Intermedullary devices for generating and applying compression within a body

Abstract

An intramedullary device includes a central bridge region having a first end and a second end. The intramedullary device also includes a bone engaging feature at both the first end and the second end. At least one of the bone engaging features includes a first barb and a second barb which, in an unbiased condition, flare outwardly from a longitudinal axis of the central bridge region and which are capable of being elastically constrained to a constrained condition such that the first end of the central bridge region may be advanced into a hole in a first bone fragment when the first barb and second barb are elastically constrained. The first barb and second barb are prevented from being withdrawn from the hole in the first bone fragment when the first barb and the second barb are not constrained. The intramedullary device i) is cannulated, ii) generates a compressive load, and iii) comprises nitinol.

What is claimed is: 
     
         1 . An intramedullary device comprising:
 a) a central bridge region having a first end and a second end, wherein the central bridge region is cylindrical; and   b) a bone engaging feature at both the first end and the second end, wherein at least one bone engaging feature comprises a first barb and a second barb which, in an unbiased condition, flare outwardly from a longitudinal axis of the central bridge region and which are capable of being elastically constrained to a constrained condition such that the first end of the central bridge region may be advanced into a hole in a first bone fragment when the first barb and second barb are elastically constrained, and the first barb and second barb are prevented from being withdrawn from the hole in the first bone fragment when the first barb and the second barb are not constrained,   wherein the first barb and the second barb of the at least one bone engaging feature combine to form a substantially continuous extension of the central bridge region when the first barb and the second barb are elastically constrained,   wherein movement of the first barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a first plane, and movement of the second barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a second plane, and the first plane intersects the second plane, and   wherein the device i) is cannulated, ii) generates a compressive load, and iii) comprises nitinol.   
     
     
         2 . An intramedullary device comprising:
 a) a central bridge region having a first end and a second end; and   b) a bone engaging feature at both the first end and the second end, wherein at least one bone engaging feature comprises a first barb and a second barb which, in an unbiased condition, flare outwardly from a longitudinal axis of the central bridge region and which are capable of being elastically constrained to a constrained condition such that the first end of the central bridge region may be advanced into a hole in a first bone fragment when the first barb and second barb are elastically constrained, and the first barb and second barb are prevented from being withdrawn from the hole in the first bone fragment when the first barb and the second barb are not constrained;   wherein the device i) is cannulated, ii) generates a compressive load, and iii) comprises nitinol.   
     
     
         3 . The intramedullary device according to  claim 2  wherein the central bridge region is cylindrical. 
     
     
         4 . The intramedullary device according to  claim 2  wherein the central bridge region is malleable. 
     
     
         5 . The intramedullary device according to  claim 4  wherein movement of the first barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a first plane, and movement of the second barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a second plane. 
     
     
         6 . The intramedullary device according to  claim 5  wherein the first plane intersects the second plane. 
     
     
         7 . The intramedullary device according to  claim 4  wherein the at least one bone engaging feature includes a third barb. 
     
     
         8 . The intramedullary device according to  claim 7  wherein movement of the first barb and the third barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a first plane, and movement of the second barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a second plane. 
     
     
         9 . The intramedullary device according to  claim 8  wherein the first plane intersects the second plane. 
     
     
         10 . The intramedullary device according to  claim 4  wherein the at least one bone engaging feature includes a fourth barb. 
     
     
         11 . The intramedullary device according to  claim 10  wherein movement of the first barb and the third barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a first plane, and movement of the second barb and the fourth barb of the at least one bone engaging feature from the constrained condition to the unbiased condition occurs within a second plane. 
     
     
         12 . The intramedullary device according to  claim 11  wherein the first plane intersects the second plane. 
     
     
         13 . The intramedullary device according to  claim 12  wherein the first plane is perpendicular to the second plane. 
     
     
         14 . The intramedullary device according to  claim 2  wherein the at least one bone engaging feature is laterally aligned the longitudinal axis of the central bridge region. 
     
     
         15 . The intramedullary device according to  claim 2  wherein the at least one bone engaging feature is laterally offset from the longitudinal axis of the central bridge region. 
     
     
         16 . The intramedullary device according to  claim 2  wherein the first barb and the second barb of the at least one bone engaging feature combine to form a substantially continuous extension of the central bridge region when the first barb and the second barb are elastically constrained. 
     
     
         17 . The intramedullary device according to  claim 2  including a removable retaining tab for elastically constraining the first barb and the second barb of the at least one bone engaging feature, wherein the removable retaining tab slides relative to the longitudinal axis of the intramedullary device to allow the first barb and the second barb of the at least one bone engaging feature to move from the constrained condition to the unbiased condition. 
     
     
         18 . The intramedullary device according to  claim 17  wherein the first removable retaining tab and the second removable retaining tab are separately detachable from the intramedullary device. 
     
     
         19 . The intramedullary device according to  claim 2  wherein an end of at least one of the first barb and the second barb of the at least one bone engaging feature includes an edge.