Knee prosthesis

Abstract

A knee joint prosthesis assembly including a femoral component and a unitary tibial component. The femoral component includes a first condyle and a second condyle. The unitary tibial component includes an engaging structure configured to rigidly secure a stationary bearing thereto. The stationary bearing is configured to articulate with the first condyle. The unitary tibial component further includes a planar tibial bearing surface configured to slidably support a mobile bearing thereon. The mobile bearing includes an inferior planar surface configured to slide along the planar tibial bearing surface and a superior surface configured to articulate with the second condyle.

What is claimed is: 
     
         1 . A knee joint prosthesis assembly comprising:
 a femoral component including a first condyle and a second condyle; and   a unitary tibial component including:
 an engaging structure configured to rigidly secure a stationary bearing thereto, the stationary bearing configured to articulate with the first condyle; and 
 a planar tibial bearing surface configured to slidably support a mobile bearing thereon, the mobile bearing including an inferior planar surface configured to slide along the planar tibial bearing surface and a superior surface configured to articulate with the second condyle. 
   
     
     
         2 . The knee joint prosthesis assembly of  claim 1 , wherein the mobile bearing is configured to slide only in an anterior-posterior direction. 
     
     
         3 . The knee joint prosthesis assembly of  claim 1 , wherein the mobile bearing is a floating bearing. 
     
     
         4 . The knee joint prosthesis assembly of  claim 1 , wherein the unitary tibial component includes a rail extending anterior-posterior, the mobile bearing is configured to slide along the rail. 
     
     
         5 . The knee joint prosthesis assembly of  claim 1 , wherein the engaging structure of the unitary tibial component includes a plurality of coupling members extending superiorly and configured to couple directly with the stationary bearing. 
     
     
         6 . The knee joint prosthesis assembly of  claim 1 , wherein the stationary bearing is a lateral bearing and the mobile bearing is a medial bearing. 
     
     
         7 . The knee joint prosthesis assembly of  claim 1 , wherein the stationary bearing is a medial bearing and the mobile bearing is a lateral bearing. 
     
     
         8 . The knee joint prosthesis assembly of  claim 1 , wherein a rail restricts rotation of the mobile bearing. 
     
     
         9 . A knee joint prosthesis assembly comprising:
 a femoral component including a first condyle and a second condyle connected by a patellar track portion, the femoral component defining an opening between the first condyle and the second condyle; and   a unitary tibial component including:
 an engaging structure configured to rigidly secure a stationary bearing thereto, the stationary bearing configured to articulate with the first condyle; 
 a planar tibial bearing surface configured to slidably support a mobile bearing thereon, the mobile bearing including an inferior planar surface configured to slide along the planar tibial bearing surface and a superior surface configured to articulate with the second condyle; and 
 a rail extending in an anterior-posterior direction and configured to restrict the mobile bearing to anterior-posterior movement. 
   
     
     
         10 . The knee joint prosthesis of  claim 9 , wherein the rail abuts a side surface of the mobile bearing. 
     
     
         11 . The knee joint prosthesis of  claim 9 , wherein the rail protrudes superiorly. 
     
     
         12 . The knee joint prosthesis of  claim 9 , wherein the rail is between the mobile bearing and the stationary bearing. 
     
     
         13 . The knee joint prosthesis of  claim 9 , wherein the mobile bearing is a medial bearing and the stationary bearing is a lateral bearing. 
     
     
         14 . The knee joint prosthesis of  claim 9 , wherein the unitary tibial component defines a slot between the rail and the engaging structure. 
     
     
         15 . A knee joint prosthesis assembly comprising:
 a femoral component including a first condyle and a second condyle connected by a patellar track portion, the femoral component defining an opening between the first condyle and the second condyle; and   a unitary tibial component including:
 a medial portion, a lateral portion, and a slot defined between the medial portion and the lateral portion; 
 an engaging structure extending superiorly from one of the medial portion or the lateral portion, the engaging structure configured to rigidly secure a stationary bearing thereto, the stationary bearing configured to articulate with the first condyle; 
 a planar tibial bearing surface at the other of the medial portion or the lateral portion, the planar tibial bearing surface configured to slidably support a mobile bearing thereon, the mobile bearing including an inferior planar surface configured to slide along the planar tibial bearing surface and a superior surface configured to articulate with the second condyle; and 
 a rail between the planar tibial bearing surface and the engaging structure, the rail extending in an anterior-posterior direction and configured to restrict the mobile bearing to anterior-posterior movement. 
   
     
     
         16 . The knee joint prosthesis assembly of  claim 15 , wherein the engaging structure extends from the lateral portion and the planar tibial bearing surface is at the medial portion. 
     
     
         17 . The knee joint prosthesis assembly of  claim 15 , wherein the rail abuts an inner surface of the mobile bearing. 
     
     
         18 . The knee joint prosthesis assembly of  claim 15 , wherein the mobile bearing is a floating bearing. 
     
     
         19 . The knee joint prosthesis assembly of  claim 15 , wherein the rail protrudes superiorly away from the planar tibial bearing surface. 
     
     
         20 . The knee joint prosthesis assembly of  claim 15 , wherein the engaging structure includes tabs at an anterior portion and a posterior portion of the unitary tibial component.