# US 9,050,389 B2 · Medical implant comprising a biodegradable magnesium-based alloy and method for its manufacture > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,050,389 B2 - Document ID: US9050389B2 - Status: Granted - Kind: B2 - Application number: 13/331,683 - Filed: 2011-12-20 - Published: 2012-06-21 - Granted: 2015-06-09 - Earliest claimed: 2010-12-21 - Assignees: DePuy Synthes Products, Inc. - Applicants: Peter Kurze; Thomas Imwinkelried; Stefan Beck; Dora Banerjee; Tamara Schwarz - Inventors: Peter Kurze; Thomas Imwinkelried; Stefan Beck; Dora Banerjee; Tamara Schwarz - Web page: https://patentgrep.com/patent/US9050389B2 ## CPC - A61L 27/047: {Other specific metals or alloys not covered by A61L27/042 - A61L27/045 or A61L27/06} - A61B 17/80: Cortical plates {, i.e. bone plates; Instruments for holding or positioning cortical plates, or for compressing bones attached to cortical plates} - A61B 17/864: {hollow, e.g. with socket or cannulated} - A61L 27/306: {Other specific inorganic materials not covered by A61L27/303 - A61L27/32} - A61L 27/58: Materials at least partially resorbable by the body - A61L 31/022: {Metals or alloys} - A61L 31/082: {Inorganic materials} - A61L 31/148: {Materials at least partially resorbable by the body} - C01F 5/24: Magnesium carbonates - A61F 2310/00425: Coating made of magnesium or of Mg-based alloys - A61L 27/303: {Carbon} - A61L 2400/18: Modification of implant surfaces in order to improve biocompatibility, cell growth, fixation of biomolecules, e.g. plasma treatment - A61L 2430/02: for reconstruction of bones; weight-bearing implants - Y10T 428/265: 1 mil or less - Y10T 428/31678: Of metal - A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K) - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - C01F: COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS (metal hydrides {monoborane, diborane or addition complexes thereof} C01B6/00; salts of oxyacids of halogens C01B11/00; peroxides, salts of peroxyacids C01B15/00; sulfides or polysulfides of magnesium, calcium, strontium, or barium C01B17/42; thiosulfates, dithionites, polythionates C01B17/64; compounds containing selenium or tellurium C01B19/00; binary compounds of nitrogen with metals C01B21/06; azides C01B21/08; {compounds other than ammonia or cyanogen containing nitrogen and non-metals and optionally metals C01B21/082; amides or imides of silicon C01B21/087}; metal {imides or} amides C01B21/092, {C01B21/0923}; nitrites C01B21/50; {compounds of noble gases C01B23/0005}; phosphides C01B25/08; salts of oxyacids of phosphorus C01B25/16; carbides C01B32/90; compounds containing silicon C01B33/00; compounds containing boron C01B35/00; compounds having molecular sieve properties but not having base-exchange properties C01B37/00; compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites, C01B39/00; cyanides C01C3/08; salts of cyanic acid C01C3/14; salts of cyanamide C01C3/16; thiocyanates C01C3/20; {double sulfates of magnesium with sodium or potassium C01D5/12; with other alkali metals C01D15/00, C01D17/00}) - A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C) - Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION ## Abstract A medical implant comprises a biodegradable magnesium-based alloy of which at least a part of its surface layer comprises a magnesium carbonate. A method for the manufacture of a biocompatible, corrosion-inhibiting protective surface layer on a medical implant comprising a magnesium-based alloy, comprises: providing an implant comprising a magnesium-based alloy to be coated; placing the implant into a reactor chamber; exposing at least part of the surface of said implant to an atmosphere comprising humid carbon dioxide to produce a coating on the surface of the implant comprising a magnesium carbonate of the formula x MgCO3.y Mg (OH)2, whereby x+y=1; removing the implant from the reactor chamber; and drying the surface of the implant. ## Claims ### Claim 1 A method for the manufacture of a biocompatible, corrosion-inhibiting protective surface layer on a medical implant comprising a magnesium-based alloy, the method comprising: placing an implant comprising a magnesium-based alloy into a reactor chamber; exposing at least part of a surface of said implant to an atmosphere comprising humid carbon dioxide, wherein the concentration of the carbon dioxide is at least 50%, and wherein the atmosphere is modified by the addition of gaseous hydrocarbons comprising methane or propane, to produce a coating on the surface of the implant comprising a magnesium carbonate of the formula x MgCO3 .y Mg (OH)2, whereby x+y=1; removing the implant from the reactor chamber; and drying the surface of the implant. ### Claim 2 (depends on 1) The method according to claim 1, wherein the atmosphere has a relative humidity of at least 30%. ### Claim 3 (depends on 2) The method according to claim 2, wherein said relative humidity is 100%. ### Claim 4 (depends on 2) The method according to claim 2, wherein the temperature in said reactor chamber is in the range of 10° C. to 50° C. ### Claim 5 (depends on 2) The method according to claim 2, wherein the temperature in said reactor chamber is in the range of 20° C. to 30° C. ### Claim 