Spinal surgery system and method

Abstract

Apparatus and method for minimally invasive spinal surgery employs an elongated flexible guide element inserted so as to pass in through a first lateral posterior incision, through the spinal column anterior to the spinal cord, and out through a second lateral posterior incision contralateral to said first incision. The guide element is used to guide various elements to a desired position within the spinal column as part of the surgical procedure. Preferably, two hollow rigid tubes rigidly coupled outside the body in converging relation are used to define a working gap within the spinal column through which the guide element passes. This provides a platform for manipulation of tissues and introduction of implants anterior to the spinal cord. Procedures described include reinforcement of a degenerative intervertebral disc and restoration of a damaged vertebral body.

1 . An apparatus for use in performing a minimally invasive spinal surgical procedure via a pair of bilateral stab wounds on either side of a subject region of the spine of a patient, the apparatus comprising: 
 (a) a first hollow rigid tube having a proximal end and a distal end, said distal end for insertion through a first of the stab wounds;    (b) a second hollow rigid tube having a proximal end and a distal end, said distal end for insertion through a second stab wound in the back of a patient;    (c) a rigid coupling for rigidly coupling said first and second tubes such that said tubes converge towards said distal ends but maintain a predefined gap between said distal ends; and    (d) an elongated flexible guide element for deployment so as to extend through said first hollow tube from said proximal end to said distal end, to traverse said gap and to extend through said second hollow tube from said distal end to said proximal end.    
   
   
       2 . The apparatus of  claim 1 , wherein said first and second tubes are implemented as substantially straight hollow tubes.  
   
   
       3 . The apparatus of  claim 1 , wherein said distal ends of said first and second tubes are implemented as inward-facing beveled ends.  
   
   
       4 . The apparatus of  claim 1 , wherein said distal ends of said first and second tubes are curved towards said gap.  
   
   
       5 . The apparatus of  claim 1 , further comprising a removable trocar removably receivable within each of said first and second tubes for facilitating insertion of said first and second tubes in the back of the patient.  
   
   
       6 . The apparatus of  claim 1 , wherein said guide element is asymmetric under rotations about its length.  
   
   
       7 . The apparatus of  claim 1 , further comprising a retractable drilling device removably associated with at least one of said first and second tubes and configured for drilling a connecting channel through said gap for insertion of said guide element.  
   
   
       8 . The apparatus of  claim 7 , wherein said drilling device is implemented as a directional drilling device configured for drilling in a direction non-parallel with a central bore of said tube.  
   
   
       9 . The apparatus of  claim 1 , further comprising a plurality of beads detachably associated with said guide element, and a release mechanism for releasing said plurality of beads from said guide element in said gap.  
   
   
       10 . The apparatus of  claim 9 , wherein said plurality of beads are interconnected as at least one chain of beads such that said plurality of beads remain interconnected after release from said guide element.  
   
   
       11 . The apparatus of  claim 9 , wherein said plurality of beads are formed from a material having a porous surface with pores of width 50-100 microns.  
   
   
       12 . The apparatus of  claim 9 , wherein said plurality of beads are formed from a material having a porous surface with pores of width 70-80 microns.  
   
   
       13 . The apparatus of  claim 9 , further comprising a net element deployable within said gap around said guide element so as to contain said plurality of beads within a predefined containment volume.  
   
   
       14 . The apparatus of  claim 13 , wherein said plurality of beads are each formed with at least one surface configured to promote scar tissue formation, and wherein said net element is formed to allow penetration of cells to facilitate scar tissue formation at said at least one surface.  
   
   
       15 . The apparatus of  claim 13 , further comprising a pair of flexible elongated fixation appendages associated with said net element so as to be locatable within said first and second tubes and adapted for fixation to bone surfaces after removal of said first and second tubes to fix said net element in a required position.  
   
   
       16 . The apparatus of  claim 1 , further comprising a directional tissue compression device removably deployable along at least one of said first and second tubes, said directional tissue compression device including at least one compression element configured for applying pressure to a slice of tissue located adjacent to said gap and extending away from said first and second tubes so as to form a cavity.  
   
   
       17 . The apparatus of  claim 16 , further comprising an expandably fillable element for deployment in said cavity.  
   
   
       18 . The apparatus of  claim 17 , wherein said expandably fillable element includes perforations configured for allowing release of a small proportion of a filler material to enhance fixation of said expandably fillable element.  
   
   
       19 . The apparatus of  claim 17 , wherein said expandably fillable element includes a pair of flexible elongated fixation appendages locatable within said first and second tubes, said fixation appendages being adapted for fixation to bone surfaces after removal of said first and second tubes to fix said expandably fillable element in a required position.  
   
   
       20 . A method for performing a minimally invasive spinal surgical procedure, the method comprising the steps of: 
 (a) inserting an elongated flexible guide element such that said guide element passes in through a first lateral posterior incision, passes through the spinal column anterior to the spinal cord, and passes out through a second lateral posterior incision contralateral to said first incision; and    (b) employing said guide element to guide at least one element to a desired position within the spinal column as part of the surgical procedure.    
   
   
       21 . The method of  claim 20 , further comprising: 
 (a) inserting a first hollow rigid tube through said first incision;    (b) inserting a second hollow rigid tube through said second incision; and    (c) rigidly coupling said first and second tubes in spatial relation so as to define a gap between distal ends of said tubes,    wherein said inserting of said guide element is performed via said first and second tubes.    
   
   
       22 . The method of  claim 21 , wherein said first and second tubes are implemented as substantially straight hollow tubes.  
   
