Method, Implant & Instruments for Percutaneous Expansion of the Spinal Canal

Abstract

A method for correcting spinal stenosis involves cannulating a passage in a vertebra, and placing a distal portion of an implant therein. Then, a circumferential vertebral cut is performed from within the passage, using a proximal end of the distal portion of the implant to align the vertebral cut. Then, a proximal portion of the implant is placed into the passage, positioned against the distal portion at the vertebral cut. Operation of the distal and the proximal portions of the implant relative to one another widens the vertebral cut and expands the spinal canal. The proximal portion can then be secured to the distal portion to stabilize the vertebral cut, allowing vertebral healing with the spinal canal expanded. Flanges may exist that radially extend outward from the implant and into the vertebral cut, or into the passage walls, to assist vertebral cut widening and stabilization.

1 . A method for expanding a spinal canal, comprising the steps of
 creating at least one passage into a vertebra;   placing a distal portion of an implant into the passage;   performing a circumferential vertebral cut from within the passage, through to the spinal canal and through to an outside of the vertebra, using a proximal end of the distal portion of the implant to align the vertebral cut;   placing a proximal portion of the implant into the passage, positioning a distal end of the proximal portion of the implant against the proximal end of the distal portion of the implant at the vertebral cut; and   operating the distal and the proximal portions of the implant relative to one another to widen the vertebral cut and expand the spinal canal.   
   
   
       2 . The method of  claim 1 , further comprising the step of:
 securing the proximal portion of the implant to the distal portion of the implant to stabilize the vertebral cut, whereby the vertebra heals with the spinal canal expanded.   
   
   
       3 . The method of  claim 1 , wherein the at least one passage and the vertebral cut extend through a pedicle of the vertebra, and where widening the vertebral cut elongates the pedicle, thereby increasing an area of the spinal canal. 
   
   
       4 . The method of  claim 1 , wherein the vertebral cut is located in a lumbar vertebra. 
   
   
       5 . The method of  claim 1 , further comprising a preliminary step of introducing a guide wire into the vertebra to guide a drilling of the at least one passage into the vertebra. 
   
   
       6 . The method of  claim 5 , wherein a cannulated drill is positioned over the guide wire to drill the at least one passage into the vertebra. 
   
   
       7 . The method of  claim 1 , wherein the at least one passage into the vertebra is located in the pedicle of the vertebra, the passage forming a hollow, cylindrical column within the pedicle. 
   
   
       8 . The method of  claim 1 , wherein, during operation of the distal and the proximal portions of the implant, at least one flange radially extends outward from the implant and into the vertebral cut, assisting the widening of the vertebral cut and a stabilization of the vertebral cut. 
   
   
       9 . The method of  claim 1 , wherein, during operation of the distal and the proximal portions of the implant, at least one flange radially extends outward from the implant and into the passage to engage side walls of the passage, thereby facilitating stabilization of the implant within the passage. 
   
   
       10 . The method of  claim 1 , wherein the distal and the proximal portions of the implant include external threads, and are threadably introduced into the passage to engage side walls of the passage. 
   
   
       11 . The method of  claim 1 , wherein:
 the proximal portion further includes a threaded device and an expanding device; and   the implant further includes a screw communicating with the threaded device and the expanding device, wherein operation of the screw moves the expanding device relative to the threaded device to increase a length of the proximal portion, the increasing length of the proximal portion, bearing against the distal portion, acts to widen a vertebral cut to expand the spinal canal.   
   
   
       12 . The method of  claim 1 , wherein the screw threadably engages an inner channel of the threaded device, and abuts a base of the expanding device, to translate the expanding device away from the threaded device, upon operation of the screw, to widen the vertebral cut. 
   
   
       13 . The method of  claim 1 , wherein the implant further includes a locking bolt configured for insertion through the proximal portion and into the distal portion, wherein engagement of the locking bolt with the proximal and the distal portions fastens the implant about the vertebral cut, whereby the vertebral cut is stabilized, allowing vertebral healing with the spinal canal expanded. 
   
