Implant

Abstract

To provide an implant which can achieve improved fluid transition and smaller change of rigidity, in transition from a blood vessel without an implant to a blood vessel with an implant.SOLUTION: An implant comprises an openwork and hollow cylindrical main body 10 which is assembled from multiple openwork and hollow cylindrical segments 11, 13 being connected mutually and arranged continuously in a longer direction L. Each of the segments includes: a terminal segment 11 located at each end of the main body 10 arranged in the longer direction; and at least one internal segment 13 arranged in the longer direction L between the two terminal segments 11. Each of the segments 11, 13 includes multiple bars having a maximum point and a minimum point and together forming a meander structure extending in a circumferential direction, and the main body 10 becomes in a compression state and an expansion state.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an implant comprising an openwork hollow cylindrical body assembled from a number of openwork hollow cylindrical segments arranged in a longitudinal sequence and connected to one another, each segment having a number of bars forming together a circumferentially extending serpentine structure having minimum and maximum points, the implant or its body being capable of being in a compressed state and in an expanded state. [Background technology]

[0002] A wide variety of medical implants (prostheses), in particular intraluminal endoprostheses, for a wide range of applications are known from the prior art.

[0003] Stents are commonly used implants, examples of which are foams that can be used to treat stenosis (vascular narrowing). Stents typically have an openwork hollow cylindrical (tubular) body that is open at both ends longitudinally (i.e., in the direction of the longitudinal axis). This type of implant is often inserted into the blood vessel to be treated using a catheter, and is used to support the blood vessel using the body for a relatively long period of time (months to years). Narrowed areas in the blood vessel can be widened by using a stent.

[0004] Implants, in particular stents, made partly or entirely of biodegradable materials are also already known. Biodegradation is understood to mean hydrolytic, enzymatic and other metabolically induced degradation processes in vivo, triggered inter alia by contact of body fluids with the biodegradable material of the implant, leading to a gradual disintegration of the structure of the implant, including the biodegradable material. As a result of this process, the implant loses its mechanical integrity at some point. The term "bioresorption" is often used as a synonym for the term "biodegradation". The term "bioresorption" includes the subsequent resorption of the degradation products by the organism.

[0005] The document EP 1 974 700 A1 describes an implant in the form of a stent having a radially expandable body, the body having a number of support segments, each segment being formed by serpentine struts. The document EP 3 034 035 A1 also describes such an implant, which is flexible and at the same time has sufficient radial stiffness to support the vessel in which it is inserted.

[0006] Known implants such as those described above, in which the body is assembled from a number of segments arranged in succession in the longitudinal direction, often have a number of struts in each segment, each of which forms a serpentine structure in the circumferential direction. The struts for this purpose are fixed to each other or transition to each other at the maximum and minimum points of the arcs of the structure. The serpentine structure has alternating minimum and maximum points, with the arc near the first end of the body being referred to as the minimum point of the segment, while the other arc near the end of the body opposite the first end is referred to as the maximum point.

[0007] Within the scope of this application, a segment is understood to mean a hollow cylindrical portion of the implant. The segment is composed of a number of struts and arcs forming a circumferential serpentine structure. The segment is circumferentially closed, i.e. the struts and arcs of the segment are interconnected to form a circumferentially closed ring. In the case of a stent, this type of embodiment is often also called a ring design.

[0008] On the one hand, the known implants assume the already mentioned compressed state in which they can be minimally invasively introduced into the body of the patient to be treated, for example by means of a catheter. On the other hand, the implant is transferred, for example by balloon expansion, into an expanded state at the treatment site where it must remain. In the expanded state, the implant supports the target vessel by its body or is fixed in the relevant organ or other body cavity. Within the scope of the present application, the expanded state is understood to mean the state of the implant provided after expansion, for example by balloon expansion, without taking into account the individual and local external influences brought about by the individual implantation sites (for example locally different vessel diameters, stiffness or deviations from a circular cross section). The expanded state therefore corresponds to the state after expansion in open air.

