Devices and methods using an expandable body with internal restraint for compressing cancellous bone

Abstract

Devices and methods compress cancellous bone. In one arrangement, the devices and methods make use of an expandable body that includes an internal restraint coupled to the body. The internal restraint directs expansion of the body. In one arrangement, a method for treating bone inserts the device having the internal restraint inside bone and causes directed expansion of the body in cancellous bone. Cancellous bone is compacted by the directed expansion.

What is claimed is:  
     
         1 . A device for compressing cancellous bone comprising: 
 an expandable body including an internal restraint coupled to the body which directs expansion of the body.    
     
     
         2 . A device according to  claim 1   wherein the internal restraint includes an internal membrane.    
     
     
         3 . A device according to  claim 1   wherein the expandable body includes an elongated axis,    and    wherein the internal restraint includes an internal membrane that extends transversely of the elongated axis between opposing interior side surfaces of the expandable structure.    
     
     
         4 . A device according to  claim 1   wherein the expandable body includes an elongated axis,    and    wherein the internal restraint includes an internal membrane that extends along the elongated axis between opposing end surfaces of the expandable structure.    
     
     
         5 . A device according to  claim 1   wherein the expandable body includes an elongated axis,    and    wherein the internal restraint includes an internal membrane that extends in one direction along the elongated axis between opposing end surfaces of the expandable structure and in a second direction transversely of the elongated axis between opposing interior side surfaces of the expandable structure.    
     
     
         6 . A device according to  claim 1   wherein the internal restraint directs expansion of the expandable body more in one direction than in another direction transverse the one direction.    
     
     
         7 . A device according to  claim 1   wherein the expandable body includes an elongated axis,    wherein the internal restraint constrains expansion of the expandable body along the elongated axis.    
     
     
         8 . A device according to  claim 1   wherein the expandable body includes an elongated axis,    wherein the internal restraint directs expansion of the expandable body more in one radial direction from the elongated axis than in a second radial direction from the elongated axis.    
     
     
         9 . A device according to  claim 8   wherein the internal restraint constrains expansion of the expandable body along the elongated axis.    
     
     
         10 . A method for treating bone comprising the steps of 
 inserting a device as defined in  claim 1  inside bone,    causing directed expansion of the body in cancellous bone, and    compacting cancellous bone by the directed expansion.    
     
     
         11 . A method according to  claim 10   wherein the directed expansion lifts vertebral end plates.    
     
     
         12 . A method according to  claim 10   wherein the directed expansion lifts tibial plateau depressions.    
     
     
         13 . A method according to  claim 10   wherein the directed expansion lifts proximal humerus depressions.    
     
     
         14 . A method according to  claim 10   wherein the directed expansion lifts cortical bone.    
     
     
         15 . A method according to  claim 10   wherein the step of compacting forms a cavity.    
     
     
         16 . A method according to  claim 15   further including the step of filling the cavity with a material.    
     
     
         17 . A method according to  claim 16   wherein the material comprises bone cement.    
     
     
         18 . A method according to  claim 16   wherein the material comprises synthetic bone substitute.    
     
     
         19 . A method according to  claim 16   wherein the material comprises a flowable material that sets to a hardened condition.    
     
     
         20 . A device for compacting cancellous bone comprising a body adapted to be inserted into bone and undergo expansion in cancellous bone to compact cancellous bone, the body including material that, during the expansion in cancellous bone, applies a force capable of moving fractured cortical bone, and further includes an interior membrane to constrain the expansion in cancellous bone.  
     
     
         21 . A device according to  claim 20   wherein the expandable body includes an elongated axis,    and    wherein the internal membrane extends transversely of the elongated axis between opposing interior side surfaces of the expandable structure.    
     
     
         22 . A device according to  claim 20   wherein the expandable body includes an elongated axis,    and    wherein the internal membrane extends along the elongated axis between opposing end surfaces of the expandable structure.    
     
     
         23 . A device according to  claim 20   wherein the expandable body includes an elongated axis,    and    wherein the internal membrane extends in one direction along the elongated axis between opposing end surfaces of the expandable structure and in a second direction transversely of the elongated axis between opposing interior side surfaces of the expandable structure.    
     
     
         24 . A device according to  claim 20   wherein the internal membrane constrains expansion of the expandable body more in one direction than in another direction transverse the one direction.    
     
     
         25 . A device according to  claim 20   wherein the expandable body includes an elongated axis,    wherein the internal membrane constrains expansion of the expandable body along the elongated axis.    
     
     
         26 . A device according to  claim 20   wherein the expandable body includes an elongated axis,    wherein the internal membrane constrains expansion of the expandable body more in one radial direction from the elongated axis than in a second radial direction from the elongated axis.    
     
     
         27 . A device according to  claim 26   wherein the internal membrane constrains expansion of the expandable body along the elongated axis.    
     
     
         28 . A method for treating bone comprising the steps of 
 inserting a device as defined in  claim 20  inside bone,    causing constrained expansion of the body in cancellous bone, and    compacting cancellous bone by the constrained expansion.    
     
     
         29 . A method according to  claim 28   wherein the constrained expansion lifts vertebral end plates.    
     
     
         30 . A method according to  claim 28   wherein the constrained expansion lifts tibial plateau depressions.    
     
     
         31 . A method according to  claim 28   wherein the constrained expansion lifts proximal humerus depressions.    
     
     
         32 . A method according to  claim 28   wherein the constrained expansion lifts cortical bone.    
     
     
         33 . A method according to  claim 28   wherein the step of compacting forms a cavity.    
     
     
         34 . A method according to  claim 33   further including the step of filling the cavity with a material.    
     
     
         35 . A method according to  claim 33   wherein the material comprises bone cement.    
     
     
         36 . A method according to  claim 33   wherein the material comprises synthetic bone substitute.    
     
     
         37 . A method according to  claim 33   wherein the material comprises a flowable material that sets to a hardened condition.