Talar implant for modifying joint kinematics

Abstract

In one embodiment, the present invention provides a talar implant, comprising: a. a superior surface, defined by an arc having at least one first radius; b. an inferior surface, defined by an arc having at least one second radius, c. a lateral side; d. a medial side; e. a posterior portion having a first width; and f an anterior portion having a second width; wherein the implant is configured to restore a joint tension between a tibio-talar joint in a neutral position, wherein the superior surface is separated from the inferior surface by a thickness, defining a height of the medial and lateral sides, wherein the at least one first radius is smaller than the at least one second radius, wherein the center of the arc having at least one first radius is offset from the center of the arc having at least one second radius in at least one plane of the talar implant selected from the group consisting of: a superior/inferior plane, an anterior/posterior plane, and a medial/lateral plane, wherein the inferior surface is configured to attach to a superior surface of the talus,and wherein the anterior portion further comprises an extension configured to provide support.

What is claimed is: 
     
         1 . A talar implant, comprising:
 a. a superior surface, defined by an arc having at least one first radius;   b. an inferior surface, defined by an arc having at least one second radius,   c. a lateral side;   d. a medial side;   e. a posterior portion having a first width; and   f. an anterior portion having a second width;
 wherein the implant is configured to restore a joint tension between a tibio-talar joint in a neutral position, 
 wherein the superior surface is separated from the inferior surface by a thickness, defining a height of the medial and lateral sides, 
 wherein the at least one first radius is smaller than the at least one second radius, 
 wherein a ration of the at lease one first radius to the at least one second radius is in a range of from about 0.60 to about 0.95, 
 wherein the center of the arc having at least one first radius is offset from the center of the arc having at least one second radius in at least one plane of the talar implant selected from the group consisting of: a superior/inferior plane, an anterior/posterior plane, and a medial/lateral plane, 
 wherein the inferior surface is configured to attach to a superior surface of the talus, and 
 wherein the anterior portion further comprises an extension configured to provide support. 
   
     
     
         2 . The talar implant of  claim 1 , wherein the superior surface of the implant is bicondylar. 
     
     
         3 . The talar implant of  claim 2 , wherein the at least one first radius varies from the medial side of the implant to the lateral side of the implant. 
     
     
         4 . The talar implant of  claim 1 , wherein the at least one second radius varies from the medial side of the implant to the lateral side of the implant. 
     
     
         5 . The talar implant of  claim 1 , wherein the inferior surface further comprises at least one peg configured to anchor the talar implant to the superior surface of the talus. 
     
     
         6 . The talar implant of  claim 1 , wherein the center of the arc having at least one first radius is offset from the center of the arc having at least one second radius in the superior/inferior plane. 
     
     
         7 . The talar implant of  claim 1 , wherein the center of the arc having at least one first radius is offset from the center of the arc having at least one second radius in the anterior/posterior plane. 
     
     
         8 . The talar implant of  claim 1 , wherein the center of the arc having at least one first radius is offset from the center of the arc having at least one second radius in the medial/lateral plane. 
     
     
         9 . The talar implant of  claim 1 , wherein the offset of the center of the arc having at least one first radius from the center of the arc having at least one second radius is different on the superior surface of the implant than the offset on the inferior surface of the implant. 
     
     
         10 . The talar implant of  claim 1 , wherein the offset of the center of the arc having at least one first radius from the center of the arc having at least one second radius is different on the medial side of the implant than the offset on the lateral side of the implant. 
     
     
         11 . The talar implant of  claim 1 , wherein, the offset of the center of the arc having at least one first radius from the center of the arc having at least one second radius is different on the superior portion of the implant than the offset on the anterior portion of the implant. 
     
     
         12 . The talar implant of  claim 1 , wherein the ratio of the at least one first radius to the at least one second radius is less than 1. 
     
     
         13 . The talar implant of  claim 1 , wherein the at least one first radius is from 15.0 mm to 20.0 mm. 
     
     
         14 . The talar implant of  claim 1 , wherein the second radius is from 22.0 mm to 30.0 mm. 
     
     
         15 . A kit, comprising a plurality of the talar implants of  claim 1 ,
 wherein an individual talar implant of  claim 1  within the plurality differs in at least one property selected from the group consisting of: the at least one first radius, the at least one second radius, the ration of the at least one first radius to the at least one second radius, the first width, the second width, the offset of the center of the arc having at least one first radius from the center of the arc having at least one second radius in the superior/inferior plane, the offset of the center of the arc having at least one first radius from the center of the arc having at least one second radius in the anterior/posterior plane, and the offset of the center of the arc having at least one first radius from the center of the arc having at least one second radius in the medial/lateral plane, from any of the other individual talar implants of  claim 1  within the plurality.   
     
     
         16 . The kit of  claim 15 , further comprising a tibial base component. 
     
     
         17 . The talar implant of  claim 1 , wherein the ration of the at least one first radius to the at least one second radius is in a range of from about 0.70 to about 0.95. 
     
     
         18 . The kit of  claim 15 , wherein each of the individual talar implants of  claim 1  which the plurality includes a ration of its at least one first radius to its at least one second radius in a range of from about 0.70 to about 0.95.