[0009] Within the scope of the following description, the term "vessel" is intended to include all internal vessels, organs or other body cavities of the patient to be treated, in which a generic implant may be inserted for therapeutic purposes, in particular blood vessels.

[0010] When an implant having the body described above is inserted into a blood vessel, the body fluid of the blood vessel flows through the implant. At the transition between the blood vessel without the implant and the blood vessel with the implant, a change in flow occurs that may impede the flow of the body fluid and cause undesirable deposition or aggregation of the contents of the body fluid in the area of ​​the transition. In the case of a moving vessel (e.g., blood vessel), the stiffness of the particular blood vessel also changes in the area of ​​the inserted implant, since the implant present at the treatment site also contributes to the stiffness. This change in stiffness should, if possible, not be abrupt. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] EP1974700A1 [Patent Document 2] EP3034035A1 Summary of the Invention [Problem to be solved by the invention]

[0012] It is therefore an objective of the present disclosure to create an implant that achieves improved flow transition and smaller stiffness changes when transitioning from a vessel without an implant to a vessel with an implant. Furthermore, an implant according to the present invention should be better and more easily implantable than comparable prior art implants. [Means for solving the problem]

[0013] The above object is achieved by an implant having the features of claim 1.

[0014] In particular, the implant according to the invention has a plurality of openwork hollow cylindrical segments arranged in succession in the longitudinal direction in a serpentine structure as described above, each of which comprises a terminal segment at each end of the longitudinally arranged body and at least one inner segment arranged longitudinally between the two terminal segments. According to the invention, the serpentine structure of at least one terminal segment has a smaller number of minimum points than the at least one inner segment.

[0015] A segment preferably has as many minimum points as maximum points, and this preferably applies equally to both end and inner segments.

[0016] The outer diameter of this at least one end segment in the expanded state is preferably substantially equal to the outer diameter of at least one inner segment in the same state. In other words, when the implant is expanded, a hollow cylindrical body is produced whose outer diameter does not differ between the inner and end segments. Within the scope of this application, "substantially equal outer diameters" is understood to mean a diameter difference of less than 3%, preferably less than 2%.

[0017] The solution according to the invention creates an implant whose body allows an improved implantation procedure. Due to the tortuous structure of the segments, the reduction in the number of minimum points in the terminal segments means at the same time a corresponding reduction in the number of maximum points and the number of bars. This means that the terminal segments can be compressed to a smaller diameter than the inner segments. During implantation, the implant is inserted head-first into the vessel. Due to the small compressed diameter of the terminal segments, the risk of the terminal segments protruding and impinging on and damaging the vessel wall during insertion is minimized. Furthermore, the flow transition is improved due to the smaller number of bars in the region of the terminal segments.

[0018] In one exemplary embodiment of the present invention, both end segments have fewer minimum points than at least one interior segment.

[0019] In further exemplary embodiments, the number of minimum points of one or both end segments is one or two times less than the number of minimum points of the inner segment. If the inner segments have different numbers of minimum points, in certain embodiments the number of minimum points of one or both end segments must be one or two times less than the number of minimum points of the inner segment having the smallest number of minimum points.

[0020] For example, the implant has interior segments that form six minimum points each in a serpentine configuration. In this exemplary embodiment, one or both end segments have, for example, four or five minimum points. Other numbers of minimum points are included in the above definition, and the number of minimum points is a natural number.

