Spinal fixation system and related methods

Abstract

Pedicle screws are secured in two columns, one along each side of the spine. Cross support rods have ends connected to pedicle screw heads. A longitudinally extending rod is supported on the cross supports and recessed in the cavity created by removal of portions of spinous processes, providing a reduced profile of the installed construct. Several types of cross supports are shown such as: arms from the screws inward to rings or yokes connecting the longitudinal rod; cross rods with ends connected to the screws and having centrally-located yokes for the longitudinal rod; cross rods with articulating longitudinal rod portions fixed or swiveled to them. These cross rods may have end portions angled posterior toward anterior to accommodate lateral positioned pedicle screws, but shorter cross rods without angled end portions enable medialized pedicle screw orientation.

What is claimed is: 
     
       1. A method of instrumentation for patients undergoing spinal treatment and inserting pedicle screws in posterior vertebrae in a medialized orientation, the method comprising:
 at a first motion segment of the spine, placing a first pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet at one side of the spine; 
 at said first motion segment, placing a second pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet at the other side of the spine; 
 at a second motion segment of the spine, placing a third pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet at the one side of the spine; and  
 at the said second motion segment, placing a fourth pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the interior facet at the other side of the spine; 
 connecting a first cross support to the first and second pedicle screws; 
 connecting a second cross support to the third and fourth pedicle screws; 
 connecting a longitudinal support to said first and second cross supports; 
 adjusting the relationship of the cross supports relative to each other; 
 and fixing the cross supports to the pedicle screws and to the longitudinal support, 
 wherein each of said pedicle screws has a medialized orientation and a trajectory from medial to lateral. 
 
     
     
       2. The method of  claim 1  and comprising:
 adjusting the relationship of the cross supports by changing the distance between the cross supports. 
 
     
     
       3. The method of  claim 1  and comprising:
 adjusting the relationship of the cross supports by changing the angle of the first cross support relative to the second cross support in a plane. 
 
     
     
       4. The method of  claim 1  and comprising:
 adjusting the relationship of the first cross support relative to the second cross support by rotating the first cross support relative to the second cross support about a longitudinal axis of said longitudinal support. 
 
     
     
       5. The method of  claim 1  and comprising:
 prior to connecting said cross supports to said pedicle screws, removing of portions of spinous processes adjacent said motion segments to establish a valley at said motion segments; 
 and locating said longitudinal support in said valley. 
 
     
     
       6. The method of  claim 5  and further comprising:
 manipulating the supports in association with the valley at levels of the spinal region associated with said motion segments. 
 
     
     
       7. The method of  claim 6  and further comprising:
 manipulating the supports by rotating one of said cross supports relative to the other cross support about a longitudinal axis of said longitudinal support. 
 
     
     
       8. The method of  claim 6  and further comprising:
 manipulation of the supports by pivoting one of said cross supports relative to said other cross support in a plane containing said other cross support. 
 
     
     
       9. The method of  claim 1 , wherein said step of placing a first pedicle screw includes orienting a head of said first pedicle screw in a medialized orientation, and said step of placing a second pedicle screw includes orienting a head of said second pedicle screw in a medialized orientation. 
     
     
       10. The method of  claim 9 , wherein said step of placing a third pedicle screw includes orienting a head of said third pedicle screw in a medialized orientation, and said step of placing a fourth pedicle screw includes orienting a head of said fourth pedicle screw in a medialized orientation. 
     
     
       11. The method of  claim 1 , further comprising the step of exposing at least one of said motion segments only to the facet joints. 
     
     
       12. A method of instrumentation for patients undergoing spinal treatment and comprising:
 at a first motion segment of the spine, placing a first pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet at one side of the spine;   at said first motion segment, placing a second pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet at the other side of the spine;   at a second motion segment of the spine, placing a third pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet at the one side of the spine;   at the said second motion segment, placing a fourth pedicle screw entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the interior facet at the other side of the spine;   connecting a first cross support to the first and second pedicle screws;   connecting a second cross support to the third and fourth pedicle screws;   connecting a longitudinal support to said first and second cross supports;   fixing the cross supports to the pedicle screws and to the longitudinal support; and   manipulating the supports by moving telescoping portions of the longitudinal support to provide desired compression and distraction at vertebral bodies associated with said motion segments.   
     
     
       13. The method of claim  12  1, further comprising making a laminectomy dissection. 
     
     
       14. The method of claim  12  1, further comprising removal of an inferomedial portion of the inferior facet. 
     
     
       15. The method of  claim 12 , wherein said manipulating includes rotating a portion of said longitudinal support relative to another portion of said longitudinal support. 
     
