Torque limiting device

Abstract

Torque limiting devices, tools comprising torque limiting devices and methods for using torque limiting devices are disclosed. In an embodiment, a torque limiting device comprises a first and a second surface disposed in substantially adjacent parallel planar relationship such that within a predetermined torque range the first and second surface rotate together such than a torque applied to the first surface is translated to the second surface. When the torque applied exceeds a certain critical torque, the first and second surfaces slip and therefore the excessive torque is not transferred.

1 . A surgical device comprising: 
 a rod having a first end and a second end;    a surgical implement attached to the first end of the rod;    a handle positioned near the second end of the rod;    a first surface attached to the rod; and    a second surface attached to the handle, the second surface in frictional contact with the first surface such that a rotation of the handle causes a rotation of the rod,    wherein when the rotation of the handle exceeds a maximum torque, the second surface disengages from the first surface, so that the rotation of the handle does not cause rotation of the rod.    
     
     
         2 . The surgical device of  claim 1  further comprising a housing attached to the handle.  
     
     
         3 . The surgical device of  claim 2 , wherein the housing defines a cavity within which the first and second surfaces are positioned.  
     
     
         4 . The surgical device of  claim 2 , wherein the first surface comprises a first plate having a notch and the second surface comprises a second plate having a tooth.  
     
     
         5 . The surgical device of  claim 4 , wherein the notch and the tooth are substantially the same size and shape.  
     
     
         6 . The surgical device of  claim 4  further comprising a compression spring disposed between the housing and the second surface, the spring exerting a force on the second surface to engage the tooth with the notch.  
     
     
         7 . The surgical device of  claim 4 , the housing further comprising a support that substantially prevents movement of the first surface in one direction along an axis of the rod.  
     
     
         8 . The surgical device of  claim 2 , wherein the first surface comprises a disk having a depression and the second surface comprises a ball of a ball plunger.  
     
     
         9 . The surgical device of  claim 8 , wherein the depression and the ball are substantially the same size and shape.  
     
     
         10 . A surgical device comprising: 
 a rod comprising a first section and a second section, the first section rotatably connected to the second section;    an implement attached to the first section of the rod;    a handle attached to the second section of the rod;    a first plate attached to the first section of the rod, the first plate having a depression;    a second plate attached to the second section of the rod, the second plate raised portion of substantially the same size and shape as the depression of the first plate;    a housing that defines a cavity, the first plate and second plate fitting inside the cavity and the first plate restrained within the housing by a ledge; and    a compression spring disposed between a cap of the housing and a surface of the second plate such that the spring pushes the second plate longitudinally away from the cap of the housing,    wherein the raised portion of the second plate engages with the depression of the first plate when the raised portion and the depression are aligned, so that a rotation of the second section of the rod causes a rotation of the first section of the rod, and    wherein when the rotation of the second section of the rod exceeds a maximum torque, the spring compresses and the raised portion of the second plate disengages from the depression of the first plate, so that the rotation of the second section does not cause rotation of the first section.    
     
     
         11 . The surgical device of  claim 10 , the rod comprising a cylindrical tube.  
     
     
         12 . The surgical device of  claim 11  further comprising an actuator disposed within the rod and operable to activate the implement.  
     
     
         13 . The surgical device of  claim 12  further comprising a trigger positioned on the handle operable to control the actuator.  
     
     
         14 . A surgical device comprising: 
 a rod;    a surgical implement attached to a first end of the rod;    a handle positioned near a second end of the rod;    a ball plunger attached to the handle, the ball plunger comprising a ball housed in a cylinder and pushed longitudinally by a spring contained within the cylinder; and    a disk attached to the rod, the disk having a depression of substantially the same size and shape as the ball of the ball plunger,    wherein the ball of the ball plunger may fit into the depression of the disk so that a rotation of the handle causes rotation of the rod, and    wherein when the rotation of the handle exceeds a maximum torque, the spring of the ball plunger compresses and the ball of the ball plunger rises out of the depression of the disk, so that the rotation of the handle does not cause rotation of the rod.    
     
     
         15 . The surgical device of  claim 14  further comprising a housing attached to the handle and the ball plunger, the housing defining a cavity in which the disk and ball plunger are positioned.  
     
     
         16 . The surgical device of  claim 15 , the cavity having a substantially cylindrical shape and a diameter.  
     
     
         17 . The surgical device of  claim 16 , wherein the disk has a diameter and the diameter of the cavity is between 0 and 10 millimeters larger than the diameter of the disk.  
     
     
         18 . The surgical device of  claim 14 , the handle having a cavity for receiving the second end of the rod.  
     
     
         19 . The surgical device of  claim 15 , the housing comprising a means for limiting a longitudinal movement of the rod.  
     
     
         20 . A method for using a surgical tool having a torque limiting device comprising the steps of: 
 inserting a surgical tool having a rod, a surgical implement, and a handle into a body;    positioning the surgical implement at a desired location within the body;    applying a torque to the handle;    reengaging the tool after an excessive torque is applied to the handle.    
     
     
         21 . The method of  claim 20 , wherein the surgical tool further comprises a first surface and a second surface in frictional contact with the second surface, and wherein the step of reengaging the tool comprises realigning the first surface with the second surface.