[0021] In one particular embodiment, at least one eyelet for placing a functional element made of a radiopaque and / or radiopaque material is provided on the serpentine structure of at least one end segment, the inner opening of the eyelet being preferably elliptical. Eyelets with a circular inner opening or with a square or rectangular inner opening or another shape are also conceivable. In the case of the implant according to the invention, the placement of a relatively large radiopaque and / or radiopaque functional element is possible compared to conventional implants, since the necessary space has been created by reducing the number of minimum points and thus the number of bars, without preventing the compression or expansion of the body in the area where it is placed. The outer length of the eyelet, i.e. the outer longitudinal dimension, is here less than or equal to the width of the end segment. Here, the width of the segment (segment width) is considered to be the outer length of the segment in a particular state in the longitudinal direction of the body. In this embodiment, the advantage of the invention with respect to the small diameter in the compressed state is particularly highlighted. Due to the reduced number of minimum points, more space is created for the functional element, and the implant together with the functional element can be compressed to a smaller diameter as a whole. The functional element does not increase in diameter in the compressed state. This allows for a smaller profile catheter system for inserting this type of implant, making for easier and less traumatic implantation.

[0022] The functional element may be made of one or more radiopaque and / or radio-opaque elements or compounds from the group including, for example, platinum, iridium, gold, tungsten, molybdenum, niobium, tantalum, yttrium, zirconium, ytterbium or alloys of these metals.

[0023] In certain exemplary embodiments, a functional element made of a radiopaque and / or radio-opaque material is disposed in at least one eyelet, the functional element being fixed to the eyelet, for example by adhesive bonding.

[0024] In certain exemplary embodiments, a further reduction in the variation in stiffness between the vessel with and without the implant can be achieved in that at least one end segment has a segment width that is greater than the segment width of at least one inner segment. Due to the greater segment width of the at least one end segment, the radial stiffness is further reduced. The segment width of the end segment can be, for example, between 1 mm and 2 mm, preferably between 1.1 mm and 1.6 mm. The segment width of the inner segment can be, for example, in a similar range. The inner segment advantageously has a smaller bar width, between 0.01 mm and 0.3 mm, preferably between 0.01 mm and 0.2 mm, particularly preferably between 0.07 mm and 0.12 mm.

[0025] In a further exemplary embodiment, the distance between the end segment and the adjacent inner segment is greater than the distance between the two adjacent inner segments. This reduces the axial stiffness in the area of ​​the relevant end segment, thus creating an improved stiffness transition. Here, the distance between two segments is understood to be the minimum length of the longitudinal space between the line connecting the minimum point of one segment and the line connecting the maximum point of the opposite side of the other segment. The longitudinal distance between the end segment and the adjacent inner segment may be, for example, between 0.10 mm and 0.13 mm, preferably between 0.11 mm and 0.12 mm. The distance between two adjacent inner segments in the longitudinal direction may be, for example, between 0.08 mm and 0.12 mm, preferably between 0.09 mm and 0.11 mm.

[0026] In a further exemplary embodiment, the bar of at least one end segment has a narrower width and / or a stronger rounding of the edges than the bar of at least one inner segment. This design of the bar of the segment creates a better flow transition towards the interior of the implant, due to the reduced material thickness in the region of the target end region. On the other hand, the radial stiffness in the region of the target end segment is further reduced. The width of the bar is understood to be the width of the bar measured in a plane that is created when the body extending on the circumference of the hollow cylinder is unfolded in a plane (unfolding plane). Here, the width of the target bar is measured in this unfolding plane, perpendicular to the outer surface of the bar lying perpendicular to the unfolding plane. A narrower width of the bar and / or a stronger rounding of the edges of the end segment can be achieved, for example, by suitable electropolishing in this region. The bar width of the end segment can be, for example, between 0.135 mm and 0.155 mm, preferably between 0.140 mm and 0.150 mm. The bar width of the bars of the inner segment may for example be between 0.145 mm and 0.160 mm, preferably between 0.150 mm and 0.155 mm. A stronger rounding of the edges is understood within the scope of this application to mean a rounded edge having a larger radius of the arc of rounding.

