Monolithic orthopedic implant with an articular finished surface

Abstract

A monolithic material including a first region having a first variability of strength and a second region joined to the first region, the second region having a second variability of strength, wherein the monolithic material has a variability of strength less than the first variability of strength of the first region and less than the second variability of strength of the second region.

1 . A method of providing a monolithic material implant having an overall implant variability of strength measured as an overall implant Weibull Modulus, the method comprising:
 forming a porous region having a first variability of strength measured as a first Weibull Modulus;   forming a transition region joined to the porous region and having a second variability of strength measured as a second Weibull Modulus, wherein the second variability of strength is less than the first variability of strength, and wherein the second Weibull Modulus is greater than the first Weibull Modulus; and   forming a dense region joined to the transition region and having a third variability of strength measured as a third Weibull Modulus, wherein the third variability of strength is less than the second variability of strength, and wherein the third Weibull Modulus is greater than the second Weibull Modulus;   wherein the overall implant variability of strength is less than the third variability of strength, and wherein the overall implant Weibull Modulus is greater than the third Weibull Modulus.   
     
     
         2 . (canceled) 
     
     
         3 . The method of  claim 1 , further comprising forming a surface on the dense region, the surface having a finish adapted for articulation against native articular cartilage. 
     
     
         4 . The method of  claim 3 , wherein forming the surface on the dense region comprises thermal processing the dense region. 
     
     
         5 . The method of  claim 3 , wherein forming the surface on the dense region comprises depositing a material on the dense region. 
     
     
         6 . The method of  claim 5 , wherein the deposited material is selected from the group consisting of pyrolytic carbon and diamond-like carbon. 
     
     
         7 . The method of  claim 3 , wherein forming the surface on the dense region comprises coating a material on the dense region. 
     
     
         8 . The method of  claim 7 , wherein the coated material comprises ceramic. 
     
     
         9 . The method of  claim 3 , wherein forming the surface on the dense region comprises forming at least one protrusion or at least one indentation on the dense region. 
     
     
         10 . The method of  claim 1 , wherein the porous region has a form of interconnected porosity similar to cancellous bone to promote skeletal fixation by bone ingrowth, and wherein the transition region has a form of interconnected porosity similar to subchondral bone. 
     
     
         11 . The method of  claim 1 , wherein the porous region has a porosity gradient that increases as a distance from the transition region increases. 
     
     
         12 . The method of  claim 1 , wherein the porous region, the transition region, and the dense region are formed of brittle materials. 
     
     
         13 . The method of  claim 1 , wherein the porous region, the transition region, and the dense region comprise one or more materials selected from the group consisting of oxides, nitrides, carbides, borides, partially stabilized zirconia, alumina, silica, silicon nitride, SiAlON, and pyrolytic carbon. 
     
     
         14 . (canceled) 
     
     
         15 . The method of  claim 1 , wherein the porous region, the transition region and the dense region are non-resorbable. 
     
     
         16 . The method of  claim 1 , wherein forming the dense region comprises forming at least one protrusion or at least one indentation on the dense region. 
     
     
         17 . The method of  claim 1 , wherein forming at least one of the porous region or the transition region comprises oxidizing a fugitive material. 
     
     
         18 . The method of  claim 1 , wherein forming at least one of the porous region or the transition region comprises dissolving a fugitive material. 
     
     
         19 . The method of  claim 1 , wherein forming at least one of the porous region or the transition region comprises using a lost foam process. 
     
     
         20 . The method of  claim 1 , wherein forming at least one of the porous region or the transition region comprises using a solid freeform fabrication process. 
     
     
         21 . The method of  claim 1 , wherein forming at least one of the porous region or the transition region comprises using a foaming process. 
     
     
         22 . The method of  claim 1 , further comprising fabricating a desired geometrical form for the porous region, the transition region and the dense region by one or more machining processes selected from the group consisting of milling, turning, grinding and other machining processes. 
     
     
         23 . The method of  claim 22 , wherein fabricating a desired geometrical form further comprises accounting for shrinkage of 10% or greater following the one or more machining processes. 
     
     
         24 . The method of  claim 22 , wherein fabricating a desired geometrical form comprises fabricating a prosthesis selected from the group consisting of a femoral knee prosthesis, a tibial knee prosthesis, a patellar knee prosthesis, a femoral head hip prosthesis, an acetabular hip prosthesis, a finger or thumb prosthesis, a wrist or ankle prosthesis, a shoulder prosthesis, a toe prosthesis, a spine prosthesis and an elbow prosthesis. 
     
     
         25 . The method of  claim 1 , wherein the porous region, the transition region and the substantially dense region have a Vickers hardness of 500 MPa or greater, a nickel content of less than 4%, and a chrome content of less than 10%.