Systems and methods for wrought nickel/titanium alloy flexible spinal rods

Abstract

Dynamic, flexible wrought Nickel/Titanium alloy spinal rods for spinal fusion or dynamic stabilization vertebral implants and methods and processes related to their manufacture. The dynamic and flexibility properties of the wrought Nickel/Titanium alloy spinal rod may be varied by altering processing parameters during manufacture that develop the shape memory characteristics, mechanical properties, and product workability characteristics to achieve custom manufacture of spinal rods having desired flexion in desired lengths. Such a custom manufactured spinal rod may be affixed to an inferior vertebral body at a standard lamina or pedicle location and to one superior vertebral body at a standard lamina or pedicle location using pedicle screws, lamina hooks, or pedicle hooks to provide dynamic stabilization between superior and inferior vertebrae in connection with a spinal fusion procedure.

1 . A process for manufacturing a dynamic and flexible spinal rod, the process comprising:
 shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which has been hot worked from about 0% to about 20% and cold worked from about 0% to about 60%, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes; and   subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and in for a time of from about 1 minute to about 120 minutes.   
   
   
       2 . The process of  claim 1 , wherein shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock comprises shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which contains less than about 54% Nickel. 
   
   
       3 . The process of  claim 1 , wherein shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which has been hot worked from about 0% to about 20% and cold worked from about 0% to about 60%, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes comprises shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which has been about 10% hot worked and about 5% cold worked, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes. 
   
   
       4 . The process of  claim 3 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment for a time of about 10 minutes at a temperature selected from the range of from about 250 deg. C. to about 800 deg. C. to result in a spinal fusion rod which has a selected rigidity of from about 0.8462 Kg/mm 2  to about 2.7501 Kg/mm 2 . 
   
   
       5 . The process of  claim 1 , wherein shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which has been hot worked from about 0% to about 20% and cold worked from about 0% to about 60%, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes comprises shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which has been about 10% hot worked and about 20% cold worked, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes. 
   
   
       6 . The process of  claim 5 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment for a time of about 10 minutes at a temperature selected from the range of from about 250 deg. C. to about 800 deg. C. to result in a spinal fusion rod which has a selected rigidity of from about 1.8462 Kg/mm 2  to about 5.7501 Kg/mm 2 . 
   
   
       7 . The process of  claim 1 , wherein shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which has been hot worked from about 0% to about 20% and cold worked from about 0% to about 60%, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes comprises shaping a cylinder as a blank for a rod suitable for a spinal fusion procedure from a Nitinol alloy stock which has been about 10% hot worked and about 40% cold worked, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes. 
   
   
       8 . The process of  claim 7 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment for a time of about 10 minutes at a temperature selected from the range of from about 250 deg. C. to about 800 deg. C. to result in a spinal fusion rod which has a selected rigidity of from about 5.8462 Kg/mm 2  to about 20.7501 Kg/mm 2 . 
   
   
       9 . The process of  claim 7 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment at a temperature of about 400 deg. C. for a time selected from the range of from about 1 minute to about 120 minutes to result in a spinal fusion rod which has a selected rigidity of from about 8.8078 Kg/mm 2  to about 22.692 Kg/mm 2 . 
   
   
       10 . A method of producing a dynamic flexible wrought Nickel/Titanium alloy rod for a spinal fusion procedure, the method comprising:
 selecting a desired amount of flexibility required in the rod;   selecting a Nitinol alloy stock for forming the rod, the Nitinol alloy stock comprising a blank which has been hot worked from about 0% to about 20% and cold worked from about 0% to about 60%, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes;   shaping a cylinder as a blank for the rod from the selected Nitinol alloy stock; and   subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and in for a time of from about 1 minute to about 120 minutes.   
   
   
       11 . The method of  claim 10 , wherein selecting a Nitinol alloy stock for forming the rod comprises selecting a Nitinol alloy stock which contains less than about 54% Nickel. 
   
   
       12 . The method of  claim 10 , wherein selecting a desired amount of flexibility comprises selecting a flexibility for promoting formation of a spinal fusion mass based on the particular characteristics of a patient needing a spinal fusion procedure. 
   
   
       13 . The method of  claim 10 , wherein selecting a Nitinol alloy stock for forming the rod comprises selecting a Nitinol alloy which has been about 10% hot worked and about 5% cold worked, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes. 
   
   
       14 . The method of  claim 13 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment for a time of about 10 minutes at a temperature selected from the range of from about 250 deg. C. to about 800 deg. C. to result in a spinal fusion rod which has a selected rigidity of from about 0.8462 Kg/mm 2  to about 2.7501 Kg/mm 2 . 
   
   
       15 . The method of  claim 10 , wherein selecting a Nitinol alloy stock for forming the rod comprises selecting a Nitinol alloy stock which has been about 10% hot worked and about 20% cold worked, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes. 
   
   
       16 . The method of  claim 15 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment for a time of about 10 minutes at a temperature selected from the range of from about 250 deg. C. to about 800 deg. C. to result in a spinal fusion rod which has a selected rigidity of from about 1.8462 Kg/mm 2  to about 5.7501 Kg/mm 2 . 
   
   
       17 . The method of  claim 10 , wherein selecting a Nitinol alloy stock for forming the rod comprises selecting a Nitinol alloy stock which has been about 10% hot worked and about 40% cold worked, and annealed at a temperature of about 800 deg. C. for a time of about 10 minutes. 
   
   
       18 . The method of  claim 17 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment for a time of about 10 minutes at a temperature selected from the range of from about 250 deg. C. to about 800 deg. C. to result in a spinal fusion rod which has a selected rigidity of from about 5.8462 Kg/mm 2  to about 20.7501 Kg/mm 2 . 
   
   
       19 . The method of  claim 17 , wherein subjecting the shaped blank to a shape setting heat treatment at a temperature of from about 250 deg. C. to about 800 deg. C. and for a time of from about 1 minute to about 120 minutes comprises subjecting the shaped blank to a shape setting heat treatment at a temperature of about 400 deg. C. for a time selected from the range of from about 1 minute to about 120 minutes to result in a spinal fusion rod which has a selected rigidity of from about 8.8078 Kg/mm 2  to about 22.692 Kg/mm 2 .