[0027] In a further exemplary embodiment of the invention, the bar of at least one end segment has a smaller thickness than the bar of at least one inner segment. A reduction in the bar thickness, as well as a reduction in the bar width, leads to an improved flow transition in the direction of the implant interior and a reduction in the radial stiffness, whereby an improved transition between a vessel without an implant and a vessel with an implant is achieved. The bar thickness within the scope of the present application will be understood to mean the thickness of the bar wall resulting from considering the cross section of the bar perpendicular to the bar width. Smaller bar widths of the subject end elements can likewise be achieved by suitable electropolishing. The bar thickness of the end segment may, for example, be 5 μm to 15 μm thinner than the bar thickness of the inner segment.

[0028] The above two embodiments are preferably combined: in this preferred combination, the bar of at least one end segment has a smaller width, a smaller thickness and / or a stronger edge rounding.

[0029] In a further exemplary embodiment, adjacent segments are connected to one another by connecting bars, at least one connecting bar having a smaller bar width and / or bar thickness than the bar of at least one inner segment and / or the bar of at least one end segment. This advantageously achieves a good axial flexibility and good bending flexibility for the implant as a whole. The bar width of the connecting bar can be, for example, between 0.07 mm and 0.10 mm, preferably between 0.08 mm and 0.09 mm, measured in the same way as the bar width of the segments. For exemplary bar widths of the bar of at least one end segment and of the bar of at least one inner segment, reference can be made to the above description.

[0030] The body of the implant according to the invention can consist entirely or partly of a biodegradable material. Such biodegradable materials are in particular metallic biodegradable materials based on magnesium or magnesium alloys, for example WE43, magnesium-zinc-aluminum, magnesium-aluminum or magnesium-zinc-calcium. Here, preferably high purity magnesium alloys are used, such as magnesium-zinc-aluminum with 0-4% by weight Zn and 2-10% by weight Al or 1.5-7% by weight Zn and 0.5-3.5% by weight Al, for example magnesium-aluminum with 5-10% by weight Al, in particular 5.5-7% by weight, particularly preferably 6.25% by weight aluminum, for example magnesium-zinc-calcium with 3-7% by weight Zn and 0.001-0.5% by weight Ca or 0-3% by weight Zn and 0-0.6% by weight Ca. Such high purity magnesium alloys contain, in addition to the aforementioned alloying elements, less than 0.006% by weight of other elements (impurities such as Fe, Cu, Co, Si or rare earths). The advantage of using this type of high purity magnesium alloy for the implant body is that the formation of the secretion can be very well controlled. By controlling the size, amount and composition of the secretion, the degradation behavior of the implant can be very precisely controlled. The degradation behavior of the implant is set so that its support function is maintained for at least 90 days after implantation in the blood vessel, and the implant is almost completely degraded, i.e. destroyed, after about one year.

[0031] Examples of suitable biodegradable polymeric compounds are polymers of the following groups: cellulose, collagen, albumin, casein, polysaccharides (PSAC), polylactides (PLA), poly-L-lactides (PLLA), polyglycols (PGA), poly-D,L-lactide-co-glycolides (PDLLA-PGA), polyhydroxybutyric acid (PHB), polyhydroxyvaleric acid (PHV), polyalkylcarbonates, polyorthoesters, polyethylene terephthalate (PET), polymalonic acid (PML), polyanhydrides, polyphosphazenes, polyamino acids and their copolymers, and hyaluronic acid. The polymers may be in pure form, in derivatized form, in the form of blends, or as copolymers, depending on the desired properties. The biodegradable material may also consist partly of metallic biodegradable materials and partly of polymeric biodegradable compounds.

[0032] In alternative embodiments, the body of the implant is formed in whole or in part from a non-biodegradable metal or metal alloy, such as stainless steel, titanium, cobalt chromium alloy, nickel titanium alloy, platinum, or a similar suitable metal alloy.

[0033] In a further preferred embodiment, the implant at least partially comprises an active ingredient-containing polymer coating, in particular the entire body is coated homogeneously, i.e. there is no difference in the coating between the end segments and the inner segments. The above-mentioned polymers can be used as polymers, in particular polylactide (PLA) or poly-L-lactide (PLLA).

