Anti-backout arthroscopic uni-compartmental prosthesis

Abstract

An improved uni-compartmental implant has a shaft having a proximal end attached to a head and a distal end, and one or more raised portions spaced apart along the shaft to resist back-out. The length between the head and distal end is preferably less than 50 mm, the distal end of the shaft has a diameter on the order of 2 to 3 mm, the proximal end of the shaft has a diameter on the order of 2 to 4 mm, and the head has a diameter ranging from 4 mm or less to 20 mm or more, making the device suitable for knee arthroscopy and other applications. The shaft and/or raised portions may include a bone-ingrowth or bone-ongrowth surface, and the shaft and/or raised portions may be made of a fiber-metal. The head portion is preferably ceramic, though a chrome-cobalt alloy, titanium, or other bio-compatible material may be used. The head portion may have a bi-convex shape, a plano-convex shape, or a concave-convex shape.

1 . A uni-compartmental implant, comprising: 
 a shaft having a proximal end attached to a head and a distal end; and    one or more raised portions spaced apart along the shaft to resist back-out.    
   
   
       2 . The uni-compartmental implant of  claim 1 , wherein the length between the head and distal end is less than 50 mm.  
   
   
       3 . The uni-compartmental implant of  claim 1 , wherein the distal end of the shaft has a diameter on the order of 2 to 3 mm.  
   
   
       4 . The uni-compartmental implant of  claim 1 , wherein the proximal end of the shaft has a diameter on the order of 2 to 4 mm.  
   
   
       5 . The uni-compartmental implant of  claim 1 , wherein the shaft includes a bone-ingrowth or bone-ongrowth surface.  
   
   
       6 . The uni-compartmental implant of  claim 1 , wherein the raised portions include a bone-ingrowth or bone-ongrowth surface.  
   
   
       7 . The uni-compartmental implant of  claim 1 , wherein the shaft is made of a fiber-metal.  
   
   
       8 . The uni-compartmental implant of  claim 1 , wherein the raised portions are made of a fiber-metal.  
   
   
       9 . The uni-compartmental implant of  claim 1 , wherein the head portion is ceramic.  
   
   
       10 . The uni-compartmental implant of  claim 1 , wherein the head portion is constructed of a chrome-cobalt alloy or other bio-compatible alloy.  
   
   
       11 . The uni-compartmental implant of  claim 1 , wherein the head portion has a bi-convex shape.  
   
   
       12 . The uni-compartmental implant of  claim 1 , wherein the head portion has a plano-convex shape.  
   
   
       13 . The uni-compartmental implant of  claim 1 , wherein the head portion has a concave-convex shape.  
   
   
       14 . The uni-compartmental implant of  claim 1 , wherein the head portion has a diameter ranging from 2 mm to 20 mm.