Sonic screw

Abstract

A screw for fixation of, for example, a fracture having a hollow shaft, a first outer thread and radial openings at its distal end, and a second outer thread and an inner engagement portion at its proximal end. The second outer thread is adapted to engage with a tissue protection sleeve. The inner engagement portion is adapted to fit to a driving end of a driving tool. By way of this, forces in axial or radial direction may be applied to the screw by the sleeve, and forces in rotational direction may be applied by the driving tool. Therefore, the screw can be installed accurately at the intended site in an object.

1 . A screw for fixation of a fracture comprising:
 a shaft having a distal end, a proximal end, and a central axis;   a through bore extending along the central axis of the shaft;   a first outer thread located at the distal end;   a radially outwardly extending collar mounted on the shaft adjacent the shaft having the proximal end;   a second outer thread formed on the collar; and   an inner tool engagement portion at the proximal end.   
     
     
         2 . The screw according to  claim 1 , wherein an outer diameter of the second outer thread is greater as an outer diameter of the shaft, the collar forming a smooth transition between the shaft and the second outer thread. 
     
     
         3 . The screw according to  claim 1 , wherein the inner tool engagement portion is formed to fit with a hexagonal or torx screw driver. 
     
     
         4 . The screw according to  claim 1 , wherein a step in the inner diameter of the through bore is formed adjacent the distal end of the shaft, so that a polymer pin inserted into the through bore of the shaft can be supported by the step. 
     
     
         5 . The screw according to  claim 1 , wherein the screw further comprises a radial opening at the distal end of the screw. 
     
     
         6 . The screw as set forth in  claim 1  wherein a surface of the collar facing the distal end is part-spherical in shape. 
     
     
         7 . A system for installation of a screw comprising:
 a screw having a distal end, a proximal end, and a central axis;   a driving tool adapted to engage with the inner tool engagement portion of the screw; and   a hollow tissue protection sleeve adapted to engage with the second outer thread of the screw, and adapted to partially accommodate the driving tool.   
     
     
         8 . The system as set forth in  claim 7  wherein the screw includes a radially outwardly extending collar located adjacent the proximal end of the screw, the collar having the second outer thread of the screw thereon. 
     
     
         9 . The system according to  claim 7 , further comprising a polymer pin made of fluidizable material, adapted to be inserted into the axial through bore of the screw, and
 an augmentation tool including a sonotrode for fluidizing the polymer material of the polymer pin, wherein the augmentation tool is adapted to be coupled with the proximal end of the tissue protection sleeve.   
     
     
         10 . A method of installation of a screw comprising:
 a screw comprising a shaft having a distal end, a proximal end, and a central axis, a through bore extending along the central axis of the shaft, a first outer thread located at the distal end, a radially outwardly extending collar mounted on the shaft adjacent the shaft having the proximal end, a second outer thread formed on the collar, an inner tool engagement portion at the proximal end;   coupling a tissue protection sleeve to the outer thread on the collar at a proximal end of the screw;   engaging with a driving end of a driving tool into the inner engagement portion at the proximal end of the screw; and   installing the screw in an object.   
     
     
         11 . The method according to  claim 10 , further comprising:
 removing the driving tool;   inserting a polymer pin in the axial through bore of the screw;   positioning a sonotrode of an augmentation tool at the proximal end of the polymer pin;   fluidizing the material of the polymer pin;   pressing the fluidized material out of the screw to augment the screw in the object; and   removing the augmentation tool as well as the tissue protection sleeve.   
     
     
         12 . The method of  claim 10  further comprising rotating the screw and tissue protection sleeve about an axis transverse to the central axis after the screw is installed.