   
       14 . The method of  claim 1 , wherein:
 the distal portion has inner threads;   the proximal portion has inner threads, wherein the inner threads of the distal portion are of a substantially different pitch than the inner threads of the proximal portion, creating a dual pitch configuration; and wherein:   the implant further includes a screw capable of communication with the distal and the proximal portions, the screw having:
 outer threads at a distal end substantially similar in pitch to the inner threads of the distal portion; and 
 outer threads at a proximal end substantially similar in pitch to the inner threads of the proximal portion; wherein 
 operation of the screw within the distal and the proximal portions translates the proximal portion relative to the distal portion, due to the dual pitch configuration, about a vertebral cut, to widen the vertebral cut and expand the spinal canal. 
   
   
   
       15 . An implant for expanding a spinal canal, comprising:
 a distal portion;   a proximal portion including a threaded device and an expanding device; and   a screw communicating with the threaded device and the expanding device, wherein operation of the screw moves the expanding device relative to the threaded device to increase a length of the proximal portion, the increasing length of the proximal portion, bearing against the distal portion, acts to widen a vertebral cut to expand the spinal canal.   
   
   
       16 . The implant of  claim 15 , further comprising a locking bolt configured for insertion through the proximal portion and into the distal portion, wherein engagement of the locking bolt with the proximal and the distal portions fastens the implant about the vertebral cut, whereby the vertebral cut is stabilized, allowing vertebral healing with the spinal canal expanded. 
   
   
       17 . The implant of  claim 16 , wherein the distal portion further comprises a floating nut movably housed therein, whereby the movable configuration of the floating nut within the distal portion facilitates acceptance of the locking bolt within the distal portion, after insertion through the proximal portion, even if a longitudinal central axis of the proximal and the distal portions becomes translationally malaligned during vertebral widening. 
   
   
       18 . The implant of  claim 15 , wherein the distal portion and the threaded device include external threads to engage a vertebra about each side of the vertebral cut, the distal portion engaging one side of the vertebral cut and the threaded device engaging another side of the vertebral cut. 
   
   
       19 . The implant of  claim 15 , wherein the screw threadably engages an inner channel of the threaded device, and abuts a base of the expanding device, to translate the expanding device away from the threaded device, upon operation of the screw, to widen the vertebral cut. 
   
   
       20 . The implant of  claim 15 , wherein the threaded device further comprises at least one flange configured to project radially from the proximal portion, into the vertebral cut, during operation of the screw. 
   
   
       21 . The implant of  claim 20 , wherein the at least one flange is movably attached to the threaded device, wherein operation of the screw causes the at least one flange to project radially from the proximal portion, into the vertebral cut, prior to a lengthening of the proximal portion to widen the vertebral cut. 
   
   
       22 . The implant of  claim 21 , wherein the at least one flange movably attached to the threaded device, upon radial projection into the vertebral cut, bears against a proximal side of the vertebral cut during vertebral widening. 
   
   
       23 . The implant of  claim 15 , wherein the expanding device further comprises at least one flange configured to project radially from the proximal portion, into the vertebral cut, during operation of the screw. 
   
   
       24 . The implant of  claim 23 , wherein the at least one flange is movably attached to the expanding device, wherein operation of the screw causes the at least one flange to project radially from the proximal portion, into the vertebral cut, prior to a lengthening of the proximal portion to widen the vertebral cut. 
   
   
       25 . The implant of  claim 24 , wherein the at least one flange movably attached to the expanding device, upon radial projection into the vertebral cut, bears against a distal side of the vertebral cut during vertebral widening. 
   
   
       26 . The implant of  claim 15 , further comprising:
 two flanges movably attached to the threaded device; and   two flanges movably attached to the expanding device, wherein;   the flanges are configured to project radially from the proximal portion, into the vertebral cut, during operation of the screw, prior to a lengthening of the proximal portion to widen the vertebral cut;   operation of the screw causes a distal end of the screw to bear against a respective distal end of each flange to radially extend each flange radially outward beyond an exterior of the proximal portion and into the vertebral cut,   the two flanges movably attached to the threaded device bear against a proximal side of the vertebral cut during the lengthening of the proximal portion; and   the two flanges movably attached to the expanding device bear against a distal side of the vertebral cut during the lengthening of the proximal portion.   
   
   
       27 . The implant of  claim 26 , wherein the flanges include osteoconductive, osteoinductive or osteogenic material to assist with healing of the vertebral cut. 
   
