Bioerodible endoprostheses and methods of making the same

Abstract

A bioerodible endoprosthesis erodes to a desirable geometry that can provide, e.g., improved mechanical properties or degradation characteristics.

1 - 23 . (canceled) 
     
     
         24 . An endoprosthesis, comprising:
 a body comprising a bioerodible metal material, the body having a cross-section in the X-Y plane and extending along a z-axis, wherein the body has an initial geometry in the X-Y plane characterized by initial dimensions, and   a predetermined geometry after erosion of at least about 50 percent of the area of the body in the X-Y plane in the shape of an I, an X, an interdigitated structure, a radially lobed structure, or a convex structure.   
     
     
         25 . An endoprosthesis, comprising:
 a body comprising a bioerodible metal material, the body having a cross-section in the X-Y plane and extending along a z-axis, wherein the body has an initial geometry in the X-Y plane characterized by initial dimensions, and   an erosion modifying material provided on the surface of the body which controls erosion to form a predetermined geometry, the modifying material being provided in a pattern of at least three separate regions in the X-Y plane.   
     
     
         26 . The endoprosthesis of  claim 25 , wherein the erosion modifying material is provided on the entire surface of the body. 
     
     
         27 . The endoprosthesis of  claim 26 , wherein the erosion modifying material includes multiple materials at select locations to control the erosion of the body. 
     
     
         28 . The endoprosthesis of  claim 24 , wherein the bioerodible metal material has an erosion rate of between about 0.2% and 5% of its initial mass per day. 
     
     
         29 . The endoprosthesis of  claim 25 , wherein the bioerodible metal material has an erosion rate of between about 0.2% and 5% of its initial mass per day. 
     
     
         30 . An endoprosthesis, comprising:
 a body comprising a bioerodible metal material, the body having a cross-section in the X-Y plane and extending along a z-axis, wherein the cross-section of the body in the X-Y plane can be characterized as an initial geometric shape having initial dimensions, and   an erosion modifying material provided on the surface of the body which controls erosion to form a predetermined geometry such that, after erosion of at least about 50 percent of the area of the body in the X-Y plane, at least one initial dimension of the initial geometric shape in the X-Y plane is maintained.   
     
     
         31 . The endoprosthesis of  claim 30 , wherein the initial dimension maintained corresponds to the maximum dimension of the initial geometric shape. 
     
     
         32 . The endoprosthesis of  claim 30 , wherein the predetermined geometry is an I shape, an X, an interdigitated geometry, a radially lobed structure, a convex structure, a square, or a rectangle. 
     
     
         33 . The endoprosthesis of  claim 30 , wherein the predetermined geometry extends substantially the full extent of the body in the Z direction. 
     
     
         34 . The endoprosthesis of  claim 30 , wherein the initial geometric shape is a square or a rectangle. 
     
     
         35 . The endoprosthesis of  claim 30 , wherein the initial geometric shape is a circular, ovaloid, or elliptical shape. 
     
     
         36 . The endoprosthesis of  claim 30 , wherein the ratio of the maximum initial dimensions to minimum initial dimensions in the X-Y plane is between about 2:1 and about 1:2. 
     
     
         37 . The endoprosthesis of  claim 30 , wherein the bioerodible metal material comprises a material selected from the group consisting of magnesium, calcium, aluminum, strontium, zirconium, zinc, manganese, iron, nickel, copper, cobalt, a rare earth element, and alloys thereof. 
     
     
         38 . The endoprosthesis of  claim 30 , wherein the erosion modifying material comprises a material selected from the group consisting of a polymer, a ceramic, an oxide, a metal, an alloy, and a composite. 
     
     
         39 . The endoprosthesis of  claim 30  wherein the erosion modifying material is provided as a layer, and the layer has varying thickness. 
     
     
         40 . The endoprosthesis of  claim 39  wherein the thickness varies in the X or Y direction. 
     
     
         41 . The endoprosthesis of  claim 30 , wherein the body comprises a strut. 
     
     
         42 . The endoprosthesis of  claim 41 , wherein the endoprosthesis comprises a plurality of struts arranged in the general form of a tube. 
     
     
         43 . The endoprosthesis of  claim 42 , wherein the endoprosthesis comprises a balloon-expandable stent.