Hammertoe implant

Abstract

The invention comprises an implant having a first end section and a second end section, where the first end has a cancellous thread for implantation in a first section of bone and the second end includes expansion slots and barbs or wings, that that resist movement out of a second section of bone. These anchors expand outwardly when a rigid wire, such as a k-wire is fed through a central cannulation in the implant and either the wire expands in diameter or the cannulation decreases in diameter. The implant also includes a collar intermediate to the first and second section which includes one or more surfaces to allow the first section to be screwed into a first bone section.

What is claimed is: 
     
         1 . An implant comprising:
 a longitudinal axis and a first end section having an external thread, and an integral second end section, the second end section having a base having at least one anchoring means comprising a radially and longitudinally extending surface which increases in diameter in a direction toward the first end section and the implant has a central cannulation along the longitudinal axis.   
     
     
         2 . An implant as set forth in  claim 1 , wherein the first end section further includes a collar having flat surfaces. 
     
     
         3 . An implant as set forth in  claim 2 , wherein the at least one anchoring means is radially symmetrical. 
     
     
         4 . An implant as set forth in  claim 3 , wherein the cylindrical base of the second section includes at least two radial expansion slots which are positioned radially symmetrically about the longitudinal axis of the second section whereby the at least one anchoring means thereby has fingers which can flex radially. 
     
     
         5 . An implant as set forth in  claim 4 , wherein the cannulation in the second end section includes a restriction in the diameter of the cannulation whereby the anchoring means flex radially outward in response to a guide wire being driven through the restriction. 
     
     
         6 . An implant as set forth in  claim 5 , wherein the second end section forms an angle of 5° to 25° degrees with respect to the first end section. 
     
     
         7 . An implant as set forth in  claim 5 , wherein the cannulation has a length and a diameter which is constant along the longitudinal axis. 
     
     
         8 . An implant as set forth in  claim 7 , wherein the anchoring means are formed as a plurality of conical collars that include at least one split. 
     
     
         9 . An implant as set forth in  claim 1 , wherein there are at least two longitudinally spaced conical collars. 
     
     
         10 . An implant as set forth in  claim 9 , wherein there are from one to three longitudinally spaced conical collars. 
     
     
         11 . The implant as set forth in  claim 1 , wherein the at least one anchoring means are selected from the group consisting of barbs, ratchets, edges and inverted wings. 
     
     
         12 . The implant as set forth in  claim 1 , wherein the second end section is adapted to be inserted into a pre-drilled hole. 
     
     
         13 . The implant as set forth in  claim 2 , wherein the collar is conical. 
     
     
         14 . An implant comprising a longitudinal axis and having a first end section and a second, opposing end section, wherein the first end has a cancellous thread and the second end has a radially extending conical collar forming barbs or shoulders that include an inverted surface. 
     
     
         15 . The implant of  claim 14 , wherein the inverted surface is provided so as to resist movement out of a second section of bone. 
     
     
         16 . The implant of  claim 14 , wherein the inverted surface forms an angle equal to or less than 90° degrees with the longitudinal axis in a direction toward the first end of the implant. 
     
     
         17 . The implant of  claim 14 , further including a cannulation co-axial with the longitudinal axis. 
     
     
         18 . The implant of  claim 14 , wherein the second end section includes one or more radial expansion slots parallel to the longitudinal axis. 
     
     
         19 . The implant of  claim 14 , wherein the second end section includes a radial activation mechanism. 
     
     
         20 . The implant of  claim 19 , wherein at least one radially extending conical collar is located distal to an end of the radial expansion slots.