System and method for sacro-iliac stabilization

Abstract

Configurations are described for conducting minimally invasive medical interventions utilizing elongate instruments and assemblies thereof to stabilize and/or fixate a sacro-iliac joint. In one embodiment, a tool assembly may be advanced from a posterior approach into the SI junction and configured to create a defect defined at least in part by portions of both the sacrum and the ilium, the defect having a three dimensional shape defined in part by at least one noncircular cross sectional shape in a plane substantially perpendicular to the longitudinal axis of the tool assembly. After a defect is created, the tool assembly may be retracted and a prosthesis deployed into the defect.

1 . A method of stabilizing an SI joint, comprising:
 a. advancing a tool assembly from a posterior approach into an SI junction defined between sacrum and ilium structures of a patient, the tool assembly being configured to create a defect defined at least in part by portions of both the sacrum and the ilium, the defect having a three dimensional shape defined in part by at least one noncircular cross sectional shape in a plane substantially perpendicular to the longitudinal axis of the tool assembly;   b. creating a defect with the tool assembly;   c. retracting the tool assembly; and   d. deploying a prosthesis into the defect.   
     
     
         2 . The method of  claim 1 , further comprising advancing an elongate guiding member into the SI junction, confirming a position of the guiding member in the SI junction, and using the guiding member as a mechanical guide while advancing the tool assembly into the SI junction. 
     
     
         3 . The method of  claim 1 , wherein confirming comprises intraoperatively capturing images of the guiding member relative to portions of the sacrum and ilium. 
     
     
         4 . The method of  claim 3 , wherein the images are captured with a modality selected from the group consisting of fluoroscopy, CT, ultrasound, radiography, and magnetic resonance imaging. 
     
     
         5 . The method of  claim 1 , wherein creating a defect comprises mechanically actuating at least a portion the tool assembly. 
     
     
         6 . The method of  claim 5 , wherein mechanically actuating induces insertion/retraction or rotational motion to a portion of the tool assembly. 
     
     
         7 . The method of  claim 1 , wherein advancing a tool assembly from a posterior approach comprises manually inserting. 
     
     
         8 . The method of  claim 1 , wherein advancing a tool assembly from a posterior approach comprises urging the tool assembly forward using a tool selected from the group consisting of a hammer, a drill, a solenoid, and a piston. 
     
     
         9 . The method of  claim 1 , wherein advancing a tool assembly from a posterior approach comprises dislodging one or more portions of the sacrum, ilium, or both. 
     
     
         10 . The method of  claim 9 , wherein the tool assembly comprises one or more coring devices configured to dislodge and remove one or more portions of the sacrum, ilium, or both. 
     
     
         11 . The method of  claim 1 , wherein the at least one noncircular cross sectional shape is selected from the group consisting of: an oval shape, an elliptical shape, a multilobed shape, an “H” shape, an “arcuate-H” shape, a rectangular shape, and a square shape. 
     
     
         12 . The method of  claim 11 , wherein the at least one noncircular cross sectional shape further comprises one or more leg portions extending away from the noncircular cross sectional shape. 
     
     
         13 . The method of  claim 12 , wherein one or more of the leg portions comprise a shape selected from the group consisting of a straight leg, an arcuate leg, and a multisegmented leg. 
     
     
         14 . The method of  claim 1 , further comprising inserting into at least a portion of the prosthesis a material selected from the group consisting of: demineralized bone matrix, autograft bone material, allograft bone material, polymethylmethacrylate, calcium-based bone void filler material, and bone morphogenic protein. 
     
     
         15 . The method of  claim 14 , wherein a bone morphogenic protein is inserted, the bone morphogenic protein selected from the group consisting of BMP-1, BMP-7, and OP-1. 
     
     
         16 . The method of  claim 1 , wherein the tool assembly is configured to create a defect shape which varies in cross section relative to the longitudinal axis of the tool assembly. 
     
     
         17 . The method of  claim 16 , wherein the tool assembly is configured to create a defect having a proximal cross sectional shape which is greater in area that a corresponding distal cross sectional shape. 
     
     
         18 . A system for stabilizing an SI joint, comprising:
 a. a defect-creating tool assembly configured to be advanced from a posterior approach into an SI junction defined between sacrum and ilium structures of a patient, the tool assembly being configured to create a defect defined at least in part by portions of both the sacrum and the ilium, the defect having a three dimensional shape defined in part by at least one noncircular cross sectional shape in a plane substantially perpendicular to the longitudinal axis of the tool assembly; and   b. a prosthesis configured to fit into the defect created by the tool assembly.   
     
     
         19 . The system of  claim 18 , wherein the tool assembly comprises one or more coring devices configured to dislodge and remove one or more portions of the sacrum, ilium, or both. 
     
     
         20 . The system of  claim 18 , further comprising a tool assembly advancing device selected from the group consisting of a hammer, a drill, a solenoid, and a piston. 
     
     
         21 . The system of  claim 18 , further comprising an image capture device configured to intraoperatively capture images of the tool assembly relative to portions of the sacrum and ilium. 
     
     
         22 . The system of  claim 21 , wherein the image capture device is selected from the group consisting of a fluoroscope, a CT system, an ultrasound system, a radiography system, and a magnetic resonance imaging system. 
     
     
         23 . The system of  claim 18 , further comprising a fixation catalyst configured to fit into the defect along with the prosthesis, the catalyst selected from the group consisting of: demineralized bone matrix, autograft bone material, allograft bone material, polymethylmethacrylate, calcium-based bone void filler material, and bone morphogenic protein. 
     
     
         24 . The system of  claim 23 , wherein a bone morphogenic protein is selected from the group consisting of BMP-1, BMP-7, and OP-1. 
     
     
         25 . The system of  claim 24 , wherein the at least one noncircular cross sectional shape is selected from the group consisting of: an oval shape, an elliptical shape, a multilobed shape, an “H” shape, an “arcuate-H” shape, a rectangular shape, and a square shape. 
     
     
         26 . The system of  claim 25 , wherein the at least one noncircular cross sectional shape further comprises one or more leg portions extending away from the noncircular cross sectional shape. 
     
     
         27 . The system of  claim 26 , wherein one or more of the leg portions comprise a shape selected from the group consisting of a straight leg, an arcuate leg, and a multisegmented leg. 
     
     
         28 . The system of  claim 18 , wherein the tool assembly is configured to create a defect shape which varies in cross section relative to the longitudinal axis of the tool assembly. 
     
     
         29 . The system of  claim 28 , wherein the tool assembly is configured to create a defect having a proximal cross sectional shape which is greater in area that a corresponding distal cross sectional shape.