     
       16. A method of instrumentation for patients undergoing spinal treatment and inserting pedicle screws in posterior vertebrae in a medialized orientation, the method comprising:
 removing some bone from spinous processes of vertebral bodies adjacent selected motion segments of the spine to provide cavities at the posterior of the spine; 
 securing a plurality of pairs of pedicle screws in said vertebral bodies, one screw of each pair being in a first column at one side of the spinal foramen, the other screw of each pair being in a second column at the other side of the spinal foramen, said pedicle screws having a medialized orientation and a trajectory from posterior medial to anterior lateral; 
 using a plurality of cross supports, each of which cross supports has first and second opposite ends, and connecting said cross supports to said pairs by connecting the first end of each cross support to one screw of one of said pairs, and connecting the second end of said cross support to the other screw of said one pair; 
 placing in said cavities, a longitudinal support connected to said cross supports; 
 manipulating said supports to positions to correct relationship of some of said vertebral bodies relative to others of said vertebral bodies; and 
 locking said supports in said positions. 
 
     
     
       17. The method of  claim 16  and further comprising:
 installing said pedicle screws with trajectory from posterior lateral to anterior medial. 
 
     
     
       18. The method of  claim 17  and further comprising:
 projecting ends of said cross supports from posterior forward around facets to connect to said pedicle screws. 
 
     
     
       19. The method of  claim 16  and further comprising:
 installing said pedicle screws entering the cephalad border of the pars interarticularis at the junction of the caudal aspect of the interior facet, at opposite sides of the spine. 
 
     
     
       20. The method of  claim 16  and wherein:
 manipulating said supports includes deforming said longitudinal support. 
 
     
     
       21. The method of  claim 16  and wherein:
 manipulating said supports includes swiveling at least one of said cross supports relative to said longitudinal support. 
 
     
     
       22. The method of  claim 21  and wherein:
 manipulating said supports includes swiveling more than one of said cross supports relative to said longitudinal support. 
 
     
     
       23. The method of  claim 16  and wherein:
 manipulating said supports includes changing the length of said longitudinal support. 
 
     
     
       24. The method of  claim 16 , further comprising the step of orienting heads of at least one of the pairs of pedicle screws in a medialized orientation. 
     
     
       25. The method of  claim 24 , wherein said step of orienting heads includes orienting the heads of at least two of the pairs of pedicle screws in a medialized orientation. 
     
     
       26. The method of  claim 16 , further comprising the step of exposing at least one of said motion segments only to the facet joints. 
     
     
       27. A method of instrumentation for patients undergoing spinal treatment and comprising:
 removing some bone from spinous processes of vertebral bodies adjacent selected motion segments of the spine to provide cavities at the posterior of the spine;   securing a plurality of pairs of pedicle screws in said vertebral bodies, one screw of each pair being in a first column at one side of the spinal foramen, the other screw of each pair being in a second column at the other side of the spinal foramen;   using a plurality of cross supports, each of which cross supports has first and second opposite ends, and connecting said cross supports to said pairs by connecting the first end of each cross support to one screw of one of said pairs, and connecting the second end of said cross support to the other screw of said one pair;   placing in said cavities, a longitudinal support connected to said cross supports;   manipulating said supports to positions to correct relationship of some of said vertebral bodies relative to others of said vertebral bodies; and   locking said supports in said positions;   wherein manipulating said supports includes rotating a portion of said longitudinal support relative to another portion of said longitudinal support.   
     
     
       28. The method of claim  27  16, further comprising the step of making a laminectomy dissection. 
     
     
       29. The method of claim  27  16, further comprising removal the step of removing an inferomedial portion of the inferior facet. 
     
     
       30. The method of  claim 27 , wherein said manipulating further includes moving telescoping portions of the longitudinal support to provide desired compression and distraction at vertebral bodies associated with said motion segments. 
     
