which represents a protective structure for the aforementioned sleeve electrode and consists of two straight cylindrical half-shells integrally connected to each other. This protective structure can be switched from an open state (in which the protective structure can be placed around the sleeve electrode applied along the nerve fiber bundle) to a closed state.

[0006] Document DE102007036862A1 describes an electrode for intraoperative nerve stimulation having a strip-shaped base that can be placed around the vagus nerve in a single loop (similar to a cable tie). For easy fixation, the strip-shaped carrier base has lateral wave-shaped locking tracks that engage with the opening during the single loop. Summary of the Invention

[0007] The objective of this invention is to improve a sleeve-shaped implant having a thin-film flexible surface substrate that is shaped by being pressed in a material-inherent manner and naturally and without external force to form a straight cylindrical shape. In this shape, the surface substrate has a cylindrical inner surface that, in the implanted state, can at least regionally form surface contact with the strip-shaped internal structure, thereby avoiding or at least significantly reducing tissue irritation to the internal structure, particularly tissue irritation caused by shear forces that may occur at the axially opposite anterior edge of the sleeve-shaped implant.

[0008] The solution to the task upon which the invention is based is given in claim 1. Further advantageous extensions of the inventive concept can be derived from the dependent claims and, in particular, from the further description of the embodiments with reference to the detailed description.

[0009] The solution of the sleeve-shaped medical implant having the features of the preamble of claim 1 is characterized in that the thin-film flexible surface substrate has two edge regions that are opposed to each other along a cylindrical axis assigned to a straight cylindrical shape in the implanted state, and the edge regions are respectively defined by a wavy edge profile.

[0010] The concept upon which this invention is based avoids the linear axial boundary edges of sleeve-shaped implants, which contact the tissue surfaces (particularly the outer membrane of nerve fiber bundles) of their respective strip-shaped internal structures in an edge-side manner. The edge regions integrally connected to the thin-film flexible substrate are laterally defined by edge contour lines that are mathematically continuous and differentiable, i.e., providing no angular lines or regions. The edge contour lines are preferably sinusoidal or formed as sinusoidal curves, and are formed by a regular repeating sequence of wave-shaped protrusions projecting laterally from the corresponding edge regions. Through the wave-shaped contour design of the edge regions, during relative movement between the sleeve-shaped implant and the strip-shaped internal structures, the shear force occurring on the edge side is uniformly distributed along all the arcuate portions of the edge contour line, thereby eliminating localized tearing of the thin-film flexible substrate along the edge regions.

[0011] Furthermore, when the sleeve-shaped implant moves significantly relative to the strip-shaped internal structure, the axially protruding tabular "peaks" at the edge of the wave-shaped structure fold axially towards the base plate and radially abut against the outer side of the straight cylindrical sleeve shape. In this way, a funnel-shaped circular contour is formed at the edge, between the outer membrane or tissue surface and the folded tabular protrusions. This contour prevents any harmful tissue irritation during the relative movement between the sleeve-shaped implant and the strip-shaped internal structure.

[0012] In a preferred embodiment, the two edge regions defined by the wave-shaped edge contour are designed to be thinner relative to the remaining surface substrate, thereby achieving greater flexibility in the edge regions and making the folding of the corresponding crested region tabs easier and faster. Preferably, the thin-film flexible surface substrate has a first film thickness D, typically 15µm ≤ D ≤ 20µm. The thickness of the edge regions defined by the wave-shaped edge contour is reduced to at least one-quarter to one-half of the thickness D. In this way, the planar flexibility of the edge regions is increased, supporting the folding process of the corresponding crested region tabs. The reduced film thickness in the edge regions also results in the absence or negligible recovery of the restoring force imprinted in the thin-film flexible surface substrate for automatically forming a straight cylindrical shape in these near-edge regions. The dimensions of the edge regions are determined on the one hand by their length (preferably corresponding to the perimeter of the sleeve-like implant) and on the other hand by their width (at least twice the amplitude that may correspond to the wave-shaped edge contour).

[0013] The two edge regions, which are axially opposite each other along the cylindrical axis, also serve as mechanical damping between the inherent stiffness of the sleeve-like implant and the tissue surface of the strip-shaped internal structure (such as the outer membrane of a nerve fiber bundle), thereby creating a soft and rounded "resistance transition" between the thin-film flexible surface substrate and the organic tissue structure.

[0014] In a preferred embodiment, the number of individual waveforms along the edge contour lines and their periodic or aperiodic sequence are adapted to the circumferential edge length of the sleeve-shaped implant's straight cylindrical shape, such that each of the two waveform edge contour lines completely encircles the circumferential edge once, i.e., only once, meaning that the crest-shaped protrusions projecting axially from the surface substrate do not overlap radially. In this way, it is ensured that the folding of the crest-shaped protrusions caused by relative movement can occur unimpeded and without colliding with other crest-shaped protrusions connected to the thin-film flexible surface substrate.

