Expandable trial with telescopic stabilizers

Abstract

Systems and methods for distracting an intervertebral disc space are provided. The systems use an expandable trial with telescopic stabilizers. The systems and methods of distracting an intervertebral space are provided in a manner that addresses the problem of subsidence. The method includes inserting the trial into the intervertebral space in a collapsed state and, once inserted, the trial is then used for distracting the intervertebral space using an expansion that includes a first stage and a second stage. The first stage includes expanding the trial laterally toward the peripheral zones of the top vertebral plate and the bottom vertebral plate, and the second stage includes expanding the trial vertically to distract the intervertebral space.

We claim: 
     
         1 . An expandable trial for an intervertebral space, including
 an expandable shell having a proximal region with an end, a mid-region, a distal region with an end, and a lumen; the proximal region having a slider-guide; the distal region having an expandable head with
 a top subhead and a bottom subhead between which a telescopic stabilizer is operably attached to (i) slidably translate and (ii) stabilize and/or align the relationship between the top subhead and the bottom subhead during operation of the expandable shell; 
 wherein, the shell has a collapsed state and an expanded state; 
   wherein, the head has a proximal portion having an end; a distal portion having an end; and, a central shell axis of the expanded state; the head configured for expanding in vivo following placement of the trial in the intervertebral space through an annular opening.   
     
     
         2 . The trial of  claim 1 , wherein
 the head has
 a transverse cross-section in the collapsed state having a maximum dimension ranging from 5 mm to 18 mm for placing the frame in an intervertebral space through an annular opening for expansion in the intervertebral space; and, 
 a transverse cross-section in the expanded state having a maximum dimension ranging from 6.5 to 28 mm in the intervertebral space. 
   
     
     
         3 . The trial of  claim 1 , wherein the shell is a single-unit formed from a single body of material, and the slider-guide and head are monolithically integral. 
     
     
         4 . The trial of  claim 1 , wherein the proximal end of a shim is configured to receive an axial proximal-to-distal force through an actuation bar for an axial translation of the shim into the shell, the actuation bar having a proximal portion with a proximal end, a distal portion with a distal end, and configured to transfer the axial proximal-to-distal force to the shim through the slider-guide. 
     
     
         5 . The trial of  claim 1 , wherein the trial has 4 telescopic stabilizers. 
     
     
         6 . A system for distracting an intervertebral space, the system comprising
 an expandable shell having a proximal region with an end, a mid-region, a distal region with an end, and a lumen; the proximal region having a slider-guide; the distal region having an expandable head with
 a top subhead and a bottom subhead between which a telescopic stabilizer is operably attached to (i) slidably translate and (ii) stabilize and/or align the relationship between the top subhead and the bottom subhead during operation of the expandable shell; 
 wherein, the shell has a collapsed state and an expanded state; 
   and,   a vertical expansion component that induces a vertical expansion of the head in an intervertebral space having a top vertebral endplate, a bottom vertebral endplate, and an annulus;   wherein, the head has a proximal portion having an end; a distal portion having an end; and, a central shell axis of the expanded state; the head configured for expanding in vivo following placement of the trial in the intervertebral space through an annular opening.   
     
     
         7 . The system of  claim 6 , further comprising a retractable retention plunger configured for retaining the trial in the collapsed state and releasing the trial for expansion into the expanded state. 
     
     
         8 . The system of  claim 6 , further comprising an actuation component having a proximal end and a distal end that is operably connected to the vertical expansion component, the actuation component configured to receive an axial proximal-to-distal force from an actuation screw that is operably attached to the proximal end of the actuation bar and transfers the force to the vertical expansion component through the distal end of the actuation bar. 
     
     
         9 . The system of  claim 6 , wherein
 the head has
 a transverse cross-section in the collapsed state having a maximum dimension ranging from 5 mm to 18 mm for placing the frame in an intervertebral space through an annular opening for expansion in the intervertebral space; and, 
 a transverse cross-section in the expanded state having a maximum dimension ranging from 6.5 to 28 mm in the intervertebral space. 
   
     
     
         10 . The system of  claim 6 , wherein the vertical expansion component includes vertical wedge configured to vertically-expand the trial. 
     
     
         11 . The system of  claim 6 , wherein the vertical expansion component includes a vertical-expansion wedge with angle θ V  ranging from 30° to 50°. 
     
     
         12 . The system of  claim 6 , wherein the vertical expansion component includes a vertical-expansion wedge with angle θ V  ranging from 10° to 90°. 
     
     
         13 . The system of  claim 6 , wherein the shell is a single-unit formed from a single body of material, and the slider-guide and head are monolithically integral. 
     
     
         14 . The system of  claim 6 , wherein the trial has at least 2 telescopic stabilizers. 
     
     
         15 . A method of distracting an intervertebral space using the trial of  claim 1 , the method comprising:
 creating a point of entry into an intervertebral disc, the intervertebral disc having a nucleus pulposus surrounded by an annulus fibrosis, and the point of entry having the maximum lateral dimension created through the annulus fibrosis;   removing the nucleus pulposus from within the intervertebral disc through the point of entry, leaving the intervertebral space for expansion of the head of the trial of  claim 1  within the annulus fibrosis, the intervertebral space having the top vertebral plate and the bottom vertebral plate;   inserting the head in the collapsed state through the point of entry into the intervertebral space; and,   distracting the intervertebral space, the distracting including slidably translating the telescopic stabilizer in the expansion of the head to the expanded state.   
     
     
         16 . The method of  claim 15 , further comprising retaining the trial with a retractable retention plunger and retracting the plunger to expand the trial. 
     
     
         17 . The method of  claim 15 , wherein the lateral dimension of the point of entry ranges from about 5 mm to about 18 mm. 
     
     
         18 . The method of  claim 15 , wherein the distracting includes selecting an amount of vertical expansion. 
     
     
         19 . The method of  claim 15 , wherein the distracting includes selecting a vertical expansion component that includes a vertical-expansion wedge with angle θ V  ranging from 30° to 50°. 
     
     
         20 . The method of  claim 18 , wherein the distracting includes selecting a vertical expansion component that includes a vertical-expansion wedge with angle θ V  ranging from 10° to 90°.