Minimally-invasive retroperitoneal lateral approach for spinal surgery

Abstract

A method is disclosed for introducing a spinal disc implant into an intervertebral space of a subject. The subject is placed in a lateral position, and the anterior face of the spinal disc intervertebral space is accessed, between the L5 and S1 vertebrae, from an anterior and lateral retroperitoneal approach. An operative corridor to the anterior face of the spinal disc space is established by introducing a retractor instrument anterolaterally to the spinal disc space between the anterior superior iliac spine and the anterior inferior iliac spine. The damaged spinal disc contents are removed from the intervertebral space through the operative corridor, and the implant is advanced into the intervertebral space at an oblique angle and pivoted to position the implant substantially laterally within the intervertebral space. Elongated retractor and insertion instruments, as well as a modified disc implant, are also disclosed for carrying out the method.

1 - 21 . (canceled) 
     
     
         22 . A system for positioning an implant in an intervertebral space of a subject, comprising:
 a retractor instrument for establishing an operative corridor to an anterior face of an intervertebral space, wherein the retractor instrument comprises:
 a proximal handle portion and 
 a distal retractor blade portion, wherein the retractor blade portion comprises opposing ipsilateral and contralateral arms that are movable toward and away from one another to define a portion of the operative corridor therebetween; 
 an ipsilateral vascular retractor blade carried by the ipsilateral arm; and 
 a contralateral vascular retractor blade carried by the contralateral arm, wherein the contralateral arm and blade extends a greater distance than the ipsilateral arm and blade; and 
   an introducer instrument for advancing a prosthetic spinal disc implant between the arms and blades of the retractor instrument to the intervertebral space, wherein the introducer instrument is capable of pivoting the implant in the intervertebral space.   
     
     
         23 . The system of  claim 22 , further comprising an implant that comprises an interface element that selectively couples with the introducer instrument at a plurality of preselected positions to pivot the implant in the intervertebral space. 
     
     
         24 . The system of  claim 23 , wherein the introducer instrument carries a plurality of docking pins and the interface element comprises a series of docking holes that cooperatively mate with the docking pins to selectively couple the implant in a preselected angular orientation to the introducer instrument. 
     
     
         25 . The system of  claim 23 , wherein the implant comprises a top bearing face, a bottom bearing face, a front face, a rear face, an ipsilateral face and a contralateral face, wherein the rear face is substantially flat. 
     
     
         26 . The system of  claim 25 , wherein the implant contralateral face is rounded to minimize trauma induced by advancing the implant into the intervertebral space at the oblique angle and pivoting it therewithin. 
     
     
         27 . The system of  claim 24 , wherein the implant comprises a pivot axis and the interface element of the implant comprises multiple pairs of spaced docking holes arranged on a curved surface that extends partially circumferentially around the pivot axis, and selected pairs of spaced docking holes are positioned to mate with the docking element of the introducer instrument. 
     
     
         28 . The system of  claim 25 , wherein the implant tapers in height from the front face to the rear face. 
     
     
         29 . The system of  claim 25 , wherein the implant is a partially hollow member in which the top face and bottom face are substantially open and separated by an internal divider wall that extends from the front face to the rear face. 
     
     
         30 . The system of  claim 25 , wherein the implant is a compressible member in which the front face is convex, the ipsilateral face comprises the interface element, and the front and rear walls are connected by an internal wall that separates the implant into an ipsilateral opening through the implant and a contralateral opening through the implant. 
     
     
         31 . The system of  claim 25 , wherein the top and bottom faces of the implant contain protuberances that promote bone growth into the implant. 
     
     
         32 . The system of  claim 31 , wherein the protuberances are frustopyramidal. 
     
     
         33 - 34 . (canceled) 
     
     
         35 . The system of  claim 22 , wherein the introducer instrument comprises a docking element that selectively docks with an interface element of the implant at a position on the interface element that alters an angle between the implant and the introducer instrument. 
     
     
         36 . The system of  claim 22 , wherein the ipsilateral vascular retractor blade and the contralateral vascular retractor blade are curved outwardly from a longitudinal axis of the retractor instrument. 
     
     
         37 . The system of  claim 22 , wherein the retractor instrument further comprises a shim mounted on the ipsilateral arm of the retractor instrument, wherein the shim curves inwardly toward a longitudinal axis of the retractor instrument.