Expandable interbodies and related methods
The present disclosure relates to expandable interbodies that include superior and inferior shells and a control assembly positioned between and inside of the shells, the control assembly including nested cages operably connected to each other with an adjustment screw. Rotation of the adjustment screw translates the cages relative to each other, which in turn causes the shells to open or expand.
1 . An expandable interbody comprising:
a control assembly;
a superior shell engaged with the control assembly, the superior shell having a superior surface at least partially defined by a superior plane; and
an inferior shell engaged with the control assembly, the inferior shell having an inferior surface at least partially defined by an inferior plane that is angled relative to the superior plane such that the superior and inferior planes converge;
wherein:
the control assembly is positioned between the superior and inferior shells,
the control assembly is configured to move the superior and inferior shells from a collapsed configuration to an expanded configuration where an angle between the superior and inferior planes is maintained constant when the control assembly moves the superior and inferior shells from the collapsed configuration to the expanded configuration,
the control assembly comprises:
an adjustment screw defining a first axis; a proximal cage threadingly engaged to the adjustment screw; and a distal cage secured to the adjustment screw; wherein the proximal and distal cages are interlocking, wherein each of the proximal and distal cages comprises a superior lateral projection and an inferior lateral projection, and wherein rotation of the adjustment screw causes the proximal and distal cages to translate relative to each other along the first axis,
the superior and inferior shells each define a distal end, a proximal end, a first lateral side with a first lateral slot, and a second lateral side with a second lateral slot the inferior lateral projections are each configured to engage with the first and second lateral slots of the inferior shell and the superior lateral projections are each configured to engage with the first and second lateral slots of the superior shell; and translation of the proximal and distal cages causes each lateral projection to slide along each respective slot to facilitate the expansion or the collapse of the superior and inferior shells, and
the convergence of the superior and inferior planes is toward the proximal end and the first lateral side of the superior and inferior shells.
2 . The expandable interbody of claim 1 , wherein the orientation between the superior and inferior planes is substantially the same in both the collapsed and expanded configurations.
3 . The expandable interbody of claim 1 , wherein the proximal end of the superior and inferior shells defines a line that is not perpendicular to either of the respective first or second lateral sides.
4 . The expandable interbody of claim 1 , wherein the adjustment screw is a dual screw comprising a distal screw and a proximal screw, wherein the distal screw is non-rotationally secured to the distal cage.
5 . The expandable interbody of claim 1 , wherein the distal cage comprises a first bore, the proximal cage comprises a second bore and a third bore, wherein the first bore is positioned between the second and third bores.
6 . The expandable interbody of claim 1 , wherein at least a portion of the superior and/or inferior shells is porous.
7 . The expandable interbody of claim 6 , wherein the portion of the superior and/or inferior shells that is porous comprises a porous material that is not contiguous with the rest of the superior and/or inferior shells.
8 . The expandable interbody of claim 6 , wherein the portion of the superior and/or inferior shells that is porous comprises a porous material that is integral to the rest of the superior and/or inferior shells.
9 . The expandable interbody of claim 7 , wherein the porous material comprises layered, porous sheets of a material that has been bonded together to form the porous material.
10 . The expandable interbody of claim 1 , wherein the superior and inferior shells are configured to nest together when the expandable interbody is in the collapsed state.
11 . The expandable interbody of claim 1 , wherein each slot is defined by a portion of a side wall of the first and second lateral sides of the superior and inferior shells, respectively, wherein at least portion of the side wall that defines each slot extends beyond the rest of the side wall so as to extend into a corresponding cutout in an opposite sidewall when the expandable interbody is in the collapsed state.
12 . The expandable interbody of claim 1 , wherein the superior and inferior shells each comprise a plurality of surface projections configured to resist migration of the expandable interbody after implantation in an intervertebral disc space, the plurality of surface projections defining a first region and a second region, the first region positioned distal to the second region and configured to provide less resistance than the second region during insertion of the expandable interbody into the intervertebral disc space.
13 . A kit comprising:
at least two expandable interbodies as in claim 1 ,
wherein the orientation between the superior and inferior planes and/or an angle of the proximal end of the superior and inferior shells is distinct between each of the expandable interbodies.
14 . The kit of claim 13 , wherein each expandable interbody is configured to achieve a predetermined lordosis upon insertion in a patient's intervertebral disc space.
15 . A method of implanting an expandable interbody, the method comprising the steps of:
accessing a patient's intervertebral disc space via a transforaminal approach;
selecting an expandable interbody from a kit, the kit comprising at least two expandable interbodies as in claim 1 , wherein the orientation between the superior and inferior planes and/or an angle of the proximal end of the superior and inferior shells is distinct between each of the expandable interbodies;
implanting the selected expandable interbody into a desired location in the patient's intervertebral disc space; and
expanding the selected expandable interbody to a desired height within the patient's intervertebral disc space.
16 . The method of claim 15 , wherein the selection is determined by a specific angle of the transforaminal approach.
17 . The method of claim 15 , wherein the selection is determined by the patient's anatomy and a desire to maximize a footprint of the expandable interbody in the patient's intervertebral disc space.