6 (depends on 2) The method according to claim 2, wherein said relative humidity is at least about 90%. ### Claim 7 (depends on 1) The method according to claim 1, wherein the concentration of carbon dioxide is at least about 90%. ### Claim 8 (depends on 1) The method according to claim 1, wherein the gaseous hydrocarbons are added in an amount of less than 10% of the total gas content. ### Claim 9 (depends on 1) The method according to claim 1, wherein the atmosphere is activated by heating up the atmosphere without heating up the implant. ### Claim 10 (depends on 9) The method according to claim 9, wherein the atmosphere is activated by heating up the atmosphere using microwaves. ### Claim 11 (depends on 1) The method according to claim 1, wherein the pressure in said reactor exceeds atmospheric pressure. ### Claim 12 (depends on 11) The method according to claim 11, wherein the pressure in said reactor chamber is in the range of about 5 to about 60 bar. ### Claim 13 (depends on 1) The method according to claim 1, wherein water is added to the reactor chamber before placing the implant into the reactor chamber. ### Claim 14 (depends on 1) The method according to claim 1, wherein the pressure in said reactor corresponds essentially to atmospheric pressure. ### Claim 15 (depends on 1) The method according to claim 1, wherein said magnesium-based implant is coated over a time period lasting about 24 hours to about 720 hours. ### Claim 16 (depends on 1) The method according to claim 1, wherein said drying is effected at 80° C. to 130° C. ### Claim 17 (depends on 1) The method according to claim 1 further comprising: treating the surface of the implant with supercritical carbon dioxide prior to exposing at least part of the surface of the implant to the atmosphere. ### Claim 18 (depends on 1) The method according to claim 1, wherein said drying is effected for about 10 minutes to about 30 minutes. ### Claim 19 A method for the manufacture of a biocompatible, corrosion-inhibiting protective surface layer on a medical implant comprising a magnesium-based alloy, the method comprising: placing an implant comprising a magnesium-based alloy into a reactor chamber wherein the pressure in said reactor exceeds atmospheric pressure; exposing at least part of a surface of said implant to an atmosphere comprising humid carbon dioxide to produce a coating on the surface of the implant comprising a magnesium carbonate of the formula x MgCO3 .y Mg (OH)2, whereby x +y =1; removing the implant from the reactor chamber; and drying the surface of the implant. ### Claim 20 (depends on 19) The method according to claim 19, wherein the atmosphere has a relative humidity of at least 30%. ### Claim 21 (depends on 20) The method according to claim 20, wherein the atmosphere is modified by the addition of hydrogen gas and/or gaseous hydrocarbons. ### Claim 22 (depends on 21) The method according to claim 21, wherein the gaseous hydrocarbons comprise methane or propane. ### Claim 23 (depends on 21) The method according to claim 21, wherein the hydrogen gas and/or gaseous hydrocarbons are added in an amount of less than 10% of the total gas content. ### Claim 24 (depends on 20) The method according to claim 20, wherein said relative humidity is 100%. ### Claim 25 (depends on 20) The method according to claim 20, wherein the temperature in said reactor chamber is in the range of 10° C. to 50° C. ### Claim 26 (depends on 20) The method according to claim 20, wherein the temperature in said reactor chamber is in the range of 20° C. to 30° C. ### Claim 27 (depends on 20) The method according to claim 20, wherein said relative humidity is at least about 90%. ### Claim 28 (depends on 19) The method according to claim 19, wherein the concentration of the carbon dioxide is at least 50%. ### Claim 29 (depends on 28) The method according to claim 28, wherein the concentration of the carbon dioxide is at least about 90%. ### Claim 30 (depends on 19) The method according to claim 19, wherein the atmosphere is activated by heating up the atmosphere without heating up the implant. ### Claim 31 (depends on 30) The method according to claim 30, wherein the atmosphere is activated by heating up the atmosphere using microwaves. ### Claim 32 (depends on 19) The method according to claim 19, wherein the pressure in said reactor chamber is in the range of about 5 to about 60 bar. ### Claim 33 (depends on 19) The method according to claim 19, wherein water is added to the reactor chamber before placing the implant into the reactor chamber. ### Claim 34 (depends on 19) The method according to claim 19, wherein said magnesium-based implant is coated over a time period lasting about 24 hours to about 720 hours. ### Claim 35 (depends on 19) The method according to claim 19, wherein said drying is effected at 80° C. to 130° C. ### Claim 36 (depends on 19) The method according to claim 19 further comprising: treating the surface of the implant with supercritical carbon dioxide prior to exposing at least part of the surface of the implant to the atmosphere. ### Claim 37 (depends on 19) The method according to claim 19, wherein said drying is effected for about 10 minutes to about 30 minutes.