Tissue Repair and Replacement

Abstract

Tissue fixation devices are provided. The devices include a first component and a second component, the components having different rates of in vivo degradation. The first component and second component are arranged so that, upon degradation of one of the components, the other component provides a scaffold into which bone can grow.

1 . A device for tissue repair or replacement, comprising first and second components having different relative rates of in vivo degradation, the first component having a higher rate of in vivo degradation than the second component, and the first and second components being arranged relative to each other so that, after implantation of the deice, the first component degrades in vivo leaving a scaffold formed of the second component, the scaffold having pores into which tissue can infiltrate, wherein the first and second components comprise ceramics.  
   
   
       2 . The device of  claim 1  wherein the device is substantially non-porous prior to implantation into a patient.  
   
   
       3 . The device of  claim 1  wherein there is at least an 8 week difference between the degradation rates of the components.  
   
   
       4 . The device of  claim 3  wherein the degradation rates differ by about 12 months to 2 years.  
   
   
       5 . The device of  claim 1  wherein at least one of the components includes a therapeutic additive.  
   
   
       6 . The device of  claim 1  wherein the ceramic is selected from a group consisting essentially of calcium phosphate, calcium sulfate, beta dicalcium pyrophosphate, calcium carbonate, and a glass.  
   
   
       7 . The device of  claim 6  wherein the calcium phosphate is selected from a group consisting essentially of hydroxyapatite, tricalcium phosphate, octacalcium phosphate, and dicalcium phosphate dihydrate.  
   
   
       8 . A device for tissue repair or replacement, comprising: 
 a porous ceramic structure comprising a first ceramic; and    a second ceramic disposed in pores of the ceramic structure, the device being substantially non-porous prior to implantation in a patient.    
   
   
       9 . The device of  claim 8  wherein the two ceramics have different relative rates of in vivo degradation.  
   
   
       10 . The device of  claim 8  wherein the ceramic structure has a pore size of between about 20 to about 2000 microns.  
   
   
       11 . The device of  claim 8  wherein the ceramic structure has a porosity of between about 10% to about 90%.  
   
   
       12 . The device of  claim 8  wherein the first ceramic comprises hydroxyapatite and the second ceramic comprises tricalcium phosphate.  
   
   
       13 . The device of  claim 8  wherein the first ceramic comprises hydroxyapatite and the second ceramic comprises calcium sulfate.  
   
   
       14 . The device of  claim 8  wherein the first ceramic comprises tricalcium phosphate and the second ceramic comprises calcium sulfate.  
   
   
       15 . The device of  claim 8  wherein the second ceramic comprises a particle size of less than about 100 μm.  
   
   
       16 . The device of  claim 8  wherein the first ceramic comprises a particle size of between about 1 nm to about 1 mm.  
   
   
       17 . A method of tissue repair or replacement, comprising implanting in a patient a device including first and second components having different relative rates of in vivo degradation, the first component having a higher rate of in vivo degradation than the second component, and the first and second components being arranged relative to each other so that, after implantation of the device, the first component degrades in vivo leaving a scaffold formed of the second component, the scaffold having pores into which tissue can infiltrate, wherein the first and second components comprise ceramics.  
   
   
       18 . A method of making a device for tissue repair or replacement, comprising forming a porous scaffold of a first component, and infiltrating the porous scaffold with a second component, wherein the first and second components comprise ceramics.  
   
   
       19 . The method of  claim 18  wherein the scaffold is infiltrated with a sufficient amount of the second component to render the device substantially non-porous.  
   
   
       20 . The method of  claim 18  wherein the infiltrating step comprises providing the second component in the form of a slurry.  
   
   
       21 . The method of  claim 18  wherein the infiltrating step comprises injection molding.  
   
   
       22 . A device for tissue repair or replacement, comprising first and second components having different relative rates of in vivo degradation, the first component having a higher rate of in vivo degradation than the second component, and the first and second components being arranged relative to each other so that, after implantation of the device, the first component degrades in vivo, wherein the first and second components comprise ceramics.