Less invasive surgical system and methods

Abstract

A system for performing a less invasive surgical procedure and, in particular, devices and methods for spinal fixation. The system comprises dilation tool(s), at least one working/insertion cannula, a plurality of screws, at least one fixation rod for connecting the screws, and a rod inserter. The dilation tool(s) may be used to dilate an incision made in a patient to form an opening. Thereafter, a drill may be used to form holes in the vertebrae. An insertion cannula may be attached to a screw and inserted into the opening. The screws may be polyaxial screws and may be inserted into the vertebrae using a screwdriver. An operator may then move the insertion cannula to manipulate a head portions of the screws such that the head portions may be aligned to receive a fixation rod. A rod inserter may be used to insert a fixation rod into the head portions. After the fixation rod is in place, it may be locked to the screws, thereby fixing the system in place on the spine.

1 - 66 . (canceled) 
   
   
       67 . A spinal fixation system comprising:
 a bone screw including a shank portion for engaging bone and a head portion operably connected to the shank portion, the head portion including a rod receiving channel sized and configured to receive a portion of a fixation rod; and   a cannula including:
 an inner cannulated shaft having a proximal end, a distal end, a bore extending from the proximal end to the distal end and at least one slot extending from the distal end toward the proximal end, the at least one slot being sized and configured to receive at least a portion of the fixation rod; 
 an outer cannulated shaft having a proximal end, a distal end, and a bore extending from the proximal end to the distal end, the bore being sized and configured to receive the inner cannulated shaft, the outer cannulated shaft further including at least one slot extending from the distal end toward the proximal end, the outer cannulated shaft being moveable with respect to the inner cannulated shaft between a first position and a second position, in the first position, the distal end of the inner cannulated shaft is sized and configured to releasably engage the head portion of the bone screw and in the second position, the head portion of the bone screw is secured within the bore of the inner cannulated shaft; and wherein, in the second position, the at least one slot formed in the outer cannulated slot aligns with the at least one slot formed in the inner cannulated slot and the rod-receiving channel formed in the head portion of the bone screw so that at least a portion of the fixation rod can be inserted through the at least one slot formed in the inner and outer cannulated shafts and into the rod-receiving channel formed in the bone screw. 
   
   
   
       68 . The spinal fixation system of  claim 67 , wherein the inner cannulated shaft is slidably movable within the bore of the outer cannulated shaft. 
   
   
       69 . The spinal fixation system of  claim 68 , wherein the outer cannulated shaft includes at least one projection extending from an interior wall of the bore for contacting at least one opening formed in the inner cannulated shaft to prevent the outer cannulated shaft from rotating with respect to the inner cannulated shaft. 
   
   
       70 . The spinal fixation system of  claim 67 , wherein in the second position, the distal end of the outer cannulated shaft is positioned closer to the distal end of the inner cannulated shaft than in the first position. 
   
   
       71 . The spinal fixation system of  claim 67 , wherein the distal end of the inner cannulated shaft includes protrusions for engaging recesses formed on the head portion of the bone screw. 
   
   
       72 . The spinal fixation system of  claim 67 , wherein the inner cannulated shaft further includes at least one flexible member for engaging the bone screw, each of the at least one flexible member including a first end portion and a second end portion, the first end portion operably connected to the inner cannulated shaft and the second end portion freely moveable into and out of the bore of the inner cannulated shaft, the second end portion engageable with the bone screw. 
   
   
       73 . The spinal fixation system of  claim 72 , wherein moving the outer cannulated shaft to the second position causes the second end portion of the at least one flexible member to engage the head portion of the bone screw. 
   
   
       74 . The spinal fixation system of  claim 73 , wherein the inner cannulated shaft includes diametrically opposed flexible members. 
   
   
       75 . The spinal fixation system of  claim 67 , wherein the outer cannulated shaft includes a spring detent, the detent engages a first groove formed on the inner cannulated shaft when the outer cannulated shaft is in the first position and engages a second groove formed on the inner cannulated shaft when the outer cannulated shaft is in the second position. 
   
   
       76 . The spinal fixation system of  claim 67 , wherein the distal end of the inner cannulated shaft includes a plurality of external threads for engaging internal threads formed on the head portion of the bone screw. 
   
   
       77 . An implantation mechanism for implanting a spinal fixation device into vertebrae, the implantation mechanism comprising:
 a shaft having a proximal end, a distal end, and an engagement portion on the distal end sized and configured to engage the spinal fixation device, wherein the implantation mechanism is sized and configured to be inserted into a passageway of a cannula.   
   
   
       78 . The implantation mechanism of  claim 77 , further comprising a protrusion on the engagement portion for engaging a longitudinal recess of a cannula, the protrusion being moveable along the recess, the protrusion and longitudinal recess being sized and configured to align the cannula relative to the spinal fixation device. 
   
   
       79 . A fixation device inserter for inserting a fixation rod into a rod-receiving channel formed in a bone screw, the inserter comprising:
 an elongated shaft;   a moveable member positioned within the elongated shaft for engaging the elongated fixation rod; and   an actuation mechanism operably associated with the moveable member, the actuation mechanism configured to move the moveable member between a first position and a second position.   
   
   
       80 . The inserter of  claim 79 , further comprising:
 a coupling portion configured to connect the fixation device inserter to a cannula;   a receiving portion configured to pivotally engage the fixation rod and to allow the fixation rod to be pivoted through an arc and into the rod-receiving channel of the bone screw.   
   
   
       81 . The inserter of  claim 80 , wherein the fixation device inserter includes:
 a first elongated member having a first jaw portion; and   a second elongated member have a second jaw portion, the second elongated member being pivotally connected to the first elongated member; and   wherein the first and second jaw portions define an engagement portion for engaging the fixation rod.