     
       31. A method of instrumentation for patients undergoing spinal treatment and inserting pedicle screws in posterior vertebrae in a medialized orientation, the method comprising:
 at a first motion segment of the spine, placing a first pedicle screw having a head, said head of said first pedicle screw being oriented in a medialized orientation; 
 at said first motion segment, placing a second pedicle screw having a head, said head of said second pedicle screw being oriented in a medialized orientation; 
 at a second motion segment of the spine, placing a third pedicle screw; 
 at said second motion segment, placing a fourth pedicle screw, wherein said third and fourth pedicle screws each have a head, said heads of said third and fourth pedicle screws being oriented in a medialized orientation; 
 connecting a first cross support to the first and second pedicle screws; 
 connecting a second cross support to the third and fourth pedicle screws; 
 connecting a longitudinal support to said first and second cross supports; and 
 fixing the cross supports to the pedicle screws and to the longitudinal support, 
 and said pedicle screws each have a trajectory from posterior medial to anterior lateral. 
 
     
     
       32. The method of  claim 31 , further comprising the step of adjusting the relationship of the cross supports relative to each other. 
     
     
       33. The method of  claim 32 , wherein said adjusting step includes at least one of distraction, compression and rotation. 
     
     
       34. A method of instrumentation for patients undergoing spinal treatment and comprising:
 removing bone from spinous processes of vertebral bodies adjacent selected motion segments of the spine;   securing a plurality of pairs of pedicle screws in said vertebral bodies, one screw of each pair being in a first column, the other screw of each pair being in a second column;   using a plurality of cross supports, each of which cross supports has first and second opposite ends, and connecting said cross supports to said pairs by connecting the first end of each cross support to one screw of one of said pairs, and connecting the second end of said cross support to the other screw of said one pair;   placing a longitudinal support connected to said cross supports;   manipulating at least said longitudinal support to correct a relationship of some of said vertebral bodies relative to at least another of said vertebral bodies, said manipulating including at least one of rotating a portion of said longitudinal support relative to another portion of said longitudinal support and moving telescoping portions of the longitudinal support.   
     
     
       35. A method for implanting a bone anchor in a vertebra in a medialized orientation, comprising the steps of:
 exposing a posterior portion of the vertebra;   locating a starting position on a medial inferior portion of the vertebra relative to a superior facet; and   angling the bone anchor from the starting position along a trajectory extending laterally away from a midportion of the vertebra as the bone anchor protects anteriorly from the posterior portion of the vertebra.    
     
     
       36. The method of claim 35, wherein the exposing step further comprises the step of performing a laminectomy exposure.  
     
     
       37. The method of claim 35, wherein the locating step further comprises the step of identifying the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet.  
     
     
       38. The method of claim 35, further comprising the step of angling the bone anchor in a cephalad direction.  
     
     
       39. The method of claim 38, wherein the angling the bone anchor in the cephalad direction step includes angling the bone anchor approximately 20°.  
     
     
       40. The method of claim 35, further comprising the step of drilling a small opening in cortical bone along the trajectory extending laterally away from the midportion of the vertebra as the bone anchor projects anteriorly from the posterior portion of the vertebra.  
     
     
       41. The method of claim 40, further comprising the step of tapping the small opening.  
     
     
       42. The method of claim 35, wherein the bone anchor has a length of 25 to 30 mm.  
     
     
       43. The method of claim 35 wherein the trajectory crosses cortical bone such that the bone anchor bicortically purchases in the vertebra.  
     
     
       44. The method of claim 35, wherein the starting point for a cephalad level is inferior to the starting position for a caudal level.  
     
     
       45. A method of implanting a bone anchor in a vertebra in a medialized orientation, comprising the steps of:
 performing a laminectomy exposure to expose a posterior portion of the vertebra; and   angling the bone anchor along a trajectory extending laterally away from a midportion of the vertebra as the bone anchor projects anteriorly from the posterior portion of the vertebra.    
     
     
       46. The method of claim 45, further comprising the step of locating a starting position for the bone anchor, wherein the starting position is the cephalad border of the pars interarticularis at the junction of the caudal aspect of the inferior facet.  
     
     
       47. The method of claim 45, further comprising the step of angling the bone anchor in a cephalad direction.  
     
     
       48. The method of claim 47, wherein the angling the bone anchor in the cephalad direction step includes angling the bone anchor approximately 20°.  
     
     
       49. The method of claim 45, further comprising the step of drilling a small opening in cortical bone along the trajectory extending laterally away from the midportion of the vertebra as the bone anchor projects anteriorly from the posterior portion of the vertebra.  
     
     
       50. The method of claim 49, further comprising the step of tapping the small opening.  
     
     
       51. The method of claim 45, wherein the bone anchor has a length of 25 to 30 mm.  
     
     
       52. The method of claim 45 wherein the trajectory crosses cortical bone such that the bone anchor bicortically purchases in the vertebra.