MEDICAL DEVICE AND MANUFACTURE THEREOF

Abstract

A medical device includes a device body preferably made of a material susceptible to corrosion or biodegradation and a shellac coating. The device body is at least partially covered by the shellac coating. The shellac coating has a thickness from 0.1 μm to 20 μm. A method for manufacturing the medical device includes the steps of providing the device body and applying the shellac coating onto a surface of the device body.

Claims

1. A medical device comprising: a device body comprising a material susceptible to corrosion or biodegradation; and a shellac coating, wherein the device body is at least partially covered by the shellac coating, wherein the shellac coating has a thickness from 0.1 μm to 20 μm, and wherein the material susceptible to corrosion or biodegradation is magnesium or a magnesium alloy.

2. The medical device according to claim 1, wherein the shellac coating has a thickness from 0.5 μm to 15 μm.

3. The medical device according to claim 1, wherein the shellac coating has a varying thickness.

4. The medical device according to claim 1, wherein the thickness of the shellac coating varies from 0.5 μm to 15 μm.

5. The medical device according to claim 1, wherein the device body is only partially covered with the shellac coating.

6. The medical device according to claim 1, wherein the shellac coating has a proportion of 10.sup.−10% by weight to 99% by weight.

7. The medical device according to claim 1, wherein the shellac coating is a wax-containing shellac coating.

8. The medical device according to claim 1, wherein the shellac coating is a wax-free shellac coating.

9. The medical device according to claim 1, wherein the device body comprises voids, wherein the voids are at least partially filled with the shellac coating.

10. The medical device according to claim 1, wherein mechanically separated and/or electrically isolated parts of the device body are at least partially covered with the shellac coating.

11. The medical device according to claim 1, wherein the device body comprises a plurality of filaments, wherein each filament is at least partially covered with the shellac coating.

12. (canceled)

13. (canceled)

14. The medical device according to claim 1, wherein the medical device is an implant.

15. A method for manufacturing the medical device according to claim 1, the method comprising the steps of: a) providing the device body; and b) applying the shellac coating onto a surface of the device body, said shellac coating having a thickness of 0.1 μm to 20 μm.

16. The medical device of claim 14, wherein the implant is selected from a group consisting of: a surgical implant, a stent, a stent-graft, a vascular prosthesis, a vascular access, a wound dressing, a suture, a surgical mesh, a surgical wire, a surgical plate, surgical screws, surgical nails, surgical anchors, surgical clips, wound closures, a volume providing implant for hard tissue, a connector, a medical tube, a bag, a medical needle and a probe.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0105] For better understanding of what has been disclosed, some figures are attached which schematically or graphically and solely by way of non-limiting example show a practical case of embodiment of the present invention.

[0106] FIG. 1 shows an embodiment of a medical device of the present invention.

[0107] FIG. 2 shows an embodiment of a part of a medical device according to the present invention.

[0108] FIGS. 3a and 3b show a further embodiment of a medical device according to the present invention.

[0109] FIG. 4 shows a further embodiment of a medical device according to the present invention.

[0110] FIG. 5 shows a further embodiment of a medical device according to the present invention.

[0111] FIGS. 6a-6g show embodiments of device bodies which can be equipped with a shellac coating according to the present invention.

DETAILED DESCRIPTION

[0112] 1. Manufacture Examples of a Medical Device According to the Present Invention [0113] 1.1 A solution having a proportion of shellac of 0.5% by weight and containing (basically water-free) ethanol was prepared. Afterwards, a stent made of magnesium was immersed into the solution during less than 1 minute. Subsequently, the solution coated stent was allowed to dry, resulting in a magnesium stent being coated with shellac in a thickness between 0.1 μm and 3 μm. [0114] 1.2 A solution having a proportion of shellac of 0.5% by weight and containing (basically water-free) ethanol was prepared. Afterwards, a stent made of the magnesium alloy “WE43” was immersed into the solution during less than 1 minute. Subsequently, the solution coated stent was allowed to dry, resulting in a stent being coated with shellac in a thickness between 0.1 μm and 3 μm. [0115] 1.3 A solution having a proportion of shellac of 0.5% by weight and containing (basically water-free) ethanol was prepared. Afterwards, the solution was sprayed onto a bone replacement scaffold made of magnesium. After drying the sprayed scaffold at 55° C. for 15 minutes, a bone replacement scaffold was obtained comprising a shellac coating having a thickness between 0.1 μm and 10 μm. [0116] 1.4 A solution having a proportion of shellac of 0.5% by weight and containing (basically water-free) ethanol was prepared. Afterwards, the solution was sprayed onto a bone replacement scaffold made of the magnesium alloy sold under the registered trademark RESOLOY®. After drying the sprayed scaffold at 55° C. for 15 minutes, a bone replacement scaffold was obtained comprising a shellac coating having a thickness between 0.1 μm and 10 μm. [0117] 1.5 A solution having a proportion of shellac of 0.5% by weight and containing (basically water-free) ethanol as a solvent was prepared. Afterwards, a stent made of magnesium was moistened with the solution. After drying the moistened stent at 55° C. for 15 minutes, a stent was obtained having a shellac coating in a thickness between 0.1 μm and 10 μm. [0118] 1.7 A solution having a proportion of shellac of 0.5% by weight and containing (basically water-free) ethanol as a solvent was prepared. Afterwards, a stent made of the magnesium alloy “WE43” was moistened with the solution. After a drying step at 55° C. during 15 minutes, a stent was obtained having a shellac coating in a thickness between 0.1 μm and 10 μm.