[0034] Antiproliferative, antimigration, antiangiogenic, anti-inflammatory, antiphlogistic, cytostatic, cytotoxic and / or antithrombotic active ingredients, antirestenotic active ingredients, corticoids, sex hormones, statins, epothilones, prostacyclins, angiogenic agents can be used as active ingredients. Paclitaxel and its derivatives or sirolimus and its derivatives are particularly preferred.

[0035] The invention will now be described on the basis of exemplary embodiments and with reference to the drawings, in which all features described and / or shown in the drawings form the subject of the invention individually or in any combination, independently of their abstraction in the claims or reference to the dependency of the claims. [Brief description of the drawings]

[0036] [Figure 1] FIG. 2 shows the body of an implant according to the invention in a state after electropolishing, shown in an exploded view from above. [Diagram 2] FIG. 2 is an enlarged view of detail D of FIG. 1 . [Diagram 3] FIG. 2 is an enlarged view of detail C of FIG. [Figure 4] FIG. 2 is an enlarged view of detail B of FIG. [Diagram 5] FIG. 2 is a side perspective view of an implant according to the present invention after electropolishing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] Fig. 1 shows the body 10 of an exemplary embodiment of an implant according to the invention in the form of a stent in a pre-compressed state after electropolishing, unfolded on the rolling surface for improved illustration of the body 10 having an openwork structure with a number of bars arranged in individual segments. Fig. 5 shows the hollow cylindrical shape of the body 10 in a compressed state when it is not unfolded, without showing the structure of the body 10 in detail.

[0038] After electropolishing, the body 10 has a diameter that is close to, but smaller than, the target diameter in the expanded state, where the diameter of the body substantially corresponds to the diameter of the tube from which it is manufactured.

[0039] The body 10 is assembled from a number of segments 11, 13, a total of eleven segments 11, 13 being fully shown in Figure 1. The segment 11 forms an end segment, since it is provided at the end of the body 10 disposed in the longitudinal direction L (the longitudinal axis direction of the hollow cylindrical body 10; see Figure 5). The other segments 13 form internal segments.

[0040] Each segment 11, 13 is connected to the adjacent segments 11, 13 by two connecting bars 15. The connecting bars 15 are highlighted in detail F of the body 10 in FIG. 1. The connecting bars 15 extend in a curved or S-shaped manner in the illustrated exemplary embodiment, but may also extend straight in their central portion. In alternative embodiments, a single connecting bar or more than two connecting bars can also be provided for the connection of adjacent segments 11, 13.

[0041] Each segment 11, 13 has a number of bars extending substantially in the longitudinal direction L or at a slight inclination thereto. The bars provided with reference 21 in Figures 2 and 4 may extend straight or arcuately or curvedly, and different straight and arcuate and curved bars can be arranged in a single segment. Two adjacent bars 21 are each connected by an arc, so that a serpentine structure is created. The arcs each form either a minimum point 23 or a maximum point 25 of the serpentine structure (see Figures 2 and 4).

[0042] In the exemplary embodiment shown (see in particular details A, D and E of Fig. 1 and Fig. 2), the inner segment 13 has 12 curved bars 21 and 12 arcs, 6 of which form the maximum point 25 and 6 arcs form the minimum point 23. In contrast, the end segment 11 is assembled from 10 bars 21 and 10 arcs, 5 of which form the maximum point 25 and 5 arcs form the minimum point 23. Eyelets 27 are arranged on the bars 21 of the end segment 11 and are shown in Fig. 3 on an enlarged scale. Here, the stent of the invention has, in the state after electropolishing, the same or substantially the same outer diameter both in the region of the inner segment 13 and in the region of the end segment 11, which outer diameter is shown in Fig. 5 as D. In the expanded state, the inner segment 13 has the same or substantially the same inner diameter as the end segment 11. The slight difference in the outer diameter D between the end segment 11 and the inner segment 13 may simply result from different springback behavior after compression or expansion due to different mechanical properties of the inner segment 13 and the end segment 11. The outer diameters D of the inner segment 13 and the end segment 11 are substantially the same.

