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.

What is claimed is: 
     
       1. A prosthetic femoral component, comprising:
 a femoral component body;   a hinge post having a longitudinal axis, said hinge post rotatably connected to said femoral component body, said hinge post rotatable relative to said femoral component body bout an axis of rotation, said hinge post including an elongate aperture, along said longitudinal axis aid elongate aperture transverse to said axis of rotation.   
     
     
       2. The prosthetic femoral component of  claim 1 , further comprising: A prosthetic knee assembly, comprising:
 a femoral component body that includes a first internal side wall opposing a second internal side wall; 
 a hinge pin having a longitudinal hinge pin axis; 
 a hinge post positioned between the first internal side wall and the second internal side wall of the femoral component body and having a longitudinal hinge post axis, said hinge pin fixed to said femoral component body and passing through a hinge pin aperture in said hinge post for rotatably, hingedly connecting said hinge post to said femoral component body so that rotation of said hinge post relative to said femoral component body is defined about the longitudinal hinge pin axis, said hinge post including an elongate hinge post extension aperture along said longitudinal hinge post axis, said elongate hinge post extension aperture transverse to said longitudinal hinge pin axis; and 
 a hinge post extension removeably locked to said hinge post, said elongate hinge post extension 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 hinge post extension aperture of said hinge post and protrudes from a second end of said elongate hinge post extension aperture of said hinge post. 
 
     
     
       3. The prosthetic femoral component knee assembly of  claim 2 , further comprising:
 securing means for securing said hinge post extension to said hinge post further comprising a tibial component into which the hinge post extension can be received, wherein, when the femoral component is attached to a femur and the tibial component is attached to a tibia opposite the femur, said hinge post extension can be separated from said hinge post to allow rotation of said hinge post about said longitudinal hinge pin axis without having to rotate the femur or tibia about said longitudinal hinge pin axis. 
 
     
     
       4. The prosthetic femoral component knee assembly 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 2 including cooperating locking tapers removeably locking the hinge post extension to the hinge post. 
 
     
     
       5. The prosthetic femoral component knee assembly of claim  1  2, 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 knee assembly of  claim 5 , wherein said predetermined point of hyperextension comprises four degrees of hyperextension of the prosthetic knee femoral component body. 
     
     
       7. The prosthetic femoral component knee assembly of  claim 5 , wherein said hyperextension stop comprises a convex protrusion. 
     
     
       8. The prosthetic femoral component knee assembly of  claim 5 , wherein said hinge post includes an internal wall, said hyperextension stop surface comprising said internal wall of said hinge post. 
     
     
       9. A prosthetic femoral component, comprising:
 a femoral component body;   a hinge post rotatably connected to said femoral component body; and   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.   
     
     
       10. The prosthetic femoral component of  claim 9 , further comprising: A prosthetic knee assembly, comprising:
 a femoral component body; 
 a hinge post rotatably connected to said femoral component body about a rotational axis; 
 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; and 
 a hinge post extension having a longitudinal axis and being removeably locked to said hinge post, an 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 post and protrudes from a second end of said elongate aperture of said hinge post, wherein the longitudinal axis of said hinge post extension is non-intersecting with said rotational axis. 
 
     
     
       11. The prosthetic femoral component knee assembly of  claim 10 , further comprising:
 securing means for securing said hinge post extension to said hinge post. 
 
     
     
       12. The prosthetic femoral component knee assembly of  claim 11 , 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. 
 
     
     
       13. The prosthetic femoral component knee assembly of claim  9  10, wherein said predetermined point of hyperextension comprises four degrees of hyperextension of the prosthetic femoral component body. 
     
     
       14. The prosthetic femoral component knee assembly of claim  9  10, wherein said hyperextension stop comprises a convex protrusion. 
     
     
       15. The prosthetic femoral component knee assembly of claim  9  10, wherein said hinge post includes an internal wall, said hyperextension stop surface comprising said internal wall of said hinge post. 
     
     
       16. A prosthetic knee, comprising:
 a femoral component; 
 a tibial component; 
 a meniscal component positioned between said femoral component and said tibial component, said femoral component including a condylar bearing surface, said meniscal component including a cooperative bearing surface facing said condylar bearing surface of said femoral component for contacting said condylar bearing surface, said femoral component rotatably connected to said tibial component; 
 a hinge pin having a longitudinal hinge pin axis;  
 a hinge post rotatably connected to said femoral component which includes said hinge pin passing through a hinge pin aperture in said hinge post for rotatably, hingedly connecting said hinge post to said femoral component so that rotation of said hinge post relative to said femoral component is defined about the longitudinal hinge pin axis, said meniscal component including an a hinge post aperture with a longitudinal hinge post aperture axis that is non-intersecting with said longitudinal hinge pin axis, said hinge post positioned within said hinge post aperture; and 
 a locking clip, said meniscal component including a locking clip aperture, said hinge post including a locking clip groove, said locking clip traversing said locking clip aperture and engaging said locking clip groove to retain said hinge post within said hinge post aperture. 
 
     
     
       17. A prosthetic knee, comprising:
 a femoral component;   a tibial component;   a meniscal component positioned between said femoral component and said tibial component, said femoral component including a condylar bearing surface, said meniscal component including a cooperative bearing surface facing said condylar bearing surface of said femoral component, said femoral component rotatably connected to said tibial component;   a hinge post extension, said hinge post extension rotatably connected to said femoral component, said hinge post extension including an annular groove; and   a tibial bushing including an annular locking protrusion and a retaining flange, said tibial component having a tibial bushing expansion groove, said retaining flange positioned in said tibial bushing expansion groove, said annular locking protrusion engaged in said annular groove.   
     
     
       18. A prosthetic knee, comprising:
 a femoral component having a hinge post rotatably connected thereto about a rotational axis; 
 a tibial component; 
 a meniscal component positioned between said femoral component and said tibial component, said femoral component including a condylar bearing surface, said meniscal component including a cooperative bearing surface facing said condylar bearing surface of said femoral component for contacting said condylar bearing surface, said meniscal component including an a hinge post aperture having a longitudinal axis that is non-intersecting with said rotational axis, whereby said hinge post is positioned within said hinge post aperture when the prosthetic knee is operably assembled; and 
 a locking clip, said meniscal component including a locking clip aperture, said hinge post including a locking clip groove, said locking clip traversing said locking clip aperture and engaging said locking clip groove to retain said hinge post within said hinge post aperture. 
 
     
     
       19. The prosthetic femoral component of claim 2, wherein said first end of said elongate aperture of said hinge post is positioned closer to said hinge pin than said second end of said elongate aperture so that said hinge post extension protrudes from said second end of said elongate aperture of said hinge post in a direction away from said hinge pin. 
     
     
       20. The prosthetic femoral component of claim 10, wherein said first end of said elongate aperture of said hinge post is positioned closer to said femoral component body than said second end of said elongate aperture of said hinge post so that said hinge post extension protrudes from said second end of said elongate aperture of said hinge post in a direction away from said femoral component body. 
     
     
       21. The prosthetic femoral component of claim 2, wherein said hinge pin includes a hexagonal indentation on a first end thereof, said first end being flush with said femoral component, said prosthetic femoral component further comprising a hinge pin plug positioned within said hexagonal indentation and being flush with said first end of said hinge pin. 
     
     
       22. The prosthetic femoral component of claim 2, wherein said longitudinal hinge post axis is non-intersecting with said longitudinal hinge pin axis.