Anatomical motion hinged prosthesis

Abstract

A hinged knee prosthesis comprises a tibial component and a femoral component. The tibial component is configured to attach to a tibia. The tibial component has a bearing surface. The femoral component is configured to hingedly attach to the tibial component and rotate relative to the tibial component. The femoral component comprises a medial condyle and a lateral condyle. The medial and lateral condyles have an eccentric sagittal curvature surface configured to rotate and translate on the bearing surface of the tibial component. A method of rotating a hinged knee through a range of flexion is provided. The method fixedly attaches a femoral component to a tibial component. Axial rotation of the femoral component is induced relative to the tibial component when the hinged knee is flexed.

1 . A method of rotating a hinged knee through a range of flexion, comprising the steps of:
 a. fixedly attaching a femoral component to a tibial component;   b. inducing axial rotation of the femoral component relative to the tibial component when the hinged knee is flexed.   
     
     
         2 . The method of  claim 1 , further comprising the step of inducing translation of the femoral component in an anterior/posterior direction relative to the tibial component when the hinged knee is flexed. 
     
     
         3 . The method of  claim 2 , wherein the inducing translation step and the inducing axial rotation steps occur simultaneously. 
     
     
         4 . The method of  claim 1 , wherein the inducing axial rotation step occurs through a portion of the range of flexion of the prosthetic knee. 
     
     
         5 . The method of  claim 1 , wherein the inducing axial rotation step occurs through a first portion of the range of flexion of the prosthetic knee and a second portion of the range of flexion of the prosthetic knee. 
     
     
         6 . The method of  claim 5 , wherein the first portion of the range of flexion is not adjacent to the second portion of the range of flexion. 
     
     
         7 . The method of  claim 1 , wherein the inducing axial rotation step occurs at varying angular velocities as the hinged knee passes through the range of flexion of the knee. 
     
     
         8 . The method of  claim 1 , wherein the fixedly attaching step comprises the steps of: a. connecting a sleeved post to the tibial insert such that a sleeved portion of the sleeved post and a post portion of the sleeved post axially rotate relative to each other; and b. fixing an axial hinge pin to the sleeved post such that the axial hinge pin transversely connects a medial condyle of the femoral component to the lateral condyle of the femoral component. 
     
     
         9 . The method of  claim 8 , further comprising the step of fixing the sleeved portion of the sleeved post to a stem in the tibial component. 
     
     
         10 . The method of  claim 8 , further comprising the step of axially displacing the sleeved portion of the sleeved post relative to the post portion of the sleeved post when the hinged knee is flexed.