Constrained prosthetic knee with rotating bearing

Abstract

A constrained prosthetic knee having a modular hinge post and a rotating bearing. A cannulated hinge post is rotatably connected to the femoral component of the knee prosthesis so that a hinge post extension may be anteriorly positioned through the hinge post and into the tibial component of the knee prosthesis, after positioning of the femoral component in the femur and the tibial component in the tibia. The hinge post is preassembled to the femoral component so that such assembly is not required during the implantation procedure. A meniscal component forming the rotating bearing of the knee prosthesis is packaged together with the hinge post extension so that the appropriate hinge post extension is readily available. The meniscal component includes a mechanism for preventing lift off of the meniscal component from the tibial component, while allowing rotation of the meniscal component relative to the tibial component.

1 . A prosthetic femoral component, comprising: 
 a femoral component body;    a hinge post rotatably connected to said femoral component body, said hinge post rotatable relative to said femoral component body about an axis of rotation, said hinge post including an elongate aperture, said elongate aperture transverse to said axis of rotation.    
   
   
       2 . The prosthetic femoral component of  claim 1 , further comprising: 
 a hinge post extension, said elongate aperture of said hinge post sized for placement of said hinge post extension therein, whereby said hinge post extension traverses a first end of said elongate aperture of said hinge post and protrudes from a second end of said elongate aperture of said hinge post, said first and second ends of said elongate aperture of said hinge post comprising opposing ends of said elongate aperture of said hinge post.    
   
   
       3 . The prosthetic femoral component of  claim 2 , further comprising: 
 securing means for securing said hinge post extension to said hinge post.    
   
   
       4 . The prosthetic femoral component of  claim 3 , wherein said securing means comprises: 
 a male taper positioned on said hinge post extension; and    a female taper positioned in said elongate aperture, said male taper engageable in said female taper to secure said hinge post extension to said hinge post.    
   
   
       5 . The prosthetic femoral component of  claim 1 , further comprising: 
 a bearing box connected to said femoral component body, said bearing box interposed between said hinge post and said femoral component body, said bearing box including a hyperextension stop, said hinge post including a hyperextension stop surface, said hyperextension stop contacting said hyperextension stop surface to prevent further hyperextension of the prosthetic femoral component body beyond a predetermined point of hyperextension.    
   
   
       6 . The prosthetic femoral component of  claim 5 , wherein said predetermined point of hyperextension comprises four degrees of hyperextension of the prosthetic knee body.  
   
   
       7 . The prosthetic femoral component of  claim 5 , wherein said hyperextension stop comprises a convex protrusion.  
   
   
       8 . The prosthetic femoral component of  claim 5 , wherein said hinge post includes an internal wall, said hyperextension stop surface comprising said internal wall of said hinge post.  
   
   
       9 . The prosthetic femoral component of  claim 2 , further comprising: 
 a male taper positioned on said hinge post extension; and    a female taper positioned in said elongate aperture, said male taper engageable in said female taper to secure said hinge post extension to said hinge post.    
   
   
       10 . The prosthetic femoral component of  claim 1 , further comprising: 
 a set screw, said first end of said elongate hinge post extension aperture being threaded, whereby said set screw will engage the threads of said elongate hinge post extension aperture, said hinge post extension including a locking taper, a hinge post extension aperture including a cooperating taper, whereby threading of said set screw into said elongate hinge post extension aperture forces said locking taper into locking engagement with said cooperating taper.    
   
   
       11 . The prosthetic femoral component of  claim 1 , wherein said hinge post is rotatably connected to said femoral component body via a hinge pin, said hinge post rotatable about a longitudinal axis of said hinge pin, said hinge pin including an indentation on a first end thereof, and 
 a hinge pin plug positioned within said indentation and being flush with said first end of said hinge pin.    
   
   
       12 . The prosthetic knee of  claim 11 , wherein said hinge pin plug is formed from an ultra-high molecular polyethylene.