Femoral and Tibial Bases

Abstract

Various embodiments are directed to femoral and tibial bases that form structures of an implantable mechanical energy absorbing system. According to one embodiment, the bases include a low-profile body having a elongate and a curved body portion. One end of the base is elevated as compared to another end. An inner surface of the low-profile body has a raised portion extending along the elongate, straight portion of the low-profile body. The bases also include a plurality of openings positioned along the low-profile body for alignment and purposes of affixation to body anatomy.

1 . A mechanical energy absorbing system comprising:
 a femoral base having a bone contacting surface with a surface area of less than 650 mm 2 , the femoral base having a single non-threaded opening therein configured to receive a compression screw and a plurality of threaded openings therein configured to receive a plurality of locking screws with threaded locking heads;   a tibial base having a bone contacting surface area of less than 750 mm 2 ;   an absorber connected between the femoral and tibial bases and configured to reduce loads born by a knee.   
     
     
         2 . The system of  claim 1 , wherein the femoral base has only three threaded openings therein. 
     
     
         3 . The system of  claim 1 , wherein the tibial base has a single non-threaded opening therein configured to receive a compression screw and a plurality of threaded openings therein configured to receive a plurality of locking screws with threaded locking heads. 
     
     
         4 . The system of  claim 1 , wherein said threaded openings are positioned at three points of a triangle. 
     
     
         5 . The system of  claim 4 , wherein the non-threaded opening is positioned at least partially within the triangle. 
     
     
         6 . The system of  claim 2 , wherein the three threaded openings each have axes which cross each other on a bone contacting side of the femoral base. 
     
     
         7 . The system of  claim 3 , wherein said threaded openings of the tibial base are positioned at three points of a triangle and the non-threaded opening is positioned at least partially within the triangle. 
     
     
         8 . The system of  claim 7 , wherein two of the threaded openings of the tibial base closest to the absorber have axes which cross each other on a bone contacting side of the tibial base. 
     
     
         9 . The system of  claim 7 , wherein a threaded opening of the tibial base furthest from the absorber has an axis which does not cross with the axes of the other two threaded openings. 
     
     
         10 . A femoral base for a mechanical energy absorbing system comprising:
 a body having a bone contacting surface and an attachment site for attaching an energy absorber;   a non-threaded opening formed in the body and configured to receive a compression screw;   a plurality of threaded openings formed in the body and configured to receive a plurality of locking screws with threaded locking heads; and   a non-threaded K-wire opening smaller than the threaded and non-threaded openings, the K-wire opening having an axis parallel to an axis of the non-threaded opening.   
     
     
         11 . The femoral base of  claim 10 , wherein the non-threaded opening is a single non-threaded opening. 
     
     
         12 . A method of implanting a femoral base for a mechanical energy absorbing system comprising:
 placing a femoral base having a bone contacting surface against the femur;   inserting a K-wire through a K-wire opening in the femoral base to hold the base in place on the femur;   inserting a compression screw through a corresponding opening formed in the base;   inserting a plurality of locking screws in threaded openings formed in the base and engaging threaded heads of the locking screws with the threaded openings, wherein the K-wire opening has an axis parallel to an axis of the compression screw opening.   
     
     
         13 . The method of  claim 12 , wherein the compression screw opening is a non-threaded opening and is the only non-threaded opening of the base. 
     
     
         14 . A kit for implantation of a mechanical energy absorbing system, the kit comprising:
 an absorber having first and second centers of rotation;   a plurality of femoral bases, each femoral base having substantially the same size and shape, while being rotated with respect to one another about the first center of rotation; and   a plurality of tibial bases, each tibial base having substantially the same size and shape, while being translated with respect to one another with respect to the second center of rotation.   
     
     
         15 . A set of femoral bases for a mechanical energy absorbing system, the set comprising:
 a set of three of femoral bases, each femoral base having substantially the same size and shape, while being rotated with respect to one another about a center of rotation.   
     
     
         16 . A method of selecting a femoral base of a mechanical energy absorbing system for implanting in a patient, the method comprising:
 providing a plurality of femoral bases having substantially the same size and shape, while being rotated with respect to one another about a center of rotation of the mechanical energy absorbing system; and   selecting one of the femoral bases from the plurality of femoral bases in order to locate the center of rotation of the mechanical energy absorbing system at a desired location with respect to a center of rotation of the knee joint and at a desired offset distance from the bone.   
     
     
         17 . The method of  claim 16 , wherein the desired offset distance is about 2 to 15 mm. 
     
     
         18 . A set of tibial bases a mechanical energy absorbing system, the set comprising:
 a set of three of tibial bases, each tibial base having substantially the same size and shape, while being translated with respect to one another such that a distance in a direction perpendicular to the bone between a mounting end of the bases and the bone contacting surfaces of the bases vary between the three bases of the set.   
     
     
         19 . A method of selecting a tibial base of a mechanical energy absorbing system for implanting in a patient, the method comprising:
 providing a plurality of tibial bases having substantially the same size and shape, while being translated with respect to a bone contacting surface; and   selecting one of the tibial bases from the plurality of tibial bases in order to locate the center of rotation of the mechanical energy absorbing system at a desired location with respect to the bone.   
     
     
         20 . A mechanical energy absorbing system, the system comprising:
 a femoral base configured for implantation on a medial aspect of the femur;   a tibial base configured for implantation on a medial aspect of the tibia;   an absorber configured to be connected to the femoral base and the tibial base in an position where the absorber is located in an absorber plane; and   wherein the bases are configured to receive the absorber in a position where the absorber plane is substantially parallel to a line connecting the medial aspects of the femoral and tibial condyles.   
     
     
         21 . The system of  claim 20 , wherein bases are configured to receive the absorber at a location offset from the line connecting the medial aspects of the femoral and tibial condyles by 2-15 mm.