   
       23 . The method of  claim 21 , wherein said first and second tubes are implemented with beveled ends, said rigidly coupling being performed so that said beveled ends face inwards towards said gap.  
   
   
       24 . The method of  claim 21 , wherein said first and second tubes are implemented with curved ends, said rigidly coupling being performed so that said curved ends curve inwards towards said gap.  
   
   
       25 . The method of  claim 21 , wherein a removable trocar is inserted into each of said first and second tubes for facilitating said inserting of said first and second tubes, said trocar being removed prior to said inserting of said guide element.  
   
   
       26 . The method of  claim 21 , further comprising employing a retractable drilling device inserted via one of said first and second tubes to drill a connecting channel through said gap for insertion of said guide element.  
   
   
       27 . The method of  claim 26 , wherein said drilling device is implemented as a directional drilling device configured for drilling in a direction non-parallel with a central bore of said tube.  
   
   
       28 . The method of  claim 20 , wherein said guide element is asymmetric under rotations about its length.  
   
   
       29 . The method of  claim 20 , wherein said guide element is inserted through an intervertebral disc.  
   
   
       30 . The method of  claim 29 , wherein said at least one element includes a plurality of beads detachably associated with said guide element, said plurality of beads being released for delivery to a desired position within said intervertebral disc.  
   
   
       31 . The method of  claim 30 , wherein said plurality of beads are interconnected as at least one chain of beads such that said plurality of beads remain interconnected after release from said guide element.  
   
   
       32 . The method of  claim 30 , wherein said plurality of beads are formed from a material having a porous surface with pores of width 50-100 microns.  
   
   
       33 . The method of  claim 30 , wherein said plurality of beads are formed from a material having a porous surface with pores of width 70-80 microns.  
   
   
       34 . The method of  claim 30 , wherein said at least one element includes a net element deployable around said guide element, said net element being deployed within said intervertebral disc so as to contain said plurality of beads within a predefined containment volume.  
   
   
       35 . The method of  claim 34 , wherein said plurality of beads are each formed with at least one surface configured to promote scar tissue formation, and wherein said net element is formed to allow penetration of cells to facilitate scar tissue formation at said at least one surface.  
   
   
       36 . The method of  claim 34 , wherein said net element is formed with a pair of flexible elongated fixation appendages, said net element being deployed with said fixation appendages extending through within said first and second contralateral incisions, respectively, the method further comprising, after release of said plurality of beads into said net element, attaching said fixation appendages to contralateral regions of bone so as to fix said net element in a required position.  
   
   
       37 . The method of  claim 20 , wherein said guide element is inserted through a vertebral body.  
   
   
       38 . The method of  claim 37 , wherein said guide element is inserted through a bore drilled in a first pedicle of the vertebra, passes through the vertebral body and passes out through a bore drilled in a second pedicle of the vertebra.  
   
   
       39 . The method of  claim 37 , further comprising introducing a directional tissue compression device into said vertebral body and operating said directional tissue compression device to apply pressure to a transverse slice of tissue within said vertebral body so as to form a cavity anterior to said guide element.  
   
   
       40 . The method of  claim 39 , further comprising introducing an expandably fillable element into said cavity and introducing a filling material said expandably fillable element so as to increase an axial dimension of said vertebral body.  
   
   
       41 . The method of  claim 40 , wherein said expandably fillable element includes perforations such that said introducing a filling material releases a small proportion of said filling material to enhance fixation of said expandably fillable element.  
   
   
       42 . The method of  claim 40 , wherein said expandably fillable element is formed with a pair of flexible elongated fixation appendages, said expandably fillable element being deployed with said fixation appendages extending through said bores in the first and second pedicles, respectively, the method further comprising, after introduction of said filling material, attaching said fixation appendages to contralateral regions of said vertebra so as to fix said expandably fillable element in a required position.  
   
   
       43 . A method for repairing an intervertebral disc having a nucleus, the method comprising the steps of: 
 (a) positioning a net element within the nucleus of the disc, said net element having openings sufficiently large to permit penetration of tissue cells;    (b) introducing into the net element a plurality of beads of material chosen to have surface properties which encourage generation of scar tissue, said beads having dimensions greater than said openings in said net element so as to be retained by said net element;    (c) sealing said net element so as to prevent release of said beads; and    (d) leaving said net element and said beads in position to allow generation of scar tissue on surfaces of said beads.    
   
   
       44 . The method of  claim 43 , wherein said beads are formed primarily from material exhibiting surface pores of width 50-100 microns.  
   
   
       45 . The method of  claim 43 , wherein said beads are formed primarily from material exhibiting surface pores of width 70-80 microns.  
   
   
       46 . The method of  claim 43 , wherein said beads are formed primarily from polypropylene.  
   
   
       47 . The method of  claim 43 , wherein said beads are substantially spherical.  
   
   
       48 . The method of  claim 43 , wherein said beads have a diameter of 1-5 mm.  
   
   
       49 . The method of  claim 43 , further comprising anchoring said net element bilaterally to bone elements of a vertebra.  
   
   
       50 . A method for restoration of a damaged vertebral body, the method comprising the steps of: 
 (a) employing a directional tissue compression device to apply pressure to a transverse slice of tissue within the vertebral body so as to form a cavity;    (b) introducing into said cavity an expandably fillable element and partially inflating said expandably fillable element with a filling material so as to deploy said expandably fillable element within said cavity; and    (c) further inflating said expandably fillable element so as to increase a height dimension of the vertebral body.    
   
   
       51 . The method of  claim 50 , wherein said expandably fillable element has a plurality of perforations configured such that said inflation causes release of a small proportion of the filling material from said expandably fillable element so as to enhance fixation of the expandably fillable element.