[0015] The present invention relates to the provision of edge regions on the axially opposite circumferential edges of a sleeve-shaped implant that automatically forms a straight cylinder, each laterally defined by a wavy edge contour line. This is particularly suitable for general designs of rolled-up sleeves, especially when used in conjunction with sleeve electrodes (e.g., the sleeve electrode described in the opening document EP3204105B1, which has an electrode structure on the cylindrical inner surface of a thin-film flexible substrate).

[0016] Similarly, it is suggested that the edge region of the present invention be provided on a protective structure that can be assembled from two cylindrical half-shells into a straight cylinder, as described in the document EP3833425B1 set forth at the beginning. Attached Figure Description

[0017] The present invention will be described below by way of example with reference to the accompanying drawings, without limiting the general concept of the invention. The drawings are as follows.

[0018] Figure 1 The diagram above shows a schematic tabular comparison between known sleeve-shaped implants (left list) and sleeve-shaped implants designed according to the present invention (right list).

[0019] Figure 2a b shows a protective structure that can be assembled from two cylindrical half-shells. Detailed Implementation

[0020] Figure 1 The left column shows a known biocompatible flexible carrier substrate 1, such as a polyimide film, which has a rectangular basic shape and automatically embosses into a straight cylindrical rolled sleeve 2 without external force through the inherent imprinting of the material. Figure 1 As shown in the left column of b. Here, the surface base 1 is wound around the side edge 4 of the surface base to form at least one complete wound layer, wherein when forming the straight cylindrical wound sleeve 2, two orthogonal side edges 7 connected to the side edge 4 of the surface base and opposite to each other form circumferential side edges 7 that are axially opposite along the cylindrical axis 3.

[0021] As an alternative to the rectangular basic shape of the base 1, a square basic shape, etc., can also be considered.

[0022] In order to apply along the strip-shaped internal structure 5 (e.g., along nerve fiber bundles, especially along the vagus nerve) Figure 1 The implanted roll-up sleeve 2 shown in the left column will be in an unfolded shape (see...). Figure 1 a) The surface base 1 is placed laterally next to the strip-shaped internal structure 5, and then applied in a self-fixing manner by automatically winding around the strip-shaped internal structure 5, such as Figure 1 c is shown in the left column.

[0023] When the rolled sleeve 2 undergoes continuous longitudinal movement 6 along the strip-shaped internal structure 5, the circumferential edge 7 of the axially opposite (relative to the cylindrical axis 3) side edge of the rolled sleeve 2 may act as a friction and cutting edge, causing damage to the strip-shaped internal structure 5, for example in the form of local tissue peeling 8.

[0024] To avoid such damage, the biocompatible flexible surface substrate 2* of the sleeve-shaped implant according to the present invention is modified such that the thin-film flexible surface substrate 1* has two opposing edge regions 10, which are laterally defined by wavy edge contour lines 11, see [reference]. Figure 1 a. Right column. The waveform edge profile 11 has no corners and is mathematically continuously differentiable. A sine curve or sinusoidal wave curve is particularly suitable as the edge profile 11, which has a periodic sequence of wave-shaped protrusions 12 protruding from the edge side.

[0025] The length 9 of the edge region 10, defined by the waveform edge contour line 11, approximately corresponds to the perimeter of the strip-shaped internal structure 5. This ensures that when the rolled-up sleeve 2* is applied around the strip-shaped internal structure 5, the two axially opposite edge regions 10 of the rolled-up sleeve 2* along the cylindrical axis 3* surround the strip-shaped internal structure 5 in a single layer only, see [reference needed]. Figure 1 b. Right column. The width 19 of the edge region 10 should correspond at least twice the amplitude A of the crested region protrusion 12, preferably three to ten times the amplitude.

[0026] If, during implantation, longitudinal relative movement occurs between the rolled-up sleeve 2* and the strip-shaped internal structure 5, see [link / reference]. Figure 1 In column c, the crest-shaped protrusions 12 of the wave-shaped edge region 10 are radially folded outward and attached to the outside of the rolled-up sleeve 2*, forming a funnel-shaped contour 13 between the rolled-up sleeve 2* and the surface of the strip-shaped internal structure 5. See also Figure 1 d Right column. The funnel-shaped profile 13 can completely avoid or at least significantly reduce the shear force generated between the rolled-up sleeve 2* and the in vivo structure 5 through the longitudinal relative movement 6, thereby preventing irreversible damage to the tissue surface of the in vivo structure 5.

[0027] To facilitate or support the folding process of the corrugated region tab 12, the edge region 10 preferably has a smaller substrate thickness than other regions of the substrate 1. Typically, a polyimide film with a thickness between 15 µm and 20 µm is used to form the substrate 1. In contrast, the thickness of the edge region 10 is only half to ¼ of the former, thereby significantly improving its planar elasticity and the associated deformability.

[0028] When the implanted roll-up sleeve is designed as a sleeve electrode... Figure 1 The surface substrate 1* shown in columns a and b* has electrode structures 18 in the surface substrate region located between the two edge regions 10 and facing the drawing. These electrode structures are in direct contact with the tissue surface of the strip-shaped internal structure 5, especially with the epidermis of the vagus nerve.