   
       28 . An implant for expanding a spinal canal, comprising:
 a distal portion having inner threads;   a proximal portion having inner threads, wherein the inner threads of the distal portion are of a substantially different pitch than the inner threads of the proximal portion, creating a dual pitch configuration; and   a screw capable of communication with the distal and the proximal portions, the screw having:
 outer threads at a distal end substantially similar in pitch to the inner threads of the distal portion; and 
 outer threads at a proximal end substantially similar in pitch to the inner threads of the proximal portion; wherein
 operation of the screw within the distal and the proximal portions translates the proximal portion relative to the distal portion, due to the dual pitch configuration, about a vertebral cut, to widen the vertebral cut and expand the spinal canal. 
 
   
   
   
       29 . The implant of  claim 28 , wherein the distal portion and the proximal portions each further comprise external threads to engage an interior of a passage within a vertebra, the outer threads of the distal portion engaging the interior of the passage on one side of the vertebral cut and the outer threads of the proximal portion engaging the interior of the passage on another side of the vertebral cut. 
   
   
       30 . The implant of  claim 28 , wherein the distal portion further comprises at least one flange movably attached thereto, configured to project radially from the distal portion, into an interior of a passage within a vertebra, to facilitate stabilization of the distal portion within the passage during operation of the screw and widening of the vertebral cut. 
   
   
       31 . The implant of  claim 30 , wherein insertion of the screw within the distal portion causes the at least one flange to project radially from the distal portion into the interior of the passage. 
   
   
       32 . The implant of  claim 28 , wherein the proximal portion further comprises at least one flange movably attached thereto, configured to project radially from the proximal portion, into an interior of a passage within a vertebra, to facilitate stabilization of the proximal portion within the passage during operation of the screw and widening of the vertebral cut. 
   
   
       33 . The implant of  claim 32 , wherein insertion of the screw within the proximal portion causes the at least one flange to project radially from the proximal portion into the interior of the passage. 
   
   
       34 . A bone saw, comprising:
 a flexible saw blade, rectangular in shape, having a central longitudinal axis and a cutting edge at a distal tip;   a shaft having:
 a central longitudinal axis; 
 a blade passage within the shaft that houses the saw blade, wherein the central longitudinal axis of the saw blade, of the shaft, and of the blade passage, are parallel; 
 a blade opening located at and through a distal end of the shaft and of the blade passage, the blade opening being essentially perpendicular to the longitudinal axis of the shaft; 
 a curved abutment within the blade passage, aligning the saw blade with the blade opening, wherein distally translating the saw blade within the blade passage causes the saw blade to conform to the curved abutment and exit the blade opening with the cutting edge essentially perpendicular to the longitudinal axis of the shaft. 
   
   
   
       35 . The bone saw of  claim 34 , further comprising a trunion at a distal tip of the shaft, the trunion located distal of the blade opening, the trunion facilitating placement of the distal tip of the shaft to precisely locate a desired blade opening location. 
   
   
       36 . The bone saw of  claim 34 , wherein:
 the saw blade further comprises a longitudinal groove along a side thereof;   the blade opening further comprises an indentor penetrating therein, the indentor positioned to align with the groove of the saw blade as the saw blade exits the blade opening, thereby facilitating desired perpendicular blade alignment upon exiting the blade opening.   
   
   
       37 . The bone saw of  claim 34 , further comprising an indentor penetrating into the blade opening, the indentor configured to introduce a crimp or counter bend to the flexible saw blade, thereby counteracting a curling of the saw blade during a passing of the saw blade through the curved abutment of the blade passage. 
   
   
       38 . The bone saw of  claim 34 , further comprising a threaded drive mechanism located at a proximal end of the shaft and communicating with the saw blade, wherein distally advancing the threaded drive mechanism distally translates the saw blade within the blade passage, causing the cutting edge to exit the blade opening, and proximally retracting the threaded drive mechanism proximally translates the saw blade within the blade passage, causing the cutting edge to retract into the blade opening. 
   
   
       39 . The bone saw of  claim 38 , further comprising a depth indicator located a proximal end of the shaft and communicating with the threaded drive mechanism, wherein a distance of advancing or retracting of the drive mechanism, associated with a length of advancing or retracting the cutting edge is indicated on the depth indicator.