Device and method for percutaneous placement and anchoring of stimulating electrodes in spine

Abstract

A system and method for anchoring an electrode that stimulates a dorsal root ganglion. The anchoring device includes a screw, collet, and locking cap. The screw is inserted into bone of the pars interarticularis and the electrode is inserted through the screw and positioned next to the dorsal root ganglion for stimulation. The screw includes a recess that is shaped to fit the collet. The collet has flexible arms. When assembled, the locking cap forces the collet into the recess thereby moving the flexible arms inward radially, impinging on the electrode and holding the electrode in place adjacent the dorsal root ganglion.

1 . An anchoring device configured to anchor an electrode to a pars interarticularis over a dorsal root ganglion, the electrode configured to stimulate the dorsal root ganglion, the anchoring device comprising:
 a screw;   a locking collet;   a recess, within the screw and shaped to fit the locking collet; and,   whereby a force pressing the locking collet into the recess causes the locking collet to impinge on the electrode.   
     
     
         2 . The anchoring device of  claim 1 , wherein the screw further comprises:
 a first set of screw threads that embed the anchoring device into the pars interarticularis; and,   a screw flange that limits a depth that the screw can be embedded into the pars interarticularis.   
     
     
         3 . The anchoring device of  claim 1 , wherein the locking collet further comprises:
 a locking cap and a removable collet adjacent the locking cap.   
     
     
         4 . The anchoring device of  claim 3 , wherein the screw further comprises:
 a second set of screw threads, matched to a set of locking cap threads in the locking cap, to secure the screw to the locking cap and to provide the force to the collet; and,   a screw lumen along a central longitudinal axis of the screw and through which the electrode is passed.   
     
     
         5 . The anchoring device of  claim 4 , wherein the locking collet further comprises:
 a collet lumen along a central axis of the collet and through with the electrode is passed; and,   a set of collet arms shaped to fit the recess of the screw and to constrict the electrode in response to the force.   
     
     
         6 . The anchoring device of  claim 5 , wherein the locking cap further comprises:
 a locking cap lumen along a central axis of the locking cap and through with the electrode is passed.   
     
     
         7 . A system for implanting an anchoring device for an electrode into a pars interarticularis, over a dorsal root ganglion, the electrode configured to stimulate the dorsal root ganglion, the system comprising:
 a guide tube having a first lumen; and,   a first configuration wherein a needle, having an awl tip, is positioned in the first lumen, and is adapted to create a hole in the pars interarticularis.   
     
     
         8 . The system of  claim 7  further comprising:
 a second configuration wherein:
 a dilator tube, having a second lumen, is positioned over the guide tube; and, 
 a guidewire is positioned in the first lumen. 
 
 
     
     
         9 . The system of  claim 8  further comprising:
 a third configuration wherein:
 an insertion tool, having a third lumen, is attached to the anchoring device and is positioned in the second lumen; and, 
 the guidewire is positioned in a fourth lumen of the anchoring device. 
 
 
     
     
         10 . The system of  claim 9  further comprising:
 a third configuration wherein:
 a drill is positioned in the third lumen and the fourth lumen. 
 
 
     
     
         11 . The system of  claim 9  further comprising:
 a mechanical stop, at a proximal end of the insertion tool, for limiting a depth of the hole. 
 
     
     
         12 . The system of  claim 10  further comprising:
 a fourth configuration wherein:
 the anchoring device further comprises a screw section, a collet adjacent the screw section and a locking cap adjacent the collet; 
 the screw section further comprises a fifth lumen; 
 the collet further comprises a sixth lumen; 
 the locking cap further comprises a seventh lumen; 
 the electrode further comprises an eighth lumen; 
 a locking cap driver, fitted to the locking cap; 
 
 wherein a stylet is positioned in the eighth lumen; and, 
 the electrode is positioned in the sixth lumen and the seventh lumen. 
 
     
     
         13 . The system of  claim 12  wherein the collet is integrally formed with the screw section. 
     
     
         14 . The system of  claim 12  wherein the screw section further comprises:
 a seating flange adapted to be positioned against the pars interarticularis. 
 
     
     
         15 . The system of  claim 12  wherein the locking cap engages the screw through a bayonet mount. 
     
     
         16 . The system of  claim 12  wherein the locking cap engages the screw through a first threaded connection. 
     
     
         17 . The system of  claim 16  wherein the screw section engages the hole with a second threaded connection. 
     
     
         18 . The system of  claim 17  wherein the first threaded connection is an opposite thread direction from the second threaded connection. 
     
     
         19 . The system of  claim 12  wherein the collet further comprises a compressible clamping section adjacent the electrode. 
     
     
         20 . The system of  claim 19  wherein the screw section further comprises:
 a compression receiver, adjacent the compressible clamping section, for controllably deforming the compressible clamping section. 
 
     
     
         21 . The system of  claim 12  further comprising:
 a fifth configuration wherein:
 the locking cap driver is positioned in the second lumen. 
 
 
     
     
         22 . The system of  claim 21  further comprising:
 a sixth configuration where:
 the collet is compressed in a compression chamber of the screw section, by the locking cap, so as to impinge on the electrode.