[0029] For manufacturing reasons and to improve the fixation of the rolled-up sleeve 2* around the strip-shaped inner structure 5, the surface base 1* has a surface extension 16, which increases the rollability of the rolled-up sleeve 2* without affecting the function of the edge region 10. Therefore, the surface extension 16 is designed to be narrower than the total length 17 of the rolled-up sleeve 2*.

[0030] Figure 2a An alternative sleeve-shaped implant designed according to the invention is shown, having a thin-film flexible surface substrate 1 in the form of two straight cylindrical semi-shell shapes 15 integrally connected along a linear connecting region 14, with edge regions 10 formed on their axially opposite circumferential edge sides, each edge region being defined by a wavy edge profile line 11. Figure 2b This illustrates a shape configuration in which two straight cylindrical semi-shell shapes 15 slightly overlap each other 16 to form a straight cylindrical shape. This is consistent with the embodiments of the invention described above (see [link to previous text]). Figure 1 (See right-hand illustration) Similarly, in this case, the edge region 10 is also designed with a smaller surface base thickness compared to the rest of the surface base region 1.

[0031] List of reference numerals in the attached diagram: 1,1*,1** base surface 2,2* Implantable Roll-Up Sleeve 3,3*Cylindrical axis 4-sided base side edge 5 strip-shaped internal structures 6. Longitudinal movement 7 circumference towards the edge side edge 8. Irreversible damage, tissue detachment 9 length 10 Edge Areas 11 Edge contour lines 12-peaked regional protrusions 13 Funnel-shaped outline 14 linear connection areas 15. Straight cylindrical semi-shell shape 16-sided base extension 17 rolls of sleeve total length 18-electrode structure 19 Edge area width A. The amplitude of the peak-shaped protrusions.

Claims

1. A sleeve-shaped medical implant having a thin-film flexible surface substrate (1*, 1**), which is shaped by being pressed in a manner inherent to the material and naturally and without external force, wherein the surface substrate (1*, 1) provides a cylindrical inner surface that, in the implanted state, can form an extravascular or extraneural surface contact along an in vivo strip structure (5) in the form of a blood vessel or nerve fiber bundle, characterized in that, The thin-film flexible surface substrate (1*,1) has two edge regions (10), which are opposed to each other along the cylindrical axis (3*) assigned to the straight cylindrical shape in the implanted state, and The edge regions (10) are defined by the edge contour lines (11) of the waveform.

2. The sleeve-shaped medical implant according to claim 1, characterized in that, The thin-film flexible substrate (1*, 1**) can be fitted with a rectangular or square basic shape.

3. The sleeve-shaped medical implant according to claim 2, characterized in that, The two edge regions (10) are arranged along two opposite sides of a rectangular or square basic shape.

4. The sleeve-shaped medical implant according to any one of claims 1 to 3, characterized in that, The two edge regions (10) extend once around the circumference of the straight cylindrical shape surrounding the rolled-up sleeve (2*).

5. The sleeve-shaped medical implant according to any one of claims 1 to 4, characterized in that, The edge contour lines (11) that define the edge regions (10) are continuously differentiable.

6. The sleeve-shaped medical implant according to claim 5, characterized in that, The edge contour line (11) corresponds to a sinusoidal curve or a sine curve.

7. The sleeve-shaped medical implant according to any one of claims 1 to 6, characterized in that, Except for the edge region (10), the thin film flexible surface substrate (1*, 1**) has a first film thickness D and a second film thickness in the edge region (10), which is less than the first film thickness D.

8. The sleeve-shaped medical implant according to claim 7, characterized in that, The thickness of the second film is reduced by a factor F compared to the thickness D of the first film, and for this factor F, the following applies: ½ ≥ F ≥ ¼, and for the thickness D of the first film, the following applies: 15µm ≤ D ≤ 20µm.

9. The sleeve-shaped medical implant according to any one of claims 1 to 8, characterized in that, The thin-film flexible surface substrate (1) is constructed in the form of a rolled-up sleeve (2), wherein the thin-film flexible surface substrate (1) can be formed by automatically rolling around a side edge (4) that can be matched with the thin-film flexible surface substrate (1).

10. The sleeve-shaped medical implant according to claim 9, characterized in that, The rolled sleeve (2*) is constructed in the form of a sleeve electrode device, which is adapted to be applied along and around the strip-shaped internal structure (5), and has an electrode structure (18) at least on the cylindrical inner surface of the rolled sleeve.

11. The sleeve-shaped medical implant according to any one of claims 1 to 8, characterized in that, The thin-film flexible surface substrate (1**) has two straight cylindrical semi-shell shapes (15) integrally connected along a linear connection region (14). The straight cylindrical semi-shell shapes are defined by thin-film substrate edges oriented parallel to the cylindrical axis (3*). The two can abut or overlap each other in the form of a straight cylindrical shape.

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