High flexion articular insert

Abstract

A knee prosthesis is provided that allows for increased flexion. The knee prosthesis includes (a) a femoral component adapted to fit on a distal end of the femur which includes a lateral condylar structure and a medial condylar structure and (b) an intermediate structure configured to cooperate with a femoral component of a knee prosthesis. The intermediate structure includes at least one surface for contacting the femoral component and a transition of a sagittal curvature of the at least one contact surface from a concave surface into a convex surface at the contact interface of the femoral component and the intermediate structure when the knee is flexed at approximately 120° to 140°. The knee prosthesis minimizes impingement on the femoral posterior cortex in deep flexion, increases the dislocation safety factor and allows for easier reengagement of the articular surface should the femoral component externally rotate off of the tibial plateau.

1 . A knee prosthesis comprising: 
 a femoral component adapted to fit on a distal end of a femur, the femoral component including a lateral condylar structure and a medial condylar structure; and    an intermediate structure configured to cooperate with a femoral component of a knee prosthesis, the intermediate structure comprising a proximal surface adapted to cooperate with an outer surface of the femoral component to allow flexion of the knee greater than 130°.    
   
   
       2 . The knee prosthesis of  claim 1 , wherein the intermediate structure is a component mounted on a tibia.  
   
   
       3 . The knee prosthesis of  claim 1 , wherein the intermediate structure is part of a tibial implant.  
   
   
       4 . The knee prosthesis of  claim 1 , wherein the intermediate structure is part of an insert adapted to fit between the femoral component and a tibial implant.  
   
   
       5 . The knee prosthesis of  claim 1 , wherein the intermediate structure comprises an articular blend at a contact interface of the femoral component and the intermediate structure when the knee is flexed approximately 120° to 140°.  
   
   
       6 . The knee prosthesis of  claim 5 , further comprising at least one surface for contacting the femoral component on the proximal surface of the intermediate structure, wherein the articular blend comprises a transition of a sagittal curvature of the at least one contact surface from a concave surface into a convex surface, the transition occurring at a contact point between the femoral component and the intermediate structure when the knee prosthesis is flexed at approximately 120° to 140°.  
   
   
       7 . The knee prosthesis of  claim 6 , wherein the at least one contact surface comprises a concave portion on a lateral side of the intermediate structure and a concave portion on a medial side of the intermediate structure, the concave portion being adapted to cooperate with the lateral condylar structure and the medial condylar structure of the femoral component.  
   
   
       8 . The knee prosthesis of  claim 6 , wherein the intermediate structure includes a contact surface on the lateral side of the intermediate structure and a contact surface on the medial side of the intermediate structure and wherein each contact surface includes an articular blend.  
   
   
       9 . The knee prosthesis of  claim 1 , further comprising a contact interface on the intermediate structure for contacting the femoral component, wherein the contact interface moves in an anterior direction on the intermediate structure and in a distal direction on the femoral component when the knee is flexed approximately 140° and greater.  
   
   
       10 . The knee prosthesis of  claim 1 , further comprising a post adapted to provide support to a posterior side of the femoral component, the post being adapted to minimize impingement on a patellar component when the knee is flexed approximately 130° or greater.  
   
   
       11 . The knee prosthesis of  claim 10 , wherein the post comprises a tapered anterior surface.  
   
   
       12 . The knee prosthesis of  claim 1 , wherein the intermediate structure further comprises a curved anterior surface adapted to minimize impingement of an intercondylar notch of the femoral component when the knee prosthesis is hyperextended.  
   
   
       13 . The knee prosthesis of  claim 1 , wherein the intermediate structure further comprises a curved posterior surface adapted to minimize impingement of a posterior cortex of a femur when the knee is flexed approximately 130° or greater.  
   
   
       14 . A knee prosthesis comprising: 
 a femoral component adapted to fit on a distal end of a femur, the femoral component including a lateral condylar structure and a medial condylar structure; and    an intermediate structure configured to cooperate with a femoral component of a knee prosthesis, the intermediate structure comprising a proximal surface comprising an articular blend at a contact point between the femoral component and the intermediate structure when the knee prosthesis is flexed at approximately 120° to 140°.    
   
   
       15 . The knee prosthesis of  claim 14 , wherein the intermediate structure is a component mounted on a tibia.  
   
   
       16 . The knee prosthesis of  claim 14 , wherein the intermediate structure is a part of a tibial implant.  
   
   
       17 . The knee prosthesis of  claim 14 , wherein the intermediate structure is a part of an insert adapted to fit between the femoral component and a tibial implant.  
   
   
       18 . The knee prosthesis of  claim 14 , further comprising at least one surface for contacting the femoral component on the proximal surface of the intermediate structure, wherein the articular blend comprises a transition of a sagittal curvature of the at least one contact surface from a concave surface into a convex surface, the transition occurring at a contact point between the femoral component and the intermediate structure when the knee prosthesis is flexed at approximately 120° to 140°.  
   
