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 - 16 . (cancelled).  
     
     
         17 . A prosthetic knee, comprising: 
 a femoral component having a hinge post rotatably connected thereto;    a hinge post extension extending from said hinge post;    a tibial component including a hinge post extension aperture, whereby said hinge post extension is positioned within said hinge post extension aperture when the prosthetic knee is operably assembled, whereby said hinge post is fully constrained by said tibial component against displacement in a direction perpendicular to a longitudinal axis of said hinge post extension, and whereby said femoral component is rotatable about said longitudinal axis of said hinge post extension; and    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 abutting said condylar bearing surface of said femoral component.    
     
     
         18 . 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; and    means for retaining the connection of said femoral component to said tibial component during flexion and extension of the prosthetic knee.    
     
     
         19 . 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 knee body beyond a predetermined point of hyperextension.    
     
     
         20 . The prosthetic femoral component of  claim 19 , wherein said predetermined point of hyperextension comprises four degrees of hyperextension of the prosthetic knee body.