Tibial component

Abstract

Methods, systems, and apparatuses are disclosed for a tibial component having shock absorbing features. In one embodiment, a tibial component of a knee joint prosthesis is provided, the tibial component comprising: a body portion; an upper surface; a first concave fossae comprising a first condyle contact surface; a second concave fossae comprising a second condyle contact surface; a lower surface; a side portion extending between the upper surface and the lower surface; a first bearing portion; a second bearing portion; and at least one cavity extending into the body portion from the lower surface; wherein a load applied substantially normally to the first condyle contact surface and the second condyle contact surface causes a tensile stress within the first bearing portion and the second bearing portion, and a compressive stress within the side portion.

1 . A tibial component of a knee joint prosthesis, the tibial component comprising:
 a body portion;   an upper surface;   a first concave fossae comprising a first condyle contact surface;   a second concave fossae comprising a second condyle contact surface;   a lower surface;   a side portion extending between the upper surface and the lower surface, comprising:
 a first lateral side portion extending between the upper surface and the lower surface, and 
 a second lateral side portion extending between the upper surface and the lower surface; 
   a first bearing portion, the first bearing portion having a first bearing portion thickness;   a second bearing portion, the second bearing portion having a second bearing portion thickness; and   not more than one first cavity extending into the body portion from the first lateral side portion, the first cavity having a first cavity length and a first cavity width;   not more than one second cavity extending into the body portion from the second lateral side portion, the second cavity having a second cavity length and a second cavity width;   wherein at least one of the first cavity and the second cavity comprise an upper surface and a lower surface, each of the upper surface and the lower surface having an arc-shaped cross-section with an arc center point above the first bearing portion and the second bearing portion, and wherein the arc center point is the point from which a radius of the arc can be measured;   wherein a load applied substantially normally to the first condyle contact surface and the second condyle contact surface causes: a tensile stress within the first bearing portion, the tensile stress within the first bearing portion extending completely throughout the first bearing portion thickness along a length corresponding to the first cavity length and along a width corresponding to the first cavity width; a tensile stress within the second bearing portion, the tensile stress within the second bearing portion extending completely throughout the second bearing portion thickness along a length corresponding to the second cavity length and along a width corresponding to the second cavity width; and a compressive stress within the side portion;   with the provisio that no compressive stress extends completely through the first bearing portion thickness along the length corresponding to the first cavity length and the width corresponding to the first cavity width; and   with the provisio that no compressive stress extends completely through the second bearing portion thickness along the length corresponding to the second cavity length and the width corresponding to the first cavity width.   
     
     
         2 . The tibial component of  claim 1 , wherein the first cavity is positioned substantially opposite the first condyle contact surface and the second cavity is positioned substantially opposite the second condyle contact surface. 
     
     
         3 . The tibial component of  claim 1 , wherein the tibial component is comprised of a substantially rigid material. 
     
     
         4 . The tibial component of  claim 1 , wherein the tibial component is comprised of a polymeric material having a Shore hardness greater than 65. 
     
     
         5 . The tibial component of  claim 1 , wherein at least one of the first condyle contact surface, the second condyle contact surface, and the upper surface is capable of operatively connecting the tibial component to a substantially rigid femoral component comprising a first condyle and a second condyle. 
     
     
         6 . The tibial component of  claim 1 , wherein:
 the first bearing portion comprises a first bearing portion length and a first bearing portion width;   the second bearing portion comprises a second bearing portion length and a second bearing portion width;   wherein varying at least one of the first bearing portion length, the first bearing portion width, and the first bearing portion thickness causes the tensile stress within the first bearing portion to change; and   wherein varying at least one of the second bearing portion length, the second bearing portion width, and the second bearing portion thickness causes the tensile stress within the second bearing portion to change.   
     
     
         7 . The tibial component of  claim 1 , wherein:
 the first cavity comprises a first cavity height;   the second cavity comprises a second cavity height;   wherein varying at least one of the first cavity length, the first cavity width, and the first cavity height causes the tensile stress within the first bearing portion to change; and   wherein varying at least one of the second cavity length, the second cavity width, and the second cavity height causes the tensile stress within the second bearing portion to change.   
     