[0043] Other numbers of minimum points, maximum points, and bars in the inner and terminal segments are similarly contemplated, and in accordance with the present invention, the number of minimum points in the terminal segments is at least one less than the number of minimum points in the inner segments.

[0044] The eyelet 27, shown in detail in FIG. 3, is used to place a functional element made of a radiopaque and / or X-ray opaque material in the inner continuous opening 28 in order to ensure the visibility of the stent when it is introduced into the body. Due to the reduction of the minimum point of the end segment, it is possible to increase the volume or the visible area of ​​the functional element, which results in an improved visibility of the stent. Here, the eyelet 27 and its inner opening 28 are approximately elliptical and have a large area compared to other shapes. The ellipse is arranged on the body 10 such that its main axis is parallel to the longitudinal direction L of the body. Furthermore, the main axes of the elliptical openings 28 of the two eyelets 27 arranged on the two end segments 11 are offset in the circumferential direction by a length e (see FIG. 1). The length of the main axis o1 of the opening 28 of the eyelet 27 is, for example, 800 μm, and the length of the auxiliary axis o2 is, for example, 350 μm. The bar width s27 of the eyelet is, for example, 100 μm.

[0045] The length of the main axis o1 of the opening 28 of the small hole 27 is, for example, 800 μm, and the length of the auxiliary axis o2 is, for example, 350 μm. The bar width s27 of the small hole is, for example, 100 μm.

[0046] The two end segments 11 have a segment width b11 of, for example, 1.36 mm, while the segment width b13 of the inner segment 13 is, for example, 1.25 mm (see FIG. 1). Other segment widths are also conceivable, preferably b11>b13. This further reduces the radial stiffness of the end segments 11.

[0047] The distances between the segments are also shown in Fig. 1. Reference symbol a11 denotes the distance between an end segment 11 and an adjacent inner segment 13, while a13 denotes the distance between two inner segments 13. In order to reduce the axial stiffness in the transition region, in the shown exemplary embodiment of the implant, a11>a13, e.g. a11=115 μm and a13=95 μm.

[0048] A better transition in stiffness from an unstented vessel to a stented vessel is also achieved if the bar width s11 of the end segment 11 is smaller than the bar width s13 of the inner segment, and the segments may have different bar widths s11, s13 within the segment. For example, s11 is between 135 μm and 149 μm and s13 is between 150 μm and 165 μm. The same applies for different bar thicknesses (not shown) between the bars of the end segment 11 and the bars of the inner segment 13.

[0049] Furthermore, in the shown exemplary embodiment of the implant, in order to ensure good axial flexibility and good bending flexibility of the stent or body 10, the bar width v of the connecting bars 15 is smaller than the bar width s13 of the bars of the inner segment 13 and the bar width s11 of the terminal segment 11. For example, the bar width v of the connecting bars 15 is between 80 μm and 90 μm.

[0050] Additionally, the bars 21, maxima 25 and minima 23 of the distal segment 11 have more rounded edges than the same elements of the serpentine structure of the inner segment 13. This also reduces turbulence of the fluid flow as it transitions into the stent.

[0051] The stent according to the invention can be produced in known manner by laser cutting from a tubular semi-finished product and subsequent electrolytic polishing. A functional element, formed similarly to the eyelet's internal opening 28 and made of a radiopaque and / or radio-opaque material, is then inserted into the opening 28 and fixed to the eyelet 27, for example by adhesive bonding.

[0052] To treat a patient, for example, a stent according to the invention can be crimped onto a balloon (not shown) of a catheter. The stent can then be introduced into the patient's body by the catheter and advanced, for example, along a blood vessel to the point to be treated. The stent is then expanded by the balloon and thereby fixed to the wall of the vessel. The stent is used to hold open and support the vessel. After fixing the stent in the vessel, the catheter is removed.