[0119] With respect to the manufacturing examples according to 1.1 to 1.7, the coating step may be repeated, if necessary or desired, in particular to generate differences in terms of corrosion or biodegradation rate, and thus release rate and/or release volume of hydrogen and/or to repair possible damages of an applied shellac layer. Alternatively, possible coating damages may be also repaired by merely applying ethanol onto the stent and bone replacement scaffold, respectively.

[0120] 2. Comparison of Corrosion or Biodegradation Rate

[0121] A wire made of RESOLOY® brand magnesium alloy having a thickness of 50 μm was coated with shellac. Afterwards, the coated wire and an uncoated wire made of RESOLOY® brand magnesium alloy and also having a thickness of 50 μm were immersed into a simulated body fluid solution. While an immediate corrosion or biodegradation could be observed in the case of the uncoated wire, the coated wire exhibited a significantly retarded corrosion or biodegradation and evolvement of hydrogen, respectively.

[0122] FIG. 1 schematically shows an embodiment of a medical device 10 according to the present invention. The medical device 10 comprises a device body 12. The device body 12 preferably comprises or consists of a material susceptible to corrosion or biodegradation such as magnesium or a magnesium alloy. In addition, the medical device 10 comprises a shellac coating 14. The device body 12 may be only partially or completely (as shown) covered with the shellac coating 14. Preferably, the shellac coating 14 has a thickness from 0.1 μm to 20 μm.

[0123] The medical device 10 may be, by way of example, in the form of a scaffold for bone replacement.

[0124] FIG. 2 schematically shows a cross-sectional view of a strut 11 of a medical device 10 of the present invention. The strut 11 is covered with a shellac coating 14. The strut 11 preferably comprises or consists of a material susceptible to corrosion or biodegradation such as magnesium or a magnesium alloy (e.g. “WE43” or RESOLOY® brand magnesium alloy).

[0125] The strut 11 may be completely covered with the shellac coating 14 (as shown). Alternatively, the strut 11 may only be partially covered with the shellac coating 14. This has the additional advantage that differences in terms of corrosion or biodegradation rate, and thus in terms of release of hydrogen during corrosion or biodegradation of the material susceptible to corrosion or biodegradation can be accomplished.

[0126] Further, the shellac coating 14 preferably has a thickness from 0.1 μm to 20 μm. Furthermore, the shellac coating 14 may have a constant thickness (as shown) or a varying thickness. A varying thickness of the shellac coating 14 is additionally advantageous inasmuch as also a varying thickness of the shellac coating 14 facilitates adjustment or generation of portions of the device body 12 which differ in terms of the corrosion or biodegradation rate of the material susceptible to corrosion, and thus in terms of release of hydrogen during the corrosion or biodegradation process.

[0127] Preferably, the medical device 10 is in the form of a stent.

[0128] FIG. 3a shows a further embodiment of a medical device 10 according to the present invention.

[0129] The medical device 10 comprises a device body 12 in the form of a scaffold and comprises a shellac coating 14. Preferably, the shellac coating 14 has a thickness from 0.1 μm to 20 μm.

[0130] The scaffold 12 preferably comprises or consists of a material susceptible to corrosion or biodegradation such as magnesium or a magnesium alloy (e.g. “WE43” or RESOLOY® brand magnesium alloy). The shellac coating 14 comprises portions 14a and 14b having a different coating thickness. Further, the scaffold 12 comprises an end or end portion 13a which is at least partially free of shellac coating 14, i.e. is not covered with shellac coating 14. The end/end portion 13a represents a starting point of corrosion or biodegradation of the material susceptible to corrosion or biodegradation, and thus facilitates control of the sequence of corrosion or biodegradation of portions of the scaffold 12. The arrow in FIG. 3a represents the direction of the corrosion or biodegradation process. Preferably, corrosion or biodegradation of portion 13b of the scaffold 12 occurs lastly.

[0131] FIG. 3b shows running corrosion or biodegradation of the medical device 10 as shown in FIG. 3a.