     
         8 . A total knee joint prosthesis, the total knee joint prosthesis comprising:
 a substantially rigid femoral component comprising a first condyle and a second condyle; and   a substantially rigid tibial component, comprising:
 a body portion; 
 an upper surface; 
 a first concave fossae comprising a first condyle contact surface; and 
 a second concave fossae comprising a second condyle contact surface; 
 a lower surface; 
 a side portion extending between the upper surface and the lower surface, comprising:
 a first lateral side portion extending between the upper surface and the lower surface, and 
 a second lateral side portion extending between the upper surface and the lower surface; 
 
 a first bearing portion, the first bearing portion having a first bearing portion thickness; 
 a second bearing portion, the second bearing portion having a second bearing portion thickness; and 
 not more than one first cavity extending into the body portion from the first lateral side portion, the first cavity having a first cavity length and a first cavity width; 
 not more than one second cavity extending into the body portion from the second lateral side portion, the second cavity having a second cavity length and a second cavity width; 
 wherein at least one of the first cavity and the second cavity comprise an upper surface and a lower surface, each of the upper surface and the lower surface having an arc-shaped cross-section with an arc center point above the first bearing portion and the second bearing portion, and wherein the arc center point is the point from which a radius of the arc can be measured; 
   wherein the first condyle operatively connects to the first condyle contact surface and the second condyle operatively connects to the second condyle contact surface;   wherein a load applied substantially normally to the first condyle contact surface and the second condyle contact surface causes: a tensile stress within the first bearing portion, the tensile stress within the first bearing portion extending completely throughout the first bearing portion thickness along a length corresponding to the first cavity length and along a width corresponding to the first cavity width; a tensile stress within the second bearing portion, the tensile stress within the second bearing portion extending completely throughout the second bearing portion thickness along a length corresponding to the second cavity length and along a width corresponding to the second cavity width; and a compressive stress within the side portion;   with the provisio that no compressive stress extends completely through the first bearing portion thickness along the length corresponding to the first cavity length and the width corresponding to the first cavity width; and   with the provisio that no compressive stress extends completely through the second bearing portion thickness along the length corresponding to the second cavity length and the width corresponding to the first cavity width.   
     
     
         9 . The total knee joint prosthesis of  claim 8 , wherein the first cavity is positioned opposite the first condyle contact surface and the second cavity is positioned opposite the second condyle contact surface. 
     
     
         10 . The total knee joint prosthesis of  claim 8 , wherein the tibial component is comprised of a polymeric material having a Shore hardness greater than 65. 
     
     
         11 . The total knee joint prosthesis of  claim 8 , wherein:
 the first bearing portion comprises a first bearing portion length and a first bearing portion width;   the second bearing portion comprises a second bearing portion length and a second bearing portion width;   wherein varying at least one of the first bearing portion length, the first bearing portion width, and the first bearing portion thickness causes the tensile stress within the first bearing portion to change; and   wherein varying at least one of the second bearing portion length, the second bearing portion width, and the second bearing portion thickness causes the tensile stress within the second bearing portion to change.   
     
     
         12 . The total knee joint prosthesis of  claim 8 , wherein:
 the first cavity comprises a first cavity height;   the second cavity comprises a second cavity height;   wherein varying at least one of the first cavity length, the first cavity width, and the first cavity height causes the tensile stress within the first bearing portion to change; and   wherein varying at least one of the second cavity length, the second cavity width, and the second cavity height causes the tensile stress within the second bearing portion to change.   
     
     
         13 . The tibial component of  claim 1 , wherein a distance between the upper surface and the lower surface is between about 8 mm and about 30 mm. 
     
     
         14 . The total knee joint prosthesis of  claim 8 , wherein the substantially rigid tibial component is comprised of a substantially rigid material. 
     
     
         15 . The total knee joint prosthesis of  claim 8 , wherein a distance between the upper surface and the lower surface is between about 8 mm and about 30 mm.