[0053] The body of the stent is composed of a high purity magnesium-aluminum alloy containing 5.5-7 wt% aluminum (preferably 6.25 wt% aluminum), up to 0.006 wt% other elements (impurities or rare earths such as Fe, Cu, Co, Si) and the remainder magnesium. The stent also has a sirolimus-containing PLLA coating, with the coating on the luminal (inner) side of the stent (2-7 μm) being thinner than the coating on the abluminal (outer) side of the stent (10-15 μm).

Claims

1. An implant comprising a hollow cylindrical body (10) assembled from a plurality of hollow cylindrical segments (11, 13) arranged continuously in the longitudinal direction (L) and connected to one another, wherein each segment includes an end segment (11) at each end of the body (10) arranged in the longitudinal direction and at least one inner segment (13) arranged in the longitudinal direction (L) between two of the end segments (11), and each segment (11, 13) includes a plurality of bars (21) that together form a meandering structure extending in the circumferential direction having a maximum point (25) and a minimum point (23), wherein the body (10) takes a compressed state and an expanded state, characterized in that the meandering structure of at least one of the end segments (11) has fewer minimum points (23) than the at least one inner segment (13), The main body is made entirely or partially from biodegradable material. The aforementioned biodegradable material is 5.5 to 7% by weight of aluminum and magnesium as the remaining component, Magnesium-aluminum alloy A magnesium-zinc-aluminum alloy comprising 0-4 wt% Zn, 2-10 wt% Al, and magnesium as the remaining component, or 1.5-7 wt% Zn, 0.5-3.5 wt% Al, and magnesium as the remaining component. A magnesium-zinc-calcium alloy containing 3-7% by weight of Zn, 0.001-0.5% by weight of Ca, and the remainder being magnesium, or 0-3% by weight of Zn, 0-0.6% by weight of Ca, and the remainder being magnesium. A high-purity magnesium alloy selected from, The aforementioned high-purity magnesium alloy is an implant containing, in addition to the aforementioned alloying elements, other elements (impurities) in a quantity of less than 0.006% by weight.

2. The implant according to claim 1, characterized in that the high-purity magnesium alloy contains 5.5 to 7% by weight of aluminum and magnesium as the remaining components and the aforementioned alloying elements, in addition to less than 0.006% by weight of other elements (impurities).

3. The implant according to claim 1 or 2, characterized in that both of the terminal segments (11) have fewer minimum points (23) than the at least one inner segment (13).

4. The implant according to any one of claims 1 to 3, wherein at least one small hole (27) is provided on the meandering structure of at least one end segment (11) of the main body (10) for arranging a functional element made of radiopaque and / or radiopaque material, and the inner opening (28) of the small hole (27) is preferably elliptical.

5. The implant according to claim 4, characterized in that a functional element made of an X-ray opaque and / or radiopaque material is disposed within the at least one small hole (27).

6. The implant according to any one of claims 1 to 5, characterized in that at least one of the terminal segments (11) has a segment width (b11) that is greater than the segment width (b13) of at least one of the inner segments (13).

7. The implant according to any one of claims 1 to 6, characterized in that the distance (a11) between the terminal segment (11) and the adjacent inner segment (13) is greater than the distance (a13) between two adjacent inner segments (13).

8. The implant according to any one of claims 1 to 7, characterized in that the bar (21) of at least one terminal segment (11) has a smaller width (s11) and / or thickness and / or a more pronounced edge curvature than the bar (21) of at least one inner segment (13).

9. The implant according to any one of claims 1 to 8, wherein adjacent segments (11, 13) are connected to each other by at least one connecting bar (15), the at least one connecting bar (15) having a bar width (v) smaller than the bar (21) of the at least one inner segment (13) and / or the bar of the at least one terminal segment.

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