Surgical cutting accessory with nickel titanium alloy cutting head

Abstract

A cutting accessory ( 20 ) for use with powered surgical tools. The cutting accessory has a hub ( 28 ) for coupling the accessory to the output shaft of a handpiece. A drive shaft ( 26 ) formed of stainless steel or other relatively rigid material extends forward from the hub. A head ( 30 ) formed from nickel titanium alloy or other metal that is more flexible than the material forming the drive shaft is attached to the distal end of the drive shaft. The head is shaped to form the cutting edges of the cutting accessory. In some versions of the invention, intermediate sections ( 60 ) of the drive shaft are formed from the flexible metal or metal alloy.

1 . A surgical cutting accessory, said cutting accessory comprising: 
 a drive shaft having opposed proximal and distal ends, said drive shaft being formed from a metal or metal alloy that has a first degree of flexibility;    a first hub integral with the proximal end of said drive shaft, said first hub being shaped to couple said drive shaft to a motor; and    a head attached to the distal end of said drive shaft to rotate in unison with said drive shaft, said head having a tip that is shaped to have at least one cutting edge, said head being formed from a metal or metal alloy that has a second degree of flexibility, the second degree of flexibility being greater than the first degree of flexibility.    
   
   
       2 . The surgical cutting accessory of  claim 1 , wherein: 
 said drive shaft has a tubular shape so as to have a hollow space and is formed with a window adjacent the distal end of said drive shaft; and    said first hub is shaped to have an opening that is in communication with the hollow space within said drive shaft.    
   
   
       3 . The surgical cutting accessory of  claim 1 , wherein said head is formed to have a solid stem that is secured to said drive shaft.  
   
   
       4 . The surgical cutting accessory of  claim 1 , wherein said head is formed so that the portion of said head that extends from said drive shaft to said head has a constant diameter and said tip has a diameter less than the diameter of the constant diameter portion.  
   
   
       5 . The surgical cutting accessory of  claim 1 , further including: 
 an outer tube disposed over said drive shaft, said outer tube having opposed distal and proximal ends; and    a second hub attached to the proximal end of said outer tube.    
   
   
       6 . The surgical cutting accessory of  claim 1 , wherein: 
 said drive shaft is formed from a metal or metal alloy that, if exposed to 1% or more strain, experiences plastic deformation; and    said head is formed from a metal or metal alloy that, when exposed to at least 3% strain, will retain the initial shape of said head.    
   
   
       7 . The surgical cutting accessory of  claim 1 , wherein: 
 said drive shaft is formed from a metal or metal alloy that, if exposed to 1% or more strain, experiences plastic deformation; and    said head is formed from a metal or metal alloy that, when exposed to at least 5% strain, will retain the initial shape of said head.    
   
   
       8 . The surgical cutting accessory of  claim 1 , wherein said head is formed from a nickel titanium alloy.  
   
   
       9 . A cutting accessory, said cutting accessory comprising: 
 a first hub shaped to engage a motor;    an accessory drive shaft that is attached to said first hub to rotate in unison with said first hub, said drive shaft extending forward from said first shaft and having a distal end that is spaced from said first hub, wherein said drive shaft is formed from steel, the steel having a first degree of flexibility; and    a head, said head having a stem that is attached to and extends from the distal end of said drive shaft and secured to said drive shaft to rotate in unison with said drive shaft and a tip located forward of said drive shaft, said tip formed with at least one cutting edge, wherein said head is formed from a metal or metal alloy that has a second degree of flexibility, the second degree of flexibility being greater than the first degree of flexibility.    
   
   
       10 . The surgical cutting accessory of  claim 9 , wherein: 
 said drive shaft has a hollow tubular shape and is formed with a window adjacent the distal end of said drive shaft;    said first hub is shaped to have an opening that is in communication with the hollow space within said drive shaft; and    said stem of said head is secured to said drive shaft at a location distal from where the window is formed in said drive shaft.    
   
   
       11 . The surgical cutting accessory of  claim 9 , wherein said head is formed so that said stem has a constant diameter and said tip has a diameter less than the diameter of said stem.  
   
   
       12 . The surgical cutting accessory of  claim 9 , wherein: 
 said drive shaft is a tubular shaft with a hollow center space and is shaped to have a main section with a first constant diameter that extends distally from said first hub, a tapered section with decreasing diameter located at a distal end of said main section, a window formed at least partially in said tapered section, and a neck that extends forward from said tapered section;    said first hub is formed with an opening that is in communication with the hollow space of said drive shaft; and    said stem of said head is fitted in said neck of said drive shaft.    
   
   
       13 . The surgical cutting accessory of  claim 9 , wherein: 
 the steel from which said drive shaft is formed from a metal or metal alloy that, if exposed to 1% or more strain, experiences plastic deformation; and    said head is formed from a metal or metal alloy that, when exposed to at least 3% strain, will retain the initial shape of said head.    
   
   
       14 . The surgical cutting accessory of  claim 9 , wherein said head is formed from a nickel titanium alloy.  
   
   
       15 . A cutting accessory, said accessory comprising: 
 a first hub, said first hub shaped to interlock with the output coupling of a motor to rotate in unison with the output coupling, said first hub shaped to have an opening;    a drive shaft formed of steel and having a hollow tubular shape that is secured to said first hub to rotate in unison with said first hub, said drive shaft shaped to have a main section with a first constant diameter, a tapered section at a distal end of said main section of decreasing diameter, a neck at the distal end of said tapered section that has a second diameter less than the first diameter wherein said drive shaft has a center space that is in communication with the opening of said hub and is further formed to have a window that is at least partially located in said tapered section wherein, the steel forming said drive shaft has a first degree of flexibility; and    a cutting head formed from a metal or metal alloy, said cutting head having: a stem that is secured in said neck of said drive shaft so that said cutting head rotates in unison with said drive shaft; and a tip located at the distal end of said cutting head, said tip shaped to form at least one cutting edge wherein, the metal or metal alloy from which said cutting head is formed has a second degree of flexibility, the second degree of flexibility being greater than the first degree of flexibility.    
   
   
       16 . The cutting accessory of  claim 15 , wherein the portion of said stem of said cutting head that extends from said drive shaft to said tip has a diameter and said tip has an outer diameter less than the diameter of the constant diameter portion of said drive shaft.  
   
   
       17 . The cutting accessory of  claim 15 , wherein the portion of said stem of said cutting head that extends from said drive shaft to said tip has a constant diameter.  
   
   
       18 . The cutting accessory of  claim 15 , further including: 
 an outer tube disposed over said drive shaft, said outer tube having opposed distal and proximal ends; and    a second hub attached to the proximal end of said outer tube.    
   
   
       19 . The cutting accessory of  claim 18 , wherein said outer tube is attached to said second hub so that said outer tube is able to move longitudinally relative to said second hub.  
   
   
       20 . The surgical cutting accessory of  claim 15 , wherein: 
 the steel from which said drive shaft is formed from a metal or metal alloy that, if exposed to 1% or more strain, experiences plastic deformation; and    said head is formed from a metal or metal alloy that, when exposed to at least 3% strain, will retain the initial shape of said head.    
   
   
       21 - 29 . (canceled)