[0132] Preferably, the medical device as shown in FIGS. 3a and 3b is in the form of a scaffold for replacing hard tissue, particularly bone tissue.

[0133] FIG. 4 shows a further embodiment of a medical device 10 according to the present invention.

[0134] The medical device 10 comprises a device body 12 in the form of a plurality of filaments. As shown, the device body 12 can be in the form of unidirectional arranged filaments. The filaments preferably comprise or consist of a material susceptible to corrosion or biodegradation such as magnesium or a magnesium alloy. Further, the filaments may be in the form of wires, monofilaments, pseudo monofilaments or multifilaments. Each filament is covered with a shellac coating 14, wherein each filament comprises an end (i.e. only one end) 13 which is free of shellac coating 14, i.e. is not covered with the shellac coating 14. The ends 13 of the filaments may advantageously act as a location for controlled corrosion or biodegradation of the filaments, and thus of evolvement of hydrogen during the corrosion or biodegradation process. Thus, degradation of the medical device 10 may advantageously occur slowly from the outside to the inside of the medical device 10. Preferably, the shellac coating 14 has a thickness from 0.1 μm to 20 μm.

[0135] Preferably, the medical device 10 is in the form of a bone replacement implant, i.e. an implant which is preferably adapted to fill bone cavities, which may be due to a traumatic event such as an accident, an infection or mandatory surgical removal of bone tissue. Due to a slow degradation of the medical device 10 from the outside to the inside, it can be facilitated that new callus tissue may be produced during degradation of old bone tissue. Preferably, the ends 13 of the filaments are adapted to be located towards soft tissue, in particular towards muscle tissue. Thus, a targeted deduction of hydrogen may be facilitated and in particular any impairment of tissue bone growth and/or bone regeneration can be avoided.

[0136] Further, the filaments may comprise a different length. Furthermore, it may be within the scope of the present invention that inner filaments do not reach an outside surface of the device body 12 so as to retard corrosion or biodegradation as long as possible.

[0137] FIG. 5 shows a further embodiment of a medical device 10 according to the present invention.

[0138] The medical device 10 comprises a device body 12 in the form of helically arranged filaments. The filaments preferably form a thread (screw thread) of the medical device 10. Each filament is covered with a shellac coating 14, wherein an end, in particular only one end, 13 of the filaments is free of shellac coating 14.

[0139] Preferably, the filaments comprise or consist of a material susceptible to corrosion or biodegradation such as magnesium or a magnesium alloy (e.g. “WE43” or RESOLOY® brand magnesium alloy).

[0140] Advantageously, the ends 13 and/or cavities between the coated filaments are adapted to facilitate a directed deduction of hydrogen during corrosion or biodegradation of the material susceptible to corrosion or biodegradation.

[0141] Preferably, the medical device 10 as shown in FIG. 5 is in the form of a bone screw. In that case, the ends 13 of the filaments 12 are preferably adapted to be located towards a soft tissue such as muscle tissue, fatty tissue or potential cavities as the belly space. Thus, a targeted conveyance of hydrogen during degradation of old bone tissue and formation of new bone tissue (callus) can be facilitated. In particular, any adverse effect on new bone tissue development and growth can be advantageously prevented.

[0142] FIG. 6a schematically shows a device body 12 in the form of a bone screw which can be covered with a shellac coating according to the present invention. The bone screw is preferably made of magnesium or a magnesium alloy.

[0143] FIG. 6b shows a device body 12 in the form of a bone fixation plate which may be covered with a shellac coating according to the present invention. Preferably, the bone fixation plate is made of magnesium or a magnesium alloy.

[0144] FIG. 6c shows a device body 12 in the form of a particulate bone replacement material, wherein particles of the bone replacement material may be covered with a shellac coating according to the present invention. The bone replacement material can, by way of example, be made of a calcium phosphate material such as hydroxyapatite, α-calciumphosphate or β-tricalciumphosphate.

[0145] FIG. 6d shows a device body 12 in the form of a clip, in particular vessel clip, which may be coated with a shellac coating according to the present invention. Preferably, the clip may be made of magnesium or a magnesium alloy.

[0146] FIG. 6e shows a device body 12 in the form of a Kirschner wire for osteosynthesis which may be covered with a shellac coating according to the present invention. The Kirschner wire may be made of magnesium or a magnesium alloy.

[0147] FIG. 6f shows a device body 12 in the form of a Cerclage wire for osteosynthesis which may be covered with a shellac coating according to the present invention. The Cerclage-wire may be made of magnesium or a magnesium alloy.

[0148] FIG. 6g shows a device body 12 in the form of an intramedullary nail which may be coated with a shellac coating according to the present invention. The intramedullary nail may be in particular made of magnesium or a magnesium alloy.