Implantable medical devices comprising bio-degradable alloys with enhanced degradation rates

Abstract

The invention provides medical devices comprising high-strength alloys which degrade over time in the body of a human or animal, at controlled degradation rates, without generating emboli and which have enhanced degradation due to the presence of a halogen component. In one embodiment the alloy is formed into a bone fixation device such as an anchor, screw, plate, support or rod. In another embodiment the alloy is formed into a tissue fastening device such as staple. In yet another embodiment, the alloy is formed into a dental implant or a stent.

1 . (canceled) 
     
     
         2 . An implantable medical device comprising a biodegradable alloy, wherein the biodegradable alloy comprises:
 iron in a range of about 55 wt % to about 80 wt %;   at least one metallic element other than iron in amount of at least 0.5 wt %; and   an iron reactive component dispersed within the biodegradable alloy in an amount of about 0.1 ppm to about 500 ppm,   wherein the biodegradable alloy is present in the form of grains, the grains having an average grain size in a range of about 0.5 microns to about 5.0 microns, the average grain size facilitating a substantially uniform degradation of the biodegradable alloy when implanted in a biological subject.   
     
     
         3 . The implantable medical device of  claim 2 , wherein the biodegradable alloy has an austenite structure or a martensite structure. 
     
     
         4 . The implantable medical device of  claim 2 , wherein the iron reactive component comprises a halogen. 
     
     
         5 . The implantable medical device of  claim 2 , wherein the iron reactive component comprises a halogen salt selected from the group consisting of sodium fluoride, sodium chloride, copper chloride, copper fluoride, magnesium chloride, silver chloride, calcium chloride, calcium fluoride, and iron chloride. 
     
     
         6 . The implantable medical device of  claim 2 , wherein the biodegradable alloy further comprises about 0.01 wt % to about 0.1 wt % of a non-metallic element selected from the group consisting of carbon, nitrogen, and silicon. 
     
     
         7 . The implantable medical device of  claim 2 , wherein the biodegradable alloy further comprises an austenite promoting component selected from the group consisting of nickel, manganese, cobalt, platinum, palladium, iridium, aluminum, carbon, nitrogen, and silicon, and a corrosion resisting component selected from the group consisting of chromium, molybdenum, tungsten, tantalum, niobium, titanium, zirconium, and hafnium. 
     
     
         8 . An implantable medical device comprising a biodegradable alloy, wherein the biodegradable alloy comprises:
 iron in a range of about 55 wt % to about 80 wt %;   at least one metallic element other than iron in an amount of at least 0.5 wt %; and   an iron reactive component dispersed within the biodegradable alloy in an amount of about 0.1 ppm to about 500 ppm,   wherein the biodegradable alloy has at least 85% austenitic structure and includes an austenitic promoting component in a range of about 10 wt % to about 40 wt %.   
     
     
         9 . The implantable medical device of  claim 8 , wherein the biodegradable alloy has a grain size in a range of about 0.5 microns to about 5.0 microns. 
     
     
         10 . The implantable medical device of  claim 8 , wherein the biodegradable alloy comprises at least one of about 0.01 wt % to about 0.255 wt % carbon, about 2.0 wt % to about 9.0 wt % nickel, about 10 wt % to about 30 wt % cobalt, about 1.0 wt % to about 14 wt % manganese, about 0.5 wt % to about 3.0 wt % chromium, about 0.5 wt % to about 3.0 wt % molybdenum, or about 1.0 wt % to about 6.0 wt % tantalum. 
     
     
         11 . The implantable medical device of  claim 8 , wherein the biodegradable alloy further comprises about 0.5 wt % to about 10.0 wt % of a corrosion resisting component. 
     
     
         12 . The implantable medical device of  claim 8 , wherein the iron reactive component comprises a halogen. 
     
     
         13 . The implantable medical device of  claim 8 , wherein the iron reactive component comprises a halogen salt selected from the group consisting of sodium fluoride, sodium chloride, copper chloride, copper fluoride, magnesium chloride, silver chloride, calcium chloride, calcium fluoride, and iron chloride. 
     
     
         14 . The implantable medical device of  claim 8 , wherein the biodegradable alloy further comprises from about 0.01 wt % to about 0.1 wt % of a non-metallic element selected from the group consisting of carbon, nitrogen, and silicon. 
     
     
         15 . The implantable medical device of  claim 8 , wherein the austenite promoting component is selected from the group consisting of nickel, manganese, cobalt, platinum, palladium, iridium, aluminum, carbon, nitrogen, and silicon, and a corrosion resisting component selected from the group consisting of chromium, molybdenum, tungsten, tantalum, niobium, titanium, zirconium, and hafnium. 
     
     
         16 . An implantable medical device comprising a biodegradable alloy, wherein the biodegradable alloy comprises:
 iron in a range of about 55 wt % to about 80 wt %;   at least one metallic element other than iron in amount of at least 0.5 wt %; and   an iron reactive component dispersed within the biodegradable alloy in an amount of about 0.1 ppm to about 500 ppm,   wherein the biodegradable alloy has an austenitic structure comprising grains having an average surface to volume ratio of greater than 0.1 μ −1 .   
     
     
         17 . The implantable medical device of  claim 16 , wherein the biodegradable alloy has an average grain size in a range of about 0.5 microns to about 5.0 microns. 
     
     
         18 . The implantable medical device of  claim 16 , wherein the biodegradable alloy contains carbon in a range of about 0.01 wt % to about 0.3 wt %. 
     
     
         19 . The implantable medical device of  claim 16 , wherein the biodegradable alloy contains chromium in a range of about 0.5 wt % to about 3 wt %. 
     
     
         20 . The implantable medical device of  claim 16 , wherein the biodegradable alloy further comprises about 0.5 wt % to less than about 10.0 wt % of a corrosion resisting component. 
     
     
         21 . The implantable medical device of  claim 16 , wherein the biodegradable alloy comprises an austenite promoting component selected from the group consisting of nickel, manganese, cobalt, platinum, palladium, iridium, aluminum, carbon, nitrogen, and silicon and a corrosion resisting component selected from the group consisting of chromium, molybdenum, tungsten, tantalum, niobium, titanium, zirconium, and hafnium.