   
       19 . The knee prosthesis of  claim 18 , wherein the at least one contact surface comprises a concave portion on a lateral side of the intermediate structure and a concave portion on a medial side of the intermediate structure, the concave portion being adapted to cooperate with the lateral condylar structure and the medial condylar structure of the femoral component.  
   
   
       20 . The knee prosthesis of  claim 18 , wherein the intermediate structure includes a contact surface on the lateral side of the intermediate structure and a contact surface on the medial side of the intermediate structure and wherein each contact surface includes an articular blend.  
   
   
       21 . The knee prosthesis of  claim 14 , further comprising a contact interface on the intermediate structure for contacting the femoral component, wherein the contact interface moves in an anterior direction on the intermediate structure and in a distal direction on the femoral component when the knee is flexed approximately 140° and greater.  
   
   
       22 . The knee prosthesis of  claim 14 , further comprising a post adapted to provide support to a posterior side of the femoral component, the post being adapted to minimize impingement on a patellar component when the knee is flexed approximately 130° or greater.  
   
   
       23 . The knee prosthesis of  claim 22 , wherein the post comprises a tapered anterior surface.  
   
   
       24 . The knee prosthesis of  claim 14 , wherein the intermediate structure further comprises a curved anterior surface adapted to minimize impingement of an intercondylar notch of the femoral component when the knee prosthesis is hyperextended.  
   
   
       25 . The knee prosthesis of  claim 14 , wherein the intermediate structure further comprises a curved posterior surface adapted to minimize impingement of a posterior cortex of femur when the knee is flexed approximately 130° or greater.  
   
   
       16 . A knee prosthesis comprising: 
 (a) a femoral component adapted to fit on a distal end of a femur, the femoral component including a lateral condylar structure and a medial condylar structure; and    (b) an intermediate structure configured to cooperate with a femoral component of a knee prosthesis, the intermediate structure comprising: 
 at least one surface for contacting the femoral component on a proximal surface of the intermediate structure between the intermediate structure and the femoral component; and  
 a transition of a sagittal curvature of the at least one contact surface from a concave surface into a convex surface, the transition occurring at a contact point between the femoral component and the intermediate structure when the knee prosthesis is flexed at approximately 120° to 140°.  
   
   
   
       27 . The knee prosthesis of claim  26 , wherein the intermediate structure is a component mounted on a tibia.  
   
   
       28 . The knee prosthesis of claim  26 , wherein the intermediate structure is part of a tibial implant.  
   
   
       29 . The knee prosthesis of claim  26 , wherein the intermediate structure is part of an insert adapted to fit between the femoral component and a tibial component.  
   
   
       30 . The knee prosthesis of claim  26 , wherein the at least one contact surface comprises a concave portion on a lateral side of the intermediate structure and a concave portion on a medial side of the intermediate structure, the concave portions being adapted to cooperate with the lateral condylar structure and the medial condylar structure of the femoral component.  
   
   
       31 . The knee prosthesis of claim  26 , wherein the intermediate structure includes a contact surface on the lateral side of the intermediate structure and a contact surface on the medial side of the intermediate structure and wherein each contact surface includes an articular blend.  
   
   
       32 . The knee prosthesis of claim  26 , further comprising a contact interface on the intermediate structure for contacting the femoral component, wherein the contact interface moves in an anterior direction on the intermediate structure and in a distal direction on the femoral component when the knee is flexed approximately 140° and greater.  
   
   
       33 . The knee prosthesis of claim  26 , further comprising a post adapted to provide support to a posterior side of the femoral component, the post being adapted to minimize impingement on a patellar component when the knee is flexed approximately 130° and greater.  
   
   
       34 . The knee prosthesis of  claim 33 , wherein the post comprises a tapered anterior surface.  
   
   
       35 . The knee prosthesis of claim  26 , wherein the intermediate structure further comprises a curved anterior surface adapted to minimize impingement of an intercondylar notch of the femoral component when the knee is hyperextended.  
   
   
       36 . The knee prosthesis of claim  26 , wherein the intermediate structure further comprises a curved posterior surface adapted to minimize impingement of a posterior cortex of a femur when the knee is flexed approximately 130° or greater.  
   
   
       37 . A knee prosthesis comprising: 
 (a) a femoral component adapted to fit on a distal end of a femur, the femoral component including a lateral condylar structure and a medial condylar structure; and    (b) an intermediate structure configured to cooperate with a femoral component of a knee prosthesis, the intermediate structure comprising: 
 at least one surface for contacting the femoral component;  
 a transition of a sagittal curvature of the at least one contact surface from a concave surface into a convex surface, the transition occurring at a contact point between the femoral component and the intermediate structure when the knee prosthesis is flexed at approximately 120° to 140°; and  
 a post adapted to provide posterior support to the femoral component, the post being adapted to minimize impingement on a patellar component when the knee is flexed approximately 130° or greater.